Inhalational Anesthetic Agents
General Considerations
The first real general anesthetics.
Set the standard.
Chloroform (too toxic), ether (diethyl ether, too flammable) and, later, methoxyflurane (too nephrotoxic)
are of primarily historical interest.
Nitrous oxide (laughing gas) continues to be a useful agent, as well as five potent volatile (inhalational) agents
(in chronological order):
Advantages of inhalational anesthesia
- Provide for completely painless induction of anesthesia.
- No IV (intravenous) access needed.
- Most rapid appearance of drug in arterial blood (agent goes direct from lungs to left heart and aorta, bypassing venous system and right heart).
- Most efficient choice in patient with difficult IV access. In fact, inhalational agents cause peripheral venous
dilation that facilitates IV access AFTER induction of anesthesia.
- So easily and safely administered by modern anesthesia machines, that inhalational agents remain the most popular
anesthetic maintenance agents in the OR (operating room).
- Safe: as long as patient is breathing satisfactorily, elimination of agent and emergence from anesthesia is essentially guaranteed.
(Spontaneous ventilation thus may be said to be safest!)
