Barbiturates

The intravenous barbiturates remain amongst the most widely studied drugs and are the standard for comparison with all new intravenous anesthetics. No drug has yet been seriously able to challenge thiopental, which remains the intravenous anesthetic of choice for most anesthesiologists. The adventages are readily apparent: rapid smooth onset of action in one arm-brain circulation time, short duration of action with rapid emergence, minimal excitatory effects, good dose response, lack of interaction with muscle relaxants, uncommon adverse reactions, and minimal postoperative vomiting or emergence delirium. The disadvantages are also well-known, including respiratory and cardiovascular depression, poor abdominal relaxation, lack of analgesia, and prolonged hangover with slow complete recovery. Although there are many relative contraindications to the use of the barbiturates, the main absolute contraindications are porphyria and known allergy. In most patients the potential for complications can be easily identified by careful history-taking and examination. Although the barbiturates are far from the ideal intravenous anesthetics, most of us have learned to live within their limitations but look forward to the discovery of improved agents for the future.