Enflurane

Question 1

What is enflurane?

Answer 1

A halogenated ethyl methyl ether.
Structural isomer of isoflurane.

Question 2

Respiratory effects

Answer 2

More depression of ventilation than the other agents. The minute volume decreases and the PaCO2 will rise.
The ventilatory response to hypoxia and hypercarbia are also blunted.

Question 3

Cardiovascular effects

Answer 3

Heart rate increases.
Cardiac output, contractility and blood pressure fall.
Small fall in SVR.
Heart is not sensitised to catecholamines and arrhythmias are uncommon.

Question 4

CNS effects:

Answer 4

High concs plus hypocarbia = 3Hz spike and wave pattern on EEG consistent with grand mal activity.
No evidence that these changes are seen more frequently in epileptics.

Increased CBF and ICP. Halothane > enflurane > isoflurane

Question 5

Metabolism

Answer 5

Only 2% in the liver. F- ions produced but rarely reach high level. Usually avoided in renal impairment anyway.

Question 6

Toxicity

Answer 6

Hepatic damage may occur

Question 7

Molecular weight

Answer 7

184.5

Question 8

BP

Answer 8

56.5

Question 9

SVP at 20 degrees

Answer 9

23.3

Question 10

MAC %

Answer 10

1.68

Question 11

Blood: gas

Answer 11

1.8

Question 12

Oil: gas

Answer 12

98

Question 13

Odour

Answer 13

non-irritant

Question 14

Cerebral blood flow

Answer 14

increased

Question 15

Cerebral O2 requirement

Answer 15

decreased

Question 16

EEG

Answer 16

epileptiform activity (3Hz spike and wave)

Question 17

Effect on uterus

Answer 17

some relaxation

Question 18

Potentiation of muscle relaxation

Answer 18

significant

Question 19

Analgesia

Answer 19

some