Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN 55905, United States.
Resuscitation. 2010 Dec;81(12):1632-6. doi: 10.1016/j.resuscitation.2010.08.007. Epub 2010 Sep 15.
Mild to moderate therapeutic hypothermia (TH) has been shown to improve survival and neurological outcome in patients resuscitated from out-of-hospital cardiac arrest (OHCA) with ventricular fibrillation (VF) as the presenting rhythm. This approach entails the management of physiological variables which fall outside the realm of conventional critical cardiac care. Management of serum potassium fluxes remains pivotal in the avoidance of lethal ventricular arrhythmia.
We retrospectively analyzed potassium variability with TH and performed correlative analysis of QT intervals and the incidence of ventricular arrhythmia.
We enrolled 94 sequential patients with OHCA, and serum potassium was followed intensively. The average initial potassium value was 3.9±0.7 mmol l(-1) and decreased to a nadir of 3.2±0.7 mmol l(-1) at 10 h after initiation of cooling (p<0.001). Eleven patients developed sustained polymorphic ventricular tachycardia (PVT) with eight of these occurring during the cooling phase. The corrected QT interval prolonged in relation to the development of hypothermia (p<0.001). Hypokalemia was significantly associated with the development of PVT (p=0.002), with this arrhythmia being most likely to develop in patients with serum potassium values of less than 2.5 mmol l(-1) (p=0.002). Rebound hyperkalemia did not reach concerning levels (maximum 4.26±0.8 mmol l(-1) at 40 h) and was not associated with the occurrence of ventricular arrhythmia. Furthermore, repletion of serum potassium did not correlate with the development of ventricular arrhythmia.
Therapeutic hypothermia is associated with a significant decline in serum potassium during cooling. Hypothermic core temperatures do not appear to protect against ventricular arrhythmia in the context of severe hypokalemia and cautious supplementation to maintain potassium at 3.0 mmol l(-1) appears to be both safe and effective.
轻度至中度治疗性低温（TH）已被证明可改善伴有室颤（VF）作为初始节律的院外心脏骤停（OHCA）患者的存活率和神经功能结局。这种方法需要管理超出传统心脏重症监护范围的生理变量。管理血清钾通量仍然是避免致命性室性心律失常的关键。
我们回顾性分析了 TH 时钾的变异性，并对 QT 间期和室性心律失常的发生率进行了相关分析。
我们纳入了 94 例连续的 OHCA 患者，并对血清钾进行了密集监测。平均初始钾值为 3.9±0.7mmol/L，在冷却开始后 10 小时降至 3.2±0.7mmol/L（p<0.001）。11 例患者发生持续性多形性室性心动过速（PVT），其中 8 例发生在冷却阶段。校正 QT 间期随低温的发展而延长（p<0.001）。低血钾与 PVT 的发生显著相关（p=0.002），血清钾值<2.5mmol/L 的患者发生这种心律失常的可能性最大（p=0.002）。复发性高钾血症未达到令人担忧的水平（最大 4.26±0.8mmol/L，发生在 40 小时），与室性心律失常的发生无关。此外，血清钾的补充与室性心律失常的发生无关。
在冷却过程中，治疗性低温会导致血清钾显著下降。在严重低钾血症的情况下，低温核心体温似乎并不能预防室性心律失常，谨慎补充以维持血钾在 3.0mmol/L 似乎既安全又有效。
