Background: The present study was conducted to investigate the influence of different operating table heights on the quality of laryngeal view and the discomfort of the anaesthetist during enodotracheal intubation.
Methods: Eight anaesthetists participated, to each of whom 20 patients were allocated. Before induction of anaesthesia, the height of the operating table was adjusted to place the patient's forehead at one of four landmarks on the anaesthetist's body (the order being determined by block randomization with eight blocks): umbilicus (Group U), lowest rib margin (Group R), xiphoid process (Group X), and nipple (Group N). Next, the anaesthetist began the laryngoscopy and evaluated the grade of laryngeal view. For this 'initial posture', the anaesthetist was not allowed to adjust his or her posture (flexion or extension of the neck, lower back, knee, and ankle). This laryngeal view was then re-graded after these constraints were relaxed. At each posture, the anaesthetist's joint movements and discomfort during mask ventilation or intubation were evaluated.
Results: The laryngeal view before postural changes was better in Group N than in Group U (P=0.003). The objective and subjective measurements of neck or lower back flexion during intubation were higher in Group U than in Groups X and N (P<0.01 for each). The improvement of laryngeal view resulting from postural changes correlated with the anaesthetist's discomfort score before the postural change (P<0.01).
Conclusions: Higher operating tables (at the xiphoid process and nipple level of the anaesthetist) can provide better laryngeal views with less discomfort during tracheal intubation. TRIAL REGISTRY NUMBER: NCT01649973 (clinicaltrials.gov).
Keywords: human engineering; intubation; laryngoscopy; patient positioning.