Laryngeal mask airway and the incidence of regurgitation during gynecological laparoscopies.
We studied the incidence of regurgitation in 100 patients undergoing elective gynecological laparoscopies under general anesthesia with intermittent positive pressure ventilation using a laryngeal mask airway (LMA). Patients ingested methylene blue capsules 10-15 min before induction of anesthesia. After induction and insertion of an LMA using the recommended insertion technique, a fiberoptic examination of the larynx was made for traces of dye and to site a pH probe in the bowl of the LMA for continuous monitoring. LMA insertion was successful in all patients within two attempts (95 at first attempt). Fiberoptic examination revealed the vocal cords or cords and posterior or anterior epiglottis in 96 and no trace of dye in 99 patients. One patient regurgitated dye immediately after induction, and the stain was seen on the LMA after removal. The remaining 99 LMAs were not stained. Thirty patients were randomly selected for fiberoptic examination of the laryngopharynx before neuromuscular block was antagonized. Methylene blue staining did not occur in any of these patients. In 91 patients with complete pH data, regurgitation (pH < 4.0) did not occur. The 95% confidence limit for a true probability of regurgitation in this study is 0.041 or a true rate of regurgitation of less than 4.1%. A larger study would be required to possibly demonstrate a lower incidence of regurgitation. This study confirms the clinical impression that the incidence of regurgitation during laparoscopies with a LMA is extremely low.
Bapat
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Laryngeal Mask Research Centre, Department of Anesthesia, Royal Berkshire Hospital, Reading, Berkshire, United Kingdom.
Verghese
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D000293:Adolescent; D000328:Adult; D000768:Anesthesia, General; D017558:Elective Surgical Procedures; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis / Q000209:etiology*; D005836:Genitalia, Female / Q000601:surgery*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007385:Intermittent Positive-Pressure Ventilation; D010535:Laparoscopy; D017214:Laryngeal Masks / Q000009:adverse effects*; D007828:Laryngoscopy; D008751:Methylene Blue; D008875:Middle Aged; D016343:Monitoring, Intraoperative
D008751:Methylene Blue