Desflurane induction

There is rapid desflurane induction of anaesthesia because of low solubility in blood, but a mask induction may produce coughing, breath holding, secretions and desaturation.

Also the high initial percentage of desflurane induction may cause tachycardia and hypertension due to sympathetic effects. It is not recommended for inhalation induction.

Recovery from desflurane induction is faster than all other volatile agents, half the time after isoflurane anaesthesia. In view of its quick induction and recovery it may be useful in daycare surgery but cost is prohibitive.

We can read the following about desflurane induction in Miller’s anesthesia –

The height of the Fa/Fi ratio at which the balance is struck depends on the solubility factor in the uptake equation (see the earlier equation for anesthetic uptake).

Greater solubility increases uptake for a given alveolar-to-venous partial pressure difference. Hence, the initial rapid rise in Fa/Fi is halted at a lower level with a more soluble agent.

This results in the first “knee” in the curve—higher for desflurane induction than for sevoflurane, higher for sevoflurane than for isoflurane, and higher for isoflurane than for methoxyflurane.

The position of nitrous oxide is discussed later (see “The Concentration Effect”). At 1 minute of anesthetic administration, the Fa/Fi ratio is approximately 0.6 for desflurane, which indicates that the Fa/Fi ratio still has 40% to rise (i.e., uptake is removing 40% of the desflurane induction delivered by ventilation).

In contrast, the Fa/Fi ratio for methoxyflurane has risen only 6.5%, thus indicating that 93.5% of the methoxyflurane delivered by ventilation is taken up.

 

Leave a Reply