Intra–Cardiopulmonary Resuscitation Hypothermia With and Without Volume Loading in an Ischemic Model of Cardiac Arrest

Abstract

Background-We investigated the effects of intra-cardiopulmonary resuscitation (CPR) hypothermia with and without volume loading on return to spontaneous circulation and infarction size in an ischemic model of cardiac arrest. Methods and Results-Using a distal left anterior descending artery occlusion model of cardiac arrest followed by resuscitation with a total of 120 minutes of occlusion and 90 minutes of reperfusion, we randomized 46 pigs into 5 groups and used myocardial staining to define area at risk and myocardial necrosis. Group A had no intervention. Immediately after return of spontaneous circulation, group B received surface cooling with cooling blankets and ice. Group C received intra-CPR 680Ϯ23 mL of 28°C 0.9% normal saline via a central venous catheter. Group D received intra-CPR 673Ϯ26 mL of 4°C normal saline followed by surface cooling after return of spontaneous circulation. Group E received intra-CPR and hypothermia after return of spontaneous circulation with an endovascular therapeutic hypothermia system placed in the right atrium and set at a target of 32°C. Intra-CPR volume loading with room temperature (group C) or iced saline (group D) significantly (PϽ0.05) decreased coronary perfusion pressure (group C, 12.8Ϯ4.78 mm Hg; group D, 14.6Ϯ9.9 mm Hg) compared with groups A, B, and E (20.6Ϯ8.2, 20.1Ϯ7.8, and 21.3Ϯ12.4 mm Hg). Return of spontaneous circulation was significantly improved in group E (9 of 9) compared with groups A plus B and C (10 of 18 and 1 of 8). The percent infarction to the area at risk was significantly reduced with intra-CPR hypothermia in groups D (24.3Ϯ4.2%) and E (4Ϯ3.4%) compared with groups A (72Ϯ5.1%) and B (67.3Ϯ4.2%). Conclusions-Intra-CPR hypothermia significantly reduces myocardial infarction size.

Intra-Arrest Transnasal Evaporative Cooling

“…16,26 In the present study, there were fewer deaths due to cardiogenic shock in the treatment group. This is consistent with previous animal studies in which ejection fraction recovered faster and more fully in nasally cooled animals.…”

“…Hypothermia during CPR has been shown to be beneficial for myocardial function in animal models, limiting myocardial infarct size and improving left ventricular function and resuscitation rate, 16 especially with volume-sparing hypothermia. 16,26 In the present study, there were fewer deaths due to cardiogenic shock in the treatment group.…”

Pulseless Electric Activity

“…There are generally many hours of delay in achieving therapeutic hypothermia after successful resuscitation, and earlier induction of hypothermia may enhance its therapeutic benefits. The effects of intra-CPR hypothermia with and without volume loading on ROSC and infarction size were investigated in a coronary occlusion model of cardiac arrest 79 (see Appendix IV for details). The results suggest that intra-CPR hypothermia significantly reduces myocardial infarction size.…”

Rapid Induction of Therapeutic Hypothermia Using Transnasal High Flow Dry Air

“…Data from recent randomized trials have raised questions on the depth of hypothermia needed for clinical benefit and on the use of large volume of cold saline for rapid induction of hypothermia (Yannopoulos et al, 2009). Despite several unanswered questions, the need for TH remains; however, there is no easy way to accomplish this in an out-of-hospital setting.…”