Influence of pharyngolaryngeal anomalies diagnosed through indirect laryngoscopy in the prediction of difficult intubation

Abstract

Objective

To determine the pharyngolaryngeal anomalies not usually included in the evaluation of difficult airway, in order to investigate the influence of these anomalies in the prediction of difficult intubation. To do this, indirect laryngoscopy with a 70° rigid laryngoscope was performed on all patients during the preoperative period.

Methods

This is an observational, prospective study on 300 consecutive patients who were scheduled for endotracheal intubation under general anesthesia. In addition to assessing the airway in the preoperative period by demographic and clinical predictors of difficult airway, rigid indirect laryngoscopy was performed to diagnose pharyngolaryngeal anomalies. Later, under general anesthesia and direct laryngoscopy it was checked to see if there was difficulty in intubating the larynx, and its association with all previous variables was investigated. A logistic regression model for prediction purposes was developed, and its power of discrimination was achieved by assessing the area under the curve.

Results

During the examination by indirect laryngoscopy 46 anomalies were found, which were as follows: 31 abnormalities of the epiglottis (22 omega epiglottis, nine flaccid or hypertrophic epiglottis); six findings of hypertrophic lingual tonsils, three cases of upper airway tumors, and six patients with tongue disorders. Intubation difficulty was found in 14 cases (4.66%). The regression model found and its coefficients to develop it were: f(x) = 1.322 + (2.173 thyromental distance <6.5 cm) + (1.813 omega epiglottis) − (1.310 cm opening mouth). Global power of discrimination was 0.83, with a 95% confidence interval from 0.709 to 0.952.

Conclusion

Indirect laryngoscopy allowed pharyngolaryngeal anomalies to be diagnosed, including omega epiglottis, which was one of the variables included in the logistic regression model.

Resumen

Objetivo

Detectar anomalías faringolaríngeas no valoradas habitualmente en la evaluación de la vía aérea difícil mediante la realización en el preoperatorio de una laringoscopia indirecta con el laringoscopio rígido e investigar su influencia en la predicción de la dificultad de intubación traqueal (DIT).

Métodos

Estudio observacional prospectivo en 300 pacientes consecutivos sometidos a intervenciones quirúrgicas programadas bajo anestesia general. Además de evaluar los predictores demográficos y clínicos comunes de la vía aérea difícil, les fue practicada en el preoperatorio una laringoscopia indirecta con el laringoscopio rígido para diagnosticar las anomalías faringolaríngeas. Después, bajo anestesia general y laringoscopia directa comprobamos en qué pacientes existía DIT. Se investigó la asociación de todas las variables anteriores con la DIT, se confeccionó un modelo de regresión logística con fines predictivos y su poder de discriminación se consiguió valorando el área bajo la curva ROC obtenida.

Resultados

Se contabilizaron 46 anomalías: 31 alteraciones de la epiglotis (22 epiglotis abarquilladas, 9 epiglotis flácidas o hipertrofiadas), 6 amígdalas linguales hipertróficas, 3 tumores en la vía aérea superior y 6 alteraciones de la lengua. Se encontró DIT en 14 casos (4,66%). El modelo elaborado y sus coeficientes para confeccionarlo fueron: f(x) = 1,322 + (2,173 distancia tiromentoniana < 6,5 cm) + (1,813 epiglotis abarquillada) − (1,310* cm abertura boca). El poder global de discriminación era 0,83 (IC 95%: 0,70–0,95).

Conclusiones

La laringoscopia indirecta permitió el diagnóstico de las anomalías faringolaríngeas, y de ellas la epiglotis abarquillada fue una de las variables incluidas en el modelo de regresión logística.