Comparison of video laryngoscope and direct laryngoscope for endotracheal intubation across different body mass index categories: A prospective study

The aim is to compare video laryngoscopy (VL) and Macintosh blade direct laryngoscopy according to the intubation difficulty scale (IDS) in patients with ASA 1 and Mallampati score I (C-MAC-D blade) according to body mass index (BMI). A total of 180 patients aged 18-70 years, scheduled for elective surgery under general anesthesia with ASA 1-2, Mallampati score I, and BMI>18 kg/m² were included. DL and VL were performed in 50% of patients. Patients were randomly assigned to six groups based on BMI and laryngoscopy type. During intubation, data on the number of tubes used, number of anesthetists attempting intubation, number of alternative techniques employed, C-L score (C-L), laryngoscopy suspension power, application of external pressure, and vocal cord imaging were recorded, and IDS was calculated. Notable variations were detected in mouth opening, thyromental distance, and C-L and IDS levels across different laryngoscopy methods. Patients in the VL group exhibited a greater frequency of mouth opening of <3 cm and thyromental distance of 6.5 cm (p=0.029 and p<0.005, respectively). The VL group demonstrated higher rates of C-L=1 and easy IDS, whereas the DL group showed increased C-L=3 and mildly difficult-to-difficult IDS ratios (p=0.049 and p<0.001, respectively). Within the BMI 25-30 kg/m² category, the VL group had a significantly larger number of patients with a thyromental distance <6.5 cm (p=0.008). No substantial differences in mouth-opening measurements were observed between the groups. The intubation duration was extended in the VL group (p=0.019). The VL group displayed a higher frequency of easy IDS, whereas the DL group showed an increased rate of mild IDS (p =0.001). For patients with BMI >30 kg/m², the VL group had considerably more individuals with a thyromental distance <6.5 cm (p<0.001). The DL group exhibited higher proportions of mildly difficult and difficult IDS, C-L=3 ratio, and prolonged intubation times (p<0.001, p=0.026, p=0.028, respectively). In obese patients who undergo endotracheal intubation, better glottic visibility with the use of VL shortens the intubation time and makes the procedure easier.