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Wendy M. Fallis By Wendy M. Fallis, RN, BScN, MN. From School of Nursing, University of Washington, Seattle, Wash. This article originally appeared in the September 2000 issue of the American Journal of Critical Care, Vol 9, No. 5, pp334-343. Abstract Many nurses are hesitant to use the oral site to measure body temperature when patients are orally intubated with an endotracheal tube. It is often thought that the temperature of the gases flowing through the tube and the patient’s inability to form a tight seal around the tube may result in an inaccurate measurement that does not reflect body temperature. Consequently, other sites such as the rectum are used, resulting in embarrassment and increased stress for patients, increased use of resources, and inappropriate use of nursing time. An integrated review and synthesis of research on the validity of using the posterior sublingual site to measure temperature in critically ill patients intubated with an oral endotracheal tube were done to determine if a change in nursing practice is indicated for these patients. Of 10 studies that address this topic, 5 specifically investigated this nursing area. The results indicate that for critically ill patients with stable hemodynamic status, the posterior sublingual pocket is a valid site for measurement of body temperature in patients who are orally intubated with an endotracheal tube. (American Journal of Critical Care. 2000;9:334-343) Various methods are available for measuring body temperature. Ideally, the mixed venous blood of the pulmonary artery (PA) provides the best site for measurement of core temperature.1 The blood at this site is composed of blood from both the periphery and central parts of the body,2 and PA temperatures have been referred to as the optimal representation of core temperature.1 Temperature in the PA is measured with a thermistor-tipped thermodilution catheter. However, a PA catheter is inserted only when continuous hemodynamic monitoring is needed. When a PA catheter is not in place, nurses must decide which alternative site to select for measurement of body temperature. The alternative site should provide easy access for measurement, be reliable over a range of temperatures, and suitably reflect temperature of the core. Because patients in critical care areas often are seriously ill and already under considerable stress, selection of a site that results in the least amount of additional stress or energy expenditure by patients yet still provides an accurate measurement of temperature also should be considered. The ear, urinary bladder, rectum, and mouth are the sites used most often for measurement of temperature when a patient does not have a PA catheter. However, each of these sites has its strengths and limitations. Controversy about ear-based measurements has been fueled by the wide variability in the measurements obtained.3-6 The displayed temperature reflects the temperature of both the tympanic membrane and the surrounding external ear canal. Individual ear characteristics7 and operator technique7,8 also may add to the variability. Tympanic thermometers use infrared technology that allows rapid measurement of temperature because unlike other types of thermometers, a tympanic thermometer does not need to draw heat from the measurement site. Measurements obtained with thermistors in the urinary bladder vary little from PA measurements of temperature3 and correlate highly (r = 0.91) with PA core temperatures.5 However, changes in bladder temperature lag behind changes in esophageal and nasopharyngeal temperatures during times of thermal dynamic change.9 Furthermore, not all patients require an indwelling bladder catheter. Rectal temperatures are generally higher than temperatures measured at other noncore sites10 and are positively correlated with PA temperatures (r = 0.68-0.91).11,12 During times of rapidly changing thermal balance, changes in rectal temperatures, like changes in bladder temperatures, tend to lag behind changes in other measurements of core temperatures,11,13 and thus rectal measurements of temperature are not recommended when rapid changes in temperature are occurring.14 Measurement of rectal temperatures also may cause increased physical or psychological stress for patients. Embarrassment, anxiety, physical discomfort, and potential for injury have been reported.15,16 The posterior sublingual cavity of the mouth, formed where the tongue joins the floor of the mouth on the right or left side of the frenulum, is a site that is readily accessible, and its use is well accepted by patients. Oral temperatures have significant high positive correlations with rectal temperatures11 and provide good estimations of blood temperature in the common carotid artery.17 Furthermore, temperatures measured in the posterior sublingual cavity are associated with less intersubject and intrasubject variability than are ear-based measurements.6 However, nurses doubt the validity of using the oral site in a patient who is orally intubated. They fear that the temperature of the contents of orogastric or endotracheal tubes might influence oral temperature and that the patient might not be able to fully close his or her mouth around these tubes. Although studies4,11,15 have indicated that neither of these factors affects measurement of oral temperature in intubated patients, questions remain about the use of the oral site in critically ill patients who are orally intubated. This article provides an integrated systematic review and synthesis of research on the suitability of using the oral site to measure temperature in patients who are intubated with an oral endotracheal tube. The findings will assist nurses in determining whether the posterior sublingual site is a valid site for measuring temperature for this population of patients in critical care. The clinical significance of the findings, that is, the difference in temperature that would affect healthcare decisions about the course of action for a patient, are addressed. The findings can be used to make evidence-based decisions about whether or not a change in nursing practice is required. Criteria for Articles Selected for Review As an initial step, criteria were selected to delimit the scope of the literature search. Oral intubation was defined as the insertion of an oral endotracheal tube. The literature selected had to be in English, and the studies described had to use adult human subjects. Both published and unpublished research, including abstracts and dissertations, were sought. Counsell18 suggests that because studies with negative or null results are infrequently published, reviews that exclude unpublished work most likely overestimate the relation between the exposure and the outcome. Databases searched were MEDLINE, CINAHL, Current Contents, and Pro Quest Digital Dissertation abstracts. The reference section of relevant articles provided additional sources of information. Keywords used for the search included oral intubation, endotracheal tube, oral temperature, and sublingual temperature. The selected articles were reviewed to determine the study design, sample size, demographics of the sample (age, sex), range of temperatures, methods, and research results. The conclusions stated by the authors were noted. The validity of the instruments used for temperature measurement was evaluated. Last, each study was summarized and critiqued for its strengths and limitations. The review begins with a brief description of the use of the oral cavity for measurement of temperature and of factors that affect this site. A summary of studies specifically undertaken to determine the suitability of using oral temperatures in patients who are intubated with an oral endotracheal tube comes next. Last, peripherally related studies (ie, studies in which the primary focus of the investigation was not the use of the oral site for temperature measurement in orally intubated patients but that included a subsample of orally intubated patients with oral temperature measurements) are reported. In both the text and the tables, differences in temperature are expressed as oral temperature minus comparison site temperature. Use of the Oral Cavity for Temperature Measurement The oral cavity is often used in routine clinical practice to measure temperature. Temperatures measured in the posterior sublingual pocket, an area supplied by branches of the carotid artery, are within ±0.2°C of the temperature of blood in the common carotid artery,17 are a mean of –0.25°C lower than the temperature of blood in the PA,19 and correlate well with measurements obtained at other body sites such as the rectum (r = 0.92).15 Furthermore, oral temperatures reflect rapid changes in core temperature faster than rectal temperatures do.11,13 Just as temperatures vary among different sites in the body, variations also occur within sites. Within the mouth, insignificant differences between the left and right sides have been reported.20 However, temperatures in the posterior sublingual pockets can be significantly higher (P < .01) than temperatures in the anterior sublingual pockets.21 In addition, various factors influence measurement of oral temperature, including ingestion of hot or cold fluids,6,22,23 smoking,6 rapid breathing,24 and gum chewing.6 However, dentition,15 administration of oxygen at rates up to 6 L/min via nasal prongs,25,26 and open versus closed mouth position15,27 do not significantly affect oral measurement of temperature. Evidence of the effect of oxygen administered via a mask is inconclusive.28,29 Earp and Finlayson30 speculate that the presence of gastric tubes and endotracheal tubes may limit access to the mouth for temperature monitoring. Studies on the effect of gastric tubes31 or nasal endotracheal tubes32 on measurement of oral temperature are limited. The effect of oral intubation with an endotracheal tube on sublingual measurement of temperature, however, has been studied more widely. Endotracheal intubation entails passing a tube through the nose or mouth into the trachea. Such intubation is used to maintain an open airway and is indicated for patients who require prolonged ventilation, have obstructed airways, or lack normal airway reflexes.33 Near the distal opening of an endotracheal tube used in adults is a flexible cuff. Inflation of the cuff is used to prevent leakage of air around the tube. Connection of the endotracheal tube to a ventilator allows the delivery of warmed and humidified gases. As a result of intubation, the intake of cooler ambient air via mouth breathing or nose breathing no longer occurs. All inspired air passes through the endotracheal tube; none directly ventilates the mouth or nasopharynx. Therefore, inspired air may affect sublingual temperature only indirectly, via the wall of the endotracheal tube. Although the mouth may remain open as a result of the tube, mouth position has no effect on oral temperature.15 Thus, the mouth of an orally intubated patient may be more, rather than less, favorable for oral measurement of temperature than is the oral site in patients without an endotracheal tube. Studies Directly Related to Oral Measurement of Temperature in Intubated Patients The search of the literature revealed 5 fully documented studies (Table 1) specifically undertaken to determine the validity of using the oral site to measure temperature in patients intubated with an oral endotracheal tube. Of these, 4 studies4,11,15,34 were published in refereed journals during a 15-year period between 1984 and 1999; 1 study35 was an unpublished master’s thesis from 1995. In each study, patients served as their own controls. x Cashion and Cason34 compared differences between oral and rectal temperatures preoperatively when patients were not intubated and postoperatively after cardiac surgery when subjects were intubated. The electronic thermometer used to measure both oral and rectal temperatures was calibrated before and after data collection. The mean error was less than 0.01°F for the oral probe and 0.00°F for the rectal probe. Rectal temperature ranged from 36.17°C to 37.44°C (97.06°F-99.34°F); oral temperature, from 35.94°C to 37.07°C (96.64°F-98.67°F). Although mean differences between oral and rectal temperatures were narrower during intubation than before intubation, the differences between temperatures obtained orally and rectally with and without an endotracheal tube in the oral site were not significant (Table 1). A lag in changes in rectal temperature, resulting in lower temperatures at this site during the thermally dynamic rewarming period after surgery, was proposed as the reason for the narrower oral-rectal temperature difference during intubation. Cashion and Cason concluded that posterior sublingual temperature measurements in orally intubated patients were accurate. The small sample size and the lack of both the temperature of the contents of the endotracheal tube and control over the sequencing effect of the oral-rectal temperature measurements are limitations of the study. Furthermore, the use of measurements obtained via the rectal site, which reflects changes in temperature slowly, in lieu of measurements obtained via a core site, as a reference for temperature comparisons during a thermally dynamic period is a serious drawback and leaves the authors’ conclusions open to question. The main purpose of the study by Konopad et al15 was to compare oral, rectal, axillary, and tympanic membrane temperatures obtained immediately before and immediately after removal of an endotracheal tube. The electronic thermometer used to measure oral temperatures had concurrent validity and reliability when tested against a laboratory thermometer in a well-stirred water bath before, during, and after data collection. Oral temperatures ranged from 36°1˚C to 38.9°C. Differences between oral temperatures measured with and without an oral endotracheal tube in place were statistically, but not clinically, significant (Table 1). Oral temperatures were higher with the endotracheal tube in place and were not significantly affected by the temperature of the contents of the endotracheal tube, ambient temperature, state of dentition, or mouth position. The investigators concluded that their findings supported the use of oral measurements of temperature for orally intubated patients. Lack of control over sequencing effect of the various temperature measurements and the undetermined effect of oxygen via mask weaken the validity of the findings of this otherwise well-designed study. Fallis et al11 compared oral temperatures with reference PA temperatures at 3 measurement times during a thermally dynamic 8-hour period in intubated patients. Temperatures were measured in rapid succession, and sequence effect was controlled. Accuracy and reliability of the electronic thermometer used to measure oral temperatures were assessed before and after data collection. PA catheters were checked for accuracy upon removal from each patient. Instruments were tested in a constantly stirred water bath against a highly accurate mercury thermometer and were accurate within 0.1°C. Temperatures ranged from 33.6°C to 38.9°C at the PA site and from 33.2°C to 39.2°C at the oral site. Mean oral temperatures were neither statistically nor clinically significantly different from mean PA temperatures at any of the 3 measurement times (Table 1). Neither ambient temperature nor the temperature of the contents of the endotracheal tube significantly affected the differences. Analysis of the data indicated significantly high positive correlations between oral and PA temperatures for each of the 3 measurement times (Table 1). The findings support the use of the posterior sublingual pocket for measurement of core temperature in orally intubated patients during a thermally dynamic period. The repeated measurements and the wide range of temperatures are strong points of the study. Goalen35 investigated the relationship between simultaneous measurements of oral and PA temperatures in patients intubated with an oral endotracheal tube. The electronic thermometer used to measure oral temperature was not tested for accuracy, but the unit self-calibrated upon each activation. PA catheters were assessed for accuracy, but the results of the testing were not reported. PA temperatures ranged from 34.9°C to 38.8°C; oral temperatures, from 35.1°C to 39.1°C. Mean oral and PA temperatures did not differ significantly, and a significant positive correlation between oral and PA temperatures was detected (Table 1). Goalen concluded that oral measurement of temperature was an acceptable method of determining body temperature in orally intubated patients. Although the wide range of body temperatures is a strength of this study, the lack of testing of the electronic thermometer for accuracy before and after a 2-month period of data collection is a limitation. Finally, in the most recent study, Giuliano et al4 compared simultaneously measured oral, ear-based, and PA temperatures of orally intubated adult critical care patients. The electronic (oral) and tympanic thermometers were calibrated before data collection. PA temperatures ranged from 34.5°C to 39.5°C; oral temperatures, from 34.39°C to 39.5°C. The difference between mean oral and PA temperatures was statistically, but not clinically, significant (Table 1). Patients’ acuity, ambient temperature, temperature of the ventilator circuit, and mean blood pressure did not significantly affect this relationship. Because measurements obtained with the ear-based thermometer varied more widely than did measurements obtained with the oral thermometer, Giuliano et al recommend oral thermometry as the best method for measuring temperature in patients who do not have a PA catheter. Testing of the study instruments, including the PA catheters, after data collection would have enhanced the validity of the findings. In summary, the data from the 5 studies specifically undertaken to determine the suitability of using the oral site to measure temperature in orally intubated critically ill patients provide strong support for the use of this site. In 3 of the studies,11,35,37 sample sizes were based on power analysis (power, 80%-90%) and were sufficient to detect differences if differences existed. In the 3 studies4,11,35 in which temperatures measured at the PA site were used as a reference, oral temperatures were similar to PA temperatures over a wide range of fluctuation in temperatures. Further, the results15 indicated that the oral site remained suitable for temperature measurement up until extubation and that neither dentition nor open versus closed mouth position significantly affected measurements at this site with or without an endotracheal tube. In the studies in which the influence of the temperature of the contents of the endotracheal tube was assessed, no significant effect on the differences in temperature was noted. However, the subjects included in the 5 studies were in a hemodynamically stable condition, and none were being managed with therapeutic cooling at the time data were collected. Studies Indirectly Related to Oral Measurement of Temperature in Intubated Patients Five additional studies3,5,12,32,38 (Table 2) done for purposes other than assessment of oral measurement of temperature in orally intubated patients included data from patients with an oral endotracheal tube and temperatures measured at the oral site. Patients served as their own controls, and convenience sampling was used. The small sample size of patients with an oral endotracheal tube in place is a general limitation of these studies. x Ozuna38 used an electronic telethermometer, a thermistor-tipped flexible probe, to measure oral and esophageal temperatures in patients having abdominal surgery who were intubated in the operating room. Oral and esophageal probes were tested for accuracy before and after data collection, and correction charts were used to correct to true temperature. The range of esophageal and oral temperatures was not reported. Intraoperatively, oral temperatures decreased a mean of 0.37°C, (range, –0.83°C to +0.04°C), and esophageal temperature decreased a mean of 0.28°C (range, –0.78°C to +0.11°C). Mean oral temperatures minus mean esophageal temperatures for the 2 measurement times were –0.57°C and –0.62°C (calculated), respectively (Table 2). Ozuna reported that generally oral temperatures paralleled esophageal temperatures and concluded that the posterior sublingual site is quite satisfactory for monitoring intraoperative body temperature. The small sample size and blind placement of the oral probe are limitations of the study. Laurent32 compared oral, axillary, rectal, and PA temperatures of acutely ill patients. As part of the study, statistical testing was done to determine if differences between oral and PA temperatures were related to different respiratory therapies. Patients were grouped into 4 categories according to respiratory therapy received: no oxygen therapy, oxygen therapy by nasal prongs, nasal endotracheal tube, and oral endotracheal tube. Peripheral temperatures were measured with an electronic telethermometer, and measurements were obtained 5 and 10 minutes after placement of the flexible probes. The oral probe tested –0.10°C to –0.46°C lower than the laboratory standard thermometer before data collection and 0.00°C to –0.20°C lower after data collection. PA catheters were 0.00°C to –0.11°C lower than the standard thermometer. For the 5 subjects with an oral endotracheal tube, the mean individual range of temperatures was 34.5°C to 36.8°C at the esophageal site and 33.9°C to 36.5°C at the oral site. Measurements of oral temperature were not significantly affected by any of the respiratory therapies. No consistent relationship was found between respiratory therapy or mouth position (open versus closed) and the difference between oral and PA temperatures. Oral temperature was lower than PA temperature for the 5 patients with an oral endotracheal tube (Table 2). The small number of subjects intubated with an oral endotracheal tube and the large discrepancy between the oral probe and the standard thermometer during initial testing severely weaken the validity of the study findings. Raulerson12 determined the relationship between PA temperature and oral, rectal, and axillary temperature in patients who were hypothermic after cardiac surgery. Subjects were orally intubated, and temperatures were measured once with an electronic telethermometer. Compared with the standard thermometer, oral probes were lower than the test thermometer by –0.2°C to –0.4°C before data collection and –0.2°C to –0.3°C after data collection. Rectal probes were between 0.0°C and –0.2°C of the test thermometer, and PA catheters were within 0.0°C to –0.17°C. Range of temperatures was 34.3°C to 36.9°C at the PA site and 33.2°C to 35.9°C at the oral site. Mean oral temperature was significantly lower than mean PA temperature (Table 2). Rectal temperature was lower than but did not differ significantly from PA temperature. A moderate but significant correlation between PA and oral temperatures was detected (Table 2). Raulerson concluded that the temperature of the rectal site most closely approximated the temperature of blood in the PA. The sample size and the wide bias between the oral probe and the standard thermometer upon testing are limitations of the study. A decade later, Heidenreich et al5 investigated invasive (PA, bladder, esophageal) and less invasive (ear, oral, axilla, and forehead skin) methods of temperature monitoring in hypothermic patients after cardiac surgery (Table 2). Subjects were intubated with an oral endotracheal tube. PA temperatures and temperatures obtained by less invasive methods were recorded every 10 minutes for 2 hours after admission to the intensive care unit. The electronic thermometer used to measure oral temperature was calibrated before and after the study. PA thermistors were tested for proper operation, but their accuracy was not determined. At the end of surgery, PA temperatures ranged from 31.8°C to 39.4°C; oral temperatures, from 31.4°C to 39.7°C. During the first postoperative hour, temperature changes of +2.5°C to –4.1°C were recorded. Mean postoperative temperature ( ±SD) was 34.7°C ± 1.4°C at the PA site and 34.6°C ±1.4°C at the oral site. Regression analysis of temperatures at different sites at increments of 1°C was used to describe the relationship between temperatures obtained by noninvasive methods and core temperatures. Low to moderate coefficients were noted for all peripheral sites; for the oral site, the coefficient was 0.36 to 0.65, indicating a low to moderate relationship. Heidenreich et al concluded that in hypothermic patients undergoing rapid changes in temperature, only invasive measurements of core temperature may be valid. However, dividing the sample into 1°C intervals based on the outcome variable (core temperature) and then fitting a regression line within each interval is not an appropriate method for determining whether peripheral temperatures can be accurately used to predict core temperature. Although the wide range of temperatures is a strong point of this study, unfortunately, the data are presented in such a way that it is not possible to tell whether the data support or refute the accuracy of prediction. The lack of calibration of the invasive instruments after removal from subjects is a further limitation. The small difference of 0.1°C (calculated) between mean oral and PA temperatures was not addressed. Finally, Erickson and Kirklin3 compared methods for measuring core temperature. The majority of the subjects had an oral endotracheal tube in place. Temperatures were measured every 20 minutes during a 4-hour period. All but one of the intubated subjects were being treated with mechanical ventilation with warmed gases. Instrument validity was assessed. PA temperature ranged from 34.4°C to 38.8°C. Mean oral temperature was higher than mean PA temperature (0.12°C ± 0.11°C) for the 25 patients with an oral endotracheal tube, lower than PA temperature (–0.29°C ± 0.22°C) for the 12 subjects with oxygen cannula or mask, and –0.23°C ± 0.43°C for the 1 patient with no respiratory device. Erickson and Kirklin suggest that the significantly higher (P < .001) mean oral temperature for subjects with an oral endotracheal tube compared with mean oral temperature for subjects with noninvasive respiratory devices was due to the influence of warmed gases delivered through the invasive respiratory devices. Because the temperature of the contents of the endotracheal tube was not measured, an alternative explanation is that this difference was due to the significantly lower oral temperatures in subjects with the noninvasive devices that resulted from breathing cool (20.0°C-28.7°C) ambient air. The use of repeated measurements is a strong point of the study. Insufficient sample size may have precluded statistical testing to determine if the difference between oral and PA temperatures for the orally intubated patients was statistically significant. Of interest is the difference in the findings between the studies in which a Yellow Springs telethermometer (Yellow Springs Instruments, Yellow Springs, Ohio) was used and those in which an IVAC electronic thermometer (IVAC Medical Systems, Inc, San Diego, Calif) was used (Table 2). The greatest mean differences between oral and reference PA or esophageal temperatures were noted by Ozuna,38 Laurent,32 and Raulerson.12 In each of these studies, a Yellow Springs telethermometer was used to measure oral temperatures. Furthermore, when the telethermometer was used over time to measure oral temperatures, 2 of the studies12,32 did not include information on how the flexible probe was securely maintained in the posterior sublingual site or on how the measurements of oral temperature were affected as a result of the telethermometer reading too low. In the studies by Heidenreich et al5 and Erickson and Kirklin3 in which the IVAC electronic thermometer was used, the mean oral minus mean PA temperature differences were –0.10°C (calculated) and 0.12°C, respectively. Electronic thermometers in the predictive mode, which uses the initial rate of increase in temperature that occurs after insertion of the probe to estimate a final temperature rather than waiting for actual temperature equilibrium to occur, are the instruments used most often in the clinical area for measurements of oral temperature. Discussion Rarely does a single study provide definitive answers to clinical questions, and it is only by undertaking multiple studies and investigating a clinical problem from various angles that answers to important clinical questions come about. Systematic reviews of the literature, therefore, are valuable scientific activities that help establish whether scientific findings are consistent and generalizable.39 Counsell18 states that the most useful reviews are those that can improve clinical practice. I did this review to determine if a change in nursing practice is required for measurement of temperature in critical care patients intubated with oral endotracheal tubes. The results reveal that this important clinical question was investigated from a variety of perspectives. The subjects were men and women 17 to 96 years old and were from various critical care areas that included coronary care, trauma, medicine, and surgery. Although the subjects of several studies were cardiac surgery patients during the immediate postoperative period, measurements also were obtained in subjects during the intraoperative period and just before extubation. In addition, measurements were obtained in patients who were hypothermic, normothermic, and hyperthermic. Although all studies were prospective, a limitation of each study was the use of convenience sampling. For the studies with small sample sizes and in which the validity of the instruments used to measure temperature was not determined, the results should be viewed with caution. Investigators of the directly related studies all concurred that the posterior sublingual site was an appropriate site to use in critical care patients with an oral endotracheal tube. In the 3 studies4,11,35 in which oral temperatures were compared with PA temperatures, differences were not significant in 2 of the studies11,35; differences between oral temperatures and rectal temperatures were also not significant.34 A statistically significant difference was noted between oral temperatures with and without an oral endotracheal tube by Konopad et al15 and between oral and PA temperatures by Giuliano et al.4 However, just as important as the testing for statistical significance is the determination of clinical significance. Although it has not been empirically verified, the value that constitutes clinical significance is between 0.2°C40,41 and 0.5°C.13 As can be seen in the review of directly related studies (Table 1) in which mean differences were reported, no clinically significant differences were found between mean oral and rectal temperatures, mean oral and PA temperatures, and, in the study by Konopad et al,15 at the oral site with and without an oral endotracheal tube in place. The mean differences between oral and PA temperatures of –0.10°C and 0.12°C calculated from the data presented by Heidenreich et al5 and reported by Erickson and Kirklin,3 respectively, also would not be considered clinically significant (Table 2). An additional factor that must be considered is the influence of the type of thermometer used to measure oral temperature. An electronic thermometer in the predictive mode is used in most settings in which measurements of oral temperature are required. Of the 10 studies reviewed, 7 used an electronic thermometer.3-5,11,15,34,35 The findings from these 7 studies revealed statistical insignificance, clinical insignificance, or both for differences between temperatures. Conclusion In summary, patients in critical care areas are often subjected to the more stressful and embarrassing rectal measurement of temperature when they are orally intubated. Patients in these settings do not require this additional stressor, and many cannot afford to expend the additional energy required to position themselves for this measurement. This integrated review reveals that the posterior sublingual pocket is a suitable and valid site for temperature measurement in critically ill patients intubated with an oral endotracheal tube. As Konopad et al15 state, the time-honored adherence by nurses to the use of the rectal site for temperature monitoring in intubated patients is not justified. Oral measurement of temperature is thus recommended in these patients. Preferably, the probe should be placed in the posterior sublingual pocket opposite the endotracheal tube. When patients cannot form a tight seal around the endotracheal tube, nurses should not be concerned, because evidence indicates lack of a tight seal does not significantly affect the oral measurements of temperature. The findings of this review are not generalizable to patients whose conditions are not reflective of patients enrolled in the reviewed studies or to patients with nasal endotracheal tubes or orogastric tubes. Further research is required on patients intubated with these devices. Continued research is needed to clarify whether the findings from the studies reviewed herein can be extended to other populations of critically ill patients, such as those whose hemodynamic condition is unstable or those who are being managed with therapeutic cooling. 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