The role of capnography during upper endoscopy in morbidly obese patients: a prospective study

Pulmonary depression remains a major concern when performing upper endoscopy in the morbidly obese patient. The aim of this prospective study is to determine the effects of sedation and role of capnography during preoperative upper endoscopy in obese patients.

Eighty-two consecutive diagnostic upper gastrointestinal endoscopies were performed in morbidly obese patients in an outpatient setting. Data on amount of drug administration and cardiorespiratory change were recorded.

Mean body mass index and duration of procedure was 46.4±8.2 kg/m2 and 9.4±2.5 minutes, respectively. The mean dose of propofol was 139.5±45.1 mg. No clinically significant cardiorespiratory complications occurred. Respiratory depression (RD) was seen in 33/82 (40.2%) patients and included a mean absolute change in end-tidal carbon dioxide (EtCO2) of 7.1±8.5 mm Hg from baseline (P=.001). 54/82 (65.9%) patients had subclinical RD with 27/54 (50%) having RD. Abnormal EtCO2 detected all episodes of RD. The sensitivity and negative predictive value in determining RD by a change in EtCO2>10 mm Hg or an absent EtCO2 waveform during any point of the procedure was 81% and 78%, respectively. The relative risk was 2.3.

Capnography provided a real time assessment of changes in ventilation and can detect early phases of respiratory depression. Utilization of propofol as a means for sedation, with extended advanced monitoring technique, can allow for reduced adverse outcomes in morbidly obese patients undergoing upper endoscopy.