Flourinated Anesthetics – Compilation

Ans. is ‘d’ i.e., 6

Methoxyflurane (MAC = 0.16 %)> Trilene (MAC = 0.2%)> Halothane (MAC = 0.74%)> Chloroform (MAC = 0.8 %) > Isoflurane (MAC = 1.15 %) > Enflurane (MAC= 1.68%) > Ether (MAC = 1.92 %) > Sevoflurane (MAC = 2.0 %) > Desflurane (MAC = 6.0%)> Cyclopropane (MAC = 9.2%) > N₂0 (MAC 104%).

Ans. is ‘b’ i.e., Enflurane

Enflurane is known to produce seizures.

B i.e. Trichloro ethylene

Sodalime with trilene forms phosgene (neurotoxic) gas.Q So this combination is contraindicated.

Sodalime is a mixture of 94% (Ca(OH)₂ + 5% NaOH as catalyst + 1% KOHQ; with granule size of 4-8 meshQ. It should not be used with :

The drier the sodalime, the more likely it will degrade & absorb volatile anesthetics. It produces compound A with sevofluraneQ (clinically significant) and carbon monoxide with desflurane, isoflurane & enflurane (clinically insignificant). However, desflurarte can be broken down to CO by dry barium hydroxide lime to such an extent that it is capable of causing clinically significant CO poisoning.

B i.e. Enflurane 

B i.e. It is a structural analogue of isoflurane 

Desflurane’s structure is very similar to that of isoflurane. The only difference is substitution of a fluride atom for isofluranes chlorine atom. Q

B i.e. Sevoflurane causes seizures, C i.e. Rapid recovery from propofol >> A i.e. Enflurane interacts with sodalime

MAC (minimal alveolar concentration) is the best measure of anesthetic potencyQ.

Sevoflurane has anticonvulsant propertiesQ with no excitatory phenomenon, no increase in CBF or intracranial pressure. Muscle tone is reduced, potentiating nondepolarizing muscle relaxants. Cerebral 02 demand is decreased.

Sevoflurane, isoflurane & desflurane have anticonvulsant propertiesQ. Whereas, the main disadvantage of enflurane is that it often causes epileptiform EEG changesQ (more commonly during hypocapnia) that may persist for several weeks. Cerebral blood flow is doubled at MAC 1 and convulsionsQ occur at MAC2, so it should be used with extreme caution (or avoided) in patients with h/o epilepsy. Muscle relaxation is greater with enflurane than with halothane or isoflurane, enhancing the action of nondepolarizing relaxants.

Enflurane interacts with sodalime but produce clinically insignificant amount of carbonmonooxide. Propofol has smooth & rapid induction and rapid recoveryQ.

Ketamine is a noncompetitive NMDA (glutamate) receptor antagonistQ and does not act on GABA-A receptor.

D i.e. Enflurane

“General anaesthesia is indicated in case of acute infection when LA may not be effective because of the local change in pH and there is a risk of spreading infecton”.Q

Anaesthesia in Dental Extraction

Local anesthesia would be adequate except in few situations as –

–  inability to tolerate dental treatment using LA (especially children).

– failure of previous attempt to treat under LA.

–   patients with special needs or disability which make it impossible to sit still (e.g. uncontrolled movements).

– allergy to LA

– acute infection when local anesthesia may not be affective because of the local change in pHQ and there is risk of spreading infection.

Enflurane is most suitable inhalational agent for dental anesthesia with fewer irritant propertiesQ than isoflurane and a short recovery time. Isoflurane is widely used in contemporary practice, but is not recommended for dental surgery in spontaneously breathing patients as it is irritant and is associated with coughing, salivation, and desaturation.

Ans. is ‘a’ i.e., Carbon monoxide 

Ans. is ‘c’ i.e., Isoflurane

Anaesthetic agents of choice for vaous conditions Day care :

Ans. is ‘a’ i.e., Methooxyflurane 

Ans. is ‘b’ i.e., Desflurane 

Ans. is ‘a’ i.e., Desflurane 

• decreasing order (Increasing order of B : G partition coefficient and blood solubility) : –

Ans. is ‘c’ i.e., Isoflurane

Induction by inhalation agents

Unpleasant    Intermediate                Smooth

 Ether Halothane Isoflurane

En flurane Desflurane  

Sevoflurane

Nitrous oxide

Ans. is ‘c’ i.e., Desflurane