Endothelin-1 elevates regional cerebral perfusion during prolonged ventricular fibrillation cardiac arrest in pigs

The Effect of Prophylactic Anticoagulation with Heparin on the Brain Cells of Sprague-Dawley Rats in a Cardiopulmonary-Cerebral Resuscitation Model

After a cardiac arrest (CA) of 5 to 10 min, a marked activation of blood coagulation occurs and microthrombi are found in the cerebral vessels. These microcirculatory disturbances directly affect the outcome on cardiopulmonary resuscitation (CPR). The purpose of this study was to investigate the effects and potential mechanisms of prophylactic anticoagulation on rat brain cells after cerebral CPR. After setting up an asphyxial CA model, we monitored the basic parameters such as the vitals and survival rate of the rats and assessed the respective neurological deficit (ND) and histological damage (HD) scores of their brain tissues. We, furthermore, investigated the influence of heparin on the expressions of TNF-α, IL-1β, CD40, NF-κB, and HIF-1α after asphyxial CA. The results showed that anticoagulation with heparin could obviously improve the outcome and prognosis of brain ischemia, including improvement of neurological function recovery and prevention of morphological and immunohistochemical injury on the brain, while significantly increasing the success rate of CPR. Treatment with heparin significantly inhibited the upregulation of CD40, NF-κB, and HIF-1α induced by asphyxial CA. Thrombolysis treatment may improve the outcome and prognosis of CPR, and future clinical studies need to evaluate the efficacy of early heparin therapy after CA.

Changes in cerebral blood flow and oxygen extraction during post-resuscitation syndrome

INTRODUCTION

Most survivors of out-of-hospital cardiac arrest (OHCA) will die subsequently from post-anoxic encephalopathy. In animals, the severity of brain damage is mainly influenced by the duration of cardiac arrest and also by the cerebral blood flow (CBF) and oxygen extraction (CEO2) abnormalities observed during the post-resuscitation period. The aim of our study was to describe CBF and CEO2 modifications during the first 72 h in OHCA patients treated by induced mild hypothermia.

METHODS

Consecutive OHCA patients were studied every 12 h over 72 h. Diastolic flow velocities (dFV), mean flow velocities (mFV) and pulsatility index (PI) were assessed by transcranial doppler (TCD) as an estimate of CBF changes. Simultaneous measurements of CEO2 were obtained using retrograde jugular catheterisation.

RESULTS

Eighteen patients (61 [47-74] years) were studied (12 non-survivors and 6 survivors). At admission, mFV values were low (27.3 [21.5-33.6]cm/s) but reached normal values after 72 h (50.5 [36.7-58.1]cm/s). Initial PI values were high (1.6 [1.3-1.9]) but reached normal values after 72 h (1.04 [0.82-1.2]). No differences were found between survivors and non-survivors regarding these CBF estimates. CEO2 values were quite normal at admission (20.4 [11-27%]) but decreased over time in non-survivors until H72 (25.8% [19.3-31.1] versus 5.7% [5.1-11.5], p=0.02).

CONCLUSION

Cerebral haemodynamic and oxygenation values are altered considerably but evolve during the first 72 h following resuscitation after cardiac arrest. In particular, these changes may lead to a mismatch between CBF and CEO2 leading to a "luxurous perfusion" in non-survivors.

Brain function after resuscitation from cardiac arrest

PURPOSE OF REVIEW

In industrial countries the incidence of cardiac arrest is still increasing. Almost 80% of cardiac arrest survivors remains in coma for varying lengths of time and full cerebral recovery is still a rare event. After successful cardiopulmonary resuscitation, cerebral recirculation disturbances and complex metabolic postreflow derangements lead to death of vulnerable neurons with further deterioration of cerebral outcome. This article discusses recent research efforts on the pathophysiology of brain injury caused by cardiac arrest and reviews the beneficial effect of therapeutic hypothermia on neurologic outcome along with the recent approach to prognosticate long-term outcome by electrophysiologic techniques and molecular markers of brain injury.

RECENT FINDINGS

Recent experimental studies have brought new insights to the pathophysiology of secondary postischemic anoxic encephalopathy demonstrating a time-dependent cerebral oxidative injury, increased neuronal expression, and activation of apoptosis-inducing death receptors and altered gene expression with long-term changes in the molecular phenotype of neurons. Recently, nuclear MR imaging and MR spectroscopic studies assessing cerebral circulatory recovery demonstrated the precise time course of cerebral reperfusion after cardiac arrest. Therapeutic hypothermia has been shown to improve brain function after resuscitation from cardiac arrest and has been introduced recently as beneficial therapy in ventricular fibrillation cardiac arrest.

SUMMARY

Electrophysiologic techniques and molecular markers of brain injury allow the accurate assessment and prognostication of long-term outcome in cardiac arrest survivors. In particular, somatosensory evoked potentials have been identified as the method with the highest prognostic reliability. A recent systematic review of 18 studies analyzed the predictive ability of somatosensory evoked potentials performed early after onset of coma and found that absence of cortical somatosensory evoked potentials identify patients not returning from anoxic coma with a specificity of 100%.