CHARLOTTESVILLE, VA—Many patients admitted to the ICU have preexisting hearing loss; others may lose their hearing temporarily as a result of drugs, sepsis, electrolyte abnormalities, or other conditions common in critically ill patients. Yet good hearing is crucial to assessments of mental status; the inability to hear spoken communication can also add to the patient’s confusion and discomfort. Despite this, few studies have addressed hearing and its effect on patient communication. Recently, investigators at the University of Virginia in Charlottesville tested the hearing of 442 consecutive critically ill patients and found that almost two thirds had hearing impairment.[1]

THREE TESTS PERFORMED

Hearing tests were performed in a surgical ICU over a 14-month period. The auditory examination, which included otoscopy, tympanometry, and otoacoustic emission (OAE) testing, was done as close to ICU admission as possible. Distortion product OAEs are low-level sounds that originate in the cochlea and can be detected in the external auditory canal when hearing is near normal. OAE testing results correlate with those from brain stem auditory evoked potential testing and do not require patient interaction.

A “passing” OAE was defined as a positive result for at least two of four measurements within a given band in an octave. Results were graded from 1 to 6 (1 and 2 = normal or slightly impaired hearing; 3 and 4 = moderate or severe hearing loss; 5 and 6 = failures due to ambient noise or technical problems).

HEARING LOSS IN MANY PATIENTS

The screening process took, on average, about nine and one-half minutes. Tympanic membrane compliance decreased and fluid accumulation increased progressively with time spent in the ICU. Normal OAE results were achieved for only 36.2% of the ears studied, while 58.4% had abnormal results indicating hearing loss severe enough to interfere with understanding speech.

“Passing” rates declined significantly as patient age increased beyond 39. For patients in their 50s and 60s, the failure rate was about 70%. Interestingly, even in those younger than 40, the “pass” rate was only 60%. The OAE failure rate was 48.6% for women, compared with 61.5% for men.

In this study, a significant number of patients failed auditory testing at thresholds within the range of normal conversational sound levels. When patients or family members were questioned before testing, there was frequently a discrepancy between perceived and actual hearing loss.

The investigators offer several clinical recommendations for managing hearing loss in critically ill patients. For example, earwax should be removed if it is impacted and causing hearing problems, and nasal decongestants should be given to patients with fluid accumulation in the middle ear. If communication is severely impaired or the patient’s true mental status is unknown, brain stem auditory evoked potential testing should be performed. If a patient is heavily sedated or extremely ill, the screening procedure should be repeated once he or she is more stable. However, no immediate intervention is necessary for patients who can communicate effectively despite poor response to OAE testing.

—Gale Jurasek

Reference
1. Hamill-Ruth RJ, Ruth RA. Evaluation of audiologic impairment in critically ill patients: results of a screening protocol. Crit Care Med. 2003;31: 2271-2277.

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