Practical Examples of Drugs used during Maintenance

Question 1

When monitoring the information of an SV anaesthetic and an IPPV anaesthetic, which parameters are fundamentally different?

Answer 1

Respiratory rate and tidal volume, ETCO2.

During IPPV the anaesthetist controls the respiratory rate and tidal volume, whereas during SV the rate and depth of breathing (and therefore also the ETCO2) are determined by the patient, and provide an additional monitor to the anaesthetist.

The respiratory pattern in response to surgical stimulation is one of the most sensitive markers of an adequate depth of anaesthesia.

Question 2

What is one of the most sensitive markers of anaesthetic depth in a SV patient

Answer 2

Respiratory rate and pattern in response to surgical stimulation

Question 3

List the four types of drugs that are administered during and anaesthetic

Answer 3

Volatile agent and N2O
Opioids (intra-operative and post-operative analgaesia)
NMB agents
Oxygen

Question 4

What is common intra-operative dosing of fentanyl and morphine during anaesthesia with a spontaneously ventilating patient and how long until the effect is observed

Answer 4

Fentanyl in increments of 25 mcg IV (up to a total of 100 mcg) will be effective within 1-2 min.

Alternatively, morphine may be given (increments of 2 mg) but has a slower onset time; it will last into the post-operative period, however.

Question 5

What does of fentanyl and morphine are required for intra-operative analgaesia in a patient undergoing IPPV and why is this different to an SV patient?

Answer 5

Fentanyl 1 - 1.5 ug/kg (50 - 100ug)

Morphine 0.1 mg/kg (5 - 10mg)

Question 6

How is the dose of a depolarizing muscle relaxant altered after giving SUX for RSI?

Answer 6

Reduced by 25%

Question 7

If top-up doses of non-depolarizing muscle relaxant is required, what dose should be administered

Answer 7

25% of the initial dose AVOID giving muscle relaxant within 10 - 15 minutes of the end of the procedure.