Canadian Anaesthetists' Society journal
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Comparative Study
Doses of epinephrine causing arrhythmia during enflurane, methoxyflurane and halothane anaesthesia in dogs.
The arrhythmogenic dosage of epinephrine, administered by constant intravenous infusion, was measured in five dogs during enflurane, methoxyflurane and halothane anaesthesia. While premature ventricular contractions were observed in only one of five dogs with enflurane and methoxyflurane, epinephrine-induced arrhythmias were seen in all animals during halothane anaesthesia. Epinephrine dosage and the resultant increase in mean arterial blood pressure at which arrhythmias occurred during halothane anaesthesia were significantly less (p less than 0.05) than with the other anaesthetics. These observations indicate that enflurane and methoxyflurane, as compared to halothane, possess relatively less arrhythmogenic potential as sensitizing agents in the presence of increased circulating catecholamines.
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Clinical Trial
Post-operative epidural analgesia: effects on lung volumes.
A study was undertaken to assess the role of post-operative pain in reducing Functional Residual Capacity (FRC) and Vital Capacity (VC). The efficacy of post-operative epidural analgesia in reversing these changes was measured in eight subjects after upper abdominal operations. ⋯ These figures indicate the pain component in the post-operative reduction of these two lung capacities. This partial restoration may be of value in the prevention of post-operative pulmonary complications by avoiding closure of small airways during tidal breathing and by increasing the effectiveness of deep breathing and coughing in the removal of secretions and the reversal of atelectasis.
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Comparative Study Clinical Trial Controlled Clinical Trial
Glycopyrrolate methobromide: 2. comparison with atropine sulphate in anaesthesia.
A double blind study of 98 patients was undertaken to compare the clinical usefulness of atropine and glycopyrrolate for pre-anaesthetic medication and their relative effectiveness in antagonizing the muscarinic effects of neostigmine methylsulphate given to reverse neuromuscular blockade. Intramuscular administration of atropine 0.4 mg or of glycopyrrolate 0.2 mg produced the same degree of dryness of the pharynx. ⋯ Administered intravenously, atropine produced a more significant tachycardia in a large number of patients prior to neostigmine administration, although the protection against a decreased pulse rate from neostigmine is greater in those patients who received glycopyrrolate. It would appear, therefore, that glycopyrrolate is more effective in antagonizing the muscarinic effects of neostigmine methylsulphate.
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Direct measurement of the inspired tracheal oxygen concentration was made in patients breathing through standard aerosol face masks. Factors affecting the tracheal FIO2 were analyzed using both mechanical and mathematical models. When oxygen is delivered to the face mask at low flow rates, there is considerable patient variation in the measured tracheal FIO2. ⋯ Changes desired in inspired oxygen concentration are accomplished by changing the concentration of the incoming gas mixture, and not by merely changing the flow rate of oxygen delivered to the system. Using the shielded mask, it is possible to deliver an inspired oxygen concentration of 100 per cent. This is not true with most other commonly used face masks, and, therefore, caution should be used to avoid administration of unnecessary high inspired oxygen concentrations with this type of mask.