Effect of mild hypothermia on renal ischemia/reperfusion injury after cardiopulmonary resuscitation in a swine model

MILD THERAPEUTIC HYPOTHERMIA REDUCES ISCHEMIA-REPERFUSION INJURY AFTER ZONE 1 REBOA IN A SWINE HEMORRHAGIC SHOCK MODEL

ABSTRACT

Background: Resuscitative balloon occlusion of the aorta (REBOA) is an endovascular hemostasis method used for the management of traumatic abdominal and pelvic hemorrhages. However, REBOA-associated ischemia-reperfusion injury complication limits its blocking time. We hypothesized that mild therapeutic hypothermia would relieve ischemia-reperfusion injury caused by prolonged zone 1 REBOA. Methods: Ten pigs were anesthetized, intubated, and subsequently struck with the experimental sliding-chamber ballistic gun to inflict liver damage. Animals were randomized to hypothermia (60 min of zone 1 REBOA with external cooling for 180 min, n = 5) or control (60 min of zone 1 REBOA with no external cooling, n = 5). Physiological and laboratory parameters were monitored and assessed. Distal organs were obtained for histologic analysis. Results: At 180 min, compared with the control, the hypothermia animals exhibited significantly increased pH and significantly reduced lactate, hemoglobin, and hematocrit (all P < 0.05). The change of lactate from 0 to 180 min in hypothermia animals was less than that in the control ( P = 0.02). The total bleeding in the control group was significantly less than the hypothermia ( P < 0.01). In the hypothermia group, prothrombin time at 120 and 180 min was significantly longer than that at baseline (all P < 0.05). Compared with the control, animals in the hypothermia group showed slighter pathological injury of the distal organs and significantly lower overall injury score (all P < 0.05). Conclusions: Mild therapeutic hypothermia during prolonged zone 1 REBOA offered extraordinary distal organ preservation and decreased metabolic acidosis.

Preconditioning against renal ischaemia reperfusion injury: the failure to translate to the clinic

Acute kidney injury (AKI) as a result of ischaemia-reperfusion represents a major healthcare burden worldwide. Mortality rates from AKI in hospitalized patients are extremely high and have changed little despite decades of research and medical advances. In 1986, Murry et al. demonstrated for the first time the phenomenon of ischaemic preconditioning to protect against ischaemia-reperfusion injury (IRI). This seminal finding paved the way for a broad body of research, which attempted to understand and ultimately harness this phenomenon for human application. The ability of preconditioning to limit renal IRI has now been demonstrated in multiple different animal models. However, more than 30 years later, a safe and consistent method of protecting human organs, including the kidneys, against IRI is still not available. This review highlights agents which, despite strong preclinical data, have recently failed to reduce AKI in human trials. The multiple reasons which may have contributed to the failure to translate some of the promising findings to clinical therapies are discussed. Agents which hold promise in the clinic because of their recent efficacy in preclinical large animal models are also reviewed.