Anaesthesia Calculations

Question 1

1. Which 2 non-rebreathing systems have a bag on the expiratory limb?
2. Which 2 non-rebreathing systems have a bag on the inspiratory limb?

Answer 1

1. T-Piece and Bain.
2. Magill and Parallel Lack.

Question 2

1. Circuit factor of the T-Piece?
2. Circuit factor of the Bain?
3. Circuit factor of Magill?
4. Circuit factor of the parallel lack?
5. What is a circuit factor?

Answer 2

1. 2-3.
2. 2-3.
5. How much you must multiply the animal’s minute volume by in order to calculate the amount of oxygen that particular breathing system will need in order to push CO2 out and keep animal alive.

Question 3

1. Which non-rebreathing systems are suitable for administering IPPV?
2. Which non-rebreathing systems are not suitable for administering IPPV?

Answer 3

1. T-Piece and Bain.
2. Magill and Parallel lack.

Question 4

1. Can long-term IPPV be administered w/ circle breathing system?
2. FGF requirement for circle?
3. Practical use of circle.

Answer 4

1. Yes.
2. Minimum 10ml/kg.
3. Usually 2-3L/min for 5-10mins, then reduce (denitrogenating the system) = personal decision but must deliver at least tidal volume.

Question 5

Why do we need breathing systems?

Answer 5

• Deliver O2.
• Deliver VA.
• Remove waste – VA and CO2.

Question 6

1. How do you calculate FGF?

Answer 6

MV x CF = FGF

Question 7

How do you calculate MV?

Answer 7

Body weight x 10ml (TV) x RR = MV

Question 8

What is tidal volume assumed to be?

Answer 8

10ml/kg.

Question 9

How to calculate simple dose when given weight in kg, drug dose in mg/kg and drug strength in mg/ml.

Answer 9

Weight (kg) x drug dose (mg/kg) / drug strength (mg/ml).

Question 10

How to calculate dose when given drug dose in mcg/kg.

Answer 10

Must divide drug dose by 1000 first. And then do normal calculation.

Question 11

How to calculate drug dose in when given drug strength as a %.

Answer 11

% x 10 and then do normal calculation.