ANZCA Physiology Vivas
External collection: Physiol viva collection 2009-2013 (115 page pdf!)
Please add what you remember of what you were asked in the Primary Physiology Vivas. Indicate what exam (eg Sept 2005) you sat. This section is for people to add their memory of what they were asked. This helps to get an idea of where the published "Introductory viva questions" can lead. For some it may also be a cathartic experience.
- Pain pathways: If you get stuck with a needle, describe the transmission of the pain pathways. (The answer I gave for a pass included c fibres, and A delta fibres). Also mention the reflex loop, causing a sudden withdrawal from painful stimulus.
- Sept 2005: Monro-Kellie doctrine: Intracranial pressure vs volume. Be able to draw graph and discuss effects of subdural haematoma/etc, and why initial volume change does not create large pressure change (due to CSF moving out initially).
- Sept 2005: Compliance of the lung. Effects of a pneumothorax on lung compliance. Pendulum breathing with a large pneumothorax. How big the hole would have to be in your chest in order to induce pendulum breathing (as a percentage of the size of your trachea).
- Sept 2005: Draw CVP wave form. Can you tell changes seen in various clinical situation. Under what conditions CVP can be negative Mark different points where valves open or close.. Draw capnograph, Mark respiratory cycles , changes in shape associated with different conditions various situations. Classify hormones. Mechanism of action of Insulin
- Sept 2005: Transducers - explaining how an arterial line measures arterial blood pressure with a transducer. How a Wheatstone Bridge works to increase sensitivity. Dampening, and the importance of the critical dampening coefficient.
- Sept 2005: Humidity, saturated vapour pressure. What the Saturated Vapour Pressure is when a fluid is boiling (atmospheric). How a wet-and-dry hygrometer works.
- Sept 2005: Venous return, and factors that determine it. Drawing a venous return curve (a Guyton curve) and showing the effects of extra fluid, artificial ventilation, etc. Superimposing the cardiac output curve was not required.
- Sept 2005: Renal, titratable acids definition and rough amounts handled and where (high flux, low gradient proximal vs low flux, high gradient distal); role and origins of phosphate. Buffering.
- Sept 2005: GABA, Location of receptors, ligands, chloride membrane eqm. potential, effect of GABA on cell as voltage vs time.
- Sept 2005: Blood Gases, in a central line, if the line went down a vein into an arm, definition of mixed veinous blood, pO2 in coronary sinus, methods to measure amount of oxygen in a blood sample.
- Sept 2005: Capnography, draw a trace, name phases, label point of inspiration and expiration, effect of re-breathing on baseline and plateau (mostly covered in Kerry's book).
My 2006 Phys viva as it happened. I would suggest you get someone else to ask you as reading everything may give away some answers
Q1: Pulse oximetry
- Tell me about pulse oximetry (discuss the principle of absorbance etc and draw graph abs vs wave length)
- A: what happens at the isobestic point (other than equal absorption- not being useful for conventional oximetry … ie can it be used for anything?).
- B: What happens with decreased Blood flow (eg hypovolaemia) … i.e. discuss the AC vs DC component.
- C: what happens with increased Venous pulse eg TR.
Q2 Draw the LV pressure vs time graph for one cardiac cycle.
- A: Now draw the LAP trace.
- B: Which pressure is greater at the A and V wave.
- C: What is happening at C wave.
- D: What is happening here ( he points to the ventricular relaxation bit).
- E: What is happening here? (points to the bit after the vent relaxation ie “rapid ventricular filling” – I drew the ventricular filling curve vs time and he was happy.
- F: Is atrial component more or less important for vent filling in tachycardia … explain.
- Shown ABG result : pH 7.1 pCO2 70 hCO3 27
A: what is happening? B; is there compensation? C: Is there a metabolic acidosis (“I ‘m not sure” ) Do you know any equations that may help? D: What is the renal mechanism for compensation? E: what are the effects of hypercapnoea. F: What are the effects of acidosis?
- What are the effects of altitude
- "hypoxia and resp alkalosis" --- how long does it last for?
- What are the effects of chronic altitude exposure?
- EPO -any other hormones?
- Tissue hypoxia, increased vasculature, increased oxidative enzymes
- 2,3 DPG with graph
- Can you increase the maximum ventilation (VC)?
- What happens to the pulmonary vasculature?
- What is the oxygen cascade? Draw it and put no's in. Asked for equations.
- Is water vapour always 47mmHg? Alveolar ventilation - why is this not in the alveolar air equation?
- Venous admixture - what is it?
- Do you know an equation? Shunt equation. How can we relate content and partial pressure O2?
- What is temp, heat, what the units. How do patients in theatre lose heat? What other ways are there to lose heat? Graph of heat loss in theatre and what's happening at each stage. *Can we reduce the first rapid (redistribution) phase? How do we prevent heat loss in theatre? Can we add heat to the patient?
- Draw a radial arterial line trace for a young fit person. Mark on it SBP and DBP.
- Where is systole taking place? How does it change in elderly/with respiration/in young & fit with sudden 1L haemorrhage? What determines SBP? DBP? How is the MAP calculated by the monitor?
- Given: pH 7.09/CO2 10/O2 143/BE -26. Comment.
- What types of metabolic acidosis are there and give examples. How/why is lactate produced? In normal state, where does lactate come from? How handled? What's so special about the liver? What other acids are formed in the body? Bell.
[Aug 2007 - Day 3]
Cardiac output & venous return
- What is cardiac output
- What is venous return
- How is cardiac output and venous return related
- What is the effect if venous return is suddenly increased
- What is Starling curve
- What is cardiac function curve (of Guyton)
- Draw vascular function curve and cardiac function curve
[then got asked about dependant and independant variable]
- What is clearance
- What is the formula for clearance of a substance
- How is GFR measured [discussion on inulin and creatinine]
- What is the significance if clearance is zero, give example
- What is the significance if clearance is negative
- Can this method be used to determine renal blood flow, how [discussion on PAH]
Pressure - time curve / IPPV
- Draw Pressure-Time diagram for patient on IPPV
- Explain graph: time constant
- Draw Flow-Time graph [what does area under flow-time curve represent]
- Define compliance
- Technique to measure total compliance and lung compliance only
- Problems with esophageal probe
- Measurement of airways resistance
- Explain how cell synthesizes protein
- Role of mRNA, tRNA
- Regulation – eg. via protein kinases
- Post translational modification
- What is a gene
- What is genetic polymorphism
[ding! saved by the bell!] - good luck. we've all gone through it before and feel your angst! -lewildbeast at gmail dot com
- What types of flow do you know? Laminar, Turbulent, Transitional
- Describe laminar flow. Poisellue's law. Describe each component
- Describe turbulent flow
- Where is the major site of airway resistance
- Factors that affect airway resistance
- Tell me about the immune system
- Innate: Physical, Soluble, Chemical, Cellular factors
- Acquired: T-cells, B-cells
- Describe the steps encountered in the immune process when an invading organism enters the body
- Define contractility. What is the normal value. How do you measure it?
- Draw a PV loop of the LV. Sumperimpose a loop with increased contractility. Is the diastolic pressure the same as the previous curve?
- If you were to increase the HR of a young individual to 220bpm, what effects would this have on contractility. How would this affect preload, coronary perfusion
- Draw a normal capnograph. Describe. Is phase III flat? When is it upsloping? Superimpose a curve in a patient with COPD. Explain the differences
- How do you measure CO2 in your hospital theatre. Side line, infrared. Tell me more...*Ring Ring*
- What causes hypercapnia if ventilation is adequate and production normal? (Note: I thought the examiners meant increased EtCO2 and I became confused as there is no answer to such a question, but more likely they said or meant Arterial PCO2, but I failed to clarify this, in which case the answer is increased alveolar dead space, about which Nunn says "This very rare cause of hypercapnia is usually diagnosed by a process of exclusion." However, increased Alveolar Dead Space will increase the Arterial/End-tidal gradient, so IMHO EtCO2 should not be elevated, but I cannot find specific citation to support this. (Look at Nunn Ch 8, 10, 28.)
COMMENT on the above: The relevant equation here is: :paCO2 is proportional to CO2 production divided by alveolar ventilation So the answer to the question about 'what causes hypercapnia if ventilation is adequate and production normal' must be NOTHING! However there are 3 aspects that make this an unsatisfactory answer. These are: * Firstly the ventilation "adequate" bit. The equation above is about "alveolar ventilation" (VA) and its quite possible to have reduced VA despite normal or increased minute ventilation (ie if dead space is increased). So if the examiners meant minute ventilation was normal (or 'adequate') then the answer they would have been seeking is this could occur if there was increased dead space such that alveolar ventilation (the term in the equation) was decreased. * Secondly the assumption for use of the equation is frequently forgotten. The equation is correct if the assumption that inspired pCO2 = 0 is true. However, if there is CO2 in the inspired gas, then the equation does not hold and hypercapnia can occur in a person with a normal CO2 production and a normal alveolar ventilation. This is of course relevant to anaesthesia. CO2 is present in the inspired gas in a variety of situations (eg use of Mapleson circuits; use of a circle system with low flows and absorber turned off or soda lime exhausted; certain equipment/circuit malfunctions). * Thirdly, if there is insufflation of CO2 into the body (laparoscopy) or excess release into the blood (eg release of lower limb torniquet) - here 'production' is normal and an increased arterial pCO2 (& end-tidal pCO2) can occur if ventilation remains fixed. SysopKB 08:05, 9 Sep 2007 (EDT)
- What types of dead space are there. How is each measured. Explain Bohr's Eqn with and without Enghoff Modification, and explain Fowlers method.
- Describe the steps in protein synthesis. This included the steps involved in transcription of mRNA from DNA by dna gyrase, and so on.
- What is the Renal Blood Flow, the Plasma Flow, the Filtration Fraction, the GFR? What cause filtration. Write Starling Eqn and give numerical values for each GCHP, GCOP, BCHP. What factors alter afferent arteriolar tone, and efferent tone, and effect of flow and filtration at the glomerulus.
- Hormone receptors: What types are there and describe structure/function of one.
- Body's response to 20% blood loss. Receptors. Limits for baroreceptors.
- Flow-volume loop. Normal and asthma. Wanted to know flows including expiratory flow rates. Dynamic airways compression. What else contibutes to loop? (I got very confused in this one)
- What is a hormone. Classify hormones. What is noradrenaline? Adrenal gland-what hormones. Aldosterone-site of action.
- Cardiac output. How much to heart? Anatomy of cardiac circulation. Factors affecting cardiac circulation. RCA/LCA flow comparisions. PO2 of coronary sinus. etc
Overall my questions were fair and stuff you would have covered. Often last question in topic may be somewhat odd/difficult/or just something you hadn't really thought about. Main problem is not panicking when you say something incorrect so that you end up unable to tell them stuff you know heaps about. Mostly quite directed questions with brief answers then next question.
Last year someone got Thromboelastographs. Other people got ECGs and how you derive lead II, what is glucose, tell me about glucokinase etc.
- What is FRC? What is the effect of anaesthesia upon FRC and why?
- What is pH? Something about usual values of pH and [H]. Explain the process of gastric acid production.
- Talk about myocardial blood supply with respect to myocardial oxygen demand. What valvular lesion creates a particularly bad situation with regard to supply and demand? Why is that?
- How is blood taken, fractionated and stored at the Red Cross?
Myocardial Action Potential
- Draw it. label ion currents.
- Which channels are working in each phase?
- How do slow and fast APs differ?
- what is a rectifier?
- how do variations in plasma [K] affect RMP?
- Nernst equation.
Glutamate & NMDA Receptor
- How is glutamate produced? where does it act? what happens at AMPA/NK1 receptor?
- What is the role of glycine?
- What is the mechanism of plasticity?
- I had a shocker here...
- Define them. What is the difference? How is each one measured in the lab?
- What are colligative properties?
- What is the osmolality of Normal saline?
- Why is it 'normal' if it's osmolality is 308.
- What is the osmolar gap?
- If you give a patient mannitol how do you know when you've given enough?
- The usual questions: What increases/reduces it. Body box plethysmography. Functions of FRC.
Muscle physiology Structure of cell, function, anatomy.... point out on a diagram Z lines I bands etc. Mechanism of contraction
- Define it, how you measure it, Frank-Starling curves ... etc.
- What happens if you rapidly ascend to the top of Mount Everest?
- Why do these changes occur?
- What occurs over the next few days? (triphasic response, in Nunn)
- What happens over the next month? (3 mechanisms: increased uptake, increased delivery, more efficient utilisation)
- Why do aeroplanes fly at particular altitudes? What is the cabin pressure? How does this affect oxygen saturation? Is it a problem?
(with regard to cabin pressure, it's about 0.7-0.8 atmospheres. cheaper airlines run at lower pressures as it means there's a reduction in the amount of air that must be moved-about 100 tons!)
- Define it.
- When might it occur (endobronchial intubation, atelectasis, pneumonia, pneumothorax)
- What are the physiological causes of venous admixture? (bronchial and coronary circulation)
- What is the PO2 in the coronary sinus? WHat colour is the blood? (black)
- How do you quantify shunt (Shunt equation). How do you measure the variables?
Reaction to injury
- "What happens if I cut my hand?" (3 possible avenues: pain pathways/stress response, bleeding, withdrawal reflexes)
- Went down the stress response pathway....sympathetic response, fluid retention, cortisol.
- What does the other hand do?
- Describe it (MAP and HR changes), what is happening in each phase?
- Square wave, and autonomic dysfunction
- Valsalva Ratio
- What are they? Base Units?
- What is Current? What is Ohm's law?
- What is a volt?
- What is Impedance? Why is it important clinically?
- Other vague questions about the voltage at a power point and what it meant!
- What is it? What does it involve? - LED's and sensor
- Beer-Lambert Laws, which is which? Wavelengths of light, Hb species
- errors and assumptions
- What do different R values mean?
- Draw the cascade. Stopped at each point
- How do I get 159mmhg for dry air?
- Alveolar ventilation, and Alveolar gas equation. What does the pCO2/R mean? Different R values? Correction factor?
- Venous admixture - define, what is it made up of? (True shunt, pathological shunt, VQ scatter)
- When does shunting occur physiologically? (ie, position, pregnancy, ageing with CC>FRC)
- How does VQ scatter change with ageing?
Overall, examiners very friendly.. despite much blathering they helped me through it!
Other people got - Hepatic Blood flow, Ultrasound, Capnography, pain pathways
Cardiac and Haemorrhage
- What is normal circulating blood volume for 70kg man.
- How do you know this?
- What physiological responses would there be if there was an instantaneous 1500mL blood loss?
- What are the sensors / effectors
- What are high and low pressure baroreceptors
- What is sleep?
- What are the physiological changes associated with sleep?
- What EEG changes do you see with sleep?
- What are the names of the different waves and complexes you see in EEGs
- How does sleep differ from general anaesthesia?
- How can you monitor levels of consciousness?
- How does BIS work?
Control of breathing
- How is breathing controlled
- What are the sensors of breathing?
- What is the name of the cells that detect oxygen in the carotid sinuses.
- How is oxygen detected by these cells?
- Explain how CO2 affects control of breathing
- Which receptors are more important? Why?
- What are the effectors of breathing
- What contribution does the diaphragm make to breathing
- What can alter the effectiveness of the diaphragm
- What are the roles of the stomach
- What are the phases of gastric acid secretion
- Which phase is most important for acid secretion?
- Draw a cell and explain what chemical processes are occurring to generate HCl
- What happens with HCO3-?
- Does it leave the cell actively or passively?
- What is the name of the cell that secretes acid in the stomach?
- What else does this cell secrete
- What is the role of HCl?
- How does it achieve this?
- What is pepsinogen
- Is it an active or passive process?
Other topics I heard mentioned by others:
- V/Q when lying on side (and how this affects diaphragm)
- Bicarb secretion by kidney and what happens when you have a bicarb load?
- MAP - what affects it (ie SVR, CO)
- Arterial pressure curves - what causes each bump
My examiners were very nice but non-committal. I did pass though.
1. Bohr Effect
- What is the Bohr Effect?
- What factors involved
- Molecular basis of it with H+ ions
- Draw Fetal Hb O2 dissociation curve
- Why is it different from Adult Hb
- What is 2,3, DPG? - Factors affecting it
2. Temperature Regulation
- Tell me about Temperature regulation.
- Responses to heat and cold
- How does anaesthesia affect the inter-threshold range
- Consequences of hypothermia in recovery
3. Normal saline & osmolality
- What is in a bag of normal saline?
- Why is it “Normal”
- What is tonicity – what is the tonicity of normal saline
- What is osmolality and osmolarity – formula for osmolarity
- Is there a difference --> osmolar gap
- How do you measure osmolality
- What are the other colligative properties
- How much does freezing point lower with increase in osmolality
- What determines the colligative properties of a fluid
- Anion gap – formula
- Clinical uses
- What type of anion gap with infusion of normal saline
- Ethylene glycol – why would I put it in my car’s radiator would same work for salt
4. Draw a CVP pressure-time trace
- What would flatten the x descent
- Transducers measure pressure – How?
- Other methods for measuring the pressure in the vessel
- Draw a Wheatstone bridge.
- what is a resistor in an electrical circuit
- what is a capacitor
- an example of capacitor in OT? ..something u charge up before using it.. (Answer: defibrillator)
- what is this resistor arrangement (examiner drawing..): in series
- what is the total resistance here
- an example of this arrangement in body
- what is this arrangement then (showing another drawing) : in parallel
- so what is the total resistance here
- is the total resistance bigger or smaller than individual R?
- an example in body?: placental-uterine circulation
- so is a pregnant lady's SVR increases or decreases
- What is a Wheatstone bridge
- how does it operates, why do we use it, where can u find it?
- what is compliance
- so in a respiratory sys, what types of compliance we r referring to:
- can u relate these 3 compliances in a graph? - drew the 3 curves in KB book
- (pointing at FRC) so here..the magnitude of these 2 recoil pressures
- what if we stick a big bore needle into a chest wall..what happens
- (pointing at the lung compliance curve) What happens to this curve in a patient with COAD?
- what measurement we need to get these curves
- how do we do it?
- what is a static compliance?
- Draw me the tracing of lead II ECG
- what is the y axis
- tell me about what happens in P, QRS and T
- what about the intervals:
- what will increases PR?
- is there any factor that affects the value
- Do u know another other waves in ECG?
- what changes u will c in sequence if we infuse K to a renal failure patient?
4. Renal Clearance
- In a renal failure patient, if you want to know his renal function, what test will you do preoperatively?
- what is included in the RFT result
- (pointing at creatinine) why do we use creatinine?
- what function of the kidneys we are looking at?
- what is GFR?
- how do we meansure it properly in a lab
- y it is use, so what is bad about creatinine
- how do u do 24 hour creatinine cl in a patient :
- so what is the usage of a spot creatinine value if we r not doing 24 hour urine collection
- what information we need in the formula
- any other blood test we can know more about the RFT? :
- Tell me about HCO3 in Kidney : BELL RINGSMeileung
1. Could you tell me about cardiovascular changes with aging
- So let's talk about HR. Why does that reduce
- Could you draw a lead 2 ECG and show me some changes
- What happens to QRS with aging
- So you mentioned compliance reduce, what's the result of that
- What happens to diastolic pressure
- What implication does increased MAP and systolic have
- Why does contractility reduce
2 What is a resting membrane potential?
- What's typical value for skeletal muscle
- What causes that
- Can you write an equation to calculate potential for ions
- Why is universal gas constant in the equation
- Why does RMP deviate from Vk
- What else contribute to rmp
- What's Gibbs Donna effect
- What happens to cell if only Gibbs Donna is in effect
- What happens if ECF k was to go up
3. What is FRC?
- What's typical values
- What's functions of FRC
- How much oxygen is there at FRC
- What if you're breathing 100% oxygen
- How do u measure FRC
- What factors change FRC
- Why does it reduce with anaes. What about pain
4. Tell me about pituitary gland
- Where are they from embryonically
- Whats the pouch of ant pituitary called
- What does their diff origin mean. What's portal circulation mean
- What hormones are produced in pituitary
- Tell me about thyroid hormones
- What are their systemic effects
- What controls their secretion
- Tell me about ACTH
1. What blood tests can be used to estimate renal function
- Which of urea and creatinine is better
- What are the problems with using urea to estimate renal function
- what are the problems with using creatinine to estimate renal function
- Can you draw a graph of plasma creatinine vs GFR - what does its shape indicate
- What is clearance
- How can clearance be used to estimate GFR
- What is eGFR and how is it different from GFR
- How is eGFR calculated
2. Resting Membrane potential - questions as listed above
3. Can you write down the alveolar gas equation
- What would happen if we dropped you out of a helicopter at the top of Mt Everest
- How would this change the alveolar gas concentrations
- What about this part (examiner pointed at PaCO2/R part of the equation), would this change
- What is the ideal alveolar gas equation
4. What is Starlings law of the heart
- Can you represent this graphically
- What clinical parameters can be alternative labels for the x and y axis (i.e. LVEDV and SV)
- What would the curve look like with sympathetic nervous system activation
- What would the curve look like in heart failure
to all part one aspirants!
April 13th : yes I did wait for this moment to post and thank "Kerry"
THE FOUR STEMS: 1. LV pressure time CURVE, 2. ARTERIAL PRESSURE 3. Pulm circulation 4. Blood gas (the stem looks easy/straight-forward.. was quite a sweat they twist it but lovely duo examiners.. who guided me through).
1. LV PRESSURE CURVE:
- draw the lv pressure time curve, LAP tracing, when does the lv filling start (after IVR), EXPLAIN DIASTOLIC PHASES.."She WANTED ME TO DRAW DIASTOLIC FLOW time curve and the area under the diastolic curve and what it represents". no idea ..
- You talked about pressure : how to measure arterial pressure .. I classified.. talk about electromanometer assembly.. I went thro.. can u explain the way the diaphragm operates.. ( detail of moving plastic on stretched wire that alters resistance and then the amplification..) phew.. lucky i crammed it prev night
3. Pulmonary Circulation Examiner 2: tell me whats the PA pressure (25/10 mean 12).. why do u think the mean is so low. i went blah blah.. he jus wanted LA PRESSURE is 10mmhg.. so no need for the RV to sweat it out !!. THEN HE GOES.. I DOUBLE THE CARDIAC OUTPUT.. how will it alter the PVR ( reduced) why/ ( recruitment and distention) .. which one of the vessels collapsed vessel/ parlty opened vessel requires higher pressure to recruit.. dint approve of my guess.. .. West zones.. when do u see zone 1.. pa occlusion.. he wanted hypotension.. i dint volunteer,, then he goes.. why dosent hypotension produce zone 1.. ?
4. Blood Gas Interpretation
- OK here is a blood gas (pH 7.5, HCO3 35, pO2 75, CO2 45 ) ; metab alkalosis, eg: vomiting. etc..
- compensation.. he goes:
- --> "WHY doesn't the kidney try sincerely to correct though the pH is alkalotic?"..[Clue: any hormone that does it?] .. At last i said it "Aldosterone mediated paradoxical aciduria in a effort to conserve volume as vomiting is continuing... "
Other questions: spinal anesthesia and pulmonary circulation, the resisters and formula and example the autonomic influence to the pacemaker potential, ions involved.. compliance curve for COAD and resistive disease
1. Oxygen cascade
- Can you draw the oxygen cascade?
- How is the alveolar value measured/calculated?
- Is there a different or better form of this equation (alv. gas eqn) and what is it?
- Why is there a correction factor? What is it for?
- Why is there a drop from alveolar to arterial?
- How is shunt written/expressed?
- Tell me about ultrasound
- How are ultrasound waves produced?
- How are they received?
- What is doppler ultrasound?
- What is the equation for doppler shift?
- Why choose one frequency over another?
- What is attenuation?
3. Smooth muscle vs skeletal muscle
- What are the differences between smooth muscle and skeletal muscle?
- What do they look like under a microscope?
- What is the tension length relationship for smooth muscle?
- What is actually happening at the bottom and top of the curve?
- What is the optimal overlap value?
- How is smooth muscle contraction different from skeletal muscle (excitation-contraction coupling and in the nature of the contractile force)?
- Is their a length-tension relationship for smooth muscle?
4. LV Pressure-time trace
- Draw a LV pressure-time trace
- Superimpose the Aortic pressure -They were meticulous about the detail, ie were the lines perfectly superimposed in the upper portion, or offset, where and by how much
- When does the mitral valve open? (I said when the atrial pressure is higher than ventricular, they wanted to hear at the end of isovolumetric relaxation)
- When does blood stop flowing out of the aorta?
- Why does the aortic pressure drop before blood stops flowing?
1. What is the normal Systolic and diastolic BP?
- What BP is in the elderly? In the child?
- How do you defined SBP and DBP? Draw Aortic root pressure.
- What determines SBP? and DBP? and What is MAP?
- What value can BP drops to if HR is very low? -- (I think the answer is MSFP)
2. What is the SI unit of Temperature? How do you define Kelvin?
- what classification of thermometers do you know? Explain principles of electrical thermometers
- How do you calibrate it? (shocker)
Q1: tell me about the hepatic circulation, where does blood flow in portal circulation come from? what factors affect hepatic blood flow, autoregulation, what happens after meal
Q2: draw the pressure time tracing obtained from the PA catheter when it's in RV, then PA, then wedged.
- difference between RV and PA tracing
- what assumptions made for wedged pressure to reflect LV preload
Q3: O2 cascade similar to the question above
Q4: what is monroe kellie doctrine, draw intracranial compliance curve, CSF production and absorption curve.
This is my viva as best I can recall. It was much more stop-start than I expected. Examiners were very calm, friendly and professional.
You start the viva standing outside the room. The bell goes and you walk in, shake hands, sit down. There is pencil and paper ready in front of you and a bottle of water. Half way through the viva the examiners stopped me and suggested I have a drink of water. My mouth was so dry and I was speaking so fast I think they were having trouble understanding me.
1. Pulmonary circulation/HPV/West zones
- What is normal pulmonary artery pressures and MAP?
- Why is it so low?
- What are the determinants of PVR?
- HPV what determines it? Is it present in the denervated lung?
- What’s the mechanism of HPV?
- When PA pressure rises what happens to PVR? How does this occur?
- West zones – describe the characteristics of each one.
- Is West zone 1 present in a normal healthy person? What situations can cause West zone 1 to be present?
- Say I’m given a drug that changes GFR. By what possible mechanisms could this be achieved? (Break up the Starling equation, changes in aff/eff art. tone, MAP, mesangial cell tone
- Write out the Starling equation, explain all the terms.
- Why is the oncotic pressure in Bowman space so low?
- How large does a molecule have to be to NOT be freely filtered? I said 7000 Daltons, they seemed happy
- Why is haemoglobin with a molecular weight of 69 kD filtered yet albumin with a weight of 70 kD not filtered? charge
- How is GFR measured in the lab? Why is it not done in day to day practice?
- How is it measured in day to day practice? Cr clearance or estimations based on age, sex and spot creatinine
- What is the relationship between plasma creatinine and GFR? Draw a graph describing this relationship.
3. RBC structure/Hb/breakdown of RBC
- Describe the structure of haemoglobin. How many Fe ions per Hb molecule?
- What binds to Hb? Ó2, CO2, H+, 23DPG
- What is the lifespan of the RBC?
- Where is it broken down? IV and RES Proportion broken down in each?
- In the liver what cells are responsible for RBC break down, by what process do they take up the RBC?
- Describe the process of RBC breakdown in IV compartment and RES.
- What happens to the protein chains?
- What happens to the Fe?
- What happens to the haem ring? I basically regurgitated the paragraph from Kerry’s book plus talked about uro- and stercobilin and how they’re excreted
4. LV/ aortic pressure traces. I got hammered in this question, it went for AGES
- Draw the LV pressure vs time trace (Hint: Draw it BIG, take up a whole page)
- Mark where the MV opens and closes
- What is happening when the MV opens? End of isovolumetric relaxation, LV pressure drops below RA pressure
- Can LV pressure ever be less than 0?
- Is ventricular relaxation in diastole an active or passive process?
- Superimpose the LV pressure vs time trace for a failing LV. I Struggled BAD
- How is the gradient of the upslope different? How about the down slope? How about the relative amount of time the failing ventricle spends in systole? I had no idea about the last two and said so
- What features of the curve are sometimes used as an index of contractility? dP/dt At what part of the curve is it measured?
- What is used as an index of contractility clinically. I floundered here but I guess an answer would be pulse pressure
- What is the Treppe phenomenon? What is the mechanism?
- Superimpose the aortic pressure vs time curve on the LV trace. Make sure you draw it exactly to-the-millimetre perfect. I was hassled about which curve was on top and at what point they cross because I didn’t draw it exactly perfectly
- Mark the points where the AV opens and closes.
- When is the rapid ejection phase, when is the slow ejection phase, why are they rapid/slow respectively?
- Definition of DBP
DING DING DING
Questions others got:
- Pain – definition, mechanism of referred pain from uterus, pain pathways
- Flow vs volume loops – mechanism of dynamic airway compression
- Electrical resistance – in series, in parallel, examples of each in the body
- Control of body water
- Resonance and damping
- Exponential functions, time constants
- Physiological changes in exercise
- Bile – components and function
- What would be a normal BP for a healthy adult?
- You are in PAC – nurse tells you a patient’s BP is 200/100. How is this likely to have been measured?
- What are the sources of error with automated NIBP.
- Why does irreg HR mean automated NIBP may struggle?
- What is most accurate – MAP>SBP>DBP
- Auscultatory method – what is measured? How could we estimate MAP?
- When should we use 5th sound over 4th sound? In what sort of patient do we not get 5th sound? What is normal BP in children cf adults?
- CV changes with pregnancy
- Why is SV increased? Why is SVR decreased?
- When during labour is the greatest strain on the heart? – which stage? What happens when the placenta is delivered?
- How is water distributed in the body?
- How could we determine the size of the ICF?
- TBW – heavy water – how do we do it? How could we account for loss of indicator in urine (conc v time curve)
- ECF? – inulin
- How is water movement regulated between ICF and ECF?
- And between ISF and PV – he wanted Starling equation
- What is the reflection coefficient? What capillary bed in body has very low reflection coefficient? – liver
- Draw a flow volume loop – max expiratory effort
- Draw flow volume loop from FRC
- Explain dynamic airways compression
- Draw flow volume loop for obstructive airway disease
- why is curve dished out?
- Explain dynamic airway compression – draw picture of alveolus/airway and show pressures, Starling resistor
- What happens to expiratory graph with extra-thoracic compression?
Physiology Viva -April/2011
Q1: Upper Respiratory Tract
- Tell me about the functions of upper respiratory tract.
- How does air get humidified?
- What is saturated vapour?
- Where does the air get fully saturated?
- What is the saturated vapour pressure?
- Why is upper respiratory tract effective at humidification?
- Does all water vapour get lost on expiration?
- At 20C, is vapour pressure lower or higher comparing to at 37C?
Q2; Blood pressure
- How does BP measured in theatre?
- Tell me about invasive BP measurement.
- What are the components of the measuring system?
- Tell me about transducer. How does it work?
- Why is Wheatstone bridge used?
- Indications of invasive BP measurement.
- How do you assess accuracy?
- Tell me about dynamic accuracy?
- What is natural frequency?
- What is resonance?
- What will change in natural frequency when column of water is connected to diaphragm?
- Draw an art BP waveform.
- What happens with this waveform when resonance happens?
- Which part is amplified the most?
- What is TPN?
- Have you prescribed TPN before?
- What are the components?
- What is the daily requirement of Na, K, and Energy?
- Why CHO is prescribed?
- We are able to making proteins from CHO, why do we still prescribe protein?
- What types of amino acid are there?
- What is essential amino acid?
- What is respiratory quotient?
- What is RQ for CHO, protein and fatty acid?
- Who needs TPN?
- Which group of patients need high energy requirement?
- What trauma group especially?
- What group of patients do you need to modify RQ?
Q4: Blood Bank
- How is blood collected?
- What is in the bag?
- Platelets get centrifuged. What temp is it stored? What is the half life of stored platelets? Half life of platelets in the body?
- How is plasma stored?
- What does citrate do?
- What happens to RBC in stored blood?
- Potassium, PH, calcium, 2,3 DPG.
- Why is K+ high in stored blood?
- Why is pH low?
- What are the complications of massive blood transfusion?
- O negative blood is reserved for what group of patient? Why?
Monday am phys:
1. Afterload/Cardiac output
- Determinants of cardiac output? Equation for cardiac output? Draw LV pressure volume loop with AL line explaining all the phases of systole and diastole. Things that affect afterload? How does viscosity affect afterload?
2. ICF/ECF concentrations of Na, K and Cl
- What determines these? Nearnst equation with figures for the differents constants. Goldman-Field and cord conductance. Gibbs Donnan effect.
3. Temperature and GA
- What is heat? Heat loss when in a fridge, then how this is accelerated by a GA. Different percentages for different mechanisms? Then heat gain in a sauna (well, a sauna with no humidity, so I guess a desert). How heat can be lost with/without humidity in this example.
- Draw a normal capnogram. Then went through several examples - bronchospasm (with explanation of dynamic airways compression and differing resistances with long time constants), decreased cardiac output, rebreathing, recovery from muscle relaxant, then a weird one about a partially loose sidestream CO2 catheter
- What is the FRC.
- What changes FRC?
- Does it change with age? Height? Anaesthesia?
- What are the functions of FRC? How much O2 within it?
2. Pituitary hormones
- Tell me about the pituitary gland. What is it anatomically. What are the embryological derivations. Is there a third lobe? What hormones does it produce (wanted all 8).
- Tell me about ADH. What are the triggers for release?
- Where are the hypothalamic osmoreceptors? Are they within or without the BBB? What are the receptors? Other than V1 & V2, are there any others? Is it a weak or strong vasoconstrictor?
3. Venous return
- What is venous return? What factors determine venous return?
- What is the mean systemic filling pressure? Draw the graph.
- Why the plateau at negative pressures?
- Is the linear component of the line really linear? Why? How does the curve change if 1 litre of fluid is rapidly infused?
- What are the normal values?
4. Temperature & regulation
- What is heat? What is temperature?
- What is the normal body temperature? What changes this? How is it detected?
- Where are the bulbs of Krause, and where do they send their signals to?
- Other than the skin and the hypothalamus, where else is temperature detected?
- What is the response to cold, and when does it 'kick in'?
- At what temperature do you shiver?
BELL - Good luck!
Monday pm Room 1:
1. Cardiovascular changes with ageing
- Changes in SBP, DBP, MAP.
- Why does conduction system slow down? Reflected pressure waves contribute to increased afterload.
- Draw radial pulse waveform for old -versus- young person
2. Fick's Law
- What describes diffusion (Ficks law), write the equation
- How does this apply to gas exchange across placenta? (diff gradient incl. Bohr and Haldane effects, diff surface area, thickness)
3. Pulmonary vascular resistance
- Why is pulmonary arteral pressure so low compared to systemic?
- Explain West zones of lung. Does recruitment or distension contribute more?
- Explain hypoxic pulmonary vasoconstriction.
- Draw graph of pulmonary vascular resistance Vs. lung volume.
- Main physiological causes (relative volume deficit, excess water). How do you calculate osmolarity? What's the difference between mmol and mEq? Explain how massive hyperglycaemia and lipidaemia cause hyponatraemia. Something about urea being an ineffective osmole. Why have hypo-, not hyper-natraemia in large volume deficit?
1. Adrenal Medulla
- What does the adrenal medulla produce?
- What are the steps for synthesis?
- Where does the tyrosine come from?
- What are the enzymes required? What do they act on?
- What are the receptor subtypes? What does each receptor subtype do?
2. Coronary circulation
- Draw the graph of flow in the left and right coronary arteries. Explain the differences.
- Why does this occur? What dictates coronary blood flow? What is it normally?
- What would happen during exercise?
- Would anything during exercise have a negative effect on coronary blood flow?
- What would happen if pulmonary vascular resistance increases?
3. Upper Airway
- What are the functions of the upper airway?
- Explain how a cough occurs.
- Explain humidification of inspired air.
- Where does this occur?
- Explain how the anatomy assists this.
- How does the water in air change if the inspired air was 20 degrees compared to 37?
- What about the vapour pressure? Describe turbulent flow.
4. Gas flow measurement
- How do you measure gas flow on an anaesthetic machine?
- Draw a pneumotachograph. Explain how it works.
- What do the capillary tubes do?
- Why is a heating element included and what does this achieve?
- Why would a wheatstone bridge be used with this? (Specifically told to not draw it).
In retrospect, I did not perform very well, as q's 1, 3 and 4 were weaknesses. I genuinely believed I had failed but somehow passed. Practise is everything - probably my saving grace. Do not be afraid to say 'I don't know' - wasting time with speculation and bullshitting will be your downfall (although trying to deduce things from 1st principles without knowing the answer off the top of your head can seem impressive). Don't be too concerned if you don't know minutia - for example, I didn't know any of the enzymes required to produce adrenaline from tyrosine, as painful and unnerving as it was to say 'I don't know' 6 times before moving on.
Tuesday PM, room 1
- Draw a capnogram. Show the phases. What is happening at each phase? Identify the alpha and beta angles. What causes the angles to change? What are the sources of error in the capnogram? How is the CO2 measured? What would be the effect of rebreathing CO2 on the capnogram? On the baseline? On the plateau?
2. Oxygen cascade
- Draw the oxygen cascade. Explain how the value at each step is derived.
- Explain venous admixture. Explain physiological causes for a change in diffusing capacity.
- Explain shunt. Write the shunt equation. Explain diffusion and perfusion limitation. Is oxygen diffusion or perfusion limitated? Under what circumstance does oxygen exchange become diffusion limited? Transit time for RBCs in pulmonary capillary? Effect of exercise on RBC transit time?
3. Temperature regulation
- What are the mechanisms of heat loss? What mechanisms of heat loss are active in a room in which the ambient temperature is 38.0 degrees?
- Draw the graph of temperature changes in GA? What is happening in each phase of the graph?
- What is the interthreshold range? What happens to the interthrehold range in GA?
- What happens to temperature regulation in pregnancy? In a menstruating woman? What is the the thermoneutral zone for adults and neonates?
4.LV Pressure-volume loop
- Draw the pressure-volume loop for an adult left ventricle.
- Identify the valve events.
- Identify diastole and systole.
- Identify stroke volume. Draw the changes be if the abdominal aorta was clamped.
- Draw the changes that cause stroke volume to be maintained.
- Show the gradient on the curve that reflects left ventricular elastance. Explain the relationship between elastance and compliance.
- Explain lusitrophy. Show how the curve would be altered if lusitrophy was impaired.
- Define shunt. causes,
- Derive shunt equation,how can me measure each component,
- What happens to Pao2 and O2 content during shunt, why?(flat part and steep part of ODC ),
- Cardiac causes of shunt, what happens to shunt during PE.
2. Foetal circulation
- Describe fetal circulation, saturation at IVC, why high PVR, why IVC blood goes to brain,
- What happens at birth- only cardiac changes
- Diameter of capillary,diameter of RBC, Starlings forces,
- why capillaries have high pressure, Law of Laplace,
- how substances cross capillary, formula for diffusion,
- describe how a capillary looks like under a microscope
4. Kidney & acid-base
- How does kidney handle hydrogen ion, how much HCO3- is filtered, what happens to H + when all HCO3- is absorbed, titratable acidity,
- Write the equation for H+ combining with HPO4-,
- How much H+ is produced per day, how much of H+ is excreted by HPO4-.
- what is body's normal phosphate level, what % of HPO4- is excreted as H2PO4,
- How much PO4 is filtered per day, do we excrete all PO4 as H2PO4(I said no)- they asked me why?.
- Other methods of H+ excretion- glutamine to NH4 and HCO3-, in what condition does glutamine broken excessively....
ding ding ding...
1. Control of ventilation
- Describe for me the control of ventilation?
- What areas of the brain are involved?
- Are there any other areas?
- What types of chemoreceptors are involved?
- Where are the chemoreceptors?
- Which (peripheral or central) are more important?
- Which are more sensitive?
- Can you draw a CO2 vs. minute ventilation curve?
- What is the slope of the line?
- Can you demonstrate what would happen to the curve in an elderly smoker?
2. Liver failure & anaesthesia
- What are the implications of a patient in severe liver failure requiring anaesthesia?
- What are the functions of the liver?
- What functions are most affected in liver failure?
- What plasma proteins are made by the liver?
- Are there any plasma proteins that are not made by the liver?
- Tell me about the role of the liver in coagulation?
- Which coagulation factors are made by the liver? Which ones aren't?
- Which coagulation tests will be affected in liver failure?
- Tell me about the liver and carbohydrate metabolism?
- What are the roles of insulin?
- What are the actions of glucagon?
- Describe the process of gluconeogenesis?
- What is glycogen?
- What happens in end-stage liver failure?
- What are the CNS effects?
- What causes them?
- Can you describe the urea cycle?
- What does the urea cycle produce and consume?
- How does the urea cycle link into carbohydrate metabolism?
3. Coronary circulation
- Can you describe for me the anatomy of the coronary circulation?
- What are the branches of the marginal artery?
- What is the venous drainage of the coronary circulation?
- Where does the coronary venous drainage go to?
- Which part of the venous drainage is most important?
- Can you draw for me a graph of Left vs. Right coronary artery flow vs. time?
- What is the total coronary flow per minute?
- What percentage of this goes to Left vs. Right?
- So can you quantify flow to the right coronary during systole in mL/min?
- What colour is the venous blood from the coronary circulation?
- What does this mean? I think he was getting at that it is dark blue due to high O2 extraction
4. Oxygen measurement
- In what forms can we measure oxygen? -I said tension, content and saturation.
- List ways to measure O2 tension -I said Clark electrode, fuel cell and paramagnetic analysis.
- What other ways are there to measure tension? -I said Raman scattering and Mass spectrometry.
- And what else? - I said there is a method using ultrasound but I wasn't sure of the details, and he moved on.
- List ways to measure O2 content? - I couldn't remember the name for it but I decribed the haemolysis technique, then couldn't think of anything else to list so said we can also calculate content from the equation... He stopped me and said he wanted only to talk about measurement :-/
- List ways to measure saturation?
- What does paramagnetic mean?
- Other than oxygen do you know of any other paramagnetic gases?
- What does diamagnetic mean?
- What diamagnetic gases do you know of?
- Can you describe paramagnetic gas analyisis?
- Are there different types of paramagnetic analyser? -I mentioned the diaphragm and the dumbell versions
- Which one do you have in the machines in your hospital?
- Can you explain how it works? -I drew the diaphragm analyser diagram
- What is the diaphragm connected to? - I said a strain gauge, and maybe a wheatstone bridge
- What is a strain gauge? Can you draw one?
- Can you explain the other (dumbell) paramagnetic analyser?
- What detects the movement of the dumbells?
- What converts the light signal to our screen display? -I started to talk about transducers and the bell rang
1. Saline & osmolality
- What is in a litre bag of normal saline?
- Why is it called “normal”.
- Difference between osmolarity and osmolality
- How is osmolality calculated
- What is the clinical use of calculating serum and urine osmolality
- What is the anion gap
- Where is ADH produced. How does it act.
- What are collegiative properties of fluids.
- Why do people put antifreeze in their car
2. Cut to Hand - Responses
- What happens if I cut my hand. They wanted to hear in general, withdrawl reflex, pain, bleeding.
- Further detail on withdrawl reflex, and then what happens to the other arm. (I bombed this part).
- Describe the anatomy of the sympathetic nervous system
2. Arterial pCO2
- What determines C02 tension in arterial blood.
- Define minute ventilation
- What would happen to paC02 in ventilated patient if resp rate was halved and tidal volume remained constant.
- Difference between alveolar ventilation and minute ventilation.
- Graph of paCO2 vs alveolar ventilation. Then how does this graph change with a large dose of opioid (in an unventilated patient).
4. Cerebral Blood Flow
- Normal cerebral blood flow (for adult and also per 100g of tissue)
- Draw graph of cerebral blood flow vs pa02. They wanted to know exactly how quickly CBF rises when pa02 drops below 50mmHg.
- How is cerebral blood flow measured. (They didn’t seem to mind when I told them that I didn’t know more apart from nitrous, and that somehow Fick’s principle is involved).
- What happens to cerebral blood flow when you’re dropped onto Mount Everest.
All the best guys! I know other people have said this, but I'll reiterate. If you don't know something, just say so and don't waste time. The examiners are actually on your side! Also, don't forget the basics - speak clearly, confidently, and take a deep breath before answering the more complicated questions.'
- Hypoxaemia types and details about each type they did ask me about how each one produces the hypoxemia in detail and I had to write down shunt equation as well as alveolar gas equation
- Hypothalamo-pit axis, post pit, details about ADH mech of axn
went in to details about ADH , all its effects like thirst, water rentention vasoconstriction and also the intracellular signal pathway GPCR
- LV pressure loop, contractility - had to draw the loop, how it changes with contractility, definition of contractility, how to measure it I said slope of IABP line , they asked more and I mentioned echocardiogram seemed to be satisfied with that, stroke volume, ejection fraction, frank starling law , graph
- Immune system : natural, acquired and details about complement - they seemed to be satisfied with my superficial knowledge about this, but I did know a bit on the complement cascade
Physiology 1: ADH
- Tell me about the production, transport and secretion of ADH.
- What Receptors does it act on?
- Are the 2nd messengers in the vasculature the same as in the kidney?
- What are the effects of alcohol on ADH release?
- What are its overall effects on the kidney- wanted dec UO?
- What are the effects on the splanchnic system?
- What are the effects on the lung- I said vasoconstriction? Are you sure – no I’m not!
- it is a pulmonary vasodilator – reduction in PVR seen
- How is it metabolised?
- Extras- are there any hormones that inhibit its secretion - ANP
Physiology 2: Pulse oximetry
- Tell me how a pulse oximeter works?
- Can you draw the graph?
- What is this point?(isobestic point)
- What is its significance? - -used to be used in older oximeters as reference point, now no longer used
- How does it tell it is arterial blood?
- What does the R value mean?
- Any conditions that could alter this?
- How accurate is it?
- What can effect the pulse oximeter accuracy?
Started doing some double barrelled questions – what would happen if you lost 30% of your blood volume and had a large intrapulmonary shunt? I just answered these separately!
Physiology 3: Saline and osmolality
- Tell me about normal saline?
- Why is it called normal?
- What is normal osmolality in the blood? --280-300
- So why is this normal and not hypertonic? -we measure it via freezing point depression rather than calculated value, so it is isoosmolar with blood when measured by freezing point depression
- Why is that? - We have extra unmeasured ions
- What is Osmolar gap(if they didn’t volunteer the above.)
- What conditions tend to cause a high osmolar gap?
- What is the difference between osmolality, what is osmolarity?
- You mentioned ethylene glycol that is also known as antifreeze – could we use salty water instead in our engines?
- What are collegitive properties of fluids?
- What happens to SVP when osmolarity is increased? - it decreases
Physiology 4: Starling's curve for LV
- Can you draw a Starlings curve for the Left ventricle (SV vs sarcomere length)
- What is the peak you have drawn there?
- What else can you put on the x-axis apart from sarcomere length? ( LVEDP, LVEDV, CVP)
- What happens either side of the peak?
- What is this? – pulled out a pressure transducer.
- If I attached this to a CVL and measured the pressure what does this tell me about the RV.
- If I took this as being a measure of LV preload what assumptions would I be making for this to be correct?
- How does this pressure transducter work?
- What is a Wheatstone bridge? How does it make your reading more accurate. What are the two ways that it can work (resistance and current sensors)
1. Vascular function
- what are the functions of the venous system? what factors affect venous return? what is the shape of veins? (wanted to hear depends on filling)Draw a vascular function curve. what is this point? (MSFP) draw how the curve changes with loss of 1.5 litres of blood? superimpose cardiac output curve? what happens with increased SNS activity?
- mechanisms of heat loss in an awake patient in theatre at 20 degrees? which is most important?
- what is radiation heat loss?how does the patient compensate? now the patient is anaesthetized and paralyzed, what happens? (drew the temp vs time graph) what is happening here? (rapid decline in temp due to redistribution) now outside at 40 degrees? now in a sauna at 70 degrees? asked something about does sweating alone cause heat loss or does having the fluid on the skin help?
- What is laplaces law? where does it apply? lung & heart, anywhere else?? you mentioned surface tension why is it important in the lung? how does the body reduce ST? what is surfactant? where is it produced? what are the functions?(wanted to hear increased compliance) how does it have an anti-wetting function? other functions of type 2 cells? function of type 1 cells? draw a compliance curve ? (i didnt draw inspiration and expiration) is that for inspiration or expiration? what is hysteresis?
- What is a cell?
- How is a RBC different from other cells?
- how do they generate energy?
- what is the fate of lactate? role of NAD+? (Embden myerhoff pathway)
- what else? what else is produce in the RBC? (23DPG) function?
- what else does RBC contain?
- tell me more about haemoglobin
Examiners were not particularly friendly, I left feeling pretty average, but I passed
1. Draw lead II of an ECG, describe what is happening at each stage. Identify diastole and systole. Why do we use lead II in anaesthetic practice for monitoring (described direction of current across the heart but they wanted more). What is the ECG monitoring for (rate, rhythm, ST changes). Why is lead II better for this. Other people got asked about calibration.
2. Tell me about the organs that receive the most blood flow.
- Since you started with the liver (!) tell me about the circulation to and from the liver.
- What feeds into the portal system. Autoregulation.
- What would happen in hypotension.
- Portal triad: portal vein, hepatic artery, bile canaliculi;
- Where does it drain – to sinusoids then central vein (wanted direction on a diagram).
3. Describe La Place’s law and when it might be applied in the body.
- Tell me more about alveolar compliance.
- What would have to an alveoli if there was no surfactant.
- What is the advantage of having a partially open alveoli.
- Draw the compliance curve for the lung (explain hysteresis).
- Is this static or dynamic compliance?
- How do you measure static compliance.
4. Tell me about EEG changes during sleep.
- What are sleep spindles; what do they look like, what do they represent.
- What is sleep vs what is anaesthesia.
- Why don’t we see REM pattern EEG in anesthesia.
- What is burst suppression, why does it occur.
- How can we use EEG to monitor anaesthesia (BIS, entropy..what else?)
- What are the principles of BIS monitoring.
Here's what I got:
1. Cardiac Action Potential
- Draw the SA node AP on these axes.
- Where does the ventricular AP occur - draw it on the same axes.
- How long after the SA node AP does the ventricular AP commence?
- What is occuring in that time? (PR interval)
- Point to different parts of the AP phases - what channels are open here?
- Can we tetanize cardiac muscle? - Why not? Moving on...
- What is your body temp right now?
- What controls it? You mentioned inter-threshold range - what is that?
- Where are your afferent receptors?
- What are your efferent mechanisms - i.e. How do you lose heat?
- What if the ambient temp > skin temp?
- You mentioned thermoneutral zone - tell me about it, draw graph? Is this graph the same for everyone (ie: right shift in neonates, prems)
- Do neonates lose/gain heat the same ways you do?
- You mentioned non-shivering thermogenesis - tell me about it? Which nerves innervate brown fat? Moving on...
- What would happen if I had an apical bleb that burst?
- You mentioned pneumothorax (PTX)- what is that?
- What are the consequences of a PTX?
- You mentioned impaired gas exchange/atelectasis/HPV/impaired VR - tell us about it?
- What happens to the air?
- You mentioned 100% O2 helping - why? (correct hypoxaemia, de-N2 blood, maintain O2 gradient) Fine, moving on...
4. Renal dysfunction
- What is GFR? How does lab calculate this - eGFR? (MDRD formula)
- You mentioned Cockcroft Gault formula - can you show us?
- Why is it different for females/males? (Muscle bulk)
- This patient is in ICU - is there another way to measure their GFR? (24hr urinary creatinine clearance) How does this work? (Renal clearance formula)
- Do you know any other tests for renal dysfunction - have you heard of cystatin C or something else...DING!
Here are my vivas
1. LV Pressure-volume loop
- Can you please draw a LV PV loop?
- Now you cross clamp the aorta, draw this?
- What is afterload?
- What other changes occur with increasing afterload? (Talked about Law of Leplace, and they wanted to talk about viscosity of blood affecting afterload)
- How do we change the loop for increasing preload, now contractility?
- What is elastance? How does the curve change with diastolic dysfunction?
- How does the curve change with aortic incompetence? What phase is this (isovolumetric relaxation?)
- Why have you drawn that line on an angle (volume change with leaking of blood through incompetent valve)
2. Temperature Regulation
- Tell me about the ways we lose heat in theatre?
- Tell me about convection, conduction, radiation, evaporation etc?
- Is there a graph you know? Explain it?
- What ways can we prevent acute heat loss in theatre?
- How does a Bair hugger work? When should it be turned on?
- What are the consequences of hypothermia for the patient?
- Can you draw a normal capnograph for me? Explain it?
- Where does inspiration start?
- In phase 3 of the graph, where is this gas coming from?
- What are time constants? Do you know an equation?
- Now your patients cardiac output has dropped by 50% ... can you superimpose the curve?
- Why did you draw that shape (dec delivery of O2 back to the lungs due to dec cardiac output)... any other reasons?? Eventually realised they wanted me to talk about west zones of the lung, in particular zone 1 changes with decreased CO.
4. Blood pressure measurement
- Can you please tell me about the oscillometric blood pressure monitor and how it works?
- Can you draw a graph for me showing the oscillations detected as it deflates? Where is sys, MAP, diastolic? What is the most accurate?
- Can you tell me about an invasive blood pressure monitor? What components are involved?
- Quickly moved me onto resonance and damping? What is resonance? What is damping?
- Why are the systems calibrated to have such a high resonant frequency (allow for increased HR)?
- Do you think the systems are optimally damped? No ....... How can you increase the damping of your system? Do you know an equation that relates resonance and damping? I said there was a complicated graph but I didnt know an equation relating them ...
All in all they were very straight forward. If you don't know the answer to a question just say I dont know. They will either ask in another way or move on. The two examiners I had in the arvo were very friendly. Best of luck
Here's what I got:
1. Oxygen carriage
- Tell me how Oxygen is carried in the blood?
- Write the oxygen flux equation. For arterial blood. For venous blood.
- What does each part of this equation mean.
- What is Hufner's number. Why is it not 1.39
- How much O2 do you require?
- What happens if patient's Hb is 50. What happens if they have no Hb. What do you do?
- Draw rough outline of Hb.
- Where does O2 bind on Hb.
- Draw OHDC for HbA. What about HbF. Why is it different. How is that an advantage.
2. Blood gases
- Shown a blood gas - analyse this.
- Mine was a pretty straight forward one, something like this (don't remember exact numbers)
- pH 7.32, pCO2 80, pO2 350, BE -20 (HCO3 not given)
- Discuss causes of metabolic acidosis and types
- Anion Gap discussion
- Where is lactate formed?
3. Draw Ventricular Action Potential
- Explain each phase
- Discuss RMP
- Write Nernst equation and discussion with regards to the ventricular AP
- Nernst potentials of Na, Cl, K
4. Gastric physiology
- Draw stomach and discuss hormones SECRETED by the stomach
- Discuss hormones ACTING on the stomach and what each one does
- Discuss anatomy (muscle layers) of the stomach
- Discuss peristalsis details - [drew a food bolus in oesophagus] - discuss what happens to this food bolus - ie. what makes it progress and what happens at each stage
I think there was discussion on gastric mucous too but don't remember
Most of this stuff is core. If you don't know it then there's a problem. They did ask some specific numbers for things which I didn't know but still passed, so I think a rough idea is all that is required.
1. Exercise physiology
- O2 consumption at rest for adult and neonate in ml/kg/min
- O2 consumption when riding bike up hill
- Draw graphic trend of SBP and DBP as exercise progresses from light to mod to heavy
- Explain trend
- What happens to SBP and DBP when you stop exercising
- Overall physiological response to exercise
2. Osmolality and osmolarity
- Given diagram of two solutions separated by semi-perm membrane (one w higher solute concentration than the other. What happens next
- Define osmotic pressure. If pressure is applied on one side will it stop the water movement?
- Colligative properties - name all 4
- How do you measure osmolality
- Osmolality vs tonicity
- Tonicity of hartmann's. tonicity for D5%. What happens when there is a insulin deficit?
- Normal MV for 70kg man.
- Scenario of asthmatic pt in ICU with MV of 10L/min but PaCo2 is still raised.
- What could be the reason?
- Discussion of physiological (anatomical, alveolar) and apparatus dead space
- How do you measure physiological dead space
- How to measure alveolar dead space. How do you get each component in Bohr eqn
- What could be the cause of increased DS in the abovementioned pt?
4. General/Sleep physiology
- Physiological changes in recovery - talked about CNS, respi, thermoregulatory changes before examiners switched focus to CNS
- EEG for asleep pt.
- What happens in a very deep GA - burst supp and isoelectric waveform
- Draw waveform for burst supp.
- What is the normal amplitude for an ECG? how abt EEG?
- EEG for awake state
- Frequencies for various EEG waveforms beta, alpha, theta, delta
- Which part of brain is involved in control of sleep - said RAS
- Which neurotransmitters are involved when you are waking up? Mentioned NA, Ach, glutamate etc (wasnt v sure so said anything that came to mind)
- Which part of the brain produces noradrenaline? bell rang before answering
My viva on 16/04/12
1. Myocardial Action Potentials
- Draw me a X and Y axis, then examiner put a dot on X axis: start from here draw me a SA node AP and don’t worry about the voltage, I just want the shape of it. Finished.
- Then draw me a LV myocardial AP starting from where you think it should be, following the SA node AP transmission. Finished.
- Why did you choose to start from here? Coz the SA node AP takes about 0.15s which falling in the range of PR interval 0.12-0.2s.
- Tell me what’s happening in the phases of the LV AP.
- Does myocardium get tetany? Why not?
- Where is absolute and relative refractory period on your graph?
- Why is it refractory?
- What happens to make it become relatively refractory? Na channel and M-H gate status
- What happens in hyperkaelemia of 8mmol/l?
- What’s the function of the stomach? Digestion of food. Does it really digest food? Then I said I don’t know.
- Draw me a picture of the stomach.
- Where are the cells secreting HCl?
- How many layers of smooth muscle does stomach have? I said 2, he said No, there are 3
- Tell me how stomach moves? Peristalsis
- But how? What’s controlling the movement of it? Vagus?
- What does the stomach secrete? It’s components?
- Draw me a picture of a parietal cell and illustrate the mechanism of grastric production.
- Is gastric acid continuous in 24 hours? What happens to the parietal cell to increase acid production?
- Draw me a normal capnography trace.
- Where do inspiration and expiration start?
- Why does expiration starts from the flat part?
- Tell me about those phases?
- Then different disease/situations.
- If a person have an arterial pCO2 of 80 mmgh what’s the physiological effects?
- What the blood PH is likely to be if it’s acute and uncompensated? I said 7.0 -> He asked if I guessed or worked out from an equation. I said guess.
- What’s the plasma concentration of Ca++? I said there are total and free Ca++
- What does Ca++ combine in plasma? -Don’t know. He said albumin.
- Tell me the functions of Ca++?. Then he focused on coagulation and muscle contraction
- How does Ca++ make muscle contract?
- What’s tetany?
- What causes it?
- How is Ca++ regulated by body?
- What’s the function of PTH?
- When do you see increased PTH?
- What condition may cause secondary PTH?-end stage RF.
- Why does it cause increased PTH?
My viva September 2012 Monday
1. Venous return & cardiac output etc
- What is VR? What is CO? How are they related? I drew the guyton curve.
- If contractility is suddenly increased, what happens to VR? To CO? To RA pressure?
- Where does the blood go? Into the arterial system
- What is the compliance of venous vs arterial system?
2. What is clearance?
- How can any substance be used to measure this?
- What substances do we use? Inulin and creatinine
- Why do we not use inulin clinically?
- Why is cr inaccurate?
- Do we need to measure urine cr to calculate this?
- So what formula do we use to find GFR from serum cr?
- Draw a graph of relationship between serum cr and Gfr.
- How much renal function do you have to lose before rise in serum cr?
- What substances what zero clearance? Albumin and glucose which are fully reabsorbed
- How to calculate renal plasma flow? What to use?
3. Draw pleural pressure time curve for normal tidal breath
- Are the pleural pressure the same in the upright lung?
- What is the pressure in the apex?
- How would this change when the person is supine?
- How would the curve change for gasping breaths?
- What explains the difference in the curves?
4. Draw nerve action potential
- What causes the depolarization/ repol?
- Where in the graph do the K channels start to open to begin repol?
- What is RMP for nerve?
- What determines this? Nernst potential for Na and K?
- How would this potential change with increase in temperature?
- Goldman equation?
- Effects of protein?
- Gibbs donnan. What is the size of effect of Gibbs donnan?
- What about Na/K ATPase? - Is this important? Size of this effect?
Sept 2012 Day 3
1. Heart and oxygen
- What is O2 consumption of heart,
- What is total body O2 consumption,
- What percentage of CO does heart receive?
- - what does this imply about oxygen use by the heart (high myocardial extraction ratio).
- What does the heart use the energy for?
- What determines coronary perfusion pressure (worth including the term starling resistor),
- Why did you use diastolic pressure in the formula?
2. Pulmonary Defences
- What are the pulmonary defence mechanisms?
- Tell me about cilia, where are the cilia,
- what is the role of mucus,
- what do alveolar macrophages do,
- how do they interact with the other components of the immune system,
- where does complement come from,
- which of the polymorphonuclear leucocytes is most important in fighting a pneumonia?
3. Types of flow.
- What types of flow do you know,
- What determines the rate of laminar flow and how is turbulent flow (I was expected to know the equations and draw them),
- What does the wavefront of laminar flow look like (parabola),
- What about turbulent flow (straight line),
- What type of flow occurs in the alveoli (trick question, diffusion is the correct answer),
- If I was to flush gas out of an anaesthetic circuit, which type of flow would I want to use (turbulent, think about the wavefront).
4. Acid base.
- Interpret these figures from a blood gas (metabolic acidosis with resp compensation).
- What is the normal pH range?
- If the pH was 7.4, what would the H+ concentration be?
- What quantity of fixed acids does the body produce in a day?
- Where do they come from (protein metabolism).
- If I infused someone with HCl, how would the body respond?
- Name some buffer systems (happy with HCO3, PO4 and proteins),
- Which is most important?
- What makes a good buffer system,
- Why is the HCO3 system so important if the pKa is so far from 7.4? (quantity of HCO3 and it is an open ended buffer system).
- What is the kidney's role in acid base balance?
1. Draw the Left ventricular pressure-volume loop.
- What are each of the events in this cycle? Quantify the volumes.
- Why does the pressure not change much during diastole? Does it really look like that? (I hadn't drawn in the atrial end-diastolic kick.)
- What will happen if you rapidly infuse one litre of normal saline into a healthy, young person? (Drew the curve with increased pre-load.)
- What will the curve look like in a healthy geriatric patient? (Struggled a bit to understand what they were getting at... Some hints: is atrial contraction more or less important in the elderly? More. Guessed that they were referring to some diastolic dysfunction, and shifted the diastolic elastance curve.) Move on...
2. Outline the Autonomic Nervous System.
- Outline the receptors at each point.
- Where else in the body do you see acetyl choline? (Neurotransmitter in ANS, in brain, NMJ... couldn't recall anywhere else.)
- Which cranial nerves are parasympathetic? (Started to slowly outline pupil innervation...' I'll just move you on, which is the main one? Vagus What does the Vagus n. innervate? (I was far too slow through this whole section and probably should've got further.)
3. Draw a graphs of (?intrathoracic) pressures during normal tidal respiration.
- What would change if the patient was pregnant? (I don't think I'd seen or thought of this before and struggled. Thinking aloud... FRC reduced, increased WOB if CC above FRC... increased intrathoracic pressures. Drew a graph.)
- What would change if you inhaled as hard as you could, paused, then blew out as hard as you could? (Really struggled again... high pressures but didn't choose the right pressures during the pause with zero flow. Some discussion about maximum intrapleural pressures.)
- Draw the flows. I commented that forced expiratory flows would be effort independent.
- Why? Explained dynamic airway closure.
- What is the limiting factor in inspiration? Airway calibre... (No, the airways are pretty large. What sort of flow will there be?) Oh, turbulent flow.
- And what is the relation between resistance and turbulent flow? Resistance rises with the square of velocity. I'll move you on...
4. What would happen if I somehow managed to infuse an acid into your veins without harming you?
- Buffering, respiratory compensation, renal correction. Tell me about the buffers in the body. Tell me about the respiratory response. How do your kidneys compensate? Started talking about bicarbonate filtration and resorption... How much bicarbonate is filtered every day? GFR 180 L/day, plasma HCO3 is 24 mmol/L... OK, we won't do the maths. I then started talking about acid secretion in DCT. (Wanted to known detail about acid generation, luminal transporters.) I started to talk about intra-luminal buffering, but the bell went...
Time is your enemy and not the examiners, who were very polite, fair and helpful. I recommend practising concise delivery of your material.
1. Cardiac Action Potentials
- Draw the action potential of a cardiac myocyte.
- Number the phases. What is happening in each phase? (changes in ion permeability and ion fluxes)
- Mark on the absolute and relative refractory periods. What causes these? (Differing states of the fast voltage-gated Na channel - p21 Levy and Pappano).
- What happens if a suprathreshold stimulus is delivered to the cell in the relative refractory period, how does this change as the period progresses (phase 0 starts off with a shallower gradient and shorter peak but becomes steeper and has a higher peak as the number of Na channels available for activation increases - p21 Levy and Pappano)
- What is meant by the terms excitability (ability of the cell to generate a new action potential - applies to the relative refractory period during which excitability increases) and irritability (size of stimulus required to bring the membrane potential to threshold, dependent on resting membrane potential and threshold potential).
- What causes the resting membrane potential? (Leakage of K from the cell, Na/K/ATPase pump, small contribution from Na leakage in to the cell, Gibbs-Donnan equilibirium - luckily did not ask me to explain Gibbs-Donnan in great depth).
- What happens to the resting membrane potential in hyperkalaemia? (Becomes less negative).
- Can you draw an action potential in hyperkalaemia? 5mins up after I said Ummmm? a few times!
2. Body water & osmolality
- How much water is present in the body (42L in a 70kg male).
- How is this water distributed? (ECF/ICF, ECF broken down to plasma, ISF, transcellular fluids)
- What are the compartments of the ECF?
- What do we mean by the term functional ECF? (Water that is readily exchangeable between fluid compartments).
- What are the sources of non-functional ECF? (Water held within bone matrix).
- What is an osmole?
- What is osmolality? What is osmolarity?
- How can osmolality be measured? (I said freezing point depression but they looked like they wanted more than this)
- How else can osmolality be measured? (I said calculated via 2Na + Glucose + Urea, they stared at my equation and gave me a look that suggested that was wrong - I checked it wasn't, maybe they were looking for something else).
- Have you heard of an osmometer? (Honesty being the best policy I said No! I have since heard that this seems to come up every year for a few people so might be worth spending a few minutes on). 5mins up so moved on.
3. Gas exchange - lungs & placenta
- Compare the lungs with the placenta as gas exchange organs (Talked about Fick's law and how they relate to the lungs and the placenta, they wanted numbers for SA and thickness which I did not know, subsequently asked me to state which was larger SA and thinner membrane - both lungs).
- What are the adaptations of the placental and uterine circulations that promote transfer of oxygen? ('Fetal haemoglobin, high fetal Hb concentration - they wanted a value at term which I didn't know, Double Bohr effect - they wanted the oxygen-Hb dissociation curve with this and then arrows demonstrating the direction of change).
- How do we measure the affinity of Hb for oxygen? (p50 value).
- What is the value for adult Hb? (26mmHg).
- What is the value for fetal Hb? (Didn't know but said it was lower as high affinity - they gave me that it was 19mmHg to try and help me out with the next part of the question).
- What is the saturation of blood in the umbilical artery and vein? (Unfortunately I knew the pO2 values but not the sats - I'd recommend learning these if poss. I estimated what the sats would be from the values I knew for pO2, they seemed relatively happy with this). 5mins up.
4. Flow, pressure & volume during breathing
- Draw graphs of the changes in gas flow, alveolar pressure and intrapleural pressure during QUIET TIDAL BREATHING. Include units. (West 8ed p111).
- How do these graphs change in IPPV? (They gave me a bit of help during these questions, I drew the intrapleural pressure graph with the wrong shape and they said "Are you sure" to which I said no and changed it - I had to think on my feet to change the graphs for IPPV).
Overall the examiners were more than fair although they didn't give much away as to how I was doing. Got some help in the form of "Are you sure" comments. I left the viva feeling like it hadn't gone great but might have passed. Subsequently passed. If I could offer any advice it would be to keep calm(ish). If a bad question comes up just think about it for a few seconds, scrape in as many marks as you can and then put it out of your mind when you start the next question. Other candidates will also have to deal with difficult questions, if you can keep calm, you will do better than the rest.
What I can remember from my Viva September 2012, Tuesday AM:
1. Change in position
- What happens when a person stands from a supine position?
- Various questions relating to site and function of baroreceptors, effect on SVR, MAP, HR
- How much blood pools in the lower limbs?
- Tell me about flow
- Laminar flow, hagan poiseuille, examples of laminar flow
- Turbulent flow, Reynolds number, examples of which. Effect of increasing viscosity/density on the flow type, tube length.
- How do we measure flow in Anaesthesia? Rotameters, pneumotachograph
- Where would you find a pneumotachograph. How does it work. What are important principles in its use?
3. What are the respiratory changes with aging?
- Various questions on the decreases, effect that Anaesthesia could have.
- Significance of FRC/closing capacity, significant ages- 45 supine, 65 erect
4. Temperature regulation
- What is thermoneutral zone? Other than adult male are there any different groups? what affects the thermoneutral zone?
- What is normal body temperature?
- What is the interthreshold range? How is this affected by Anaesthesia?
- Draw me a graph of heat loss during general Anaesthesia, explain each step.
- What ways can heat be lost in theatre?
- What is the main way?
- How does this occur?
Reasonably fair viva overall, examiners were very friendly. Agree with the comment above that time is your enemy. If you don't know, say so and move on so you can answer something you do know! It really isn't like practice vivas where people try to catch you out. Good luck!
1. Blood Pressure Measurement
- Shown a picture of a monitor screen with IA line and NIBP. How is the blood pressure monitored in this case? (two ways IA line and NIBP).
- What are the causes for inaccuracies in each?
- How is intra-arterial BP monitored? (explained where SBP and DBP and MAP was)
- You have shown me where the lines are, but how does the IA line get these numbers? (Explained about transducer and change in resistance in the circuit, but he didnt seem to happy)
- How is NIBP measured? talked about oscillotonometry and drew the graph of oscillation vs time and marked out sbp and map and dbp and explained that DBP can be calculated? What is the formula for this calculation?
2. Oxygen Stores
- Name the sources of oxygen in the body.
- How much does the Lung store?
- How much does Hb store?
- Oxygen flux equation and of each variable.
- So how much is in the body in total?
- Oxygen consumption in neonate versus adult.
3. BP & exercise
- Draw the SBP DBP and MAP change for mild moderate and severe exercise.
- Why does the SBP line rise faster than the DBP line?
- What about MAP, why does it rise as such? (explained its due to the contribution of SBP and DBP).
- What happens when exercise stops (BP dips the rises again due to baroreceptor reflex)
- What is the role of oxygen in this? (aerobic respiration in the mitochondria, final step in electron transport chain').
- Write the formula for final step (formula for metabolic water).
- What does oxygen do in this step? (electron acceptor)
- You mentioned oxygen debt, when does it happen? whats the difference between oxygen debt and deficit?
4. Nerve Action Potential
- Name some excitable cells in the body.
- Draw a nerve action potential. What is happening at the upstroke? What is happening at the downstroke? where is there an overshoot for potassium? (the channels open longer).
- What is the resting membrane potential. What is it due to? How can this be determined (Nernst equation).
- What is the membrane potential if it was due solely to potassium?
- What about if the RMP was due solely to sodium? Which direction do Na and K move in?
- Why does action potential travel only forward? (due to refractory periods)
- What is the refractory period of nerve?
- Draw the graph for ion conductance for Na and K in a nerve. Draw a muscle action potential. What is the refractory period of muscle?
Examiners were nice and helpful. I struggled with the 2nd question and said I don't know a couple of times and the examiners moved on --- My viva (for 'old exam') on Monday:
Examiner 1: 1. Flow
- what kinds of flow are there? what are their differences? what is the flow within alveoli? what factors would contribute to different kinds of flow? if you want to flush an anesthetic circuit, which kind of flow would you use? draw a graph with Y axis being AWR and X-axis being from "mouth to alveoli"
- What is resting membrane potential?
- Complete a form for various extra- and intra-cellular ion concentrations
- What are the factors contributing to RMP?
- Derive the nernst equation, explain each item in the formula.
- What will the membrane potential be like if solely due to potassium? it will be more negative, why?
- Tell me the goldman form of the equation.
Examiner 2: 3. Coronary blood supply
- anatomy of coronary arteries.
- draw curves of left and right coronary arteries flow vs time.
- what happens to coronary blood flow with sympathetic stimulation?
- what are the regulating factors for coronary blood flow?
- functions of placenta?
- tell me about gas transport across placenta, do you know any equation governing it?
- tell me about double Bohr effect, draw curves.
- tell me about the endocrine functions of the placenta.
BELL... Good luck to everybody who will be taking the new exam! :D