Reviewing the effectiveness of tympanic thermometers

Tympanic thermometers have become a popular alternative to glass mercury thermometers for recording patients' temperatures. This article reviews studies that have been performed to audit their use in clinical practice. It examines the accuracy of tympanic thermometers and discusses ways to improve the use of this instrument and the implications for nursing practice.     

The effect of ambient temperature extremes on tympanic and oral temperatures.

Exposure to ambient temperature extremes immediately preceding emergency department triage may affect tympanic membrane temperatures taken with infrared emission detection thermometers. In a prospective, unblinded study, 20 healthy subjects, on 2 separate days, underwent 15-minute exposures to hot (43.5 degrees C) and cold (-5 degrees C) temperature extremes in an environmental control room (ECR). Tympanic and oral temperatures were taken at baseline and at 2-minute intervals for 20 minutes after exiting the ECR. Rectal temperatures remained stable during the exposures. Oral temperatures rose significantly after hot exposure (P less than .05; max 0.4 degrees C) and briefly decreased after cold exposure (max 0.5 degrees C). Tympanic temperatures were elevated for 20 minutes after hot exposure (max 0.8 degrees C) and decreased briefly only in male subjects after cold exposure (max 0.7 degrees C). Individuals demonstrated wide variability in their temperature responses. Tympanic and oral temperatures taken within the first 20 minutes after exposure to outdoor temperature extremes may fail to accurately reflect the patient's true temperature.     

Comparison of tympanic and oral temperatures in surgical patients

The purpose of this study was to compare tympanic and oral temperatures at four times during the perioperative period in 60 adults having major abdominal surgery. Tympanic temperature was measured with an infrared thermometer and oral temperature with a predictive thermistor thermometer. Measurements at the two sites were similar in pattern and moderately well correlated. Tympanic temperature was somewhat more sensitive to the effects of an intervention influencing body temperature. The tympanic-oral temperature offset was relatively stable over time, with tympanic readings having a smaller range of values at each measurement. Tympanic temperature measurement variation was fairly small, with 92% of readings reproducible within 0.5 degree F (0.3 degree C); comparable oral data were not available. The findings suggest that the tympanic site offers some advantage, but that either tympanic or oral readings would be satisfactory for routine intermittent monitoring of body temperature during the perioperative period.     

A comparison of the use of tympanic, axillary, and rectal thermometers in infants.

This study examined the relationship between three instruments used in measuring tympanic, axillary, and rectal temperatures in infants less than 1 year of age. Temperatures were measured by Oto-temp Pedi Q tympanic thermometers, Becton Dickinson axillary thermometer, and rectal thermometers. A convenience sample of 5 infants less than 90 day and 54 greater than 90 days with fever, as well as 34 infants less than 90 days and 27 infants greater than 90 days without fever were studied. Correlations of infants less than 90 days and greater 90 days of age, as well as differences between infant temperature with and without fevers as variables, were examined. Results indicated a strong statistical relationship between Oto-Temp Pedi Q, Becton Dickinson axillary temperatures, and rectal temperatures, but not strong enough to base critical clinical decisions. Age and presence or absence of fever significantly affected the relationships between thermometers.     

NexTemp thermometer can be used interchangeably with tympanic or mercury thermometers for emergency department use

Objectives To determine the agreement between the chemical dot NexTemp thermometer with mercury and tympanic thermometers and the repeatability of measurements using these devices. Methods A prospective study involving a convenience sample of 194 consenting adult patients presenting to the ED, Freemasons Hospital, East Melbourne, Victoria, Australia. A survey of emergency medical staff was conducted to determine what they considered an acceptable level of agreement and repeatability for a putative new thermometer. The NexTemp thermometer’s performance was judged against this. For each thermometer, a set of two temperature measurements was made in every patient. The sequence of the set of readings (and hence device) was random between patients and the staff member performing one set was blinded to the results of the other two sets of readings in each patient. The method of Bland and Altman was used for assessing agreement and repeatability. Results Clinicians considered that a new thermometer should exhibit repeatability of ±0.3°C and agree with existing devices within ±0.5°C. The tympanic thermometer had 95% limits of repeatability of ?0.8–0.5°C compared with the NexTemp (?0.3–0.4°C) and mercury thermometers (?0.3–0.4°C). The NexTemp thermometer agreed with mercury thermometer within ?0.6–0.5°C. The tympanic thermometer agreed with the mercury thermometer within ?1.0–1.1°C. Conclusion Based on temperature measurement only, the NexTemp thermometer can be used interchangeably with current mercury and tympanic thermometers.     

Agreement between measures of pulmonary artery and tympanic temperatures

The purposes of this study were to compare pulmonary artery, oral, axillary, and two tympanic temperatures and test agreement between measures of pulmonary artery and tympanic temperatures in a convenience sample of 32 Intensive Care Unit patients. The correlation coefficients for pulmonary artery and oral, axillary, and tympanic temperatures were moderate to strong and significant at the p <.01 level. However, intraclass correlation coefficients estimated the intermethod reliability and were below the .75 criterion of acceptability. Thus, one method of temperature measurement could not be interchanged for another. ©1995 John Wiley & Sons, Inc.     

Comparison of oral and tympanic temperatures in adult surgical patients.

Monitoring patients' temperatures is an important aspect of clinical nursing. In surgical areas, we rely on accurate temperature readings to determine appropriate therapy. Various body sites have been used for temperature measurement: oral, axillary, rectal, and tympanic. Oral temperature readings have long been considered the gold standard. However, oral temperature readings may be contraindicated, depending on surgical incision and level of consciousness or in cases of seizure. Tympanic temperature monitoring is often the next choice. The literature supports the accuracy of tympanic monitoring; however, some clinicians have questioned its accuracy. This study used a repeated-measures design to determine the reproducibility of tympanic and oral temperature measurements. A difference of 0.2 degrees C was considered clinically significant. Outcome data indicated that variability was similar with oral and tympanic temperatures. There was no significant difference between average tympanic and average oral temperatures. Therefore, this study supports the use of tympanic thermometers in addition to oral thermometers in obtaining temperatures.     

Using low-tech thermometers to measure body temperatures in older adults. A pilot study

Many studies compare temperature sites and equipment, but none have examined the validity of groin temperatures in older adults, or compared Galinstan-in-glass with mercury-in-glass thermometer products. The purpose of this pilot study was to collect and analyze data related to human body temperature monitoring in adults 50 and older. Groin temperature (Tg) was compared with simultaneous oral (To) and rectal (Tr) temperature measures for each participant using two thermometer types (i.e., mercury-in-glass and Galinstan-in-glass). A high degree of correlation was found among sites and devices. Further study will be needed to include a larger, more diverse study population for the Galinstan non-mercury thermometer devices. Further study will also be needed to assess various temperature assessment sites for a larger, more diverse study population (e.g., age, gender, race, disease state).     

A comparison of 2 methods of measuring rectal temperatures with digital thermometers.

BACKGROUND: Digital rectal thermometers typically have 2 distinct modes of operation: dwell or monitor, in which body temperature is displayed continuously, and predictive, in which body temperature is mathematically estimated on the basis of the curve of temperature rise that occurs after the thermometer is inserted. Although the dwell mode is generally considered more accurate, the predictive mode allows more rapid measurement. Direct comparisons of these 2 methods are lacking. OBJECTIVE: To determine if measurements of rectal temperatures obtained with the predictive mode differ significantly from those obtained with the dwell mode. METHODS: For each of 10 subjects, both dwell and predictive modes were used to measure early morning rectal temperature. For comparison of the 2 modes during states of temperature flux, 8 subjects had rectal temperatures measured after swimming in cold water. Initial predictive values were measured directly after each subject exited from the water. Initial dwell values were estimated by linear extrapolation of measured 3- and 6-minute dwell values. Paired-sample statistical methods were used to compare data. RESULTS: Measurements of early-morning temperatures obtained with the predictive mode did not differ significantly from those obtained with the dwell mode (P = .64). Predictive values also did not differ significantly from extrapolated dwell values for measurements obtained during mild temperature flux after immersion in cold water (P = .33). CONCLUSION: The predictive and dwell modes of digital rectal thermometers yield similar measurements of temperature during steady-state conditions and during states of mild temperature flux.     

Ashworth Scales are unreliable for the assessment of muscle spasticity

Ashworth Scales are the most widely used tests to assess the severity of muscle spasticity. These scales offer qualitative and subjective information; consequently, there are issues concerning validity and reliability. This article presents the results of a study comparing interrater reliability of the original and of the modified Ashworth Scales for measuring muscle spasticity in elbow flexors. Fifteen patients with hemiplegia (nine men and six women) with a median age of 52 years (interquartile range, 28-64) participated in this study. Two physiotherapists rated the muscle tone of elbow flexors according to ratings criteria of the Ashworth and the modified Ashworth Scales. Kappa values for the original Ashworth and the modified Ashworth Scales were 0.17 (SE 0.21; p = 0.41) and 0.21 (SE = 0.12; p = 0.08), respectively. The scales showed similar levels of reliability (chi2= 0.0285, df=1, p = 0.7). The Ashworth Scales are not reliable for the assessment of muscle spasticity. In the absence of interrater reliability, the validity of the measurements may also be questioned.     

Infrared emission detection tympanic thermometry May be useful in diagnosing acute otitis media

To determine the utility of infrared emission detection (IRED) tympanic thermometry in diagnosing acute suppurative otitis media (ASOM), a prospective, nonblinded sampling of ear temperatures was performed. Children between the ages of 6 months and 6 years presenting to an urban emergency department were included in the study. Tympanic temperatures were determied in all subjects. Clinical data, tympanic audiometry, and telephone follow-up were used to define ASOM. Temperature differences were determined for children with unilateral ASOM and those without ear infection. Data from 48 patients were analyzed. The mean temperature difference in the control group, 0.23° ± 0.15°C (95% confidence interval [Cl], 0.17° to 0.29°C) differed from those with ASOM: 0.39° ± 0.29°C (95% Cl, 0.25° to 0.53° C, P = .047). Logistic regression was used to describe the predictive relationship between temperature difference and probability of ASOM. We conclude that IRED tympanic thermometry may be useful in diagnosing ASOM when used with other clinical data.     

Comparing tympanic temperatures in both ears to oral temperature in the critically ill adult.

Tympanic temperatures are often used in the critical care units to measure core body temperatures when pulmonary artery catheters are not available. This study was conducted to compare tympanic temperatures in the right and left ear with oral temperatures. The findings of this study show that choosing the optimal site for each patient and using patient-specific site consistently would result in better tracking of changes in temperature and, thus, timely diagnosis of fever.     

Adrenaline activity is not significantly altered by high ambient temperatures.

Drugs used in prehospital care are exposed to extremes of temperature, which exceed the manufacturerer's recommended storage conditions, and may result in degradation of the formulation. Adrenaline, which can be degraded by high temperatures, is a key agent for the effective management of cardiac arrest and acute anaphylaxis in the prehospital setting. We demonstrate that the activity of adrenaline vials carried in St John's ambulances in the Perth metropolitan area during summer months when ambient temperatures can reach 40°C was not significantly altered.     

Performance of a hydrophobic heat and moisture exchanger at different ambient temperatures

Objective To evaluate the effect of different room temperatures on hydrophobic heat and moisture exchangers (HME) humidifying capability and efficiency.Methods Stock HMEs were tested in vitro using an already described test model, with separation of inspiratory and expiratory gas. Absolute humidity (AH) was measured by means of dry-wet dual thermocouple, and HME efficiency was computed as the ratio between expired to inspired. AH, at room termperature of 20 and 26°C.Results Inspired gas temperature and AH were significantly higher at 26 than at 20°C; since expired AH remained substantially unchanged, HME efficiency was also higher in warmer environment.Conclusions Hydrophobic HMEs appear to be affected by room temperature, increasing their humidifying ability and their efficiency with its rise.     

Accuracy of pacifier thermometers in young children

Nurses and families are continually searching for less invasive yet accurate methods of measuring temperature in children. Although pacifier thermometers are readily accessible to consumers, few studies report the accuracy of such instruments. This study aimed to determine the validity/reliability of one type of pacifier thermometer in approximating core body temperature using a prospective, within-subjects design, comparing pacifier and rectal temperatures in children (n=25), ages 7 days to 24 months, in one pediatric hospital-based setting. The mean +/-SD difference between rectal and supralingual temperatures adjusted upward by 0.5 degrees F was 0.012 degrees F +/- 0.777 degrees F, which was not statistically significant. The 95% confidence interval (-0.309-0.333) fit within the manufacturer specifications. The correlations between the rectal and adjusted pacifier temperature was 0.772 and between 3-and 6-minute pacifier temperatures was 0.913. These data provide support to previous assertions that pacifier thermometry is an acceptable method of temperature approximation in young children.     

Monitoring body-cors temperature from the trachea: Comparison between pulmonary artery,tympanic, esophageal, and rectal temperatures

Introduction. We designed an endotracheal tube (ETT) for acquiring body-tore temperature from the trachea. This ETT had two temperature sensors, one attached to the inside surface of the cuff, the other mounted on the ETT shaft underneath the cuff. The ETT was evaluatedin vitro and in dogs to determine: 1) optimal position of temperature sensors and 2) the responsiveness, accuracy, and resistance to ventilatory artifacts.Methods.In vitro. An artificial trachea assessed the response-time and accuracy of ETT temperature sensors to abrupt temperature changes and ventilatory flow-rates.In vivo. Body temperature in 5 dogs was lowered to approximately 26°C then elevated toward 39°C using a heat exchanger during carotid jugular bypass. ETT temperature measurements were compared simultaneously with those from the artificial trachea (in vitro) or from the pulmonary artery, tympanic cavity, esophagus, and rectum of dogs using dry and humidified gas.Results. Cuff temperature sensor responded quickly and accurately to temperature changes and was less prone than the tube sensor to ventilatory and humidity artifacts. During carotid-jugular bypass,in vivo tube and cuff mean temperatures averaged 1.4°C and 0.36°C lower, respectively, than pulmonary artery temperatures. There were no statistical differentes (P > 0.05) between cuff temperatures and those measured from the pulmonary artery, tympanic cavity, esophagus, and rectum. Heating and humidifying the inspiratory gas of dogs with a water-bath humidifer or heat moisture exchanger (HME) had minimal effects on the cuff temperature sensor. An in-line HME increasedin vivo tube temperature from baseline values by 1.13 ± 0.80 °C, while cuff temperature increased by 0.21 ±0.24°C.Conclusion. The cuff of the ETT is a reliable site for measuring body-tore temperature in intubated patients.     

Monitoring body-cors temperature from the trachea: Comparison between pulmonary artery,tympanic, esophageal,and rectal temperatures

Introduction. We designed an endotracheal tube (ETT) for acquiring body-tore temperature from the trachea. This ETT had two temperature sensors, one attached to the inside surface of the cuff, the other mounted on the ETT shaft underneath the cuff. The ETT was evaluatedin vitro and in dogs to determine: 1) optimal position of temperature sensors and 2) the responsiveness, accuracy, and resistance to ventilatory artifacts.Methods.In vitro. An artificial trachea assessed the response-time and accuracy of ETT temperature sensors to abrupt temperature changes and ventilatory flow-rates.In vivo. Body temperature in 5 dogs was lowered to approximately 26°C then elevated toward 39°C using a heat exchanger during carotid jugular bypass. ETT temperature measurements were compared simultaneously with those from the artificial trachea (in vitro) or from the pulmonary artery, tympanic cavity, esophagus, and rectum of dogs using dry and humidified gas.Results. Cuff temperature sensor responded quickly and accurately to temperature changes and was less prone than the tube sensor to ventilatory and humidity artifacts. During carotid-jugular bypass,in vivo tube and cuff mean temperatures averaged 1.4°C and 0.36°C lower, respectively, than pulmonary artery temperatures. There were no statistical differentes (P > 0.05) between cuff temperatures and those measured from the pulmonary artery, tympanic cavity, esophagus, and rectum. Heating and humidifying the inspiratory gas of dogs with a water-bath humidifer or heat moisture exchanger (HME) had minimal effects on the cuff temperature sensor. An in-line HME increasedin vivo tube temperature from baseline values by 1.13 ± 0.80 °C, while cuff temperature increased by 0.21 ±0.24°C.Conclusion. The cuff of the ETT is a reliable site for measuring body-tore temperature in intubated patients.