Tympanic membrane thermometry in the care of out-of-hospital patients

Abstract

Study objectives: To determine the effectiveness of tympanic membrane (TM) thermometry in the out-of-hospital setting and to characterize the patients with abnormal out-of-hospital temperatures.

Design: Prospective, randomized, single-month study.

Setting: Inner city.

Participants: Subjects transported by ambulance for whom consent was obtainable.

Results: TM probes set to rectal equivalent were assigned to three of the ambulance units of the local health department on randomly selected shifts during August 1992, one half at night and one half during the day. Simultaneous left and right ear temperatures at the scene and at the hospital, ambient temperatures, and patient's hospital temperatures were recorded. Other data recorded included each patient's mental status, activity level, and environment temperature. Paramedics noted whether they suspected a temperature problem before using the probe and whether any treatment was directed toward the patient's temperature. Regression, bias analysis, and chi 2 testing were performed; P was considered significant if it was less than .05. Right and left ear TM temperatures were correlated both at the scene and at the hospital (r = .91 and .92, respectively). TM temperatures and hospital temperatures were also correlated (r = .83 for right ear and .78 for left ear). Evaluation of agreement indicated that TM and hospital methods were equal, with a bias of -0.55 degrees F for oral and +0.66 degrees F for rectal temperatures. Thirty-two subjects (17%) were hyperthermic at the scene; of these, 9 of 32 (28%) were suspected before use of the probe. The paramedics initially treated 5 of the 9 suspected to have a temperature-related problem before using the probe and none of the 23 who were not suspected before using the probe (chi 2, P < .001).

Conclusion: The TM probe functioned well despite a month of vigorous handling. Temperature correlation with the gold standard and between ears was acceptable in this setting. Presence of the probe did not help with the management of hyperthermic patients in this study.