Temperature measurement - Assessment and clinical practice

Recommendations for practice





Critically ill unstable patients (see Definitions for patient groups) require continuous invasive temperature (using brain, intra-vascular or urinary bladder) monitoring that is recorded at least hourly.




Complex patients (see Definitions for patient groups) require invasive temperature (using brain, intra-vascular or urinary bladder) measurement that is recorded at least second hourly.




For routine monitoring of stable patients (see Definitions for patient groups) measurement of temperature, using either oral or axillary methods, is required at least four-hourly.


(3, 13, 14)


Tympanic or temporal artery temperature measurement methods should not be used, as these methods do not accurately reflect core body temperature.


(4-6, 10, 15, 16)

The evidence review for these recommendations was current to May 2012. Clinicians are advised to check the literature as research may have been published that change these recommendations

The systematic review revealed that the evidence base for temperature measurement in critically ill adults is limited by the quality of studies. When examining the accuracy of different methods of temperature measurement, researchers have generally sought to identify which methods were equivalent; that is within a clinically acceptable range of ±0.3C⁰, to core temperature or a surrogate, such as pulmonary artery or urinary bladder. The evidence base shows that (in order of volume and quality) urinary bladder and oesophageal thermometry are equivalent to intra-vascular or direct brain thermometry. All available studies were level III.2 and had a range of bias; the weight of evidence supports urinary bladder temperature over oesophageal temperature. Rectal thermometry was found to not be equivalent to core temperature (1, 15).

Non-invasive or surface thermometries (including axilla, oral, tympanic and temporal artery methods) have been evaluated across a variety of critical care settings. All available studies were level III.3 and outcomes were variable according to temperature measurement method. Axillary and oral methods had mixed results however a recent systematic review (7) found them to be within clinically acceptable ranges. By contrast, researchers consistently found that tympanic and temporal artery methods were not equivalent to core body temperature (including direct brain, intravascular or urinary bladder). This means these methods are probably unreliable, unsafe and should not be used, even for stable patients. Operator error is a significant problem impacting on accuracy of tympanic temperature method. It should be noted:

  • that the more a patient’s temperature deviates from normal the greater the discrepancy across all surface methods
  • there is no reliable method of adjusting one body temperature measurement for another (16)
  • there were few studies where the sample included adequate numbers of patients with abnormal temperatures.

Definitions for patient groups

Critically ill and unstable




Patients with significant haemodynamic, respiratory, thermoregulatory or neurological instability.

Patients whose condition is stable, however have potential for complication or deterioration.

Patients who do not require intense or invasive physiological monitoring.

Patient groups – examples only

  • Multiple organ dysfunction
  • Multi trauma
  • Traumatic brain injury (17)
  • Severe sepsis
  • Burns
  • Post-op cardiothoracic surgery
  • Major surgery (18)
  • Ventilated patients
  • Acute stroke (19)
  • Sepsis
  • Routine post op
  • Diabetic ketoacidosis (DKA)
  • Cleared for discharge

Treatment –examples only

  • Therapeutic thermoregulation (6)
  • Massive blood transfusion (20)
  • Rapid fluid resuscitation
  • Blood product transfusion
  • Invasively ventilated
  • non-invasive positive pressure ventilation (NiPPV)

Please note this table is provided as a GUIDE only. Units should decide how these definitions relate to their patient population.

What clinicians should consider before choosing a method of temperature measurement

When selecting the most appropriate method of temperature measurement clinicians need to decide how important a patient’s temperature is within the full scope of diagnosis, treatment and potential complications. More invasive and continuous methods should be utilised where identification of accurate temperature is time-critical and significantly important to patient outcomes. This was the guiding principle when developing the categories in ‘Definitions for patient groups’ that outlines patients and interventions. However, this table should not be seen as exhaustive. Clinicians should consider using monitoring devices already in situ when choosing an invasive method. For most patients the default method would be urinary bladder temperature measurement because:

  • urine measurement is required by most, if not all adults in critical care units, even routine post-operative or simple cardiac patients
  • IDUC remain in situ after many other monitoring devices have been removed
  • there are a number of potential problems impacting on the correct placement of rectal and oesophageal probes
  • the use of pulmonary artery catheters is becoming less common in intensive care.

See 'Clinical considerations when choosing temperature measurement method'.

Clinical considerations when choosing temperature measurement method


Clinical considerations

Potential problems

Non-invasive >>>>>>>>>>>>>>>>>>>>> Highly invasive


Probe should be in non-injured tissue

  • Highly invasive, reading may be influenced by injury/ischaemia

Direct blood


Requires aseptic insertion and should be removed when there is no longer an indication

  • Blood stream infection

Urinary catheter

Requires aseptic insertion and should be removed when there is no longer an indication for urine measurement

  • May be effected by urine output (the  effects of oliguria on accuracy are unknown (3))
  • Inaccurate with severe hypothermia


Probe needs to be located within distal third of oesophagus (confirmed by CXRay to be within cardiac shadow) (21)

  • Can take significant time to insert (21)
  • Training to ensure accurate placement  (21, 22)
  • Fluids passing through enteral tubes  may alter the temperature (no research evidence was located)


Tip should be 4cm inside rectum (16)

  • Presence of hard faeces impairing  placement, inflammation around rectum and heat producing microorganisms in  faeces
  • Inappropriate for patients with rapid  temperature flux (23)


Must be placed in posterior sublingual pocket (perfused by branch of external carotid) (16)

  • Oral or mouth breathing,  administration of oxygen or warmed gases via an ETT do not effect accuracy (14)


Placement in central position with arm adducted to the chest wall (14)

  • May be significantly affected by  ambient temperature, local blood flow, sweat, inappropriate placement of  probe, correct timing (16)

Grading of recommendation taxonomy

Grade of recommendation



Body of evidence can be trusted to guide evidence


Body of evidence can be trusted to guide practice in most situations


Body of evidence provides some support for recommendation/s but care should be taken in its application


Body of evidence is weak and recommendation must be applied with caution


Consensus was set as a median of ≥ 7

Grades A–D are based on NHMRC grades (22)


  1. Lefrant J-Y, Muller L, de La Coussaye JE, Benbabaali M, Lebris C, Zeitoun N, et al. Temperature measurement in intensive care patients: comparison of urinary bladder, oesophageal, rectal, axillary, and inguinal methods versus pulmonary artery core method. Intensive care medicine. 2003;29(3):414-8.
  2. Fallis WM. Monitoring urinary bladder temperature in the intensive care unit: state of the science. American Journal of Critical Care. 2002;11(1):38-45.
  3. Fallis WM. The effect of urine flow rate on urinary bladder temperature in critically ill adults. Heart & Lung: The Journal of Acute and Critical Care. 2005;34(3):209-16.
  4. Moran JL, Peter JV, Solomon PJ, Grealy B, Smith T, Ashforth W, et al. Tympanic temperature measurements: Are they reliable in the critically ill? A clinical study of measures of agreement*. Critical care medicine. 2007;35(1):155-64.
  5. O’Grady NP, Barie PS, Bartlett JG, Bleck T, Carroll K, Kalil AC, et al. Guidelines for evaluation of new fever in critically ill adult patients: 2008 update from the American College of Critical Care Medicine and the Infectious Diseases Society of America. Critical care medicine. 2008;36(4):1330.
  6. Olson D, Grissom JL, Dombrowski K. The Evidence Base for Nursing Care and Monitoring of Patients During Therapeutic Temperature Management. Therapeutic Hypothermia and Temperature Management. 2011;1(4):209-17.
  7. Jefferies S, Weatherall M, Young P, Beasley R. A systematic review of the accuracy of peripheral thermometry in estimating core temperatures among febrile critically ill patients. Critical care and resuscitation: journal of the Australasian Academy of Critical Care Medicine. 2011;13(3):194.
  8. Hooper VD, Andrews JO. Accuracy of noninvasive core temperature measurement in acutely ill adults: the state of the science. Biological Research for Nursing. 2006;8(1):24-34.
  9. Rubia-Rubia. Measurement of body temperature in adult patients: Comparative study of accuracy, reliability and validity of different devices. Measurement of obdy temperature in adult patients: comparative study of accuracy, reliability and validity of different devices. 2011;48(7):872-80.
  10. Kimberger O, Cohen D, Illievich U, Lenhardt R. Temporal artery versus bladder thermometry during perioperative and intensive care unit monitoring. Anesthesia & Analgesia. 2007;105(4):1042-7.
  11. Khan T, Vohra H, Paul S, Rosin M, Patel R. Axillary and tympanic membrane temperature measurements are unreliable early after cardiopulmonary bypass. European Journal of Anaesthesiology (EJA). 2006;23(7):551&hyhen.
  12. Giuliano KK, Giuliano AJ, Scott SS, Maclachlan E, Pysznik E, Elliot S, et al. Temperature measurement in critically ill adults: a comparison of typmpanic and oral methods. American Journal of Critical Care. 2000;9:254-61.
  13. Farnell S, Maxwell L, Tan S, Rhodes A, Philips B. Temperature measurement: comparison of non-invasive methods used in adult critical care. Journal of clinical nursing. 2005;14(5):632-9.
  14. Lawson L, Bridges EJ, Ballou I, Eraker R, Greco S, Shively J, et al. Accuracy and precision of noninvasive temperature measurement in adult intensive care patients. American Journal of Critical Care. 2007;16(5):485-96.
  15. Childs C, VAil A, Protheroe R, King AT, Dark PM. Differences between brain and rectal temperatures during routine critical care of patients with severe traumatic brain injury. Anaesthesia. 2005;60(8):759-65. Epub 29 June 2005.
  16. Sund-Levander M, Grodzinsky E. Time for a change to assess and evaluate body temperature in clinical practice. International journal of nursing practice. 2009;15(4):241-9.
  17. Childs C, Wieloch T, Lecky F, Machin G, Harris B, Stocchetti N. Report of a consensus meeting on human brain temperature after severe traumatic brain injury: its measurement and management during pyrexia. Frontiers in neurology. 2010;1. Epub 23 November 2010.
  18. Karalapillai D, Story D, Calzavacca P, Licari E, Liu Y, Hart G. Inadvertent hypothermia and mortality in postoperative intensive care patients: retrospective audit of 5050 patients. Anaesthesia. 2009;64(9):968-72.
  19. Adams HP, Del Zoppo G, Alberts MJ, Bhatt DL, Brass L, Furlan A, et al. Guidelines for the Early Management of Adults with Ischemic Stroke. Circulation. 2007;115:e478-e534.
  20. Lier H, Bottiger BW, Hinkelbein J, Krep H, Bernhard M. Coagulation management in multiple trauma. Intensive Care Medicine. 2011;37:572-82. Epub 12 February 2011.
  21. Paik U, Lee TR, Kang MJ, Shin TG, Sim MS, Jo IJ, et al. Sucess rates and procedure times of oesophageal temperature probe insertion for therapeutic hypothermia treatement of cardiac arrest according to insertion methods in the emergency department. Emergency Medicine Journal. 2012;0:1-5.
  22. Makic MBF, Lovett K, Azam MF. Placement of an Esophageal Temperature Probe by Nurses. AACN Advanced Critical Care. 2012;23(1):24-31.
  23. Hannenberg AA, Sessler DI. Improving Perioperative Temperature Management. Anesthesia & Analgesia. 2008;107(5):1454-7.
  24. NHMRC. NHMRC additional levels of evidence and grades for recommendations for developers of guidelines:PILOT PROGRAM 2005 - 2007. Australian Government; 2005.


The information on this page is general in nature and cannot reflect individual patient variation. It reflects Australian intensive care practice, which may differ from that in other countries. It is intended as a supplement to the more specific information provided by the doctors and nurses caring for your loved one. ICNSW attests to the accuracy of the information contained here but takes no responsibility for how it may apply to an individual patient. Please refer to the full disclaimer.