The mechanism which normally affects distribution of blood flow through unventilated areas of the lung is hypoxic pulmonary vasoconstriction; this acts to divert the blood to well ventilated alveoli, resulting in a better ratio of ventilation to perfusion. Several reports have focused attention on the reduction or abolition of this reflex in the unventilated lung by most of the volatile anaesthetic agents used in clinical practice. This response was not abolished by the intravenous anaesthetic agents.
South African Medical Journal = Suid-Afrikaanse Tydskrif Vir Geneeskunde
Etomidate (Hypnomidate; Ethnor) in an alcoholic solution was used as the hypnotic component of a technique of total intravenous anaesthesia in an open pilot evaluation in 50 patients undergoing surgery. No anaesthetic gases were used. Despite cardiovascular stability, lack of respiratory depression and a short awakening time, unwanted movements by the patients made total intravenous anaesthesia with this technique unsatisfactory.
Surveys indicate that the adolescent, in particular, suffers from acute anxiety in relation to dentistry. This anxiety is promoted by the general opinion they form of dentists and dentistry through portrayal by their peers and the media. In addition, their own attitude to dentistry, both positive and negative, is influenced to a large extent by the dentist himself. This patient-dentist relationship is, therefore, especially important when treating the adolescent and this should be emphasized in the dental undergraduate curriculum.
A review of the hypnotic, anticonvulsant and brain protective action of etomidate in animals shows that when given as a single injection in different animal species recovery from hypnosis is quick and that the safety margin is large. In dogs a bolus or infusion produces high amplitude theta activity on the electroencephalogram (EEG). During infusion burst suppression is seen. After high doses, behaviour and EEG changes returned to normal within 3 hours. The wide spectrum of anticonvulsant activity suggests that etomidate may be useful in the treatment of status epilepticus.
An etomidate infusion regimen for hypnosis as part of balanced, totally intravenous anesthesia was designed to maintain plasma etomidate concentrations above the awakening concentration of 300 ng/ml while avoiding dose-related side effects. The etomidate infusion regimen of 0.1 mg/kg/min for 3 min, 0.02 mg/kg/min for 27 min, and 0.01 mg/kg/min for the remainder of the anesthesia was used together with intravenous bolus doses of fentanyl, droperidol, and pancuronium. This was evaluated in 11 patients and the kinetics of etomidate were reexamined.
Currently available anesthetic induction agents provide adequate hypnosis but are not ideal, particularly in the high risk patient (ASA class III-V), because most cause myocardial and/or respiratory depression and some have other important side effects. Etomidate was recently marketed as an intravenous anesthetic induction agent. It is a non-barbiturate hypnotic without analgesic properties that has less cardiovascular and respiratory depressant actions than sodium thiopental, even in patients with minimal cardiovascular reserve.