Frequency distribution of modified Cormack-Lehane views-A retrospective audit of tracheal intubation in children with normal airways.

Background: Paediatric patients with an unanticipated poor grade of laryngoscopic view during tracheal intubation represent a challenging situation potentially associated with increased morbidity and mortality. The aim of this study was to investigate the frequency of modified Cormack-Lehane (MCL) views and to elucidate variables for poor views in a large collective of children without anticipated airway difficulties.

Methods: The departmental anaesthesia patient database was searched for patients who had undergone general anaesthesia with tracheal intubation between January 2007 and March 2017. Inclusion criteria were age from birth to 17.99 years, general anaesthesia with tracheal intubation using direct laryngoscopy, no history, symptoms or signs of a difficult airway and the best obtained MCL view documented in the database. Patient- and anaesthesia-related variables associated with a poor view (MCL IIb, III and IV) were elucidated using a logistic regression model.

Results: In all, 22 965 patients were included; of these, 17 593 were observed only once. The prevalence of the first observed MCL views I, IIa, IIb, III and IV was 90.6%, 8.5%, 0.86%, 0.05% and 0%, respectively. The logistic regression model indicates that age and gender are the most important variables associated with MCL views IIb and III in the model. The probability for MCL views IIb/III decreases across the first 5-7 years before increasing again.

Conclusions: The incidence of a poor grade of laryngoscopic view was found to be very low in children with a normal airway. They mainly occurred in infants and adolescent patients and were more common in male patients.