Anaesthesia
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Comparative Study
Respiratory depression in children at different end tidal halothane concentrations.
Respiratory motor function and timing were investigated at end tidal halothane concentrations of 1.5%, 1.0% and 0.5% before and during 4% carbon dioxide stimulation in 10 spontaneously breathing children who weighed between 10.2 and 25.2 kg, during hypospadias repair under halothane anaesthesia. Their tracheas were intubated and all received a caudal block to eliminate surgical stimulation. Pneumotachography and capnography were used and in three cases movements of ribcage and abdomen were also studied by magnetometers. ⋯ Respiratory timing was unaltered by carbon dioxide stimulation. It is concluded that the ventilatory motor response to carbon dioxide is dose dependent and improves at more superficial anaesthetic levels, while respiratory timing is unresponsive to carbon dioxide stimulation irrespective of the halothane concentration used. Paradoxical breathing existed at end tidal halothane concentrations higher than 1%.
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A patient required respiratory support with jet ventilation via a minitracheotomy tube 2 days after right upper lobectomy. After initial improvement, the patient's condition deteriorated because of migration of the minitracheotomy tube out of the larynx. This complication has not been described previously. A number of possible causative factors and remedies are discussed.
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Arterial oxygen saturation in 132 patients was measured using a Biox IV oximeter with an ear probe, during transfer from theatre to recovery room following a variety of surgical procedures. Oxygen saturation decreased to 85% or less in 21.9% of patients and to 90% or less in 61.4%. No predictive factors were identified. It is recommended that supplementary oxygen be given to all patients in the immediate postoperative period, including the period of transit to the recovery room.