Anaesthesia
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A constant pressure differential valve for the control of tracheal tube cuff pressure was tested under clinical conditions. Fifty-one patients underwent controlled ventilation and 20 patients were allowed to breathe spontaneously. Nitrous oxide 66% with oxygen 33% and halothane were used via a circle system. ⋯ Fifty-two control patients had the same incidence of sore throat (40%) and hoarseness (30%) at 24 h. With spontaneous ventilation, fresh gas flows of 5-15 l.min-1 maintained the cuff pressure above 10 cmH2O. We conclude that this valve prevents excessive tracheal cuff pressure while maintaining the airway seal.