SAQ 2017.2 Question 5

Outline the factors which influence the time taken for loss of consciousness with an inhalational induction of anaesthesia.

Loss of consciousness will be faster with a smaller FRC     TRUE/FALSE

Loss of consciousness will be faster in a patient who is anxious and struggling    TRUE/FALSE

Loss of consciousness will be faster with a more soluble anaesthetic agent    TRUE/FALSE

Loss of consciousness will be faster with an increased cardiac output    TRUE/FALSE

Benzodiazepine premedication may speed the process in some patients, and slow it in others    TRUE/FALSE

 

 

SAQ 2017.2 Question 3

a) Describe the immediate cardiovascular responses to the sudden loss of 30% of the blood volume in a healthy awake person
b) How are these responses different if the patient is undergoing anaesthesia with sevoflurane?

The decrease in blood volume will be detected by the high pressure baroreceptors in the atria    TRUE/FALSE

The response will be mediated by the cardiovascular centre in the medulla    TRUE/FALSE

There will be arterial but not venous constriction    TRUE/FALSE

Sevoflurane will impair contractility    TRUE/FALSE

Sevoflurane will depress baroreceptor signalling    TRUE/FALSE

 

Aviation 6 – Decompression Illness

Today we return to North Africa.  Flying Officer Reynolds flew 25 missions above 40,000 feet over a single month.  The German Ju 86’s flew at ever increasing altitudes as three out of the four available aircraft had been shot down by British Spitfires.  The final Ju 86 flight was at nearly 50,000 ft and Reynolds was again in pursuit.

He had been at over 45,000 feet for over an hour and he was suffering from the effects of altitude:

“his whole cockpit, instrument panel, control column and perspex were thickly coated with ice; his body was racked with pain and his arms temporarily paralysed, and his eyesight also failing with weakness.”  — John Frayn Turner.   British Aircraft of the Second World War

Reynolds was probably suffering from “The Bends” or decompression illness.  You may have encountered this condition in the context of diving but it is also well recognised in high altitude aviation.

Occasionally and ironically, tourists are diagnosed with decompression illness in Alice Springs. How is this possible you ask?

Well, they go diving in North Queensland and then fly to the Red Centre, the exposure to altitude soon after diving is enough to “Bend” them.

The relevance of decompression illness to anaesthesia may seem a little obscure.  The body in decompression illness is simply behaving like a human vapouriser where nitrogen is the volatile agent.

BT_SQ 1.12 Describe the principles and safe operation of vaporisers

TRUE/FALSE Henry’s Law is relevant to vaporiser functioning 

TRUE/FALSE The Aladin cassette vaporiser is an example of an injection vaporiser system

TRUE/FALSE Modern vaporisers use an electrical heating coil to compensate for the cooling caused by latent heat of vaporisation

TRUE/FALSE A plenum vaporiser is designed so that the gas leaving the bypass is fully saturated under normal conditions

TRUE/FALSE The Tec Mark 5 vaporiser is designed to be ‘tip resistant’

As an extra exercise, see if you can find or work out the properties of nitrogen and the circumstances that relate to it “vapourising” in the body at altitude (in the same the way you would think about an inhalational agent).

BT_GS 1.53 Describe the synergism between anaesthetic agents, opioids and regional blockade and how this is used clinically

TRUE/FALSE  Moderate doses of opioids can reduce MAC of volatile agents by as much as 75%.

TRUE/FALSE  50% reduction in doses is expected when propofol and midazolam are used together for hypnosis.

TRUE/FALSE  The exact degree of drug synergism can be calculated from pharmacokinetic data of individual agents.

TRUE/FALSE  The bispectral index is additive when propofol and remifentanil are used in total intravenous anaesthesia.

TRUE/FALSE  Midazolam has no effect on the ketamine dose required to suppress movement to a noxious stimulus.

BT_GS 1.50 Describe the concept and clinical application of MAC in relation to inhaled anaesthetic agents

TRUE/FALSE  MAC-AWAKE for Nitrous Oxide is approximately 30% of its MAC-Value

TRUE/FALSE  Sevoflurane is metabolised by the cytochrome p450 enzyme 2E1

TRUE/FALSE  The MAC of sevoflurane in a 6 month child is approximately 2%

TRUE/FALSE  The higher the inspired anesthetic concentration, the less it then diminishes because of uptake

TRUE/FALSE  Administration of 50% Nitrous oxide will double the volume of air-filled spaces

SS_OB 1.11 Describe the pharmacology of tocolytic agents with particular reference to beta 2 agonists, calcium antagonists, magnesium, inhalational anaesthetics, nitrates and NSAIDS

TRUE/FALSE  Sublingual GTN spray can be used as a uterine relaxant during Caesarean section

TRUE/FALSE  The emergency management of eclamptic seizures includes the administration 4g of Magnesium sulphate by intravenous (bolus) injection

TRUE/FALSE  Exposure to NSAIDs after 30 weeks’ gestation is associated with an reduced risk of premature closure of the fetal ductus arteriosus and oligohydramnios

TRUE/FALSE  Nifedipine is contraindicated in pregnant women with pre-existing cardiac disease

TRUE/FALSE  Calcium channel blockers are associated with a higher incidence of neonatal respiratory distress syndrome than other tocolytic drugs

SS_PA 1.79 Describe the maximum safe doses of local anaesthetic agents in different age groups

TRUE/FALSE  Neonates are more prone to develop methaemogolbinaemia with prilocaine administration due to the presence of foetal haemoglobin

TRUE/FALSE  Transfer of local anaesthetics across the placenta is inversely proportional to drug lipophilicity

TRUE/FALSE  Methaemoglobin reductase requres NADH as an electron donor

TRUE/FALSE  Methaemoglobin reductase is functionally deficient in the neonate

TRUE/FALSE  Children are more prone to cocaine toxicity due to reduced cholinesterase activity

Paediatric Pharmacokinetics

Paediatrics.png

SS_PA 1.51  : Describe how the pharmacokinetics of drugs commonly used in anaesthesia in neonates and children differ from adults and the implications for anaesthesia

TRUE/FALSE Water soluble drugs have a larger volume of distribution in neonates

TRUE/FALSE The half life of drugs is longer in 2 year olds than in neonates

TRUE/FALSE The FA/Fi curves in infants is steeper than in adults

TRUE/FALSE Drugs that depend on redistribution into fat compartments for their termination of action have longer durations of action in neonates

TRUE/FALSEPlasma protein binding in neonates varies both qualitatively and quantitatively

Compartmental Modelling

BT_GS 1.7 Explain the concept of pharmacokinetic modelling of single
and multiple compartment models and define:
· Half life
· Clearance
· Zero and first order kinetics
· Volume of distribution
· Bio-availability
· Area under the plasma concentration time curve
· Extraction ratio

 

TRUE/FALSE Initial volume of distribution of propofol is similar to plasma volume.

TRUE/FALSE A polyexponential curve can be expressed mathematically as

C = A/at + B/bt + C/ct

TRUE/FALSE Using a semi-log plot of plasma concentration vs time converts the curve to the sum of a number of straight lines

TRUE/FALSE Varea is calculated by extrapolating the second part of a semi-log plot back to the Y axis and using this concentration as an initial stirred volume.

TRUE/FALSE VDss is obtained by measuring plasma concentrations of drug during infusion to steady state

BT_PO 1.108 Alteration in drug response due to hepatic disease

If I want to check a registrar’s understanding of a certain topic, I will often ask about the basic physiology or pharmacology and then add a complication. This might be a disease process, a drug or an altered state of physiology. Those who have memorised an answer soon come unstuck when they are asked to apply their knowledge.

When you look through the ANZCA Primary Syllabus, such that it is, you will find a number of LOs related to these “complications”, including this one…..

BT_PO 1.108 Describe alterations to drug response due to hepatic disease

This little guy was in the case with the bears from yesterday’s photo (oh, how times have changed….)

OLYMPUS DIGITAL CAMERA

 

The clearance of propofol is minimally affected by hepatic disease  TRUE/FALSE

Patients with hepatic failure have a hyper-dynamic circulation, which will protect them from the cardiac depression effects of an induction dose of propofol     TRUE/FALSE

Reduced plasma protein levels may result in a longer than expected duration of action for highly protein bound drugs     TRUE/FALSE

All volatile anaesthetic agents have been shown to decrease hepatic blood flow independent of a reduction in mean arterial pressure   TRUE/FALSE

Oral bioavailability of drug with a high extraction ratio, such as morphine, may be markedly reduced in patients with severe liver disease     TRUE/FALSE