Physiology of Anaesthesia Questions

Question 1

Which areas of the brain are responsible for control of respiration?

Answer 1

Pons, medulla oblongata

Question 2

Explain the mechanism by which slow or shallow respiration stimulates a fall in blood pH and how the body responds in a non-anaesthetised animal

Answer 2

1, Slow or shallow respiration leads to accumulation of CO2 in the blood which lowers pH .
2, Detected by chemoreceptors in the medulla oblongata which
3, Stimulate an increased respiratory rate to remove more CO2 from the respiratory system and lower blood levels

Question 3

Explain the meaning of the term Tidal volume and how it would be calculated for a patient who weighs 14kg.

Answer 3

Tidal volume is the volume of gas passing in or out of the lungs in one breath. For a patient of 14kg tidal volume would be 14kg x 10ml/kg = 140ml.

Question 4

Explain what is meant by the term ‘dead space’.

Answer 4

This is where gas passes into the respiratory tract but does not participate in actual gas exchange

Question 5

give one cause of hypoxia that may be related to anaesthetic equipment

Answer 5

cylinder empty/faulty O2 supply, obstruction of ET tube or circuit….

Question 6

List the factors that might affect heart rate and therefore cardiac output in an anaesthetised patient

Answer 6

Drugs used, pre-existing health condition, depth of anaesthesia, pain

Question 7

List 3 factors that affect systemic vascular resistance in a patient

Answer 7

Local metabolic, sympathetic nervous system increasing vascular tone, hormones and drugs

Question 8

Explain why the doses of some drugs may need to be lowered when

administered to a patient with known hepatic disease

Answer 8

The liver is responsible for the metabolism of many anaesthetic drugs