Effects of short‐term endotracheal intubation on vocal function

Abstract

Transient voice change associated with endotracheal intubation has generally been attributed to vocal fold trauma. To assess the role of altered vocal fold function in transient voice change, a study was designed to evaluate the audioacoustic, endoscopic, and laryngostroboscopic characteristics of the postintubation voice. Vocal function of 10 patients undergoing short-term outpatient surgical procedures using general anesthesia and endotracheal intubation were studied preoperatively and postoperatively. A second group of 10 patients that did not have surgery or general anesthesia was used as an age-matched control. Fundamental frequency, frequency perturbation, electroglottography, endoscopy (including laryngeal stroboscopy), and subjective speech analysis by experienced listeners were used to assess vocal function. No consistent differences in fundamental frequency were observed, although patient-to-patient variation was marked. Statistically significant increases in cycle-to-cycle fundamental frequency variation (jitter) were found postoperatively in the majority of the postintubation patients (P less than 0.05). Electroglottography, laryngeal endoscopy, and stroboscopic laryngoscopy did not demonstrate consistent changes in glottic mucosal function. Listener judgments characterized the postintubation voice change by decreased intensity, increased roughness, and lowered affect without consistent changes in pitch. The perception of decreased affect in the voices (characterized by reduction in pitch variation, vocal stress, and increases in pause times) was a strong perceptual marker for change in the post-intubation voice. Objective measures of laryngeal function suggest that the glottic contribution to postintubation voice change is minimal and that this dysphonia is probably multifactorial.

Short-Term Effects of Endotracheal Intubation on Voice

“…Administration of anesthetic agents may affect the vocal tract neuromuscular activity, fine motor control, and sensorium, all of which can result in changes in the fundamental frequency and perturbation parameters. 9,26 The significant decrease in the MPT witnessed in our study can be secondary to the postanesthetic decrease in the breathing support discussed previously, to a decrease in the breathing control secondary to the aforementioned changes in the vocal folds, or to the surgical impact on the power source for phonation, such as the chest and abdomen.…”

“…Both laryngeal and extralaryngeal structures may be affected. 9 At the glottic level, damage to the mucosal surface of the vocal folds can markedly change the voice. Desiccation of the mucosal surface secondary to inhalation of gaseous anesthetic substances or intake of drying medications such as atropine, which was consistently given preoperatively to all our patients, can result in an increase in the vocal fold viscosity and impaired vibration.…”

“…Desiccation of the mucosal surface secondary to inhalation of gaseous anesthetic substances or intake of drying medications such as atropine, which was consistently given preoperatively to all our patients, can result in an increase in the vocal fold viscosity and impaired vibration. 9,11,12 Clinically, patients will experience an increase in phonatory threshold pressure reported often as vocal fatigue. They may require more effort to initiate and sustain a vowel.…”

“…However, the results of selected acoustic variables measured preintubation and postintubation were inconsistent or lead to many controversies. [8][9][10] Many of these results were based on a small number of subjects or did not include other objective measures of laryngeal function. Whether these vocal changes are secondary to alteration in the vocal tract only or to extralaryngeal factors is still unanswered.…”

Anesthesia Care for the Professional Singer

“…In their analysis, singing skills of a patient had no impact on the development of these laryngopharyngeal symptoms. Acoustic studies [14][15][16][17] have shown that jitter (fluctuation in vocal pitch) and shimmer (fluctuation in vocal intensity) have consistently increased after extubation, while maximum phonation time (ability to sustain a prolonged vowel sound) is decreased, thus underscoring the temporary instability of the voice after extubation.…”