Drug:

System:

Effect:

Halothane

Central Nervous System

Fast smooth induction, stadium II absent

↑ cerebral blood flow and ↑ intracranial pressure

Autonomic

Bradycardia

CVS

↓ BP, sensitized myocardium for arythmogenic effects of catecholamines

Respiratory system

No saliva, bronchial secretions or cough

Musculo-skeletal

Skeletal muscle relaxing effects stadium III, ↑ action non-depol, ↓ action depol., Post-operative shaking → hypoxia

Uterus

↓ muscle contractions, → external twisting of baby

Liver

Hepatotoxic (rare, unpredictable)

Status

Not often used because of hepatotoxicity + newer drugs

Enflurane

CNS

Fast, smooth induction convulsions sometimes, NOT epileptics

CVS

No sensitization of the myocardium, less ↓ than Halothane

Respiratory

More↓ than Halothane

Status

Not often used. Maintenance

Isoflurane

CNS

Faster induction + recovery than Halothane

CVS

Less ↓ than Halothane + Enflurane No sensitization of myocardium

Respiratory

Potent ↓ effect. Strengthens because of potent skeletal muscle relaxing effect

Status

More ideal drug than Halothane and Enflurane. Widely used. Has replaced Halothane and enflurane. Not for patients who have to breath spontaneously.

Desflurane

CNS

Even faster induction + recovery than Isoflurane, ↑ cerebral blood flow and intracranial pressure

CVS

Less ↓ than Halothane + Enflurane

Respiratory

Strong smell, irritate airways, if used as induction drug → cough, shortness of breath and laringospasm

Status

Even more ideal than Isoflurane or sevoflurane. Potential to be used for various surgical procedures. Because of effect on resp → NOT as induction

Sevoflurane

CNS

Potentiate the effects of the non-depolarising muscle relaxants like the other halogenated ethers

Respiratory

Effects similar to Desflurane, less irritation of airways

Status

Induction and maintenance

Nitrous Oxide

CNS

Weak anesthetic, potent analgesic, amnesia

CVS

No effect

Respiratory

Pure N2O → hypoxia, always mix with O2 or air. Recovery phase: N2O fast diffusion from blood to alveoli, ↓ O2 pressure, → hypoxia

Status

As additive drug in anesthesia

Single drug for short dental procedures e.g. extractions