Abstract
BackgroundMild therapeutic hypothermia (HT) has been implemented in the management of post cardiac arrest (CA) syndrome after the publication of clinical trials comparing HT with common practice (ie, usually hyperthermia). Current evidence on the comparison between therapeutic HT and controlled normothermia (NT) in CA survivors, however, remains insufficient.MethodsEight female swine (sus scrofa domestica; body weight 45 kg) were randomly assigned to receive either mild therapeutic HT or controlled NT, with four animals per group. Veno-arterial extracorporeal membrane oxygenation (ECMO) was established and at minimal ECMO flow (0.5 L/min) ventricular fibrillation was induced by rapid ventricular pacing. After 20 min of CA, circulation was restored by increasing the ECMO flow to 4.5 L/min; 90 min of reperfusion followed. Target core temperatures (HT: 33°C; NT: 36.8°C) were maintained using the heat exchanger on the oxygenator. Invasive blood pressure was measured in the aortic arch, and cerebral oxygenation was assessed using near-infrared spectroscopy. After 60 min of reperfusion, up to three defibrillation attempts were performed. After 90 min of reperfusion, blood samples were drawn for the measurement of troponin I (TnI), myoglobin (MGB), creatine-phosphokinase (CPK), alanin-aminotransferase (ALT), neuron-specific enolase (NSE) and cystatin C (CysC) levels. Reactive oxygen metabolite (ROM) levels and biological antioxidant potential (BAP) were also measured.ResultsSignificantly higher blood pressure and cerebral oxygenation values were observed in the HT group (P<0.05). Sinus rhythm was restored in all of the HT animals and in one from the NT group. The levels of TnI, MGB, CPK, ALT, and ROM were significantly lower in the HT group (P<0.05); levels of NSE, CysC, and BAP were comparable in both groups.ConclusionsOur results from animal model of cardiac arrest indicate that HT may be superior to NT for the maintenance of blood pressure, cerebral oxygenation, organ protection and oxidative stress suppression following CA.
Highlights
Mild therapeutic hypothermia (HT) has been implemented in the management of post cardiac arrest (CA) syndrome after the publication of clinical trials comparing HT with common practice
Mild therapeutic hypothermia (HT) was introduced into the clinical management of cardiac arrest survivors after the publication of the results of two clinical trials showing a benefit compared with standard treatment [1,2], and has been included in the guidelines for post-cardiac arrest care from the American Heart Association [3] and the European Resuscitation Council [4]
At 70, 80, and 90 min, the mean arterial blood pressures and brain oxygen saturations were significantly higher in the HT group, despite the fact that the norepinephrine doses administered to this group were significantly lower compared with the NT group (P
Summary
Mild therapeutic hypothermia (HT) has been implemented in the management of post cardiac arrest (CA) syndrome after the publication of clinical trials comparing HT with common practice (ie, usually hyperthermia). Mild therapeutic hypothermia (HT) was introduced into the clinical management of cardiac arrest survivors after the publication of the results of two clinical trials showing a benefit compared with standard treatment [1,2], and has been included in the guidelines for post-cardiac arrest care from the American Heart Association [3] and the European Resuscitation Council [4]. In analyses of the available randomized data, they showed that the evidence for the benefits of HT in cardiac arrest survivors remains inconclusive [7,8] Their criticisms were based on the small size of published trials, low-quality data and non-negligible risks of systematic and random errors [7,8]. The relative lack of evidence regarding the benefits of mild therapeutic HT in cardiac arrest survivors has led to the establishment of a large multicenter randomized controlled trial comparing mild therapeutic HT with controlled normothermia (NT) in CA survivors (the Target Temperature Management trial), which is currently underway [12]
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