Rewarming With Closed Thoracic Lavage Following 3-h CPR at 27°C Failed to Reestablish a Perfusing Rhythm

Joar O Nivfors; Rizwan Mohyuddin; Torstein Schanche; Jan Harald Nilsen; Sergei Valkov; Timofei V Kondratiev; Gary C Sieck; Torkjel Tveita

doi:10.3389/fphys.2021.741241

Rewarming With Closed Thoracic Lavage Following 3-h CPR at 27°C Failed to Reestablish a Perfusing Rhythm

Front Physiol. 2021 Sep 29:12:741241. doi: 10.3389/fphys.2021.741241. eCollection 2021.

Authors

Joar O Nivfors¹, Rizwan Mohyuddin¹, Torstein Schanche^{1

2}, Jan Harald Nilsen^{1

3

4}, Sergei Valkov¹, Timofei V Kondratiev¹, Gary C Sieck², Torkjel Tveita^{1

2

3}

Affiliations

¹ Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, Tromsø, Norway.
² Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States.
³ Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway.
⁴ Department of Research and Education, Norwegian Air Ambulance Foundation, Drøbak, Norway.

Abstract

Introduction: 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 O₂ delivery (DO₂) 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. Materials and Methods: 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. Results: 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, DO₂ and O₂ extraction rate (VO₂) 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. Conclusion: The CPR for 3-h at 27°C managed to sustain lower levels of CO and MAP sufficient to support global DO₂. 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.

Keywords: accidental hypothermia; cardiopulmonary resuscitation; hypothermic cardiac arrest; organ blood flow; reperfusion.