Evaluation of the laryngoscopy view using the modified Cormack-Lehane scale during tracheal intubation in an intensive care unit. A prospective observational study

Abstract

Background and objectvies: Tracheal intubation in the Intensive Care Unit is associated with a high incidence of difficult intubation and complications. This may be due to a poor view of the glottis during direct laryngoscopy. The aim of this study is to determine if there is a relationship between laryngoscopy view using the modified Cormack-Lehane scale with the incidence of difficult intubation and complications.

Methods: All patients who were subjected to tracheal intubated with direct laryngoscopy in the Intensive Care Unit over a 45 month period were included in the study. In all patients, an evaluation was made of the laryngoscopy view using the modified Cormack-Lehane scale, as well as the technical difficulty (number of intubations at first attempt, operator-reported difficulty, need for a Frova introducer), and the incidence of complications (hypotension, hypoxia, oesophageal intubation).

Results: A total of 360 patients were included. When the grade of the modified Cormack-Lehane scale was increased from 1 to 4, the incidence of first success rate intubation decreased (1: 97%, 2a: 94%, 2b: 80%, 3: 60%, 4: 0%, p<.001), the incidence of moderate and severe difficulty intubation increased (1: 2%, 2a: 4%, 2b: 36%, 3: 77%, 4: 100%, p<.001.), as well as the need for a Frova guide (1: 7%, 2a: 8%, 2b: 45%, 3: 60%, 4: 100%, p<.001). When the grade of the modified Cormack-Lehane scale increased from 1 to 4, the incidence of hypoxia<90% increased (1: 20%, 2a: 20%, 2b: 28%, 3: 47%, 4: 100%, p=.0073), as well as hypoxia<80% (1: 11%, 2a: 10%, 2b: 12%, 3: 27%, 4: 100%, p=.00398). No relationship was observed between the incidence of hypotension and the grade of the modified Cormack-Lehane scale (p=ns).

Conclusions: During tracheal intubation in the Intensive Care Unit a close relationship was found between a poor laryngoscopy view using the modified Cormack-Lehane scale and a higher difficulty technique of intubation. A relationship was found between the incidence of hypoxia with a higher grade in the modified Cormack-Lehane scale. No relationship was found between hypotension and the modified Cormack-Lehane scale.

Keywords: Complicaciones; Complications; Critical care; Cuidados críticos; Hipotensión; Hipoxia; Hypotension; Hypoxia; Intensive Care Unit; Intubación orotraqueal; Orotracheal intubation; Unidad de Cuidados Intensivos.