Assessment of the short-term effects of endotracheal intubation on vocal functions
Authors: Ghandour Hassan H. , Shoeib Rasha M. , Nassar Jilan F. , El-Shafei Mohammed M. 
Published: September 2023

EnAbstract
Background
Transient voice change associated with endotracheal intubation has generally been attributed to vocal fold trauma.

Aim
The aim of this study was to examine the effects of short-term endotracheal intubation on the vocal fold vibratory pattern using videokymography in order to aid the early detection and prevention of these changes.

Participants and methods
This study was carried out on 40 patients who were scheduled for a variety of elective surgical procedures under general anesthesia. They were 26 males, ranging in age from 17 to 61 years, mean age of 36.4±4.2 years, and 14 females ranging in age from 16 to 54 years, mean age of 34.6±5.3 years. Evaluation of vocal functions was carried out at three intervals, 1 day before intubation, 1 day after extubation, and 1 week later. All patients were subjected to analysis of their complaints, auditory perceptual assessment of their voice, and assessment of vocal fold vibration using videokymography.

Results
Sixteen patients complained of postoperative voice change, ranging in severity from good in 11, moderate in four, and bad in one patient. After 1 week, five patients were still complaining of voice change, ranging from good in four to moderate in one. There was a positive significant correlation between the degree of voice change and both the duration of anesthesia and tube size. There was postextubation mild to moderate voice change in 12 patients. The pitch was decreased in nine patients, increased in two patients, and there was diplophonia in one patient. The loudness was fluctuating in eight patients and was decreased in four patients; after 1 week, there was an improvement in all the perceived parameters; however, persistent dysphonia was perceived in three patients. There was a positive significant correlation between the degree of dysphonia and both the duration of anesthesia and the tube size. The normal video mode of videokymography, performed 1 day after extubation, indicated evidence of traumatic laryngeal lesions in 15 patients. In the high-speed mode of videokymography performed before intubation, 1 day after extubation, and 1 week after extubation, a significant difference was found in most of the parameters when comparing before intubation and 1 day after extubation; also, a significant difference in all the parameters was found 1 day after extubation and 1 week after extubation, whereas a nonsignificant difference was found when comparing before intubation and 1 week after extubation. There was a significant positive correlation between both the duration of intubation and the tube size with the severity of voice complaint and grade of dysphonia. Also, there was a significant positive correlation between the aperiodicity in both the amplitude of mucosal wave and the glottal cycle time, and both the duration of intubation and the tube size in the dysphonic group.

Conclusion
Traumatic lesions of the laryngeal structures that occur during intubation, in addition to possible subepithelial changes, are the most common causes of postoperative dysphonia, with a tendency toward a regressive course of the resulting dysphonia. As such, it is important to establish an early diagnosis and adopt preventive measures.