Pharmacology for Anaesthesia and Intensive Care

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Section IICoredrugs in anaesthetic practice

Table 8.8.Cardiovascular effects of inhaled anaesthetics.

Halothane Isoflurane Enflurane Desflurane Sevoflurane

Contractility ↓↓↓ ↓ ↓↓ minimal ↓

Heart rate ↓↓ ↑↑ ↑ ↑(↑↑>1.5

MAC)

nil

Systemic vascular

resistance

↓↓↓↓↓↓ ↓

Blood pressure ↓↓ ↓↓ ↓↓ ↓↓ ↓

Coronary steal syndrome no possibly no no no

Splanchnic blood flow ↓ unchanged↓ unchanged unchanged

Sensitization to

catecholamines

↑↑↑ nil ↑ nil nil

Table 8.9.Respiratory effects of inhaled anaesthetics.

Halothane Isoflurane Enflurane Desflurane Sevoflurane

Respiratory Rate ↑↑↑↑↑↑↑↑↑

Tidal volume ↓↓↓↓↓↓ ↓↓ ↓

PaCO 2 unchanged ↑↑ ↑↑↑ ↑↑ ↑

it appears to increase the cerebral blood flow in a variable manner, and its use in

anaesthesia for neurosurgery is not recommended.


Analgesia – it has significant analgesic properties.

Elimination

Xenon is not metabolized in the body, rather it is eliminated via the lungs.

Non-anaesthetic medical gases

Oxygen

Manufacture and storage

Oxygen (O 2 )ismanufactured by the fractional distillation of air or by means of an

oxygen concentrator in which a zeolite mesh adsorbs N 2 so that the remaining gas is

about 97% O 2 .Itisstored as a gas in black cylinders with white shoulders at 137 bar

and as a liquid in a vacuum insulated evaporator (VIE) at 10 bar and− 180 ◦C, which

must be located outside. The VIE rests on three legs; two are hinged while the third

serves as a weighing device, enabling its contents to be displayed on a dial.

Physiochemical properties


Boiling point− 182 ◦C


Critical temperature− 119 ◦C


Critical pressure 50 bar