Minimum blood concentration--a universal concept of anaesthetic potency

Beyond Ether Day: Betsey Magoun, The Forgotten Patient

Although the analgesic effects of ether were conclusively established during a series of public demonstrations of anesthesia at Massachusetts General Hospital in 1846, ether anesthesia was neither immediately nor universally introduced into practice. Betsey Magoun, the fourth patient undergoing surgery under anesthesia at the hospital, suffered life-threatening hypoxia and respiratory complications. Severe intraoperative problems witnessed by large audience may have contributed to the cautious introduction of anesthesia into routine practice. Ether inhalation was not commonly used until more effective methods of induction and maintenance of anesthesia were discovered.

Awareness, muscle relaxants and balanced anaesthesia

The incidence of awareness during insufficient anaesthesia is reported to be one per cent. It is usually due to the use of muscle relaxants, a balanced technique and the lightest possible depth of anaesthesia. Increased incidences were noted in open-heart surgery, during intubation-endoscopy procedures and in caesarean delivery patients. Experiences of awareness are disturbing to patients, who are usually benefited by a sympathetic and forthright explanation of the event. Fourteen representative cases of the problem are reported. Since no adequate sign or test exists for detection of awareness during very light anaesthesia or with associated paralysis, more meticulous attention is required in using relaxants or the balanced technique. Greater anaesthetic supplementation and reduction in the use of relaxants are recommended to halt the recurrence of this most serious anaesthetic problem.