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Table 2 Studies testing different approaches of target temperature management in healthy subjects.

From: Insight into the use of tympanic temperature during target temperature management in emergency and critical care: a scoping review

Study Population Cooling approach Tympanic TM device Core TM sites Other TM sites Main results
Location Protocol Feasibility Comparability
Bagić et al. [32] N: 10
Age: [21–47] y
Male: 50%
Head and neck cooling Cooling session lengths: 30 and 60 min. Cooling device T: 1.5 to 4.5–5 °C. IRTT, Braun PRO 3000 Thermometer, Braun GmbH, Germany; TTy measured in both ears. Intestinal pill Scalp, forearm, abdomen, leg, face, and mouth In both ears, TTy displayed significant differences between the start and end of cooling (p < 0.001). A significant difference was observed in scalp T (p < 0.001), but not in intestinal T (p = NS).
Kallmünzer et al. [33] N: 10
Age: 35 (28–42) y
Male: 60%
Neck cooling Cooling session length: 190 min
Cooling device T: 4 °C.
IRTT, Genius 2, Tyco Healthcare Group, USA Rectal None TTy displayed a significant drop after neck cooling (−1.7 °C, p = 0.001). Rectal T displayed a smaller decrease (−0.65 °C, p = 0.019).
Koehn et al. [34] N: 11
Age: 42 ± 11 y
Male: 45%
Neck cooling Cooling session length: 90 min.
Cooling device T: 4 °C.
Thermocouple thermometer, ELan Med GmbH, Germany Rectal Neck skin TTy showed a slight but significant decrease (from 35.6 ± 0.2 °C to 35.0 ± 0.8 °C, p = 0.026) within 10 min of cooling, reaching minimal values (34.7 ± 0.4 °C, p < 0.001) after 50 min Neck skin and rectal T decreased respectively by a higher and lower extent than TTy.
Koehn et al. [35] N: 10
Age: 35 ± 13 y
Man: 100%
Head and neck cooling Cooling session length: 120 min
Cooling device T: 4 °C.
Thermocouple thermometer, ELan Med GmbH, Germany Rectal Forehead skin TTy decreased to minimal values (from 36.6 ± 0.7 °C to 31.8 ± 1.2 °C, p < 0.001) after 40 min of cooling, with a slow increase thereafter. Forehead skin and rectal T achieved the respective lowest values at 20 and 120 min, respectively.
Zweifler et al. [36] N: 22
Age: 31 ± 8 y
Male: 45%
Chest and thighs cooling Active cooling plus hypothermia maintenance: < 5 h.
TT: 34–35 °C (tympanic).
Shivering suppression by meperidine, buspirone, and MgSO4.
Thermocouple thermometer, Mon-a-Therm, Mallinckrodt Anesthesia Products, USA; ear canal occluded with cotton and gauze, ear probe taped in place. Rectal None TTy reached the TT=35 °C in a median time of 88 min (mean cooling rate of 1.4 ± 0.5 °C/h). A time-dependent gradient was observed between TTy and rectal T (from −0.1 ± 0.3 °C at baseline to −0.6 ± 0.4 °C at 105 min, −0.3 ± 0.5 °C at maintenance phase).
Zweifler et al. [37] Intervention 1:
N: 8
Age: 33 ± 8 y
Male: 37%
Intervention 2:
N: 14
Age: 30 ± 9 y
Male: 36%
Chest and thighs cooling Active cooling plus hypothermia maintenance: < 5 h.
TT: 34–35 °C (tympanic).
Shivering suppression by meperidine, buspirone, or ondansetron, with (intervention 1) or without MgSO4 (intervention 2).
Thermocouple thermometer, Mon-a-Therm, Mallinckrodt Anesthesia Products, USA; ear canal occluded with cotton and gauze, ear probe taped in place. Rectal None Baseline TTy was 36.8±0.2 °C in intervention 1 and 37.0±0.3 °C in intervention 2. TTy depicted the prolongation of cooling time induced by meperidine (delay of 36 min, p = 0.003, for each 50 mg of drug) and the reduction of cooling time by MgSO4 (17 min, p = 0.039). Baseline rectal T was 37.0±0.2 °C in intervention 1 and 37.0±0.3 °C in intervention 2.
Zweifler et al. [38] Intervention 1:
N: 5
Age: 36 ± 5 y
Male: 60%
Intervention 2:
N: 5
Age: 30 ± 11 y
Male: 20%
Intervention 1:
Chest and thighs cooling
Intervention 2:
Thighs, back, and abdomen cooling
Intervention 1:
Active cooling plus hypothermia maintenance: < 5 h. TT: 34–35 °C (tympanic).
Intervention 2: Active cooling plus hypothermia maintenance: < 5 h. TT: 34.5 °C (rectal).
In both, shivering suppression by meperidine, or chlorpromazine
Thermocouple thermometer, Mon-a-Therm, Mallinckrodt Anesthesia Products, Inc, USA. Rectal Mean skin-surface T from calf, thigh, chest, and upper arm skin. TTy reached the TT=35 °C in 77 ± 23 min (mean cooling rate of 1.5 ± 0.6 °C/h) in Intervention 1 and in 90 ± 53 min (mean cooling rate of 1.4 ± 0.4 °C/h) in Intervention 2. Rectal T displayed higher values than TTy over the cooling procedure in intervention 2.
Mahmood et al. [39] N: 18
Age: 32 ± 8 y
Male: 44%
Chest and thighs cooling Active cooling plus hypothermia maintenance: ≤ 5 h.
TT: 34.5 °C (tympanic).
Shivering suppression by meperidine and/or ondansetron and/or buspirone.
NR Rectal None TTy changes correlated with the mean flow velocity of the middle cerebral artery (p < 0.001). At baseline TTy was 36.9 ± 0.3 °C, while rectal T was 37.0 ± 0.2 °C.
Adams and Koster [40] N: 10
Age: > 18 y
Male: 50%
Face and neck cooling Device application at ambient T of 19 °C. IRTT, Genius 3000A, Sherwood-Davis & Geck, Gosport UK None None TTy showed a difference of 0.433 °C (p < 0.0001) between baseline and end of cooling exposure. NR
Doufas et al. [41] N: 10
Age: 24 ± 4 y
Male: 100%
Whole body cooling by lactated Ringer’s solution (~4 °C) Lactate infusion to decrease TTy by 1–2 °C/h until identification of the shivering threshold. Conditions tested: no drug, dexmedetomidine and/or meperidine. Thermocouple thermometer, Mon-a-Therm, Mallinckrodt Anesthesiology Products, Inc., Ireland; ear canal occluded with cotton, probe taped in place, bandage over the ear. None Mean skin surface T from 15 area-weighted sites. TTy detected the significant (p < 0.001) reduction of the shivering threshold induced by meperidine (drop of 1.2°C), dexmedetomidine (0.7 ± 0.5 °C), and their combination (2.0 ± 0.5 °C). NR
Jackson et al. [42] N: 12
Age: 27 ± 11 y
Male: 42%
Head and neck cooling Cooling session length: 90 min.
Cooling device settings: (i) maximum cooling; (ii) bypass mode in each participant.
IRTT, Genius 2, Tyco Healthcare Group, USA None Sublingual In condition (i), TTy decreased from 37.01 ± 0.34 °C to 36.70 ± 0.38 °C (60 min) and to 36.76 ± 0.33 °C (90 min).
In (ii), TTy decreased to a smaller extent, from 36.93 ± 0.30 °C to 36.85 ± 0.29 °C (60 min) and 36.85 ± 0.27 °C (90 min).
Sublingual T showed a slower response. In (i), it decreased from 36.80 ± 0.14 °C to 36.70 ± 0.10 °C (60 min) and to 36.70 ± 0.12 °C (90 min).
In (ii), it decreased from 36.74 ± 0.12 °C to 36.72 ± 0.11 °C (60 min) and 36.71 ± 0.08 °C (90 min).
Wadhwa et al. [43] N: 9
Age: 27 [18–40] y
Male: 100%
Whole body cooling by lactated Ringer’s solution (~4 °C) Lactate infusion via central venous catheter for 2 h to decrease TTy by ≈1.5 °C·h−1.
Condition tested: intravenous MgSO4 (bolus of 80 mg·kg−1 plus infusion of 2 g·h−1), or an equal volume of saline solution.
Thermocouple thermometer, Tyco-Mallinckrodt Anesthesiology Products, Inc, USA; ear canal occluded by cotton and gauze. None Skin surface TTy detected a significant reduction of the shivering threshold (0.3 ± 0.4 °C, p = 0.040) by MgSO4 infusion.
TTy was 36.6 ± 0.2 °C after 30 min of MgSO4 infusion vs. 36.8 ± 0.3 °C after 30 min of saline solution infusion.
Skin T was 33.2 ± 0.7 °C after 30 min of MgSO4 infusion vs. 33.6 ±1.3 °C after 30 min of saline solution infusion.
  1. Data are numbers (N), percentages (%), mean ± standard deviation, or [range], as available. HR, heart rate; IRTT, infrared tympanic thermometer; MgSO4, magnesium sulfate; NR, not reported; TTy, tympanic temperature; T, temperature; TM, temperature measurement: TT, target temperature; vs., versus; y, years