Comparison of ease of intubation and glottic visualisation using Miller (paraglossal approach) and Macintosh laryngoscope in adults: A randomised crossover study

Previous randomised controlled trials have produced inconclusive results about the initial success rates of intubation when comparing the adult Miller and Macintosh blades. A prospective randomised crossover study involving 200 adult ASA I or II patients scheduled for elective surgery under general anaesthesia. This study aimed to evaluate the efficacy of intubation with the adult Miller blade using a paraglossal approach compared to the Macintosh blade in adult patients. Tocompare the ease of orotracheal intubation and glottic visualisation using the adult Miller and Macintosh blades. After obtaining approval from the ethical committee, 200 adult patients satisfying inclusion criteria were enrolled. Group allocation was determined by the order of blade usage during laryngoscopy, with randomisation conducted via computer-generated random numbers. Patients were divided into two groups: Group MAC (where the initial laryngoscopy was performed using the Miller blade, followed by intubation with the Macintosh blade) or Group MIL (where the initial laryngoscopy was performed using the Macintosh blade, followed by intubation with the Miller blade). Following standard anaesthesia protocols, the first laryngoscopy was carried out with the randomly assigned blade, accompanied by the administration of a 10% Lignocaine spray. After one minute of mask ventilation, the second laryngoscopy was performed with the alternate blade, and intubation was completed. Parameters were documented, including the first attempt intubation success rate, Cormack-Lehane grade, intubation duration, utilisation of ancillary devices for intubation, and hemodynamic measures. The first attempt success rate was 92% and 95% in Group MIL and Group MAC, respectively (P=0.081). Cormack-Lehane grade I was seen in 73% of cases in Group MIL and 68% of in Group MAC (P=0.022). The average intubation time was 16.42±1.60 seconds in Group MIL and 16.68±1.38 seconds in Group MAC (P=0.221). Utilizing the Miller laryngoscope and paraglossal technique for adult intubation demonstrates comparable first-attempt intubation success rates to the Macintosh blade while providing superior glottic visualisation.