Effect of different positions during induction of anesthesia on lower esophageal pH and ease of intubation in morbidly obese patients

Abstract

Background This randomized-controlled study was designed to assess the effect of a patient’s position on lower esophageal pH and ease of intubation during induction of anesthesia in morbidly obese patients. Methods Sixty-six morbidly obese patients undergoing laparoscopic gastric banding surgery were allocated according to the patient’s position before induction of anesthesia to one of three equal groups: group S (control), ‘sniff’ position with the patient supine, group R, ‘ramp’ position, and group RT 30π reverse-Trendelenburg position. The primary outcome measure was lower esophageal pH. The secondary outcome measures were ease of intubation, laryngoscopic view, and changes in heat rate, mean arterial blood pressure, and arterial oxygen saturation during induction. Results Lower esophageal acidity was significantly increased in group S compared with group RT and group R, P less than 0.001, with a significant increase in group R compared with group RT, P less than 0.001. Although the laryngoscopic view was the best in group R, there were no significant differences in intubation time and ease of intubation between group R and group RT, P =0.069. Heart rate was significantly increased in reverse-Trendelenburg 30π (group RT) after induction of anesthesia compared with before induction P less than 0.001. There were statistically significant reductions in the mean arterial blood pressure after induction of anesthesia in group RT and group R compared with before induction, P =0.001 and 0.020, respectively, but it was not clinically significant. Oxygen saturation was significantly higher in group RT and group R compared with group S, P =0.001. Conclusion During induction of anesthesia in morbidly obese patients, the reverse-Trendelenburg 30π position is the best as it increases the lower esophageal pH, allows easy laryngoscopy, and provides an adequate laryngoscopic view.