An exhaustive, 24-page article released Tuesday in the Annals of Internal Medicine shows that taking body temperature rectally is most accurate, short of actually sticking a needle in a vein. Show
That finding confirms that these types of thermometers are more accurate than so-called peripheral thermometers: those that are held under the tongue, laid across the forehead or against the temple, tucked into armpits, and gently placed in ear canals. But how important is it to get super-precise temperatures? In the latest study, researchers reviewed 75 published studies comparing peripheral thermometers with central ones — mostly either temperatures taken from a vein or from the rectum. advertisement They found that rectal thermometers were highly accurate. Peripheral thermometers were further off, with oral thermometers doing best among the runners-up. The peripheral thermometers were especially inaccurate in patients with very high fevers. At those extremes, thermometers in armpits and ears could read “as much as one to two degrees higher or lower than actual body temperature,” the researchers wrote. advertisement But does a degree or two one way or the other really matter? More importantly, does it matter enough to warrant sticking a thermometer where the sun don’t shine? Lead researcher Dr. Daniel Niven of the University of Calgary said the one- to two-degree difference is not a problem for most people. “If you have a fever from a cold or something like that, then you can use an oral thermometer, which is a bit more accurate than the (armpit or ear thermometers). “But there are select circumstances where accuracy really matters,” he added. The researchers determined that peripheral thermometers are especially bad at detecting low-grade fevers. Catching these more subtle rises in body temperature is important in early detection of infection or illness in particularly vulnerable patients — the elderly, the immunocompromised, or patients with tumors or with connective tissue disease. The temperatures of such patients tend to be closely monitored already. But Niven said that the most accurate thermometers are not necessarily the most used. “There’s not data to show what thermometers are being used where, but anecdotally, the primary method used in ICUs are axillary (armpit thermometers),” said Niven, an intensive care physician. But for regular consumers, Niven has just this one piece of advice: Don’t use armpit thermometers. “They are the least accurate,” he said. John E. Bennett MD, in Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 2020 Although clinicians frequently regard
temperature readings from various anatomic sites as equivalent approximations of body temperature,1 no one temperature provides a comprehensive description of the thermal status of the human body.12 This is because the body has many different temperatures, each representative of a particular body part. Nevertheless, within the body, there are two basic thermal compartments worthy of special consideration: the shell and the
core.12,13 The shell, which consists of mostly of skin, subcutaneous fat, and bones, insulates the core from the external environment. The core, of which the brain, thoracic viscera, and arterial and central venous blood are major components, although insulated by the shell, has temperature gradients of its own resulting from differences in the metabolic rates, blood flow patterns, and heat dissipation in the various organs
contained therein. Even during baseline conditions, organs with higher metabolic rates have higher temperatures than those with lower metabolic rates and can be up to 1.3°C (2.3°F) higher than the temperature of arterial blood.14 In addition, tissues close to the skin generally have lower temperatures than those at deeper locations.13 Although such differences are normally small, muscle temperatures rise markedly during vigorous exercise compared
with those of less metabolically active organs. During shock and under extreme environmental conditions, regional anatomic variations in temperature may also be exaggerated. Rectal measurements were once regarded as the most practical and accurate means of obtaining routine estimates of core temperature. However, rectal (and colonic) temperature readings are consistently higher than those obtained at other sites (even pulmonary artery blood), which some authorities have suggested might be caused
by heat generated as a result of the metabolic activity of fecal bacteria,13 even though an early study showed no significant decrease in the rectal temperature after a reduction in the colonic bacterial content. A significant effect on rectal temperature, however, is also exerted by that of the blood returning to the core from the lower extremities, because the internal iliac vein passes near the anorectal canal. Thus, during shock, the core area
expands, the shell shrinks,12 and perfusion of the rectum is markedly impaired, causing the rectal temperature to lag significantly behind a rapidly rising or falling core temperature.15 For this reason, Houdas and Ring16 have concluded that the rectal temperature provides a reliable approximation of the core temperature only if the patient is in thermal balance. In neonates and small children, even in the absence of
shock, the rectal temperature measured by standard technique has been reported to correlate poorly with the core temperature as measured by a deep rectal (colonic) probe.17,18 Fever
Patricia S. Lye, Emily M. Densmore, in Nelson Pediatric Symptom-Based Diagnosis, 2018 Fever: Temperature MeasurementRectal temperature measurement is considered to be the gold standard for children 3 years of age or younger. The most widely accepted definition of fever is rectal temperature of 38°C (100.4°F) or higher. It is important to consider that infants, especially those younger than 2 months of age, may have a blunted febrile (or hypothermic) response to infection. Hence, lack of fever should not be used as a criterion for ruling out infection in infants. Although rectal temperature measurement is the gold standard, it should be avoided in neutropenic immunocompromised patients, in whom rectal manipulation may seed the blood with bacteria. Oral thermometry can be considered for cooperative patients who are older than 4-5 years of age. Axillary temperatures are commonly done and tympanic membrane and temporal artery temperatures are newer modalities with some studies examining their reliability. Axillary temperatures are less precise than rectal temperatures. There is a correlation between axillary and rectal temperature measurements; the axillary temperature is usually 0.5-0.85°C lower. Tympanic membrane thermometers are often inaccurate in children. Temporal artery temperature measurement correlates well with rectal temperature in some studies, but has been shown to be inferior when patients are febrile. It can be considered in settings when children are not likely to be febrile and are over 3 months of age. When detection of fever is critical for diagnosis and management, rectal temperatures should be used in the child 3 years of age and younger. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B978032339956200039X Vital Signs MeasurementJames R. Roberts MD, FACEP, FAAEM, FACMT, in Roberts and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care, 2019 Peripheral Body Sites Approximating Core TemperatureA body temperature measurement by IR radiation can be detected from the ear, including the auditory canal and TM; it is easy to use, hygienic, convenient, and quick. It can be used as a general screening technique, particularly in cases when temperature is not of great importance, such as in minor trauma. Though clearly superior to axillary temperature readings,219 controversy remains regarding the sensitivity and specificity of IR TM readings in the ED. In a cohort of ICU patients, agreement of tympanic with PA temperature was inferior to that of urinary temperature. Compared with PA temperatures, Δ (limits of agreement) were 0.36°C (–0.56°C, 1.28°C), –0.05°C (–0.69°C, 0.59°C), and 0.30°C (–0.42°C, 1.01°C) for tympanic, urinary, and axillary temperatures, respectively.220 It is possible that alterations of regional blood flow accompanying critical illness (TMs may behave as an extension of the skin or the mucous membrane in the critically ill) and the peripheral vasoconstriction that occurs with inotropes and some forms of shock may occur in the TM, making such measurements less accurate in this population. More work is being done in the pediatric population, with an overall sensitivity of between 50% and 80% and a specificity of 85%. The lower sensitivities are found in newborns and infants younger than 3 years.221–223 Systematic reviews of pediatric studies have pooled data suggesting 65% sensitivity, which is unacceptable in the clinical setting.224 A 2010 study found that neither TM nor skin thermometers could reliably predict rectal temperature, and it concurred that these methods could not replace rectal temperature measurement as the “gold standard” for detecting fever in the pediatric population.225 Adult studies, though generally more favorable in recommending TM temperatures, have shown gaps in reliability as well.226 However, a 2011 systematic review suggested that TM and oral thermometry provides an accurate measure of core temperature in critically ill adults with fever.227 Temporal artery scanning to detect fever is increasingly being examined. In general, these devices show better sensitivity in detecting fever in infants than TM thermistors do (66% versus 49% sensitivity) and may be useful in excluding fever,228 defined as a rectal temperature higher than 38.3°C if the temporal artery readings are lower than 37.7°C.229 The point can be argued that a sensitivity of 60% in any population lacks the required sensitivity to be useful clinically. A theoretical disadvantage of TM temperatures might be a falsely elevated estimate of the core temperature in the presence of otitis media. In one study, TM thermometers accurately reflected oral temperatures in children with otitis media.230 Sports MedicineJanice K. Loudon PT, PhD, ATC, in Orthopaedic Physical Therapy Secrets (Second Edition), 2006 IN FEMALES• Masculinizing effect •Menstrual irregularities •Hirsutism (excessive hair on face and body) •Deepening of voice 24. List the symptoms, presentation, and treatment of heat exhaustion and heat stroke.
25. What actions can be taken to prevent heat exhaustion and heat stroke? •Prevention requires careful monitoring of ambient temperature and humidity. •Regular hydration before, during, and after sports participation is a must. •Consumption of 8 to 16 ounces of water is required for every 15 minutes of strenuous exercise. •Rehydration with 24 to 40 ounces of water after exercise is needed. •Cold water absorbs faster than warm water in the gastrointestinal tract. 26. Is extra protein needed when participating in athletics? Yes. The recommended dietary allowance (RDA) for sedentary individuals is 0.8 g/kg/day. Endurance athletes require 1.2 to 1.4 g/kg/day, and strength athletes require 1.4 to 1.8 g/kg/day. This protein requirement can be found in a normal diet; extra protein supplements are not necessary. Female athletes and amenorrheic athletes may not consume enough protein. 27. List examples of foods that contain 10 g of protein. •50 g of grilled fish •35 g of lean beef •40 g of turkey •2 small eggs •300 ml of skim milk •3 cups of wheat flake cereal •2 cups of cooked pasta 2 cups of brown rice •3/4 cup of cooked kidney beans •120 g of soybeans •60 g of nuts 28. What is glucosamine, and what is it used for? Glucosamine is a nutritional supplement that has been used for individuals with osteoarthritis. Glucosamine is an essential building block for the synthesis of glucosaminoglycans. Studies have shown that supplementing the body with additional amounts of glucosamine (1500 mg) daily promotes the production of chondrocytes, reduces pain, and increases joint function. In addition to glucosamine, chondroitin sulfate may inhibit several enzymes that degrade articular cartilage. Clinically, chondroitin supplements appear to reduce osteoarthritis symptoms. The American Academy of Orthopaedic Surgeons position statement indicates that there is good evidence that glucosamine and chondroitin sulfate may help symptomatically with no side effects. 29. What is turf toe? Turf toe is an acute sprain to the first metatarsophalangeal joint. The mechanism usually involves the athlete hyperextending this joint as the foot gets jammed on the artificial turf while trying to push-off. 30. List treatments for turf toe. •Applying ice •Strapping the toe •Using nonsteroidal antiinflammatory drugs 31. What is chronic compartment syndrome? The lower leg is divided into four compartments that contain muscles plus neurovascular bundles. An increase in volume in the compartment may result from exercising muscles causing excessive pressure within the compartment (preexercise pressure, >15 mm Hg; 1-minute postexercise, >30 mm Hg; 5-minute postexercise, >20 mm Hg; normal values, 5 to 10 mm Hg). Symptoms of chronic compartment syndrome include compartment tightness, which occurs during or after exercise. Swelling may exist as well as paresthesia over the dorsum of the foot. 32. List treatment options for chronic compartment syndrome. •Fasciotomy •Training modification •Icing •Stretching •Strengthening •Biomechanical correction 33. Why might an athlete collapse on the field? Traumatic •Head injury •Spinal cord injury •Thoracic injury (multiple rib fractures, hemothorax, tension pneumothorax, cardiac tamponade, cardiac contusion) •Abdominal injury (ruptured viscus) •Multiple fractures •Blood loss Nontraumatic •Cardiac (coronary artery disease, arrhythmia, congenital abnormality) •Hyperthermia •Hypothermia •Hyponatremia •Respiratory (asthma, spontaneous pneumothorax, pulmonary embolism) •Allergic anaphylaxis •Drug toxicity •Vasovagal response (faint) •Postural hypotension •Hyperventilation •Hysteria 34. How are concussions classified, and what are the return-to-play guidelines? Return-to-Play Guidelines
Adapted from Cantu RC, Micheli LJ: ACSM's guidelines for the team physician, Philadelphia, 1991, Lea & Febiger. Copyright © 1991 Lea & Febiger 35. What is exercise-induced asthma (EIA)? Exercise-induced asthma (EIA) is characterized by a transient narrowing of the airway following intense exercise lasting longer than 10 minutes. This transient narrowing is associated with bronchospasms. EIA is more common in exercises such as long-distance running and cross-country skiing. A positive test for EIA is a >10% decrease of the forced expiratory volume in 1 second (FEV1). Management of EIA usually involves the use of a β2-agonist with a mast cell stabilizer before exercising. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781560537083500258 Procedures Pertaining to Hypothermia and HyperthermiaJames R. Roberts MD, FACEP, FAAEM, FACMT, in Roberts and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care, 2019 Measurement of Core TemperatureBecause of the nonspecific nature of the symptoms of hypothermia, accurate assessment of temperature is a necessity when considering this diagnosis. It is of paramount importance not only for confirmation of the diagnosis but also for guidance in further diagnostic and therapeutic decisions. Any thermometer that does not record temperatures in the hypothermic range isinappropriate for evaluating significant hypothermia. Standard glass/mercury thermometers generally cannot record temperatures lower than 34°C (< 93.2°F), although some models are available that record temperatures as low as 24°C (75.2°F) (Dynamed, Inc., Carlsbad, CA). An electronic probe with accompanying calibrated thermometer is recommended when monitoring this vital sign. Examples of thermometers with accompanying accuracy at various temperature ranges are shown inFig. 65.1. Core temperature is traditionally estimated with a rectal probe, but due to large gradients within the body, rectal temperature often lags behind core temperature by up to 1 hour, reading higher than esophageal temperature during cooling and lower than esophageal temperature during rewarming.28,30 Esophageal probes may be used, although they may be affected by warm humidified air therapy. Other possible sites for measurement of temperature include the tympanic membrane, nasopharyngeal tract, and urinary bladder.1,31,32 Fresh urine temperature can closely approximate core temperature. “Deep forehead” temperatures measured with a Coretemp thermometer (Teramo, Tokyo) have also demonstrated excellent accuracy and approximation of core temperatures.33 For continuous monitoring purposes, rectal or bladder probes are preferred. Infrared tympanic temperatures have demonstrated excellent correlation with core temperatures. However, studies show that although easier to use and faster, infrared tympanic temperatures can be inaccurate at extremes of temperature by underestimating higher temperatures and overestimating lower temperatures.34 When a rectal probe is used, insert it at least 15 cm beyond the anal sphincter and verify its position frequently.8 One should remember that temperature gradients exist in the human body and therefore consistency of monitoring at one or more sites is mandatory. A chart and formula that convert centigrade to Fahrenheit temperatures will assist the clinician in assessing the severity of hypothermia (seeFig. 65.1C). Bacteremia/SepsisCarol A. Mccarthy MD, in Pediatric Clinical Advisor (Second Edition), 2007 Basic InformationDefinition• Fever: a rectal temperature of higher than 38°C •Bacteremia: the presence of bacteria in the blood •Sepsis: systemic inflammatory response syndrome (SIRS) associated with infection •Fever without source: acute febrile illness without identified etiology after history and physical examination •Serious bacterial infection (SBI): bacteremia, meningitis, pneumonia, urinary tract infection, cellulitis, bone or joint infection, and enteritis ICD‐9‐CM Codes780.6 Fever 790.7 Bacteremia 995.91 Sepsis Epidemiology & Demographics• Fever is a very common reason for health care visits in the young child. •Most febrile illnesses in young children are caused by viral infections. •Increased hospitalization in young febrile infants corresponds with influenza and enterovirus outbreaks. •In nontoxic‐appearing febrile infants less than 3 months of age, the incidence of serious bacterial infection is about 10%. The incidence of bacteremia in this group is about 2%. •The risk of occult bacteremia in children 3 to 36 months of age with temperature ≥39°C was about 5% but is decreased with current immunizations. Clinical Presentation• It is important to do a quick assessment. If ill appearance, stabilize and obtain cultures without delaying intravenous antibiotics. •A thorough history is important including a complete review of systems. •Details of fever history should record how temperature was measured and height of fever and its duration. •Obtain medication and immunization history. •Past medical history should include premature birth, prior antibiotics, prior illness, and previous hospitalization. •Parental medical history is important. •Social history should include family situation, unusual exposures, and travel. This history may influence need for hospitalization. •The physical exam includes an overall general assessment and accurate vital signs. •A complete exam is important. EtiologyCommon Bacterial Pathogens •Streptococcus agalactiae (group B streptococcus)* •Listeria monocytogenes* •Streptococcus pneumoniae •Neisseria meningitidis •Haemophilus influenza •Enterococcus •Streptococcus pyogenes •Salmonella species •Escherichia coli •Staphylococcus species Common Viral Pathogens •Enteroviruses •Respiratory syncytial virus •Influenza viruses •Parainfluenza viruses •Rotavirus •Rhinovirus •Human herpes virus 6, 7 •Herpes simplex virus •Parvovirus •Adenovirus •Cytomegalovirus •Varicella zoster virus Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780323035064100392 Heat StrokeStephen V. Cantrill MD, in Critical Care Secrets (Fourth Edition), 2007 1 What is heat stroke?Heat stroke is equated with a rectal temperature of approximately 40.5°C (105°F) or greater in a person with a history of exposure to exercise or increased temperature and humidity with accompanying neurologic disturbance, usually in the form of altered mental status. Anhidrosis (i.e., lack of sweating) is not a criterion; sweating may or may not be present. Bouchama A, Knochel MD: Heat stroke. N Engl J Med 346:1978–1988, 2002. Vicario S: Heat illness. In Marx JA, Hockenberger RS, Walls RM, et al (eds): Rosen's Emergency Medicine: Concepts and Clinical Practice, 6th ed. St. Louis, Mosby, 2006, pp 2254–2267. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781416032069100795 Laboratory Tests and Diagnostic ImagingWilliam Micheo, ... José Correa, in Clinical Sports Medicine, 2007 ENVIRONMENTAL PROBLEMS IN ATHLETESBox 14.1 Key Points Heat illness•Basic tests •Initial rectal temperature •Clinical assessment, blood pressure and heart rate •Emergency room •CBC, serum chemistries (electrolytes BUN/creatinine, phosphate, magnesium, calcium, CPK and liver enzymes), PT and PTT, INR, urinalysis and arterial blood gases •Hospitalized athlete •Follow-up of above studies, electrocardiogram if there is electrolyte disturbances, fibrin split products if coagulopathy is suspected, brain MRI or CT scan if neurologic deficit appears. Exertional heat illness/injuriesThis illness is commonly seen in the summer and particularly in warm and humid climates. Heat illness can be classified in five exertional heat syndromes: heat edema, heat cramps, heat syncope, heat exhaustion and heat stroke.5 In addition, slow runners or participants in long duration events such as ultramarathons may collapse from hyponatremia associated to over-zealous hydration.6 Complications related to severe heat stroke are acute renal failure, disseminated intravascular coagulation, rhabdomyolysis, acute respiratory distress syndrome, acid base disorders and electrolyte disturbances. The prognosis for the patient is better when heat stroke is diagnosed early with appropriate studies and management with cooling measures and fluid and electrolytes replacement is started early. Prognosis is poor if treatment is started after 2 h of the initiation of symptoms.7 The initial evaluation of the athlete with suspected heat illness should include documentation of core temperature with a rectal probe, since tympanic membrane, oral or axillary temperatures do not correlate with core temperature. In addition, complete blood cell count (CBC), serum chemistries (electrolytes, blood urea nitrogen (BUN)/creatinine, phosphate, magnesium, calcium, creatine phosphokinase (CPK) and liver enzymes level), coagulation studies (prothrombin time (PT), partial thromboplastic time (PTT) and INR), urinalysis and arterial blood gases should be obtained.8 The initial abnormal findings may include elevated core temperature, as high as 104°F in the case of heat stroke, leukocytosis or thrombocytopenia in the CBC, hypokalemia associated with catecholamine effects, hyperventilation and sweat losses, as well as physiologic hyperaldosteronism.9 After a few hours, hyperkalemia is found associated with sustained hyperthermia, hypoxia and hypoperfusion, hypocalcemia and elevated BUN and creatinine secondary to renal dysfunction. Other laboratory abnormalities will include hypophosphatemia due to an increase in glucose phosphorylation seen in alkalosis, hyperuricemia secondary to purine release from injured muscles, and an increase in liver enzymes AST, LDH and total bilirubin commonly seen associated with liver dysfunction. In severe cases of heat illness, a coagulation disorder with evidence of disseminated intravascular coagulation (DIC)/consumption coagulopathy can be seen with elevated fibrin split products, PT, PTT and INR. Muscle damage can be associated with rhabdomyolysis with elevated CPK and myoglobin casts in the urine. Other ancillary diagnostic studies include an electrocardiogram which may show tachycardia, rhythm disturbances (atrial fibrillation, supraventricular tachycardia), conduction defects (right bundle branch block (RBBB), intraventricular conduction defect), prolongation of QT interval most common secondary to hypocalcemia, hypomagnesemia or hypokalemia, or ST changes of myocardial ischemia. Neurological tests may be required in patients with central nervous system involvement associated with heat stroke. Neurological deficits are possibly secondary to metabolic changes, cerebral edema or ischemia. The cerebellum is the most susceptible area to heat illness and cerebellar atrophy can be found after several weeks.9 Brain CT scans or MRI are indicated in patients with persistent neurologic deficit after heat stroke. In exertional hyponatremia, usually the electrolyte tests will reveal sodium levels in the range of 110–130 mmol/l accompanied by symptoms of headache, nausea, dyspnea and muscle cramps. A high level of suspicion is required for this condition that affects particularly the slow runners in long distance events.6 Cold injuriesBox 14.2 Key Points •Basic tests •Initial field clinical assessment, blood pressure and heart rate •Low reading rectal thermometer •Emergency room •Serum electrolytes, arterial blood gases, CPK and electrocardiogram •Hospitalized athlete •PT, PTT, INR, follow-up of emergency room laboratories. Hypothermia usually occurs associated with exercise in the cold when the body temperature falls below 95°F (35°C). Mild hypothermia is seen when the body core temperature is 35°C or greater. Shivering, tachycardia, tachypnea and cool extremities are usual associated symptoms. Moderate hypothermia is seen when the body core temperature drops below 34°C. At this stage, there will be signs of CNS depression and the athlete is confused, displays gross incoordination, slurred speech, drowsiness and may become dehydrated. Shivering is diminished or may not be present at all. In severe hypothermia, the body core temperature is less than 32°C. At this stage, the athlete displays marked cognitive impairment and may be comatose. The body is rigid, cool and there is no shivering. The athlete is hypotensive with bradycardia, and cardiac arrhythmias are commonly seen. Almost all mild hypothermic healthy athletes recover normally. In athletes with moderate to severe hypothermia, rates of recovery are lower with ventricular fibrillation being the most common cause of death.10 A low reading rectal thermometer should be available in the first aid kit to document low temperature during cold weather athletic events.11 If this type of thermometer is not available, the core temperature can be grossly estimated by evaluating if the athlete is shivering, in which case the core temperature is usually >90°F (32°C), or if the athlete is obtunded and not shivering usually the core temperature is <90°F (32°C). Laboratory studies should be performed after the patient arrives at a medical care facility and re-warming is started, and include serum electrolytes, a renal panel and arterial blood gases. An electrocardiogram should also be done. Abnormal findings include increased BUN-creatinine ratio associated with acute tubular necrosis, increased CPK associated with rhabdomyolysis, and fluctuating potassium (K+) levels. Arterial blood gases can show hypoxemia, carbon dioxide retention and acidosis. A coagulation panel can reveal abnormalities compatible with a self-limited coagulopathy.12 The electrocardiogram can reveal atrial or ventricular fibrillation due to myocardial irritability. Sinus bradycardia is seen in mild hypothermia. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781416024439500179 Evaluation of occupational clothing for surgeons: achieving comfort and avoiding physiological stress through suitable gownsW. Nocker, in Handbook of Medical Textiles, 2011 20.7 Controlled wear testsThe findings of the laboratory measurements (see Chapter 4) have to be checked by controlled wear tests with human test subjects in a climate-controlled chamber with monitored test measurements. This is necessary to find out whether the theoretically obtained results also apply in practice. What is most important for successful tests is to select suitable and comparable test subjects. This is ensured by prior medical examinations assessing health condition and physical fitness. Only persons meeting the requirements qualify as test subjects. Here are some examples: Their perspiration intensity should be neither extremely strong nor extremely weak. As they need to subjectively describe how they feel they should be highly sensitive to feel even minor differences in heat perception, moisture perception, workloads and wear comfort. Once the test subjects have been selected, they have to be made familiar with the test conditions: When the actual tests begin, there should be no habituation effects falsifying the results. The tests should always be performed at the same time of the day in order to exclude time-related fluctuations. Never will so-called ‘quick and dirty tests’ with individual persons of unknown profiles lead to reliable results. The objective parameters to be measured are, for example: •Rectal temperature, Tre, as a measure of body core temperature •Skin temperature, Ts, as an average of measurements on up to 10 different spots •Heart rate, HR •Temperature, TM •Relative humidity, FM, in the microclimate, measured between the skin and the innermost textile layer. This brings potentially disturbing variables under control and renders the tests in the climate-controlled chamber reproducible. In some cases, the work to be performed in the specific end use of the clothing cannot be done in a climate-controlled chamber. In this case, only the metabolic turnover can be simulated so that a work-specific factor is missing. 20.7.1 Results of wear tests with reusable and disposable gownsStudy 1In its study AIF No. 11090 (1999) the Hohenstein Institute of Clothing Physiology tested 21 OR gowns on the articulated mannikin and 34 textile samples (with and without barrier effect) using the methods described in Section 20.5. The results served to work out a physiological profile of requirements to specify the wear comfort of OR gowns. It is based on water vapour transmission resistance, Ret, as determined by the skin model according to ISO 11092 (1993). Table 20.2 shows a rating in grades ranging from ‘very good’ to ‘unsatisfactory’ which is assigned to the corresponding water vapour transmission rate, Ret,B, of the barrier textile and Ret,R of the back textile and the physiological properties deducted thereof. The ratings in Table 20.2 serve to classify the barrier textiles tested as shown in Fig. 20.3. The water vapour transmission resistance Ret,R of the back textiles ranged from 1.31 to 4.75 m2 Pa/W. Table 20.2. Physiological profile of demand for OR barrier and backside textiles, based on ISO 11092 measurements
Ret,B = water vapor resistance of barrier textile; Ret,R = water vapour resistance of backside textile. Source: Hohensteiner Report (2000, p. 12).  Figure 20.3. Classification of barrier textiles. Source: Hohensteiner Report (2000, p. 12).Four OR gowns were selected. The data obtained from measurements on the skin model and on the mannikin were fed into a prediction model (Mecheels and Umbach, 1976, 1977; AIF No. 7504, 1992). The metabolic turnover was assumed to be 200 W and an extended phase of discomfort was considered acceptable. In this test setup, the thermal application range of the entire clothing system was calculated. For details, please see Table 20.3. Table 20.3. Calculated ‘range of utility’, gown no. according AIF-report 11090
Ret,B = water vapour resistance of barrier textile; Ret,R = water vapour resistance of backside textile. For the controlled wear tests, the ambient climate was selected to be 25 °C, 50% RH, which is the upper temperature range according to DIN 1946, the metabolic turnover was 200 W. The test lasted for three hours. The rectal temperature, Tre, and the heart rate, HR, allow for a determination of the wearer’s physical strain. At the end of the tests, all rectal temperatures were in the range of 37.15 ± 0.05 °C and the heart rates were in the range of approximately 95 ± 5/minute which means that the wearers did not suffer from physiological stress. Although the values had not reached a steady state at the end of the test, but still slightly rose, it is not to be expected that the discomfort zone would be reached, which begins at Tre = 37.5 °C, even if the test took twice as long. Corresponding to the small differences in rectal temperatures, the average skin temperatures differed only to a minimum degree which are therefore considered to be insignificant. As expected, the average relative humidity in the microclimate showed significant differences between the OR gown with the impermeable barrier layer (no. 33–34/34) and the other samples. For more details, see Fig. 20.4. When relative humidity rises to 70%, the discomfort zone will be reached (Diebschlag, 1976). The wearers perceived this OR gown to be warmer, more humid and less comfortable than the other samples. Figure 20.4. Relative humidities in a microclimate. Source: AIF No. 11090 (1999, p. 100).Study 2Experience shows that the wear comfort of OR gowns made from microfibre fabrics is high. Often, a lower wear comfort is expected for multi-layer constructions. In another study (Hohenstein Test Report, 2000) 10 OR gowns made from three-layer laminates, microfibre fabrics and coated nonwovens were compared with each other. The task was to find out how comfortable three-layer products are to wear, compared to the other products. At first, the gowns and their materials were subjected to the tests described in Section 20.5. Subsequently, predictive calculations were performed to calculate the admissible thermal application range under conditions where the metabolic rate is 200 W and discomfort is acceptable for an extended period of time. The results are shown in Table 20.4. Table 20.4.. Calculated ‘range of utility’ according the Hohenstein Test Report (2000)
MF = microfibre; 3 L = three-layer laminate with PTFE membrane or PU membrane; PC = partial coating; Ret,B = water vapour resistance of barrier textile; Ret,R = water vapour resistance of backside textile. Under typical conditions in OR theatres, with room temperatures between 22 °C and 26 °C (see Section 20.3.1), and at an assumed metabolic turnover of 200 W, merely slight losses of comfort can only be expected for the microfibre products and the laminates 5 and 8. For the other laminates, higher discomfort levels have to be expected; number 6 is already comparable to the uncomfortable impermeable products. The admissible application range of the ten clothing systems tested excludes operating theatres for treating burns where the typical temperature is around 32 °C. For the wearer this means that the longer he works the more probably he will suffer from rising discomfort and even hyperthermia due to his rising body core temperature. When the body core temperature exceeds 38.2 °C, it is considered unacceptable to work on (Goldmann, 1988). The time until this point is reached is called ‘tolerance time, ttol’. When it is reached, the wearer should take a break. It is considered impossible to work when the body core temperature is higher than 38.5 °C. For use of the ten clothing ensembles in an operating theatre for treating burns, the body core temperature at the end of a three hours’ surgery was calculated for a metabolic turnover of 200 W for a standard man. For all three microfibre products and for the three laminates with a PTFE membrane, Tre was < 37.6 °C. This shows that these clothing systems are only slightly less comfortable than during use in a normal operating theatre. The second best class contains ensemble number 7 with PU-membrane: Tre = 37.8 °C. The situation becomes worse for the ensembles number 6 (PU-membrane) and number 9 (partial coating). In them, core temperatures rise to 38.1 and 38.0 °C. This is an intolerable discomfort, as liquid sweat is running down the wearer’s entire body. The physiologically poorest ensemble appears to be number 10, which is mainly made of a non-breathable coated nonwoven. Final rectal temperature is Tre = 38.3 °C. The critical value of 38.2 °C is reached after ttol = 121 min. Hence, this clothing system is not to be used in a burn injury OR. At 25 °C, the ten OR gowns were subjected to controlled wear tests. After 150 minutes, the objective and subjective data was evaluated (data from W.L. Gore). In the three microfibre products and in the laminates 5 and 8, the lowest body core temperatures were measured. In the two impermeable products the highest body core temperatures were measured. The relative humidities in the microclimate, measured in the chest area, were lowest (approx. 60% RH) for the microfibre products and for laminate number 8, the highest values (approx. 90% RH) were measured for the impermeable products and for laminate number 6. The perceived moisture was assessed by grades and correlated (r2 = 0.78) with the moistures measured: •Grade 5 (= sweat flows at some areas) for the impermeables •Grade 4 (= moist body, clothing sticks to the body) for laminate 6 •Grade 3 (= moist body) for all other products. The heat perception correlates (r2 = 0.88) with the body core temperatures: •Grade 5 (= very hot) for the impermeables •Grade 4 (= hot) for laminate 6 •Grade 3 (= very warm) for all other products. The wear comfort had to be rated in grades ranging from grade 1 (= very good) to grade 6 (insufficient). The test subjects had not been given any criteria for this judgement. The results: •Grade 4 (= sufficient) for the impermeable clothing system number 9 •Grade 3 (= satisfactory) for the impermeable clothing system 10 and for laminate 6 •Grade 2 (= good) for all others. Based on the thermo-physiological data alone, a worse rating of the wear comfort could have been expected. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781845696917500200 Thermoregulation: From Basic Neuroscience to Clinical Neurology Part IMatthew D. White, in Handbook of Clinical Neurology, 2018 Passive hyperthermia and human thermal hyperpneaThe magnitude of human thermal hyperpnea is seen with an elevation of human rectal temperature by ~ 1.0°C, and it gives increases of pulmonary ventilation by ~ 35% and of venous blood pH from ~ 7.38 to 7.46 (Gaudio and Abramson, 1968). Coupled to these two changes are decreases in both plasma bicarbonate from ~ 25.5 to 22.3 mEq/L and Paco2 from ~ 44 to 33 Torr (Gaudio and Abramson, 1968). Similar evidence shows that, after an increase in tympanic temperature by ~ 2.3°C, PETco2 decreased from 37 to 30.8 Torr (Saxton, 1981). In an extreme case, when TRE increased to 39.2°C, blood pH increased to ~ 7.6 and Paco2 decreased to ~ 20 Torr (Iampietro et al., 1966). In resting volunteers rendered hyperthermic, other known modulators of pulmonary ventilation, including plasma norepinephrine (Brenner et al., 1997) and potassium (Coburn et al., 1966; Francesconi et al., 1997), remain close to their resting normothermic concentrations. Collectively, the evidence supports that at rest an elevation in core temperature (TC) alone during hyperthermia can directly increase pulmonary ventilation. The magnitude of this increase in pulmonary ventilation is more pronounced for an increasing TC relative to a stable but elevated TC (Bazett and Haldane, 1921; Bazett, 1924; Landis et al., 1926; Sancheti and White, 2006). Depending on whether the TC is stable or increasing, and on the site of TC measurement, an elevation of TC from a resting value by 1.0–2.0°C gives a typical sensitivity of pulmonary ventilation from ~ 2.0 to ~ 4.0 L/min/°C (Gaudio and Abramson, 1968; Vejby-Christensen and Petersen, 1973; Vejby-Christensen and Strange Petersen, 1973; Cabanac and White, 1995). The site of TC measurement employed can also complicate expression of the size of this hyperventilation, since TRE gives a more sluggish response than tympanic, esophageal, or intracranial temperatures (Mariak et al., 1993, 2003). Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B978044463912700014X Which part of the body has the most accurate temperature?Rectal temperatures are considered most accurate indication of the body's temperature. Oral and axillary temperature readings are about ½° to 1°F (.
What is the most common body temperature site?These thermometers can be used on the forehead, mouth, armpit or rectum. Most electronic thermometers have a digital display that shows you the temperature reading. Rectal temperatures provide the most-accurate readings for infants, especially those 3 months or younger, as well as children up to age 3.
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Which body site is generally considered to be the most accurate for obtaining temperatures?
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