Canadian Anaesthetists' Society journal
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This paper reports the case of a 2 1/2-year-old male who appeared to have drowned in the family swimming pool. Immediate continuous cardiopulmonary resuscitation eventually restored circulation and respiration. ⋯ Prompt and continuous use of measures to support cerebral resuscitation were successful and the child subsequently was completely normal. A reevaluation of current information seems indicated in regard to the prognosis of the near-drowned child.
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The volume of carbon dioxide rebreathed by spontaneously breathing patients under halothane anaesthesia at various fresh gas flow rates (FGF) with the Bain modification of the Mapleson "D" breathing circuit is measured. The effect of rebreathing on a heterogeneous patient population is shown to be unpredictable hypercapnia in those patients who cannot respond adequately to this carbon dioxide challenge. All adults rebreathe significant volumes of carbon dioxide at a FGF rate of 100 ml . kg-1 . min-1. ⋯ Rebreathing occurs because the inspired carbon dioxide load is unpredictable in a given patient and the patient's response is uncontrolled. Patients respond to this carbon dioxide challenge by increasing inspiratory flow rate (Vt/Ti), which results in increased rebreathing of carbon dioxide from the expiratory limb of the circuit. To prevent potentially dangerous rebreathing of carbon dioxide in all patients the fresh gas flow rate must be much higher than presently recommended.
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Continuous positive airway pressures (CPAP) of 0.49 kPa and 0.98 kPa were applied to ten healthy volunteers and nine critically ill patients with acute respiratory failure. A modified Godart-Statham NV 16003 spirometer was used to measure respiratory frequency (f), tidal volume (VT), oxygen consumption (VO2), and changes in functional residual capacity (delta FRC). During CPAP of 0.49 kPa, volunteers had a decrease in f, and increased VT and minute volume (MV). ⋯ VO2 in the patient group rose significantly at 0.49 and 0.98 kPa CPAP. Some of the patients were uncomfortable with 0.49 kPa pressure, while all the patients were distressed at 0.98 kPa CPAP. The effects of increased oxygen consumption and patients discomfort should be considered in critically ill patients receiving CPAP therapy.
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Comparative Study
An evaluation of gas density dependence of anaesthetic vaporizers.
Four commonly used vaporizers were studied for the effect of carrier gas density on vaporizer output. Vapour concentrations from a halothane Cyprane (Fluotec) Mark 2 increased in relation to the density of carrier gas, whereas the concentrations delivered by an enflurane Ohio vaporizer decreased. The halothane Cyprane (Fluotec) Mark 3 and enflurane Cyprane vaporizers were largely independent of density. Of clinical importance, nitrous oxide/oxygen (75/25), compared with oxygen alone, increased the vapour concentration outputs of the halothane Mark 2 up to 30% and decreased the outputs of the enflurane Ohio unit up to 20%.