Influence of operating table height on laryngeal view during direct laryngoscopy: A randomized prospective crossover trial

Background: Operating table height/patient level in relation to anaesthesiologist influences mask ventilation, laryngoscopy, intubation and task performance in terms of physical and mental workload. The same was evaluated in this study. Methods: Twenty five specialist anaesthesiologists performed mask ventilation and laryngoscopy thrice and intubation once on six patients each, [n = 150] at three different operating table levels (Level X: patient at level of xiphisternum of anaesthesiologist, level A: 5 cms above; level B: 5 cms below xiphisternum). Primary variable was quality of laryngoscopic view obtained. Secondary variables were anaesthesiologist's comfort, ease of performing these tasks and movements at various joints in anaesthesiologist assessed in subjective and objective ways. Results: Laryngoscopic view was best at levels X and A when compared to B (p = 0.0004). Mask ventilation was most comfortable at level B and least at level A (p < 0.01). At level B, there was maximum discomfort in 76.6% during laryngoscopy and 60% during intubation (p < 0.001). Level A had the fastest time (mean ± SD) for both laryngoscopy (8.30s) and intubation (18.3s) (p < 0.01). Total joint movements were maximal at level B (p < 0.001). Conclusion: Higher operating table levels are ideal for laryngoscopy and intubation whereas lower levels favour mask ventilation.