Are Digital Oral Thermometer Readings Accurate in Adult Emergency Department Patients?

Background Inaccurate vital signs may lead to inadequate treatment and skew the differential diagnosis in patients presenting to the emergency department (ED), and thus could cause a delay in diagnosis and treatment. Our study sought to evaluate and compare oral and rectal temperatures in patients with medical conditions that may have fever as part of their presentation to the ED. Objectives To determine if oral and rectal temperatures correlate in patients with medical conditions who have a fever, dry mucous membranes, and are warm to the touch on exam. To identify which patient presentations are more likely to have incongruous temperatures. Our hypothesis is that digital oral thermometers are inaccurate and understate the temperature in patients who present with dry mucous membranes and tactile warmth. Methods A prospective cohort of adult patients in the ED was asked to consent to the comparison of rectal temperature if they presented with a medical condition that could result in a fever. Oral and rectal (core) temperatures were obtained, along with demographic data, chief complaint, current medications, recent ingestion of warm or cold liquids, use of antipyretics, and the treating physician's assessment of mucous membrane dryness and tactile warmth. Results A total of 111 patients were enrolled in the study. 55.8% of patients were male, and the mean age was 61 years. The most common presenting complaint was lower respiratory tract related; 87% had dry mucous membranes, and 85.5% were warm to the touch. Fever or hypothermia was missed in 55 patients (49.5%) if only oral temperatures were obtained. Patients were more likely to consent if their doctor was concerned about a fever and requested a rectal temperature as part of their workup. Conclusions This is one of the first studies to evaluate the difference between oral and rectal routes of obtaining body temperature in the ED in adult patients. Our data reveal that many fevers are "missed" if only oral temperatures are used in medical decision-making in patients with dry mouths and with tactile warmth. Our study is limited by the small sample size and the potential for selection bias.