Physiology in Anaesthesia: Part 5

Question 1

What is the calculation of body mass index

Answer 1

BMI = mass (kg) / height^2 (m)

Question 2

What is the FEV1 / FVC ratio

Answer 2

The forced expiratory volume in the first second, as compared to the total forced vital capacity

Question 3

What is the function of the FEV1/FVC ratio

Answer 3

It is indicative of the severity of obstructive airway disease;
Can be used to assess response to bronchodilator therapy

Question 4

What are the normal and pathological values of the FEV1/FVC ratio

Answer 4

Normal: 0.75-0.8
Mild COAD: <0.7
Moderate COAD: <0.6
Severe COAD: <0.5

Question 5

Complications of total parenteral nutrition

Answer 5

A. METABOLIC
1. hyper/hypoglycaemia
2. hypophosphataemia / hypomagnasaemia / hypocalcaemia / hypokalaemia
3. hyperosmolar non-ketotic states
4. hyperchloraemic metabolic acidosis
B. IATROGENIC
1. volume overload
2. increased work of breathing secondary to raised PaCO2, due to overfeeding
3. catheter sepsis
ORGANS
1. renal dysfunction
2. hepatic dysfunction

Question 6

What are the oxygen requirements of
1. adults
2. neonates

Answer 6

1. 3-4ml/kg/min
2. 7-9ml/kg/min

Question 7

What is the usual pulse oximetry reading in methaemoglobinaemia

Answer 7

85%

Question 8

Mixed venous saturation:
1. normal value
2. factors affecting the value

Answer 8

1. 75%
2. Hb
   cardiac output
   PaO2
   O2 consumption

Question 9

Three major goals in management of atrial fibrillation

Answer 9

1. control of ventricular rate
2. assessment and attainment of anticoaggulant needs
3. conversion to sinus rhythm

Question 10

What compensatory mechanisms exist for respiratory alkalosis

Answer 10

1. increased production of CO2 by the bicarbonate buffer system
2. production of lactate and pyruvic acid by glycolysis of phospho-fructinase
3. decreased reabsorption of bicarbonate by renal tubules of the nephrons

Question 11

Name the components of work of breathing

Answer 11

1. work required to overcome elastic forces of the lung
2. work required to overcome frictional resistance of the airways

Question 12

Name causes of leftward shifts of the oxygen-haemoglobin dissociation curve

Answer 12

1. alkalosis
2. hypothermia
3. foetal haemoglobin
4. carboxyhaemoglobinaemia
5. methaemoglobinaemia
6. sulphahaemoglobinaemia
7. reduced 2,3-DPG

Question 13

Name causes of a rightward shift of the oxygen-haemoglobin dissociation curve

Answer 13

1. acidosis
2. hyperthermia
3. raised 2,3-DPG
4. pregnancy
5. sickle Hb
6. thallasaemia