AWABS - Day 3 SBA questions Flashcards
Atmospheric pressure at sea level
1 Atm which almost equal to 1 Bar
Boyle’s law
Pressure inversely proportional to volume
How to calculate atmospheric pressure underwater
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)
Calculating Nitrous oxide capacity in a
Avagadro’s hypothesis
Moles = weight of N2O in grams / 44
1 mole of any gas will occupy 22.4 L of volume
Laser resistant ETT
Laser resistant material - stainless steel
Dual cuff - still provides airway protection if top cuff bursts
Inflate cuff with saline for fire protection
What does Laser stand for
Light Amplification by Stimulated Emission of Radiation
Potential hazards of Laser use in clinical practice
Airway fire from ETT ignition
Other laser fires from drapes or alcohol skin prep
Gas embolus
Accidental vessel or viscus perforation
Eye damage
Immediate steps to manage an airway fire in an intubated patient
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
Pin index safety system numbers for each gas
Air 1 and 5
Oxygen 2 and 5
Nitrous oxide 3 and 5
On arterial line set, what pressure should saline bag be at and what rate does it flush the system
Pressure well above systolic BP - usually set to 300 mmHg
4ml per hour
Example of normal, overdamped and underdamped arterial line trace
Disadvantages of invasive blood pressure monitoring
Risk of infection
Arterial damage
Ischaemia
Thrombi
Haemorrhage
Factors which affect laminar flow through a tube
Hagen-Poiseuille equation gives the answers
Monro-Kellie doctrine
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
Cushing’s response
Physiological signs associated with raised ICP and impending herniation through the foramen magnum.
Cushing’s triad:
Bradycardia
Hypertension
Irregular breathing
Coronary vessel anatomy
1 - Left coronary artery main stem
2 - Circumflex artery
3 - Right coronary artery
4 - Left anterior descending branch
5 - Right marginal branch
Venous drainage of the heart
80% via coronary sinus
20% directly into right atrium via smaller venous system inc Thebesian vein
