C&P: Physiological Effects of Inhalational Agents

Question 1

Cardiac Contractility

Answer 1

Halothane: massive fall
Isoflurane: some fall
Sevoflurane: some fall
Desflurane: no change
Nitrous oxide: some fall

Question 2

Heart Rate

Answer 2

Halothane: big fall
Isoflurane: big rise
Sevoflurane: no change
Desflurane: rise (big rise at >1.5 mac)
Nitrous oxide: no change

Question 3

Systemic Vascular Resistance

Answer 3

Isoflurane + desflurane–big fall

All others moderate fall

Question 4

Blood Pressure

Answer 4

Sevoflurane is the least fall, all have overall falls

Question 5

Sensitivity to Catecholamines

Answer 5

Halothane: increased +++

No change to others

Question 6

Respiratory Rate

Answer 6

Increased for all

Question 7

Effect of PaCO2

Answer 7

Same for nitrous and halothane

Increased for all others

Question 8

Bronchodilation

Answer 8

Halothane and sevoflurane bronchodilate (also enflurane)

Desflurane is an irritant

Question 9

Cerebral Blood Flow

Answer 9

Halothane: big increase
Isoflurane: increased
Sevoflurane: preserved autoregulation
Desflurane: increase
Nitrous oxide: increase

Question 10

Cerebral Metabolic Rate (O2 consumption)

Answer 10

Reduced for all except nitrous oxide (moderate increase)

Question 11

EEG

Answer 11

Burst suppression except enflurane (epileptiform activity)

Question 12

Uterus

Answer 12

Significant relaxation in all volatiles except nitrous

Question 13

Misc

Answer 13

Halothane: hepatotoxic, stored in 0.01% thymol, light sensitive
Isoflurane: coronary steal, maintains renal blood flow
Sevoflurane: renal toxicity
Desflurane: nil
Nitrous oxide: oxidizes cobalt ion in vitamin B12