Nitrotyrosine and nitrate/nitrite levels in cardiac arrest survivors treated with endovascular hypothermia

Ischemic Postconditioning and Nitric Oxide Administration Failed to Confer Protective Effects in a Porcine Model of Extracorporeal Cardiopulmonary Resuscitation

The protective effects of ischemic postconditioning (IPC) and nitric oxide (NO) administration have been demonstrated in several ischemic scenarios. However, current evidence regarding the effect of IPC and NO in extracorporeal cardiopulmonary resuscitation remains lacking. Fifteen female swine (body weight 45 kg) underwent veno-arterial extracorporeal membrane oxygenation (ECMO) implantation; cardiac arrest-ventricular fibrillation was induced by rapid ventricular pacing. After 20 min of cardiac arrest, blood flow was restored by increasing the ECMO flow rate to 4.5 L/min. The animals (five per group) were then randomly assigned to receive IPC (three cycles of 3 min ischemia and reperfusion), NO (80 ppm via oxygenator), or mild hypothermia (HT; 33.0°C). Cerebral oximetry and aortic blood pressure were monitored continuously. After 90 min of reperfusion, blood samples were drawn for the measurement of troponin I, myoglobin, creatine-phosphokinase, alanine aminotransferase, neuron-specific enolase, cystatin C, and reactive oxygen metabolite (ROM) levels. Significantly higher blood pressure and cerebral oxygen saturation values were observed in the HT group compared with the IPC and NO groups (P < 0.05). The levels of troponin I, myoglobin, creatine phosphokinase, and alanine aminotransferase were significantly lower in the HT group (P < 0.05); levels of neuron-specific enolase, cystatin C, and ROM were not significantly different. IPC and NO were comparable in all monitored parameters. The results of the present study indicate that IPC and NO administration are not superior interventions to HT for the maintenance of blood pressure, cerebral oxygenation, organ protection, and suppression of oxidative stress following extracorporeal cardiopulmonary resuscitation.

Status of systemic oxidative stress during therapeutic hypothermia in patients with post-cardiac arrest syndrome

Therapeutic hypothermia (TH) is thought to be due to the downregulation of free radical production, although the details of this process remain unclear. Here, we investigate changes in oxidative stress and endogenous biological antioxidant potential during TH in patients with post-cardiac arrest syndrome (PCAS). Nineteen PCAS patients were enrolled in the study. Brain temperature was decreased to the target temperature of 33°C, and it was maintained for 24 h. Patients were rewarmed slowly (0.1°C/h, <1°C/day). The generation of reactive oxygen metabolites (ROMs) was evaluated in plasma samples by d-ROM test. Plasma antioxidant capacity was measured by the biological antioxidant potential (BAP) test. Levels of d-ROMs and BAP levels during the hypothermic stage (33°C) were suppressed significantly compared with pre-TH induction levels (P < 0.05), while both d-ROM and BAP levels increased with rewarming (33-36°C) and were correlated with brain temperature. Clinical monitoring of oxidative stress and antioxidant potential is useful for evaluating the redox state of patients undergoing TH after PCAS. Additional therapy to support the antioxidant potential in the rewarming stage following TH may reduce some of the observed side effects associated with the use of TH.

Mild therapeutic hypothermia is superior to controlled normothermia for the maintenance of blood pressure and cerebral oxygenation, prevention of organ damage and suppression of oxidative stress after cardiac arrest in a porcine model

BACKGROUND

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). Current evidence on the comparison between therapeutic HT and controlled normothermia (NT) in CA survivors, however, remains insufficient.

METHODS

Eight 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.

RESULTS

Significantly 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.

CONCLUSIONS

Our 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.

Blood levels of copeptin on admission predict outcomes in out-of-hospital cardiac arrest survivors treated with therapeutic hypothermia

Introduction

Prognostic stratification of cardiac arrest survivors is essential for the selection of the most appropriate therapeutic strategy. However, accurate early outcome predictions for this patient population remain challenging. At present, there is a lack of data examining the prognostic value of C-terminal provasopressin (copeptin) in cardiac arrest survivors.

Methods

A group of 40 out-of-hospital cardiac arrest survivors who were treated with endovascular hypothermia was analyzed. Copeptin levels were measured in blood samples taken at admission using a commercially available immunoassay. Neurological outcome was assessed at 30 days post admission according to the Cerebral Performance Category (CPC): CPC 1, no neurological deficit; CPC 2, mild to moderate dysfunction; CPC 3, severe dysfunction; CPC 4, coma; and CPC 5, death.

Results

Copeptin levels were significantly lower in patients with CPC 1 compared with CPC 2 or CPC 3 to CPC 5 (74.3 ± 14.4 pmol/l, 219.8 ± 33.9 pmol/l and 302.7 ± 52.1 pmol/l, respectively; P < 0.0001). Using an optimal cutoff value ≤ 217.9 pmol/l calculated from the receiver operating characteristic curve (area under curve = 0.801, 95% confidence interval = 0.644 to 0.910; P = 0.0001), the sensitivity of predicting survival with good neurological outcome was 78.6% and the specificity was 75.0%. Multiple logistic regression analysis revealed that a copeptin level > 217.9 pmol/l was an independent predictor of severe neurological dysfunction or death, with an adjusted odds ratio of 27.00 (95% confidence interval = 2.27 to 321.68; P = 0.009).

Conclusion

The present study found that copeptin levels have a significant prognostic value at the time of hospital admission, and are a promising diagnostic tool for predicting outcomes in out-of-hospital cardiac arrest survivors.