Videolaryngoscopes in the Morbidly Obese

This study will evaluate four videolaryngoscopes used for intubation of extremely obese (class 3 obesity) patients scheduled for bariatric surgery. One hundred adult patients will be scheduled for an elective sleeve gastrectomy at the Mazowiecki Szpital Specjalistyczny in Radom, Poland. All patients will receive premedication with 300 mg pregabalin 30 minutes before the start of anaesthesia. An extended monitoring will be applied. This consists of ECG, IBP (invasive blood pressure), SpO2, TOF (train-of-four), entropy and volatile anaesthetic concentration. All patients will be placed in a ramped position (HELP - Head-elevated Laryngoscopy Position) and will be pre-oxygenated with FiO2 1.0 for three minutes prior to induction. A standardised local protocol of opioid-free anaesthesia for bariatric patients will be utilised. Prior to proper induction of anaesthesia, IV infusions of 1% lidocaine and dexmedetomidine 10 µg ml-1 will be started. This will be followed by induction with IV propofol (200 mg) and ketamine (50 mg). Rocuronium (100 mg) will be used as a neuromuscular blocking agent. Adequate neuromuscular block will be confirmed and controlled throughout the procedure with TOF Watch (Organon, Dublin, Ireland). A cuffed, size 8.0 tracheal tube with stylet (Sumi, Sulejówek, Poland) will be used for intubation. A single-use hyperangulated blade will be used in all studied devices. Correct placement of the tracheal tube will be confirmed by videolaryngoscopy, capnography and chest auscultation. All patients will be anaesthetised by experienced consultant anaesthetists with over 10 years of clinical practice after completion of specialist training. Furthermore, all anaesthetists participating in the study will be trained with all VLs used until they feel competent. Only two intubation attempts with a studied videolaryngoscope will be allowed. A single attempt will be limited to 60 seconds. A failure is defined as an attempt which lasted more than 60 seconds, when saturation dropped below 90%, after two unsuccessful attempts, when airway injury or bronchospasm occurred. A single-digit number will be allocated to each of the studied videolaryngoscopes: 1 for the C-MAC PM, 2 for the McGrath MAC, 3 for the VisionPro and 4 for the AceScope. A single sheet of paper containing printed number will be placed in an opaque envelope. Then they will be assigned to the participating anaesthetist by computer-generated randomization. The SPSS 29.0 software (IBM, Armonk, NY, USA) will be used for allocation. Furthermore, patients will be blinded to randomization.

Collected data will be analysed using Statistica 14.0 (TIBCO Software, Palo Alto, CA, USA) and Microsoft Office Excel 2021 spreadsheet (Microsoft, Redmond, WA, USA). The Wilcoxon signed-rank test and the paired Student t-test will be used for data analysis. Continuous variables will be presented either as mean ± SD (standard deviation) or median (IQR - interquartile range) for non-normally distributed data. The Kolmogorov-Smirnov test determines whether the analysed variables match the characteristics of a normal distribution. The investigators assumed that the overall success rate of intubation in obese patients would be 90% (α = 0.05, 2-sided, β = 0.1, 95% CI). The calculated sample size requires 95 participants and the final adjusted sample size will be 100 patients to compensate for dropouts. A p-value of less than 0.05 (p < 0.05) is considered statistically significant.

Inclusion criteria

• class 3 obesity
• bariatric surgery
• over 18 years old
• male and female

Exclusion criteria

• known difficult laryngoscopy
• difficult face mask ventilation
• aged under 18 years old
• previous history of awake tracheal intubation