Mendrala, Konrad

Background: Renal replacement therapy (RRT) can be used to rewarm patients in deep hypothermia. However, there is still no clear evidence for the effectiveness of RRT in this group of patients. This systematic review aims to summarize the rewarming rates during RRT in patients in severe hypothermia, below or equal to 32 °C. Methods: This systematic review was registered in the PROSPERO International Prospective Register of Systematic Reviews (identifier CRD42021232821). We searched Embase, Medline, and Cochrane databases using the keywords hypothermia, renal replacement therapy, hemodialysis, hemofiltration, hemodiafiltration, and their abbreviations. The search included only articles in English with no time limit, up until 30 June 2021. Results: From the 795 revised articles, 18 studies including 21 patients, were selected for the final assessment and data extraction. The mean rate of rewarming calculated for all studies combined was 1.9 °C/h (95% CI 1.5–2.3) and did not differ between continuous (2.0 °C/h; 95% CI 0.9–3.0) and intermittent (1.9 °C/h; 95% CI 1.5–2.3) methods (p > 0.9). Conclusions: Based on the reviewed literature, it is currently not possible to provide high-quality recommendations for RRT use in specific groups of patients in accidental hypothermia. While RRT appears to be a viable rewarming strategy, the choice of rewarming method should always be determined by the specific clinical circumstances, the available resources, and the current resuscitation guidelines.

AbstractSevere accidental hypothermia carries high mortality and morbidity and is often treated with invasive extracorporeal methods. Continuous veno‐venous hemodiafiltration (CVVHDF) is widely available in intensive care units. We sought to provide theoretical basis for CVVHDF use in rewarming of hypothermic patients. CVVHDF system was used in the laboratory setting. Heat balance and transferred heat units were evaluated for the system without using blood. We used 5L of crystalloid solution at the temperature of approximately 25°C, placed in a thermally insulated tank (representing the “central compartment” of a hypothermic patient). Time of warming the central compartment from 24.9 to 30.0°C was assessed with different flow combinations: “blood” (central compartment fluid) 50 or 100 or 150 mL/min, dialysate solution 100 or 1500 mL/h, and substitution fluid 0 or 500 mL/h. The total circulation time was 1535 minutes. There were no differences between heat gain values on the filter depending on blood flow (P = .53) or dialysate flow (P = .2). The mean heating time for “blood” flow rates 50, 100, and 150 mL/min was 113.7 minutes (95% CI, 104.9‐122.6 minutes), 83.3 minutes (95% CI, 76.2‐90.3 minutes), and 74.7 minutes (95% CI, 62.6‐86.9 minutes), respectively (P < .01). The respective median rewarming rate for different “blood” flows was 3.6°C/h (IQR, 3.0‐4.2°C/h), 4.8 (IQR, 4.2‐5.4°C/h), and 5.4 (IQR, 4.8‐6.0°C/h), respectively (P < .01). The dialysate flow did not affect the warming rate. Based on our experimental model, CVVHDF may be used for extracorporeal rewarming, with the rewarming rates increasing achieved with higher blood flow rates.