Canadian Anaesthetists' Society journal
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Research on the benzodiazepines has shown that they have certain advantages over the opiates as premedicants. Diazepam, which produces good tranquilization, is well absorbed when given orally though absorption is influenced by other drugs given at the same time. Oral lorazepam leads to more prolonged sedation and amnesia but the final elimination is more rapid. ⋯ Ketamine is gradually finding its rightful place in anaesthesia but its use is becoming limited to anaesthesia in difficult circumstances. The future concomitant use of other drugs and separation of isomers of ketamine may again broaden its applications. The new water-soluble steroid minaxolone has its own disadvantages, and the water-soluble benzodiazepine midazolam is as unpredictable for induction of anaesthesia as diazepam.
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Out-patient surgery for infants and children offers the advantages of minimal emotional upset, less risk of infection, and fiscal economy. Many different operations can be done in the out-patient department and most children can be accepted for general anaesthesia for these operations. Preparation of the child is similar to that required for in-patient surgery. ⋯ Careful tracheal intubation should be utilized whenever indicated. Regional analgesia has many advantages over narcotic analgesics in the treatment of post-operative pain. A follow-up service should be provided.
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Pulmonary gas exchange is disturbed during general anaesthesia; both oxygenation and elimination of carbon dioxide are impaired. The shape of the chest wall alters after induction of anaesthesia-paralysis in recumbent subjects, and its motion during inspiration is also altered. The mechanical properties of lung and chest wall are also affected and FRC may be reduced. ⋯ These regions may progress into right-to-left shung during 100 per cent oxygen breathing. The low ventilation-to-perfusion regions and the shunt may both impair oxygenation. The development of lung regions with high ventilation-to-perfusion ratios after induction of anaesthesia-paralysis contributes to the inefficient elimination of carbon dioxide.
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Review Case Reports
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. ⋯ 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.