The importance of surface area for the cooling efficacy of mild therapeutic hypothermia

作者：Weihs Wolfgang; Schratter Alexandra; Sterz Fritz^*; Janata Andreas; Hoegler Sandra; Holzer Michael; Losert Udo M; Herkner Harald; Behringer Wilhelm

来源：Resuscitation, 2011, 82(1): 74-78.

DOI：10.1016/j.resuscitation.2010.09.472

• Hypothermia
• Methodology
• Post-resuscitation period
• Safety
• Temperature

Aim of the study: Mild hypothermia after cardiac arrest should be induced as soon as possible. There is a need for improved feasibility and efficacy of surface cooling in ambulances. We investigated which and how much area of the body surface should be covered to guarantee a sufficient cooling rate.
Methods: Each of five adult, human-sized pigs (88-105 kg) was randomly cooled in three phases with pads that covered different areas of the body surface corresponding to humans (100% or 30% [thorax and abdomen] or 7% [neck]). The goal was to quickly lower brain temperature (Tbr) from 38 to 33 degrees C within a maximum of 120 min. Linear regression analysis was used to test the association between cooling efficacy and surface area. Data are presented as mean +/- standard deviation.
Results: The 100% and 30% cooling pads decreased the pigs' Tbr from 38 to 33 degrees C within 33 +/- 7 min (8.2 +/- 1.6 degrees C/h) and 92 +/- 24 min (3.6 +/- 1.1 degrees C/h). The 7% achieved a final Tbr of 35.8 +/- 0.7 degrees C after 120 min (1.1 +/- 0.4 degrees C/h). The 30% and 7% cooling surface areas achieved 37 +/- 11% and 15 7% of the cooling rate compared to the 100% cooling pads. For every additional percent of surface area cooled, the cooling rate increased linearly by 0.07 degrees C/h (95% CI 0.05-0.09, p = 0.001). No skin lesions were observed.
Conclusions: The cooling pads were effective and safe for rapid induction of mild hypothermia in adult, human-sized pigs, depending on the percentage of body surface area covered. Covering only the neck, chest, and abdomen might achieve satisfactory cooling rates.

• 出版日期2011-1