MINIMAL ALVEOLAR CONCENTRATION (MAC)

MINIMAL ALVEOLAR CONCENTRATION (MAC)

Q. 1 Which of the following statements about inhalation anesthetic agents is wrong?

 A Sevoflurane is more potent than isoflurane

 B

Sevoflurane is less cardiodepressant than isoflurane

 C

Desflurane has lower blood-gas partition coefficient than sevoflurane

 D

Sevoflurane has a higher MAC than isoflurane

Q. 1

Which of the following statements about inhalation anesthetic agents is wrong?

 A

Sevoflurane is more potent than isoflurane

 B

Sevoflurane is less cardiodepressant than isoflurane

 C

Desflurane has lower blood-gas partition coefficient than sevoflurane

 D

Sevoflurane has a higher MAC than isoflurane

Ans. A

Explanation:

Sevoflurane is less potent than isoflurane as it lacks coronary vasodilating properties.

Ref:  Handbook of Clinical Anesthesia By Barash, Cullen, Stoelting , 5th Edition, Page 216; Handbook of Clinical Anesthesia By Paul G. Barash, Bruce F. Cullen, Robert K. Stoelting, M. Christine Stock, 6th Edition, Page 231


Q. 2

Exception of Meyer overton rule are A/E

 A

Nonanaesthetics

 B

Nonimmobilizer

 C

Cut off effect

 D

Hydrophobic site

Ans. D

Explanation:

D i.e. Hydrophobic site 

Non anesthetics/ nonimmobilizers, cut off effect convulsant gases, isomers, hydrophilic site and critical volume expanism hypothesis provide exceptions to the meyer – overton ruleQ.


Q. 3

NOT TRUE regarding sevoflurane

 A

MAC is higher than isoflurane

 B

Blood gas coefficient is higher than desflurane

 C

Potency more than isoflurane

 D

Sevoflurane is less cardio depressant than isoflurane

Ans. D

Explanation:

D i.e., Sevoflurane is less cardio depressant than isoflurane

Sevoflurane is an inhalational agent of choice for induction of anaesthesia in pediatric patients and adults, because of rapid onset of action & nonpengency

Desflurane & isoflurane are more pungent and are associated with more coughing breath holding & laryngeal spasm during inhalational induction, so not used as the first choice.

Methoxyflurane is highly nephrotoxic, so not preferred.

Sevoflurane is not recommended in the closed-circuit because there is a chance of production of a toxic metabolic product compound A, Q (an olefin) in closed circuit.

– Unlike isoflurane & desflurane, both of which lead to tachycardia, sevoflurane has minimal effect on heart rate.

Sevoflurane can cause direct myocardial depression (via calcium channels) and produce dose-dependent depression of cardiac output, & reduction in systemic vascular resistance similar to that seen in isoflurane



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