How reliable is axillary temperature measurement?

AIM: To assess whether axillary temperature measurements reliably reflect oral/rectal temperature measurements. METHODS: This observational study compared paired axillary-rectal and axillary-oral temperatures in a general paediatric ward with the participation of 225 children aged < or = 4 y and 112 children aged between 4 and 14 y. RESULTS: Changes in oral/rectal and axillary temperatures correlated significantly (p < 0.0001). However, axillary temperature measurements were significantly lower than both oral (mean -0.56 degrees C, SD 0.76 degrees C) and rectal measurements (0.38 degrees C; SD 0.76 degrees C). Ninety-five percent of axillary measurements fell within a 2.5-3 degrees C range around respective paired oral/rectal measurements. The mean difference increased with increasing temperature, and was 0.4 degrees C at low body temperatures, and over 1 degree C with a fever of 39 degrees C. Neither seasonal fluctuations nor the amount of clothing worn influenced this difference. CONCLUSION: Axillary temperatures in young children do not reliably reflect oral/rectal temperatures and should therefore be interpreted with caution.     

The inaccuracy of axillary temperatures measured with an electronic thermometer

Temperatures were measured using an electronic thermometer in an emergency department to determine the relationship between oral or rectal and axillary measurements. A total of 164 data pairs were obtained--95 in afebrile children, and 69 in febrile children. The correlation coefficient was .74 for oral-axillary pairs, and .70 for rectal-axillary pairs. The mean difference between oral and axillary temperatures was 1.17 degrees C +/- 0.72 degrees C, and between rectal and axillary temperatures was 1.81 degrees C +/- 0.97 degrees C. Using 37.4 degrees C (greater than or equal to 2 SDs) axillary as the upper limit of normal, the sensitivity, specificity, and positive and negative predictive values were calculated for detecting a fever. The sensitivity was 46%; specificity, 99%; positive predictive value, 97%; and negative predictive value, 72% for combined oral-axillary and rectal-axillary data. It was concluded that axillary temperatures are not sensitive enough to determine a fever when measured with an electronic thermometer. Electronic thermometers should be used to determine oral or rectal temperatures; axillary temperatures may be misleading and should be abandoned in the outpatient setting.     

Is axillary temperature an appropriate surrogate for core temperature?

The ideal technique for measuring temperature should be rapid, painless, reproducible and accurately reflect the core temperature. While axillary temperature is commonly used because of convenience and safety, there are conflicting reports abouts its accuracy. To determine whether axillary temperature can act as a surrogate for oral/rectal temperatures, a prospective comparative study was conducted. The axillary and rectal temperatures (Group 1: infants < 1 year age) and axillary and oral temperatures (Group 2: children 6–14 years age) were compared using mercury-in-glass, thermometers. Various tests of agreement were applied to the data obtained. Rectal and axillary temperatures for infants agreed well; the mean difference (95% limits of agreement) between the two being 0.6°C (−0.3°C, 1.4°C). Similarly, the mean difference (95% limits of agreement) between oral and axillary measurements for children aged 6–14 years was observed to be 0.6°C (−0.4°C, 1.4°C). Axillary temperature appears to be an acceptable alternative to rectal/oral temperature measurements in children.     

Infrared tympanic thermometry in comparison with other temperature measurement techniques in febrile children.

OBJECTIVE:: To determine whether infrared tympanic thermometry (ITT) measurements more accurately reflect core body temperatures than axillary, forehead, or rectal measurements during fever cycles in children. DESIGN:: Prospective cohort study. SETTING:: Pediatric and cardiac intensive care units at a tertiary care children's hospital. PATIENTS:: Critically ill children <7 yrs of age with indwelling bladder catheters. INTERVENTIONS:: Simultaneous temperatures were recorded during both febrile and nonfebrile periods using ITT, indwelling bladder (core), axillary, forehead, and indwelling rectal measurements in 36 children. MEASUREMENTS AND MAIN RESULTS:: Overall ITT measurements were 0.03 +/- 1.43 degrees F less than core temperature measurements. In comparison, rectal, forehead, and axillary measurements averaged 0.62 +/- 1.44, 0.56 +/- 1.81, and 1.25 +/- 1.73 degrees F less than core temperature measurements. ITT measurements had better agreement with core measurements during increasing and decreasing temperature cycles. Receiver operating characteristic analysis performed on increasing and decreasing temperature cycle data revealed that ITT measurements performed well, with an area under the curve of 0.855 (95% confidence interval, 0.797-0.913) in comparison with rectal measurement area under the curve of 0.777 (95% confidence interval, 0.701-0.853), forehead measurement area under the curve of 0.710 (95% confidence interval, 0.715-0.888), and axillary measurement area under the curve of 0.664 (95% confidence interval, 0.579-0.750). CONCLUSIONS:: ITT measurements more accurately reflect core temperatures than any other measurement site during febrile and nonfebrile periods in children. ITT measurements are a reproducible and relatively noninvasive substitute for bladder or rectal measurements in febrile children.     

Limited accuracy and reliability of infrared axillary and aural thermometers in a pediatric outpatient population

OBJECTIVE: To evaluate the accuracy and reliability of infrared axillary and aural thermometers in the outpatient setting. STUDY DESIGN: A prospective observational study of infrared axillary, aural, and digital rectal temperature values from 198 children, aged 3 to 36 months (mean, 1.3 years). RESULTS: Sensitivity and specificity of the axillary thermometer for rectal fever were 63.5% and 92.6%, respectively (diagnostic accuracy, 83.3%); those for the aural thermometer were 68.3% and 94.8%, respectively (diagnostic accuracy, 86.4%). For all patients, the mean biases of the axillary and aural temperatures were -0.33 degrees F and -0.24 degrees F, respectively. The biases of both thermometers' measurements were significantly correlated with rectal temperature (P <.02); thus, as rectal temperature increased, the accuracy of the compared axillary and aural temperature decreased. Underestimation of rectal temperature was greatest among febrile 1- to 3-year-old children (axillary bias, -1.20; aural bias, -0.36). Age was correlated with an axillary temperature bias (P <.01). CONCLUSION: Axillary and aural infrared thermometers were comparable, albeit significantly different than rectal temperature measurements, particularly as the child's age and rectal temperature increased. These thermometers may be useful as noninvasive screening methods in outpatient settings for children who are at least 3 months old, but rectal values should be used for clinical accuracy.     

Comparison of axillary, rectal and tympanic temperature measurements in children admitted with malaria

We compared axillary, rectal and tympanic temperatures in children admitted with severe malaria. The axillary temperatures were 0.74 degrees C (95% limits of agreement -0.85 to 2.33 degrees C) less than rectal temperatures and tympanic temperatures 0.42 degrees C (95% limits of agreement -0.16 to 2.44 degrees C) less than rectal temperatures. The difference was greater on admission than 24 hours later. These differences may be important in defining criteria for clinical syndromes.     

Screening for a raised rectal temperature in Africa.

The main purpose of this study was to compare rectal and axillary temperature measurements in African children. Altogether 573 sick children were seen in an outpatient setting in rural West Africa. Rectal and axillary temperatures were measured and the parent or guardian was asked if they thought that the child had a raised body temperature. Normal ranges were defined from an age matched population of 203 healthy children. A raised axillary temperature predicted a raised rectal temperature with a sensitivity of 98% and a specificity of 88%. The parents' impression that their child had a fever was a less sensitive (89%) and less specific (59%) indicator of raised rectal temperature. A raised axillary temperature is a good screening test for a raised rectal temperature in African children.     

Screening for a raised rectal temperature in Africa

The main purpose of this study was to compare rectal and axillary temperature measurements in African children. Altogether 573 sick children were seen in an outpatient setting in rural West Africa. Rectal and axillary temperatures were measured and the parent or guardian was asked if they thought that the child had a raised body temperature. Normal ranges were defined from an age matched population of 203 healthy children. A raised axillary temperature predicted a raised rectal temperature with a sensitivity of 98% and a specificity of 88%. The parents' impression that their child had a fever was a less sensitive (89%) and less specific (59%) indicator of raised rectal temperature. A raised axillary temperature is a good screening test for a raised rectal temperature in African children.     

Comparison of temporal artery thermometer to standard temperature measurements in pediatric intensive care unit patients.

OBJECTIVES: To determine the accuracy of noninvasive infrared temporal artery thermometry compared with rectal, axillary, and pulmonary artery catheter measurements in pediatric intensive care patients, and to determine whether temporal artery temperatures are affected by circulatory shock or by vasopressor use. We hypothesized that temporal artery temperatures do not differ from axillary and rectal temperatures in critically ill children, but temporal artery accuracy is decreased by shock or vasopressor use. DESIGN: Observational study, unblinded. SETTING: Pediatric intensive care unit of a quarternary referral children's hospital. PATIENTS: Seventy-five temperature comparison pairs were obtained in 44 pediatric intensive care unit patients. INTERVENTIONS: Temperature measurements were made using a temporal artery thermometer with simultaneously obtained rectal, axillary, and, when available, pulmonary artery catheter measurements. MEASUREMENTS AND MAIN RESULTS: Mean bias was calculated between comparison pairs using each temperature method. Bland-Altman analysis demonstrated wide variability between methods. No significant differences in mean bias were seen between method pairs for all temperatures, but bias was significantly less in pulmonary artery catheter-rectal pairs compared with other method pairs. In febrile (> 38 degrees C) patients, bias in rectal-temporal artery and rectal-axillary was significantly greater than in temporal artery-axillary pairs (p < .001). Mean bias in pulmonary artery catheter-rectal pairs was also significantly smaller than in other pairs for all patients (p = .008) and febrile patients (p = .049). Presence of shock or vasopressor use did not significantly increase bias in any comparison pair. Sensitivity and specificity of both temporal artery and axillary for diagnosing fever were similar and improved with fever definition at temperatures > 38.5 degrees C. CONCLUSIONS: Temporal artery and axillary temperature measurements showed variability to rectal temperatures but had marked variability in febrile children. Neither was sufficiently accurate to recommend replacing rectal or other invasive methods. As temporal artery and axillary provide similar accuracy, temporal artery thermometers may serve as a suitable alternative for patients in whom invasive thermometry is contraindicated.     

A probability nomogram to predict rectal temperature in children.

The relationship between rectal and peripheral-site temperature was investigated to achieve two objectives: 1) to evaluate a prevailing practice of intersite adjustment by use of an invariant temperature difference; and 2) to develop a statistical method for intersite temperature predictions in the individual child, especially for fever as defined by rectal measurement. Rectal, oral, axillary, left abdomen skin, and forehead skin temperatures (degrees F) were measured with an electronic thermometer in 257 children. Objective 1 was not achieved because a simple temperature difference between a peripheral site and the rectal site could not be used to predict rectal temperature reliably. For objective 2, intersite differences met three statistical criteria so that normal distribution theory could be used to derive the probabilities for occurrence of each difference. Accordingly, cumulative probability nomograms were constructed to estimate rectal-site fever from measurements at peripheral sites. This nomogram method produces a clinically reliable prediction of rectal-site fever from temperature measurement at peripheral sites, especially the oral and axillary sites. These predictions offer useful assessments of febrile illness severity when rectal temperature is not available.     

Comparison of ear to rectal temperature measurements in infants and toddlers.

The purpose of this study was to compare arterial heat balance ear temperature measurements to rectal temperatures in infants and children and to determine the ability of the ear thermometer being tested to detect fever. From 12/95 to 2/96, 1,175 pairs of ear and rectal temperature measurements were prospectively obtained from 140 infants and toddlers. The mean rectal temperature was 37.58 degrees C (sd = 0.68) and the mean ear temperature was 37.60 degrees C (sd = 0.85). However, at the low end of the rectal temperature scale, ear temperatures tended to be higher, and at the high end of the rectal temperature scale, ear temperatures tended to be lower. There were 292 readings with a rectal temperature > or = 38.0 degrees C and in 204 (70%) the ear temperature was also > or = 38.0 degrees C. A retrospective analysis of 53 children who became febrile in hospital (ear or rectal temperature > or = 38.0 degrees C) showed that fever was detected first by rectal measurement in seven, by ear measurement in 31 (59%), and by both in 15 (28%). These data indicate that, on the average, rectal and ear temperature measurements are not different. Fever that developed in children after hospitalization was more likely to be first detected by ear than by rectal measurement.     

Sleeping body temperatures in 3-4 month old infants.

Rectal, skin, and ambient temperatures were continuously recorded overnight from 3-4 month old normal infants in their home cots under conditions of room temperature and wrapping chosen freely by parents. It was found that rectal temperature was above 37 degrees C when infants were put down, but fell rapidly to 36.4 degrees C within one and a half hours, then stabilised for a few hours before rising steadily. This pattern was tied more closely to the time of putting down than time of day. The extent and rate of temperature fall did not correlate with any feature of the thermal environment. We also found that skin temperature changed much less than rectal temperature over the night, and for the first two hours in the cot there was no relation between skin and rectal temperature. There is therefore a well organised, endogenous rhythm of temperature in 4 month old infants.     

Lack of agreement of tympanic membrane temperature assessments with conventional methods in a private practice setting.

An infrared tympanic membrane thermometer (FIRST temp) said to approximate core temperature accurately is being marketed as a noninvasive, quick, and easy-to-use clinical instrument. The determination of tympanic membrane temperatures by this device was compared with the determination of oral, rectal, or axillary temperatures by a conventional glass thermometer. Subjects were patients of a pediatric group practice in Houston, Texas. FIRST temp and conventional temperature determinations on individual patients were completed within 5 minutes of each other. The presence or absence of otitis media was noted by the examining physician. Agreement between the two methods of temperature determination was assessed by calculating limits of agreement within which 95% (+/- 2 standard deviations) of individual differences would fall. The location of conventional thermometer (oral, rectal, axillary), time interval between the two separate measures, and the presence or absence of otitis media were entered into a multiple regression analysis to determine whether these factors influenced the observed differences between the two methods. A total of 144 patients were enrolled in the study; oral comparisons were obtained in 92 (57%) patients, rectal in 35 (24%), and axillary in 29 (19%). The upper and lower limits of agreement between temperature methods were 1.12 degrees C and 0.89 degrees C and the mean difference was -0.12 degrees C. Regression analysis revealed that only the site of conventional thermometer location (oral, rectal, axillary) was a significant predictor of FIRST temp/conventional differences. Each site had a range of agreement greater than 1.65% degrees C; axillary temperatures had the greatest range (-0.94 degree C to +1.30 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of temple temperatures with rectal temperatures in children under two years of age

We assessed the agreement between rectal and noninvasive temporal artery temperature measurements in infants and children. We also evaluated the temple thermometer as a screening tool for rectal fever in this age group. Finally, we compared the performance of parents with that of nurses in using the temple thermometer. The 95% limits of agreement between the difference in rectal and average temple temperature were -1.03 and +1.52 degrees C. Mean temple temperatures obtained by parents and by nurses were similar (95% limits of agreement, -0.6 degrees C to +0.7 degrees C). A maximum temple temperature cutoff of 37.2 degrees C (99.0 degrees F) distinguished children with rectal fever of > or =38.0 degrees C with 91% sensitivity and 53% specificity. A cutoff of 37.8 degrees C (100.0 degrees F) distinguished moderate rectal fevers (> or =38.5 degrees C) with 97% sensitivity and 84% specificity. A cutoff of 38.3 degrees C (101.0 degrees F) distinguished a high rectal fever (> or =39.0 degrees C) with a sensitivity of 95% and specificity of 95%. In conclusion, temple temperatures do not reliably predict rectal temperatures, but the temple thermometer can be used as an effective screen for clinically important rectal fever in children 3-24 months old. The findings do not support use of temple temperatures to screen young infants for rectal fever > or =38.0 degrees C. Temperatures obtained by parents were comparable to those obtained by nurses.     

Infrared thermometry of newborn infants

An infrared thermometer, the FirstTemp, was tested among newborn infants by comparing tympanic membrane temperature measurements in three operating modes, "Cal-tympanic," "Cal-surface," and "Cor-tympanic," with nearly simultaneous tympanic membrane, rectal, and axillary temperature measurements using other standard methods. The FirstTemp underestimated other measurements of body temperature in the "Cal-tympanic" mode and overestimated them in the "Cor-tympanic" mode. In the "Cal-surface" mode, the First-Temp readings were significantly lower than tympanic membrane temperatures measured with a thermistor probe and electronic thermometer (mean difference 0.2 degrees C) but not significantly different from rectal or axillary temperatures. According to these results, the FirstTemp can be used reliably in the "Cal-surface" mode but not in the "Cal-tympanic" or "Cor-tympanic" mode. Its speed and ease of operation offer significant advantages over traditional clinical methods of temperature measurement.     

Postnatal hypothermia and cold stress among newborn infants in Nepal monitored by continuous ambulatory recording.

AIMS: To describe the pattern of hypothermia and cold stress after delivery among a normal neonatal population in Nepal; to provide practical advice for improving thermal care in a resource limited maternity hospital. METHODS: The principal government funded maternity hospital in Kathmandu, Nepal, with an annual delivery rate of 15,000 (constituting 40% of all Kathmandu Valley deliveries), severe resource limitations (annual budget Pounds 250,000), and a cold winter climate provided the setting. Thirty five healthy term neonates not requiring special care were enrolled for study within 90 minutes of birth. Continuous ambulatory temperature monitoring, using microthermistor skin probes for forehead and axilla, a flexible rectal probe, and a black ball probe placed next to the infant for ambient temperature, was carried out. All probes were connected to a compact battery powered Squirrel Memory Logger, giving a temperature reading to 0.2 degree C at five minute intervals for 24 hours. Severity and duration of hypothermia, using cutoff values of core temperature less than 36 degrees C, 34 degrees C, and 32 degrees C; and cold stress, using cutoff values of skin-core (forehead-axilla) temperature difference greater than 3 degrees C and 4 degrees C were the main outcome measures. RESULTS: Twenty four hour mean ambient temperatures were generally lower than the WHO recommended level of 25 degrees C (median 22.3 degrees C, range 15.1-27.5 degrees C). Postnatal hypothermia was prolonged, with axillary core temperatures only reaching 36 degrees C after a mean of 6.4 hours (range 0-21.1; SD 4.6). There was persistent and increasing cold stress over the first 24 hours with the core-skin (axillary-forehead) temperature gap exceeding 3 degrees C for more than half of the first 24 hours. CONCLUSIONS: Continuous ambulatory recording identifies weak links in the "warm chain" for neonates. The severity and duration of thermal problems was greater than expected even in a hospital setting where some of the WHO recommendations had already been implemented.     

Thermoregulatory alterations as a marker for sepsis in normothermic premature neonates.

To evaluate the core-peripheral temperature alterations as a marker for sepsis in normothermic premature newborns, 50 normal term neonates and 11 preterms with sepsis and 11 normal preterms (controls) were studied. Axillary, rectal and sole temperatures were recorded in all babies using a single mercury-in-glass thermometer by a single observer. There was significant widening of the rectal-sole and axillary-sole temperatures in the preterms with sepsis (p less than 0.001). There was no significant difference (p greater than 0.05) between the axillary and rectal temperatures in the term, normal preterms or those with sepsis. With an overall accuracy of 90.9%, a rectal-sole temperature difference of greater than or equal to 2.3 degrees C (100% sensitivity) or greater than or equal to 3.2 degrees C (100% specificity) is a useful marker to differentiate normothermic preterms with or without sepsis. Using the axillary-sole temperature difference, the respective values were greater than or equal to 2.2 degrees C and greater than or equal to 3.0 degrees C.     

Modern electronic and chemical thermometers used in the axilla are inaccurate

Rectal and axillary temperatures were measured simultaneously in 83 children using three different thermometer devices providing 166 pairs of results. In the first series consisting of 22 febrile children (44 measurements) and 20 afebrile children (40 measurements), the rectal mercury measurement was compared to an axillary mercury and axillary Tempa-DOT thermometer. The axillary mercury had sensitivity of 14/22 (64%) and specificity of 20/20 (100%) while the Tempa-DOT had sensitivity of 15/22 (68%) and specificity of 19/20 (95%). In the second series comprising 21 febrile children (42 measurements) and 20 afebrile children (40 measurements) the axillary mercury had sensitivity of 11/21 (52%) and specificity of 20/20 (100%) while the electronic thermometer had sensitivity of 10/21 (48%) and specificity of 20/20 (100%). Regardless of the thermometer used , the axilla is a poor alternative to rectal measurements in the diagnosis of fever. Conclusion Mercury-free thermometers, when used in the axilla are as poor alternatives to rectal measurements as mercury-in-glass thermometers. Received: 14 November 1995 Accepted: 5 March 1996     

Heat Loss Prevention (HeLP) in the delivery room: A randomized controlled trial of polyethylene occlusive skin wrapping in very preterm infants

OBJECTIVES: To determine if polyethylene occlusive skin wrapping of very preterm infants prevents heat loss after delivery better than conventional drying and to evaluate if any benefit is sustained after wrap removal. STUDY DESIGN: This was a randomized controlled trial of infants <28 weeks' gestation. The experimental group was wrapped from the neck down. Only the head was dried. Control infants were dried completely. Rectal temperatures were compared on admission to the neonatal intensive care unit immediately after wrap removal and 1 hour later. RESULTS: Of 55 infants randomly assigned (28 wrap, 27 control), 2 died in the delivery room and 53 completed the study. Wrapped infants had a higher mean rectal admission temperature, 36.5 degrees C (SD, 0.8 degrees C), compared with 35.6 degrees C (SD, 1.3 degrees C) in control infants ( P = .002). One hour later, mean rectal temperatures were similar in both groups (36.6 degrees C, SD, 0.7 degrees C vs 36.4 degrees C, SD, 0.9 degrees C, P = .4). Size at birth was an important determinant of heat loss: Mean rectal admission temperature increased by 0.21 degrees C (95% CI, 0.04 to 0.4) with each 100-g increase in birth weight. CONCLUSIONS: Polyethylene occlusive skin wrapping prevents rather than delays heat loss at delivery in very preterm infants.     

Assessment of newborn baby's temperature by human touch: a potentially useful primary care strategy.

Fifty healthy term neonates delivered at All India Institute of Medical Sciences Hospital were assessed by three pediatricians for skin temperature to the nearest +/- 0.5 degrees C at the three body sites, i.e., mid-forehead, abdomen and dorsum of right foot by touch. The predicted temperatures at different sites were compared with simultaneously recorded temperatures at the same sites with the help of an electronic thermometer having a sensitivity of +/- 0.1 degree C. Rectal temperature was also recorded in all the babies with a rectal thermister to compare the variations between the core and skin temperatures. There was a good correlation between the skin temperatures of the babies as perceived by touch and values recorded with the help of an electronic thermometer. All the hypothermic babies were correctly picked up by all the observers. There was good correlation between core temperature and skin temperature at different sites except forehead. It is amazing that even during the month of May, when ambient temperature was maintained between 26-28 degrees C, nearly one fifth of the healthy term babies were under cold stress as evidenced by greater than 2 degrees C difference between the core and peripheral skin temperatures. It is recommended that health professionals and mothers should be explained the importance of evaluating the core and peripheral skin temperature by touch for early identification of babies under cold stress in order to prevent occurrence of life threatening hypothermia.