• Y P Cheong, S K Park, Y Son, K C Lee, Y K Song, J S Yoon, and T Y Kim.
• Department of Anesthesiology, Wonkwang University School of Medicine, Iksan, Cheonbuk, South Korea. ypcheong@wonnms.wonkwang.ac.kr
• J Clin Anesth. 1999 Dec 1;11(8):657-62.

Study ObjectivesTo compare the incidence of gastroesophageal reflux and regurgitation associated with laryngeal mask airway (LMA) removal when signs of rejecting the LMA, such as swallowing, struggling, and restlessness, were observed and when the patient could open his or her mouth on command.DesignRandomized clinical trial.SettingOperating room and recovery room of a tertiary care referral hospital.Patients63 ASA physical status I and II adult patients scheduled for elective orthopedic surgery.InterventionsUsing a standardized general anesthetic technique, patients were allocated randomly to Group A (n = 34; LMA removed when signs of rejection, such as swallowing, struggling, and restlessness, were observed) or Group B (n = 29; LMA removed when the patient could open his or her mouth on command).Measurements And Main ResultsTo detect gastroesophageal reflux throughout anesthesia, a pH monitoring probe was positioned in the lower esophagus on the day before surgery. To assess regurgitation during emergence, a gelatin capsule of methylene blue (50 mg) was swallowed prior to induction. At the end of anesthesia, episodes of reflux and regurgitation of gastric contents were analyzed/determined by pH below 4 and bluish staining of the pharynx and/or LMA, respectively. Physical events such as bucking, straining, and coughing during the arousal phase were recorded in both groups by an independent observer. The incidence of reflux (pH < 4) from the time of the appearance of rejection signs to LMA removal and the total incidence of reflux in Group B were significantly higher than in Group A (p < 0.05). Staining of the LMA and the pharynx by methylene blue was not observed in patients from either experimental group. The number of physical events in Group B during the arousal phase was significantly increased compared to Group A (p < 0.05). Considering all patients in Group A and Group B, physical events were associated with the occurrence of reflux (p < 0.05). Desaturation (SpO2 < 95%) and clinical evidence of aspiration of gastric contents did not occur in either group.ConclusionMaintenance of the LMA until the patient can open his or her mouth on command increases the incidence of gastroesophageal reflux.

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