Induction and maintenance of therapeutic hypothermia after pediatric cardiac arrest: efficacy of a surface cooling protocol

Abstract

Objective: To assess the feasibility, effectiveness, side effects, and adverse events associated with a standardized surface cooling protocol. Induced therapeutic hypothermia after pediatric cardiac arrest is an important intervention.

Design: Prospective intervention trial.

Setting: Urban, tertiary care children's hospital.

Patients: Twelve pediatric cardiac arrest survivors.

Interventions: Standardized surface cooling protocol.

Measurements and main results: Patients (age: median, 1.5 yrs; interquartile range, 0.5-6.25; cardiopulmonary resuscitation duration: median, 18 mins; interquartile range, 10-45) were cooled by a standard surface cooling protocol for rapid induction and maintenance of goal rectal temperature (T) 32°C-34°C for 24 hrs, with prospectively defined rescue protocols. Side effects and clinical interventions were recorded. Median time to rectal T ≤34°C was 1.5 (1, 1.5) hrs from cooling initiation and 6 (5, 6.5) hrs from arrest. T was documented every 30 mins. Maintenance target T 32°C-34°C was attained in 78% (414 of 531) of measurements, overshoot hypothermia <32°C in 15% (81 of 531), and overshoot hyperthermia >34°C in 7% (36 of 531). Mean bias between rectal vs. esophageal T was -0.42°C (95% confidence interval, -0.49 to -0.35), and between rectal and bladder T was 0.16°C (95% confidence interval, 0.11-0.22). Side effects observed included: hypokalemia <3.0 mEq/L in 67% of patients and bradycardia <2% for age in 58%. There were no episodes of bleeding or ventricular tachyarrhythmia that required treatment. Six (50%) of 12 patients survived to discharge.

Conclusions: A standard surface cooling protocol achieved rapid induction of hypothermia after pediatric cardiac arrest. During maintenance of hypothermia, 78% of measures were within target T 32°C-34°C. Commonly employed temperature sites (esophageal, rectal, and bladder) were similar. Overshoot hypothermia and associated side effects were common, but there were no serious adverse events attributable to induced therapeutic hypothermia in this case series. Surface cooling protocols to induce and maintain therapeutic hypothermia after pediatric cardiac arrest are potentially feasible.

Figure 1

Induction and Maintenance Cooling Protocol from T= 0 to T=24 C: Celsius, kg: kilograms

Figure 2

Standardized rewarming protocol from T= 24 up to T= 48. C: Celsius, kg: kilograms

Figure 3

Mean (+/− standard deviation) rectal temperature during therapeutic hypothermia induction, maintenance and rewarming for all study patients. Dark line denotes mean temperatures over time. Lines at 32 and 34 degrees denote goal temperature range during maintenance of hypothermia.

Figure 4

Rectal, bladder, skin and esophageal temperatures (°C) measured at each time point are graphed over the 48 hours of induction, maintenance and rewarmin