ROLE OF DIFFERENT COMPONENTS OF BALANCED ANESTHESIA IN TOLERANCE TO ENDOTRACHEAL INTUBATION

  • 1 January 1977
    • journal article
    • research article
    • Vol. 66  (5) , 254-257
Abstract
To demonstrate the role of anesthesia, analgesia and muscle paralysis in suppressing the responses to nociceptive stimuli during balanced anesthesia, the effect of tolerance to endotracheal intubation was used as a model during recovery from a suxamethonium block after different combinations of thiopental and fentanyl. The induction groups were: thiopental, 4, 6 or 8 mg/kg, and thiopental, 4 mg/kg, supplemented with fentanyl, either 1 .mu.g/kg or 2 .mu.g/kg. All 107 patients received suxamethonium 1.5 mg/kg, after precurarization and recovery of muscle strength were recorded by measuring the twitch tension of thumb adduction caused by indirect supramaximal stimulation of the ulnar nerve. With 4 mg/kg thiopental 60% of the patients reacted against the tube before the suxamethonium block had subsided. Increasing the dose to 8 mg/kg or supplementing the 4 mg/kg thiopental with 1 .mu.g/kg fentanyl reduced the reactions to about 30%. After supplementing with 2 .mu.g/kg fentanyl, 90% of patients tolerated the tube. Reactions against the tube, if any, usually occurred before the twitch tension had recovered by more than 30%. After 4 and 6 mg/kg thiopental, about 10% of the patients started reacting before there were signs of recovery of twitch tension. If bucking or coughing are used as an indication of inadequate muscle paralysis overcurarization can easily occur. Tolerance to the endotracheal tube is more rationally achieved by small doses of narcotic analgesics (e.g., fentanyl, 0.5-1 .mu.g/kg) than by increasing the dosage of thiopental. This simple model was found useful in demonstrating the basic principles of balanced anesthesia at the beginning of training in the specialty.