Nivfors Joar O, Mohyuddin Rizwan, Schanche Torstein, Nilsen Jan Harald, Valkov Sergei, Kondratiev Timofei V, Sieck Gary C, Tveita Torkjel
Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, Tromsø, Norway.
Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States.
Front Physiol. 2021 Sep 29;12:741241. doi: 10.3389/fphys.2021.741241. eCollection 2021.
Previously, we showed that the cardiopulmonary resuscitation (CPR) for hypothermic cardiac arrest (HCA) maintained cardiac output (CO) and mean arterial pressure (MAP) to the same reduced level during normothermia (38°C) vs. hypothermia (27°C). In addition, at 27°C, the CPR for 3-h provided global O delivery (DO) to support aerobic metabolism. The present study investigated if rewarming with closed thoracic lavage induces a perfusing rhythm after 3-h continuous CPR at 27°C. Eight male pigs were anesthetized, and immersion-cooled. At 27°C, HCA was electrically induced, CPR was started and continued for a 3-h period. Thereafter, the animals were rewarmed by combining closed thoracic lavage and continued CPR. Organ blood flow was measured using microspheres. After cooling with spontaneous circulation to 27°C, MAP and CO were initially reduced by 37 and 58% from baseline, respectively. By 15 min after the onset of CPR, MAP, and CO were further reduced by 58 and 77% from baseline, respectively, which remained unchanged throughout the rest of the 3-h period of CPR. During CPR at 27°C, DO and O extraction rate (VO) fell to critically low levels, but the simultaneous small increase in lactate and a modest reduction in pH, indicated the presence of maintained aerobic metabolism. During rewarming with closed thoracic lavage, all animals displayed ventricular fibrillation, but only one animal could be electro-converted to restore a short-lived perfusing rhythm. Rewarming ended in circulatory collapse in all the animals at 38°C. The CPR for 3-h at 27°C managed to sustain lower levels of CO and MAP sufficient to support global DO. Rewarming accidental hypothermia patients following prolonged CPR for HCA with closed thoracic lavage is not an alternative to rewarming by extra-corporeal life support as these patients are often in need of massive cardio-pulmonary support during as well as after rewarming.
此前，我们发现，对于低温心脏骤停（HCA）实施的心肺复苏（CPR），在正常体温（38°C）与低温（27°C）期间，能将心输出量（CO）和平均动脉压（MAP）维持在相同的降低水平。此外，在27°C时，持续3小时的CPR可提供整体氧输送（DO）以支持有氧代谢。本研究调查了在27°C下持续3小时CPR后，采用闭式胸腔灌洗复温是否能诱导灌注节律。八只雄性猪麻醉后进行浸浴冷却。在27°C时，电诱导HCA，开始并持续进行3小时的CPR。此后，通过联合闭式胸腔灌洗和持续CPR使动物复温。使用微球测量器官血流量。在自主循环冷却至27°C后，MAP和CO最初分别比基线降低37%和58%。CPR开始后15分钟，MAP和CO分别比基线进一步降低58%和77%，在CPR剩余的3小时期间保持不变。在27°C进行CPR期间，DO和氧摄取率（VO）降至极低水平，但同时乳酸小幅增加和pH值适度降低，表明存在维持的有氧代谢。在闭式胸腔灌洗复温期间，所有动物均出现心室颤动，但只有一只动物能通过电转复恢复短暂的灌注节律。在38°C时所有动物均因循环衰竭而复温结束。在27°C进行3小时的CPR能够维持较低水平的CO和MAP，足以支持整体DO。对于HCA长时间CPR后的意外低温患者，采用闭式胸腔灌洗复温并非体外生命支持复温的替代方法，因为这些患者在复温期间及复温后通常需要大量心肺支持。
