Frequency band of EMG in anaesthesia monitoring.

undergoing abdominal surgery. After animal use committee approval, 14 pigs were anaesthetized and the tracheas intubated with appropriately sized Hi-Lo Evac (n1⁄47) or TaperGuard Evac (n1⁄47) tracheal tubes. Saline based-fluid (pH 2.5/0.3 ml kg) stained with Methylene-Blue was instilled into the area below the vocal cords but above the inflated tracheal tube cuff via the Evac port. The cuff pressure was measured every 15 min and maintained between 25 and 30 mm H2O for both tracheal tubes using a Posey cufflator (Posey Health Care Products, Arcadia, CA, USA). The lungs were ventilated to achieve normocarbia and each pig underwent abdominal surgery. At the end of surgery, the pigs were killed by lethal injection and the tracheal tubes were left in place with the cuffs inflated until the autopsy. At autopsy, a gross visual assessment was made of dye distribution into the trachea and lungs. Gross and histological examination of large, intermediate, and small airway mucosa and pulmonary parenchyma was performed to assess for inflammatory changes related to aspiration. However, one pig in the TaperGuard group had to be excluded due to accidental cuff deflation. The incidence of microaspiration was significantly less for TaperGuard in the dye leak and bronchitis groups (Table 1). As a result of the dye leak from the accidental cuff deflation, the difference in the other two categories did not reach statistical significance but may be clinically significant. We suggest further animal and clinical studies to confirm our results and impressions.