Intravascular versus surface cooling for targeted temperature management after out-of-hospital cardiac arrest - an analysis of the TTM trial data

Abstract

Background: Targeted temperature management is recommended after out-of-hospital cardiac arrest and may be achieved using a variety of cooling devices. This study was conducted to explore the performance and outcomes for intravascular versus surface devices for targeted temperature management after out-of-hospital cardiac arrest.

Method: A retrospective analysis of data from the Targeted Temperature Management trial. N = 934. A total of 240 patients (26%) managed with intravascular versus 694 (74%) with surface devices. Devices were assessed for speed and precision during the induction, maintenance and rewarming phases in addition to adverse events. All-cause mortality, as well as a composite of poor neurological function or death, as evaluated by the Cerebral Performance Category and modified Rankin scale were analysed.

Results: For patients managed at 33 °C there was no difference between intravascular and surface groups in the median time taken to achieve target temperature (210 [interquartile range (IQR) 180] minutes vs. 240 [IQR 180] minutes, p = 0.58), maximum rate of cooling (1.0 [0.7] vs. 1.0 [0.9] °C/hr, p = 0.44), the number of patients who reached target temperature (within 4 hours (65% vs. 60%, p = 0.30); or ever (100% vs. 97%, p = 0.47), or episodes of overcooling (8% vs. 34%, p = 0.15). In the maintenance phase, cumulative temperature deviation (median 3.2 [IQR 5.0] °C hr vs. 9.3 [IQR 8.0] °C hr, p = <0.001), number of patients ever out of range (57.0% vs. 91.5%, p = 0.006) and median time out of range (1 [IQR 4.0] hours vs. 8.0 [IQR 9.0] hours, p = <0.001) were all significantly greater in the surface group although there was no difference in the occurrence of pyrexia. Adverse events were not different between intravascular and surface groups. There was no statistically significant difference in mortality (intravascular 46.3% vs. surface 50.0%; p = 0.32), Cerebral Performance Category scale 3-5 (49.0% vs. 54.3%; p = 0.18) or modified Rankin scale 4-6 (49.0% vs. 53.0%; p = 0.48).

Conclusions: Intravascular and surface cooling was equally effective during induction of mild hypothermia. However, surface cooling was associated with less precision during the maintenance phase. There was no difference in adverse events, mortality or poor neurological outcomes between patients treated with intravascular and surface cooling devices.

Trial registration: TTM trial ClinicalTrials.gov number https://clinicaltrials.gov/ct2/show/NCT01020916 NCT01020916; 25 November 2009.

Keywords: Brain injuries; Critical care; Fever; Hypothermia; Induced; Out-of-hospital cardiac arrest; Shivering; Temperature.

Fig. 1

Patient temperature for the 33 °C group over the intervention periods. Mean and standard deviation temperature (°C). Blue line and shading is intravascular group, red line and shading is surface group. Time in hours

Fig. 2

Patient temperature for the 36 °C group over the intervention periods. Mean and standard deviation temperature (°C). Blue line and shading is intravascular group, red line and shading is surface group. Time in hours

Fig. 3

Performance of surface versus intravascular devices in induction phase. Effect estimates and 95% confidence intervals. SFC surface device, IV intravascular

Fig. 4

Performance of surface versus intravascular devices in maintenance phase. Effect estimates and 95% confidence intervals. SFC surface device, IV intravascular

Fig. 5

Adverse events for surface versus intravascular devices. Effect estimates and 95% confidence intervals. SFC surface device, IV intravascular