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Factors to Consider in Preventing Laryngeal Injury Following Intubation

by Paul W. Flint, MD •

Does the duration of intubation, size of endotracheal tube or type of endotracheal tube impact the degree of laryngeal injury following intubation?

Background: The incidence of laryngeal injury following intubation remains surprisingly high and has been attributed to duration of intubation and size of the endotracheal tube (ETT). Conflicting studies suggest the factors leading to laryngeal injury due to intubation are not fully understood, and modification of the ETT has not necessarily reduced the incidence of ETT trauma.

Study design: Prospective study.

Synopsis: Patients intubated for more than 48 hours were evaluated within 24 hours after extubation by video flexible nasolaryngoscopy and numerically scored based on severity of injury (none–0 through 4–severe), including arytenoid edema/erythema, vocal fold edema/erythema, ulceration, granulation, mobility and subglottic narrowing. Sixty-one patients were evaluated. The mean duration of intubation was 9.1 days (range 2-28), and ETT size varied from six to eight. A standard ETT was used in 61 percent of patients, and the Hi-Lo Evac ETT was used in the remainder. The Hi-Lo ETT has a larger outer diameter relative to a standard ETT, with comparable inner diameter.

All patients demonstrated some degree of injury. The most common findings were arytenoid edema (95 percent) and erythema (97 percent) followed by vocal fold edema and erythema (67 percent and 87 percent), vocal process granulation tissue (53 percent), vocal fold motion impairment (24 percent) and vocal process ulceration (21 percent). Vocal fold motion impairment was more likely to occur on the left side. In this study, duration of intubation, ETT size and ETT type did not correlate with degree of injury.

Bottom line: The incidence and degree of injury appear to be related to other factors besides duration of intubation and ETT size. Other mechanisms of injury should be considered, including trauma at time of insertion, reflux and pressure-induced myopathy and neuropathy.

Citation: Colton House J, Noorzdzij JP, Murgia B, et al. Laryngeal injury from prolonged intubation: a prospective analysis of contributing factors. Laryngoscope. 2011;121(3):596-600.

— Reviewed by Paul W. Flint, MD