2. Materials and Methods
HEART, MORBID OBESITY
This study was a prospective, randomized, patient-blinded trial from July 2017 to August 2018 after obtaining approval from the Institutional Review Board of the Hallym University Sacred Heart Hospital (IORG0004993, IRB00005964, approved date: 25 April 2017), and it was internationally registered for clinical trials (ClinicalTrials.gov unique identifier: NCT03516539). Written informed consent for this study was obtained from all participants before the day of a scheduled surgery.We initially screened 100 patients aged 19 to 70 years, using the American Society of Anesthesiologists physical status classification system (ASA) 1 or 2, who were scheduled for surgery requiring orotracheal intubation under general anesthesia at our institution. The exclusion criteria were as follows: a requirement for rapid sequence intubation, cervical instability or cervical spine injury, morbid obesity (body mass index > 40 kg/mAll patients were premedicated with glycopyrrolate 0.1 mg intramuscularly just before entering the operating room. All patients were monitored in the operating room through electrocardiography, non-invasive arterial blood pressure measurement, pulse oximetry, capnography, and a Bispectral IndexAfter pre-oxygenation with 100% oxygen for 2 min, propofol (effect site concentration, 5.0 μg/mL) and remifentanil (effect site concentration, 4.0 μg/mL) were administered through a target-controlled infusion (TCI) pump (OrchestraThe primary outcome variable was the intubation success rate. Successful intubation was defined as tracheal intubation within 30 s at the first attempt [Categorical variables are shown as frequencies with percentages, and continuous variables are shown as medians and interquartile ranges or means and standard deviations. The categorical variables were compared using the chi-square test, and the continuous variables were analyzed using Student’s 