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.     

Should we rely on nasopharyngeal temperature during cardiopulmonary bypass?

A potential morbidity of incomplete re-warming following hypothermic cardiopulmonary bypass (CPB) is cardiac arrest. In contrast, attempts to fully re-warm the patient can lead to cerebral hyperthermia. Similarly, rigid adherence to 37.0 degrees C during normothermic CPB may also cause cerebral overheating. The literature demonstrates scant information concerning the actual temperatures measured, the sites of temperature measurement and the detailed thermal strategies employed during CPB. A prospective, randomized, controlled study was undertaken to investigate the ability to manage perfusion temperature control in a group of hypothermic patients (28 degrees C) and a group of normothermic patients (37 degrees C). Eighty patients presenting for first-time, elective coronary artery bypass graft surgery (CABG) were randomly allocated to the hypothermic and normothermic groups. All surgery was performed by one surgeon and the anaesthesia managed by one anaesthetist. Temperature measurements were made at the nasopharyngeal (NP) site, as well as in the arterial line of the CPB circuit. The hypothermic group had the arterial blood temperature lowered to 25.0 degrees C to maintain the NP temperature at 28.0-28.5 degrees C. During re-warming, the arterial blood was raised to 38.0 degrees C. Meanwhile, in the normothermic group, the arterial blood temperature was raised to a maximum of 37.0 degrees C to maintain NP temperature at 36.5-37.0 degrees C. Despite strict guidelines, some patients transgressed the temperature control limits. Two patients in the hypothermic group failed to reach an NP temperature of 28.5 degrees C. Twenty-six patients were managed entirely within the control limits. During rewarming in both groups, control of both arterial and NP temperature was well managed with only 25% patients breaching the respective upper control limits. During the re-warming phases of CPB, we were unable to make any correlation between NP temperature and arterial blood temperature, using body weight or body mass index as predictors. Based on the results obtained, we recommend that strict criteria should be implemented for the management of temperature during CPB, in conjunction with more emphasis being placed on monitoring arterial blood temperature as a marker of potential cerebral hyperthermia. We should, therefore, not rely on NP temperature measurement alone during CPB.     

Incidence of atrial fibrillation after mild or moderate hypothermic cardiopulmonary bypass

OBJECTIVES: Atrial fibrillation remains a significant source of morbidity after coronary artery bypass grafting (CABG). Whether cardiopulmonary bypass (CPB) temperature influences the occurrence of postoperative atrial fibrillation in CABG patients has not been specifically examined. In the present study, we reviewed postoperative data from patients who were prospectively randomized to mild or moderate hypothermic CPB for elective CABG to determine the incidence of postoperative atrial fibrillation. DESIGN: Randomized, single center, observational study. SETTING: Tertiary university medical center. PATIENTS: Adults undergoing elective CABG surgery. INTERVENTIONS: Enrolled patients were prospectively randomized to mild (34 degrees C [93.2 degrees F]) or moderate (28 degrees C [82.4 degrees F]) hypothermic CPB. MEASUREMENTS AND MAIN RESULTS: The incidence of postoperative atrial fibrillation was determined by review of ICU and hospital records. There was a significantly higher incidence of atrial fibrillation in the moderate compared with the mild hypothermic CPB group. Patients who had postoperative atrial fibrillation were significantly older than those without atrial fibrillation. Furthermore, a significant increase in the relative risk of developing postoperative atrial fibrillation was found for both age and CPB temperature. CONCLUSIONS: Our results indicate that the temperature of systemic cooling during CPB is an important factor in the development of atrial fibrillation after CABG surgery. In addition, this study confirms that increasing age is a significant determinant of postoperative atrial fibrillation.     

Acceptable agreement between tympanic and rectal temperature in acute stroke patients

Major concerns remain about the reliability of tympanic thermometers. The aim of this study was to investigate the agreement between rectal and tympanic thermometry and compare this with the repeatability of each method in patients with acute stroke. Tympanic temperature readings were from 0.7 degrees C below to 0.8 degrees C above rectal readings. As to repeatability, we found second rectal readings to be between 0.3 degrees C below and 0.4 degrees C above first readings, and second tympanic readings to be between 0.4 degrees C below and 0.5 degrees C above first readings. The agreement between the two methods is acceptable in clinical practice. Tympanic thermometry is useful in serial measurements, whereas, for a single accurate measurement, rectal mercury thermometry remains the method of choice.     

Assessment of hypothermia with a new “tympanic” thermometer

Objective. Rapid and accurate core temperature measurement is vitally important in trauma patients, especially in those with accidental hypothermia. We tested a new aural thermometer to measure “tympanic” temperatures and assessed its accuracy during normothermic and hypothermic cardiopulmonary bypass.Methods. Tympanic, esophageal, and blood temperatures were compared in 10 patients undergoing open-heart surgery. In addition, the stability and reaction time of the tympanic thermometer was evaluated in 5 volunteers in a cold room, with and without facial fanning.Results. We observed a good linear correlation between tympanic and esophageal (r = 0.96) and blood (r = 0.81) temperature measurements during normothermia and hypothermia. There was no evidence of iatrogenic ear lesions in any of the patients. In the cold-room tests, stability was excellent and the time for adjustment of tympanic temperature measurement was about 2 min (with and without facial fanning).Conclusion. The new tympanic thermoprobe is a simple, fast, and reliable device for measuring core temperature. The device was designed particularly for, and may be useful for, patients suffering from accidental hypothermia.     

Impact of operator technique and device on infrared emission detection tympanic thermometry

Preliminary data on the use of infrared emission detection (IRED) tympanic thermometers suggest that operator technique may be important in IRED readings. No systematic investigation of specific technique and available IRED devices has previously been performed. In a prospective, blinded trial, 40 healthy adult subjects using six IRED thermometers with two techniques were examined in random sequence. Differences between IRED tympanic, oral, and rectal temperatures were compared using ANOVA. Significant differences were observed between all temperatures, the IRED devices, and the method of probe insertion. Differences between oral or rectal temperatures and IRED tympanic readings were reduced by an ear tug (as for routine otoscopy) for all but one device. An “ear tug” results in increased IRED readings that may improve accuracy of tympanic thermometers using IRED.     

The Accuracy of Oral Predictive and Infrared Emission Detection Tympanic Thermometers in an Emergency Department Setting

OBJECTIVE: To assess the accuracy of an oral predictive thermometer and an infrared emission detection (IRED) tympanic thermometer in detecting fever in an adult emergency department (ED) population, using an oral glass mercury thermometer as the criterion standard. METHODS: This was a single-center, nonrandomized trial performed in the ED of a metropolitan tertiary referral hospital with a convenience sample of 500 subjects. The temperature of each subject was taken by an oral predictive thermometer, an IRED tympanic thermometer set to "oral" equivalent, and an oral glass mercury thermometer (used as the criterion standard). A fever was defined as a temperature of 37.8 degrees C or higher. The subject's age, sex, triage category, and diagnostic group were also recorded. Sensitivity, specificity, positive and negative likelihood ratios, positive and negative predictive values, and corresponding 95% confidence intervals were calculated. Logistic regression was used to identify predictors of fever. RESULTS: The sensitivities and specificities for detection of fever of the predictive and the IRED tympanic thermometers were similar (sensitivity 85.7%/88.1% and specificity 98.7%/95.8%, respectively). The predictive thermometer had a better positive predictive value (85.7%) compared with the IRED tympanic thermometer (66.1%). The positive and negative likelihood ratios for the predictive oral thermometer were 65 and 0.14, respectively, and for the IRED tympanic thermometer 21 and 0.12, respectively, indicating that the predictive thermometer will "miss" 1 in about 7 fevers and the IRED tympanic thermometer will "miss" 1 in about 8 fevers. CONCLUSIONS: Although quick and convenient, oral predictive and IRED tympanic thermometers give readings that cannot always be relied on in the detection of fever. If we are to continue using electronic thermometers in the ED setting, we need to recognize their limitations and maintain the importance of our clinical judgment.     

Comparison of rectal and tympanic thermometry during exercise

BACKGROUND: Heat-related deaths are among the most preventable injuries in athletics. We sought to examine two methods of monitoring body temperature during exercise as a means of preventing heat-related illnesses. METHODS: Ten adult subjects exercised in hot, humid conditions while body temperature was monitored by rectal (Tre) and tympanic (Tty) thermometry. RESULTS: Our results indicate that increase in Tty was significantly greater than increase in Tre during exercise. However, rectal temperatures continued to increase after exercise cessation and peak temperatures were not significantly different. Temperature readings of the two devices during exercise had a strong correlation. There was a poor correlation between the two methods of measurement in the recovery phase. CONCLUSIONS: Tympanic thermometry is reliable for monitoring changes in body temperature during exercise. This could be valuable for monitoring individuals during long exercise in an effort to prevent heat exhaustion or heat stoke.     

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.     

Effects of normothermia versus hypothermia on extravascular lung water and serum cytokines during cardiopulmonary bypass: a randomized, controlled trial

OBJECTIVE: To evaluate the influence of perfusion temperature on the systemic effects of cardiopulmonary bypass (CPB), including extravascular lung water index (EVLWI), and serum cytokines. DESIGN: Prospective, randomized, controlled study. SETTING: Cardiothoracic intensive care unit of a university hospital. PATIENTS: Patients undergoing elective coronary artery bypass grafting. INTERVENTIONS: Twenty-one patients undergoing elective coronary artery bypass grafting were randomly assigned to receive either normothermic bypass (36 degrees C, n = 8) with intermittent antegrade warm blood cardioplegia (IAWBC), or hypothermic (32 degrees C, n = 13) CPB with cold crystalloid cardioplegia. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure, heart rate, cardiac output, systemic vascular resistance, mean pulmonary arterial pressure, and pulmonary vascular resistance were determined at baseline, i.e., after induction of anesthesia but before sternal opening (T-1), at arrival in the intensive care unit (T0), and 4 hrs (T4), 8 hrs (T8), and 24 hrs (T24) after surgery. EVLWI, intrathoracic blood volume index (ITBVI), and EVLW/ITBV ratio were obtained by using thermal dye dilution utilizing an arterial thermistor-tipped fiberoptic catheter and were recorded at T-1, T0, T4, T8, and T24. Serial blood samples for cytokine measurements were obtained at each hemodynamic measurement time point. Before, during, and after CPB, there were no differences in the conventional hemodynamic measurements between the groups. There were no changes in EVLWI up to T8 in either group. Furthermore, no change in the ratio EVLW/ITBW was observed between the groups at any time, further indicating the absence of a change in pulmonary permeability. Plasma levels of interleukin-6, tumor necrosis factor-alpha, and interleukin-10 increased during and after CPB, independently of the perfusion temperature. CONCLUSION: Normothermic CPB is not associated with additional inflammatory and related systemic adverse effects regarding cytokine production and EVLWI as compared with mild hypothermia. The potential temperature-dependent release of cytokines and subsequent inflammation has not been observed and normothermic CPB may be seen as a safe technique regarding this issue.     

Cardiopulmonary bypass is not associated with increased jugular venous blood free radical activity

We have measured jugular venous oxygen saturation (sjv(O2)) and lactate, arterial and jugular venous blood levels of lipid peroxidation products--malondialdehyde (MDA) and diene conjugates as an index of free radical activity in eight adults undergoing coronary artery bypass surgery. Measurements were carried out at six specific times: T1--within 5 min before cardiopulmonary bypass (CPB), T2--within the first minute after the commencement of CPB, T3--during stable temperature (28 degrees C) on CPB, T4--during rewarming at 34 degrees C, T5--15 min after CPB and T6--at skin closure. There were no significant changes in arterial, jugular venous and arterio-jugular venous (a-jv) differences in diene conjugates and MDA. There was no correlation between sjv(O2), lactate and a-jv differences in MDA and diene conjugates. These results are not indicative of ischaemia-reperfusion injury across the cerebral circulation during hypothermic CPB.     

Comparison of tympanic, transponder, and noncontact infrared laser thermometry with rectal thermometry in strain 13 guinea pigs (Cavia porcellus).

The purpose of this experiment was to assess the practicality, ease, and reliability of using tympanic, transponder, and noncontact infrared laser thermometry versus rectal thermometry in strain 13 guinea pigs. Body temperatures were measured by all four methods within each animal over 10 min, and three sets of measurements were taken over 2 days. Each method was compared for agreement over time and agreement with the rectal temperature of each animal. Over time the transponder temperatures were the most reliable and had the closest agreement with the rectal temperatures. There was an overall difference in mean temperatures among methods but not between times, indicating that the guinea pigs had stable body temperatures over different time periods. Although the mean temperatures from the transponder and tympanic thermometers were not significantly different from the rectal temperatures, only the transponder method was in close agreement with the rectal method. The tympanic and noncontact infrared laser methods had poor agreement with the rectal method. These study results suggest that transponder thermometry is an easy and accurate alternative to rectal thermometry in strain 13 guinea pigs.     

Cerumen Occlusion Lowers Infrared Tympanic Membrane Temperature Measurement

Objective: To examine the effect that cerumen occlusion of the ear canal has on infrared tympanic membrane temperature measurement.
Methods: A prospective, randomized, single-blind human study was carried out in a university hospital observation unit. The subjects were a convenience sample of human volunteers aged 18 years or older who did not have cerumen occlusion or scarred tympanic membranes. A paraffin-coated human cerumen plug was placed in one randomly chosen ear, and after 20 minutes of equilibration the temperature in each ear was measured with an infrared thermometer. Analysis of the difference in mean temperature between the occluded and nonoccluded ears was by Student's paired t-test.
Results: Infrared tympanic membrane temperatures were measured in 43 subjects aged 21 to 58 years. The mean temperature of the occluded ear canal was 0.3°C lower than that of the opposite ear canal (p = 0.0001, 95% CI 0.16–0.45°C).
Conclusion: Cerumen occlusion of the ear canal causes underestimation of body temperature measured by infrared tympanic membrane thermometry.     

Effect of cardiopulmonary bypass on lactate metabolism

Objective We have investigated the role of cardiopulmonary bypass on lactate metabolism in patients undergoing uncomplicated surgery for elective coronary artery bypass grafting (CABG).Design Prospective non-randomized observational study.Settings National Cardiovascular Center.Patients Three independent groups were studied: preoperative (n=20), postoperative with bypass (CPB, n=20) and postoperative without bypass (NO-CPB, n=20).Interventions Lactate metabolism was investigated with the use of an exogenous lactate challenge test (2.5 mmol Na-lactate/kg body weight in 15 min). Blood lactate was sequentially determined after the end of infusion. Lactate clearance and endogenous production were estimated from the area under the curve, and a bi-exponential fitting permitted modeling the lactate-decay into two compartments.Measurements and main results Lactate metabolism parameters (basal lactate, clearance, endogenous production and half-lives [HL] I and II) were not different between the NO-CPB and preoperative groups. In the CPB group, as compared to the other two groups, basal lactate and endogenous production were not significantly affected while lactate clearance (CPB: 6.02±0.97 versus preoperative: 9.41±0.93 and NO-CPB: 9.6±0.8 ml/kg per min) and HL-I (CPB: 10.6±1.4 versus preoperative: 17.2±2.3 and NO-CPB: 18.8±2.5 min) were decreased (p<0.001) and HL-II was increased (CPB: 171±41versus preoperative: 73±12 and NO-CPB: 48±2.9 min, p<0.01).Conclusion While surgery and anesthesia per se do not seem to alter lactate metabolism, CPB significantly decreased lactate clearance, this effect being possibly related to a mild liver dysfunction even in uncomplicated elective surgery.     

A comparison of tympanic thermometer readings to pulmonary artery catheter core temperature recordings

The purpose of this study was to determine the accuracy of FirstTemp (Intelligent Medical Systems, Carlsbad, CA) tympanic thermometer readings compared with core body temperatures obtained via pulmonary artery catheter (PAC). Five measurements were obtained on 19 cardiovascular surgery patients. Tympanic thermometer measurements tended to be higher than PAC measurements. However, most of the differences were not clinically significant. Differences found between right and left ear measurements were most likely due to poor measurement technique. When the correct technique is used, nurses can be confident that tympanic temperature readings are clinically accurate.     

Does near-infrared spectroscopy provide an early warning of low haematocrit following the initiation of hypothermic cardiopulmonary bypass in cardiac surgery?

This study investigated 151 patients undergoing cardiac surgery to determine whether measurement of regional cerebral oxygen saturation (rS(c)O(2)) using near-infrared spectroscopy (NIRS) can indicate a low haematocrit after initiation of hypothermic cardiopulmonary bypass (CPB). Haematocrit, rS(c)O(2), haemoglobin level, arterial partial pressures of carbon dioxide and oxygen, systemic blood pressure, and nasopharyngeal and rectal temperatures were determined 5 min after the initial administration of heparin for CPB and 90 s after completion of the first cardioplegic solution injection. Immediately after initiation of hypothermic CPB, rS(c)O(2), haemoglobin and haematocrit values were significantly lower than those before CPB. No significant correlations were found between the change in haematocrit and changes in left, right and mean rS(c)O(2); thus, changes in rS(c)O(2) before and after initiation of hypothermic CPB did not reflect changes in haematocrit values. This indicates that NIRS cannot provide early warning of a low haematocrit immediately after initiation of hypothermic CPB in cardiac surgery.     

Infra-red thermometry: the reliability of tympanic and temporal artery readings for predicting brain temperature after severe traumatic brain injury

Introduction

Temperature measurement is important during routine neurocritical care especially as differences between brain and systemic temperatures have been observed. The purpose of the study was to determine if infra-red temporal artery thermometry provides a better estimate of brain temperature than tympanic membrane temperature for patients with severe traumatic brain injury.

Methods

Brain parenchyma, tympanic membrane and temporal artery temperatures were recorded every 15–30 min for five hours during the first seven days after admission.

Results

Twenty patients aged 17–76 years were recruited. Brain and tympanic membrane temperature differences ranged from -0.8 °C to 2.5 °C (mean 0.9 °C). Brain and temporal artery temperature differences ranged from -0.7 °C to 1.5 °C (mean 0.3 °C). Tympanic membrane temperature differed from brain temperature by an average of 0.58 °C more than temporal artery temperature measurements (95% CI 0.31 °C to 0.85 °C, P < 0.0001).

Conclusions

At temperatures within the normal to febrile range, temporal artery temperature is closer to brain temperature than is tympanic membrane temperature.     

Highest core temperature during cardiopulmonary bypass and rate of mediastinitis

Temperature control during cardiopulmonary bypass (CPB) may be related to rates of bacterial infection. We assessed the relationship between highest core temperature during CPB and rates of mediastinitis in 6955 consecutive isolated coronary artery bypass graft (CABG) procedures in northern New England. The overall rate of mediastinitis was 1.1%. The association between highest core temperature and mediastinitis was different for diabetics than for nondiabetics. A multivariate model showed that there was a significant interaction between diabetes and temperature in their association with mediastinitis (p=0.015). Diabetic patients showed higher rates of mediastinitis as highest core temperature increased, from 0.7% in the < or = 37 degrees C group to 3.3% in the > or = 38 degrees C group (p(trend) = 0.002). Adjusted rates were similar. Nondiabetic patients did not show this trend (p(trend) = 0.998). Among diabetic patients, a peak core body temperature > 37.9 degrees C during CPB is a significant risk factor for development of mediastinitis. Avoidance of higher temperatures during CPB may lower the risk of mediastinitis for diabetic patients undergoing CABG surgery.     

Use of infrared thermometry to measure lavage and intravenous fluid temperature

A study was conducted to determine the accuracy of tympanic thermometers for measuring the temperature of warmed fluids in fluid bags and in tubing at the delivery site (ie, beside the intravenous [IV] catheter). One-liter 0.9% saline bags were warmed in a microwave oven. A thermocouple electronic temperature probe was then used to measure the reference temperature. The probe was inserted into each bag and bathed in the fluid. Temperature changes were recorded simultaneously over a 20-minute period using the probe and a First Temp Tympanic Thermometer (Intelligent Medical Systems, Inc, Carlsbad, CA). The warmed fluid was then allowed to run through microdrip IV tubing. Temperature of the effluent was measured in the tubing using the tympanic thermometer externally and the probe internally at the same point. The two measures were compared using linear regression and Student's t tests. Overall, the correlation between the two probes was r = 0.99 for both the fluid bags and the IV tubing. The overall mean differences were small, 0.7°C and 1.2°C for the bags and tubing, respectively, but they were statistically different (P > .05). Data were analyzed in three temperature ranges: <36°C, 36°C to 41°C, and >41°C. Again, small differences were found on the order of 1°C. It was concluded that infrared thermometry is an accurate method for measuring the initial and delivery temperature of warmed fluids. Although tympanic thermometer measurements were statistically different from reference readings in certain temperature ranges, these differences were small and not clinically significant. Tympanic thermometers can measure the temperature of warmed fluid bags and lavage and IV effluent adjacent to the catheter site, ensuring that hypothermic patients receive fluid at therapeutic temperatures.     

低温体外循环术后体温变化对血乳酸及氧代谢的影响

目的探讨低温体外循环心脏术后复温过程中体温变化对血乳酸水平及氧代谢的影响,为合理控制患者体温提供依据。方法对60例低温体外循环心脏术后患者进行监测,分别在肛温37,37．5,38,38．5℃时采集动、静脉血标本,检测动静脉血氧代谢及血乳酸值。结果复温时全身的氧耗量明显增加;动脉血乳酸值在肛温37．5℃时最接近正常,37,38℃时次之,肛温38．5℃时血乳酸值最高（高乳酸血症）,差异有统计学意义。结论在低温体外循环心脏术后复温过程中,体温变化是影响氧耗量和血乳酸水平的重要因素,护理人员应将患者体温控制在37．5℃左右的安全范围内。