Isoflurane Flashcards
What is isoflurane?
A halogenated ethyl methyl ether.
A structural isomer of enflurane.
Molecular weight of isoflurane
184.5
BP of isoflurane
48.5 degrees C
SVP at 20 degrees (kPa)
33.2
MAC %
1.17
Blood:gas partition coefficient
1.40
Oil:gas partition coefficient
98
Odour
Irritant
Effect on EEG
Burst suppression
Effect on uterus
Some relaxation
Potentiation of muscle relaxation
Significant
Analgesia
Some
What are the respiratory effects of isoflurane?
Depresses ventilation (enflurane> isoflurane > halothane)
Minute volume decreased while RR and PaCO2 increased.
Pungent smell can irritate upper airways, coughing and breath holding.
Can cause some bronchodilation.
What are the cardiovascular effects of isoflurane?
Reduces SVR. Carotid sinus baro reflex preserved as there is a reflex tachycardia.
Only a small decrease in cardiac contractility and CO.
Coronary steal syndrome: normally responsive coronary arterioles dilate and take blood from atherosclerotic arterioles, leading to ischaemia (shouldn’t occur as long as coronary perfusion maintained).
May have myocardial protective properties via its effect on ATP-dependent potassium channels.
CNS effects of isoflurane
Of all the volatile agents, produces the best balance of reduced cerebral O2 requirement and minimal increase in cerebral blood flow.
At concentrations up to 1 MAC cerebral autoregulation is preserved.
