The effect of respiratory rate and ingestion of hot and cold beverages on the accuracy of oral temperatures measured by electronic thermometers

MedSurg Nursing, April, 2007 by Beth Quatrara, Julie Coffman, Tricia Jenkins, Kristi Mann, Kathryn McGough, Mark Conaway, Suzanne Burns

In 1948, Brim and Chandler performed one of the first studies of the effects of hot and cold liquids, cigarette smoking, and chewing on accuracy of oral temperatures. Although their results were inconclusive due to temperature fluctuations and varied reaction patterns, the stage was set to evaluate various factors that potentially influence oral temperature readings. From the 1960s through 1980s, studies continued to focus on the importance of accurate oral temperatures (Durham, Swanson, & Paulford, 1986; Forster, Alder, & Davis, 1970; Neff, Ayoub, Longman, & Noyes, 1989; Tandberg & Sklar, 1983; Woodman, Parry, & Simms, 1967). However, the precise impact of beverage consumption and respiratory rate on the accurate temperature recording remains unclear.

In acute care medical-surgical settings, understanding the effect of respiratory rate and ingestion of hot and cold beverages on the accuracy of oral temperatures is vital to basic patient care (Brim & Chandler, 1948; Durham et al., 1986; Erickson, 1980; Forster et al., 1970; Neff et al., 1989; Tandberg & Sklar, 1983; Woodman et al., 1967). Potentially inaccurate temperature readings may result if meal delivery time coincides with the recording of vital signs. Similarly, various medications (opiates, benzodiazepines, barbiturates, alcohol) and medical conditions (uremia, anxiety, pulmonary disease, structural intracranial lesions) can lead to an altered respiratory state (LeBlond, DeGowin, & Brown, 2004; Smeltzer & Bare, 2003).

Many variables remain unanalyzed in the area of temperature precision research. Some temperature precision research has examined tachypnea, but no studies have evaluated the effects of bradypnea, which is important considering its presence among opioid-sedated postoperative patients (Maheswaran, 2006). Furthermore, studies historically excluded women because of hormonal influences on temperature (Forster et al., 1970; Woodman et al., 1967). Finally, results of the majority of existing research hinged on the accuracy of the glass mercury thermometer, an apparatus that has virtually disappeared from the clinical setting with the advent of electronic upgrades.

Purpose

The purpose of the study was to determine the effect of respiratory rate as well as hot and cold beverage consumption on the accuracy of oral temperature readings measured with an electronic thermometer. Striving to improve the use of oral thermometry by reducing the number of inaccurate oral temperatures, the researchers hoped to establish a standard of care that would lead to more expedient identification and treatment of true fevers. Appropriately focusing care interventions on true fevers (38.5[degrees]C or greater) reduces the incidence of prescribing unnecessary medications and procedures (Kasper et al., 2004).

Hypothesis

Tachypnea and cold beverages will lower temperature readings as measured by electronic oral thermometers, while bradypnea and hot beverages will increase temperature readings.

Methods

The study was approved by the institutional human investigations committee at a regional medical center in the Southeast. A prospective convenience sample of 64 volunteers was assigned to test the variables of interest. The volunteers (males and females of at least age 18) were excluded from the study if they ate, drank, or smoked 1 hour prior to testing. They also were removed from the study if they were unable to ingest the total volume, incapable of completing the assigned respiratory pattern, breathed with an open mouth, or were febrile. Verbal consent was obtained from participants. After the volunteers received instruction on using the Welch Allyn Sure Temp[R] electronic thermometer and measured baseline temperatures, they were randomized into one of four groups to test the assigned variable (hot beverage, cold beverage, tachypnea, or bradypnea).

One segment of the study analyzed the effect of respiratory rate on oral temperature readings. Subjects were assigned randomly to one of two groups: the bradypnea cohort (Group 1) or the tachypnea cohort (Group 2). Each group was located in a designated room. The data collection instrument was given to each subject to facilitate self-monitoring of temperature readings. When subjects entered the room, baseline oral temperatures, respiratory rates, and weights were obtained and recorded. Subjects were instructed to withdraw from the assigned breathing pattern routine if they experienced lightheadedness, dizziness, anxiety, or panic.

Because consistency of method among subjects in self-monitoring their oral temperature readings was critical, subjects underwent a review of the proper measurement technique using the Welch Allyn Sure Temp electronic oral thermometer within the Mode setting. They were instructed to use the posterior sublingual pocket as the site of temperature measurement, hold the probe during the entire measurement process, keep the probe tip in contact with tissue at all times, and maintain a closed mouth with firmly sealed lips during the temperature reading. Additionally, subjects were directed to choose either the right or left sublingual pocket and to maintain that side throughout the study for reliability.