Comparison of core and peripheral temperature measurement in adult critically ill patients with acute brain injury and sepsis

Two groups of temperature measurements (at least three hours apart) will be made on two consecutive study days. The use of physical cooling (ice packs or cooling blankets), renal replacement therapy and nasal devices including nasogastric tubes, nasal intubation, high flow nasal prongs or nasal prongs will be recorded with each group of temperature measurements. Total daily urine output and serum creatinine will be recorded for each of the two study days on which temperature measurements are made. The equipment used for measuring temperature will be the Braun Thermoscan Type 6021 for tympanic measurements, the Protec BX/144 digital thermometer for axillary measurements, the General Electric Vital-Temp general-purpose probe for nasopharyngeal measurements, and the Nellcor Mon-a-therm Foley Temp 400 series for intravesical measurements. Temperature will be measured at each site as follows: a. Tympanic- an ear-tug will be performed by pulling the pinna upward and backward whilst inserting the probe with a slight rotating motion aiming towards the anterior inferior third of the tympanic membrane. To prevent interference from the air temperature, the probe should penetrate at least one third of the external auditory meatus and form a seal. If the patient wears a hearing aid, this will be removed for 20 minutes prior to measurement. Similarly if the patient has been lying in a lateral position, they will be laid supine at least 20 minutes prior to measurement to avoid ear-warming. Paired measurements will be taken in both the right and left ears and averaged. b. Axillary- the thermometer will be placed on dry skin deep into the apex of the axilla with the patient’s arms adducted so that the tip of the thermometer is covered by the arm to prevent interference from air temperature. Paired measurements will be taken in both the right and left axillae and averaged. c. Nasopharyngeal- the probe will be positioned in the nasopharynx posterior to the soft palate by inserting approximately 10cm into the left or right nostril. The probe should be in situ for at least 20 minutes prior to measurement to allow for temperature to equilibrate. Patients with clinical or radiological evidence of base of skull or facial fractures will not have a nasopharyngeal probe inserted due to the risk of incorrect positioning. d. Intravesical- the temperature sensing urinary catheter will be inserted as for a standard urinary catheter. The catheter should be in situ for at least 20 minutes prior to measurement to allow for temperature to equilibrate. After the cessation of physical cooling, at least 20minutes should be allowed to pass before temperature measurement to allow for temperature to equilibrate.