AWABS - Day 3 SBA questions

Question 1

Atmospheric pressure at sea level

Answer 1

1 Atm which almost equal to 1 Bar

Question 2

Boyle’s law

Answer 2

Pressure inversely proportional to volume

Question 3

How to calculate atmospheric pressure underwater

Answer 3

Calculate as cmH2O and then convert to relevant unit (usually Bar)

Eg:
20m underwater
= 2000 cmH2O
= 200 kPa
= 2 Bar

Therefore atmospheric pressure = 3 Bar total (1 bar at sea level + 2 bar as 20m underwater)

Question 4

Calculating Nitrous oxide capacity in a

Answer 4

Avagadro’s hypothesis

Moles = weight of N2O in grams / 44

1 mole of any gas will occupy 22.4 L of volume

Question 5

Laser resistant ETT

Answer 5

Laser resistant material - stainless steel
Dual cuff - still provides airway protection if top cuff bursts
Inflate cuff with saline for fire protection

Question 6

What does Laser stand for

Answer 6

Light Amplification by Stimulated Emission of Radiation

Question 7

Potential hazards of Laser use in clinical practice

Answer 7

Airway fire from ETT ignition
Other laser fires from drapes or alcohol skin prep
Gas embolus
Accidental vessel or viscus perforation
Eye damage

Question 8

Immediate steps to manage an airway fire in an intubated patient

Answer 8

Calling for help
Inform theatre staff
Stop laser
Disconnect ventilator / fresh gas flow
Extinguish fire by flooding airway
Remove flammable or tube on fire from airway
Restart ventilation with minimal gas flow initially
Examine airway for damage
Consider bronchoscopy / reintubation once stable

Question 9

Pin index safety system numbers for each gas

Answer 9

Air 1 and 5
Oxygen 2 and 5
Nitrous oxide 3 and 5

Question 10

On arterial line set, what pressure should saline bag be at and what rate does it flush the system

Answer 10

Pressure well above systolic BP - usually set to 300 mmHg

4ml per hour

Question 11

Example of normal, overdamped and underdamped arterial line trace

Answer 11

Question 12

Disadvantages of invasive blood pressure monitoring

Answer 12

Risk of infection
Arterial damage
Ischaemia
Thrombi
Haemorrhage

Question 13

Factors which affect laminar flow through a tube

Answer 13

Hagen-Poiseuille equation gives the answers

Question 14

Monro-Kellie doctrine

Answer 14

Sum of the volumes within the skull must remain constant.

In increase in volume of one (eg blood) must result in a decrease in volumes of the others to compensate

Question 15

Cushing’s response

Answer 15

Physiological signs associated with raised ICP and impending herniation through the foramen magnum.

Cushing’s triad:
Bradycardia
Hypertension
Irregular breathing

Question 16

Methods to maintain cerebral perfusion pressure

Answer 16

Neurosurgery
Avoid tight tube ties / collars
Maintain oxygenation
Normocarbia
Normoglycaemia and electrolytes
Maintain MAP
Head up to allow venous drainage
Avoid hyperthermia
Avoid coughing - paralyse pt if needed

Question 17

Coronary vessel anatomy

Answer 17

1 - Left coronary artery main stem
2 - Circumflex artery
3 - Right coronary artery
4 - Left anterior descending branch
5 - Right marginal branch

Question 18

Origin of coronary arteries

Answer 18

Aortic sinuses

Question 19

Venous drainage of the heart

Answer 19

80% via coronary sinus
20% directly into right atrium via smaller venous system inc Thebesian vein