Desflurane, Sevoflurane, Enflurane and Isoflurane

Desflurane

Rapid onset & recovery

Desflurane has low blood gas partition coefficient, thus rapid onset and recovery.

Pungent / irritant

It is pungent and irritant to airways, and is not used for induction, as will cause irritation in awake patients, leading to bronchospasm and laryngospasm.

It also increases secretions, but can be used during maintenance phase, as reflexes are abolished.

Low volatility

It has low volatile property to make it vaporize, thus special vaporizers are used.

Sevoflurane

Rapid onset & recovery

Sevoflurane has low blood gas partition coefficient, thus has rapid onset and recovery.

Nephrotoxic

It is a potential nephrotoxic compound because:

1. Compound A – soda lime

When it passes through anesthetic machine, it interacts with soda lime (CO2 absorber) and produces toxic compound A. It is in part metabolized by beta lyase, which is an intra-renal enzyme, leading to formation of toxic metabolites.

2. Hepatic – Fl^–

Part is metabolized by liver, free inorganic fluoride ions are produced, which are nephrotoxic.

Enflurane

Slow induction & recovery

Enflurane has higher blood gas partition coefficient thus has slow induction and recovery.

Potential nephrotoxic – beta-lyase

It is potentially nephrotoxic. It is part metabolized by beta lyase intra-renally, producing inorganic fluoride ions, which are toxic to renal tissue. Till certain levels, it does not disturb kidney functions.

Seizure-like activity

By acting on central nervous system seizure like activity is observed. It is self-limited and does not cause permanent damage. So this agent is not used in epileptic patients or with other such related disorders.

Isoflurane

Rapid onset & recovery

Isoflurane has low blood gas partition coefficient, thus has rapid onset and recovery.

Advantage:

Coronary vasodilatation –because of this beneficial in patients of ischemic heart disease

As has pungent characteristic so no used for induction, so may cause irritation, increased secretions, laryngospasm and bronchospasm.

Afterwards used for maintenance phase.

Halothane	Isoflurane
Sensitizes heart to catecholamines	Less sensitization
Can be used for induction	Not used
Not cardio stable	Cardio stable
No coronary steal syndrome	Coronary steal syndrome
No nausea, vomiting, less irritant	Cough, irritant, nausea, vomiting