Ischemic postconditioning at the initiation of cardiopulmonary resuscitation facilitates functional cardiac and cerebral recovery after prolonged untreated ventricular fibrillation

Objectives: Ischemic postconditioning (PC) with " stuttering" reintroduction of blood flow after prolonged ischemia has been shown to offer protection from ischemia reperfusion injury to the myocardium and brain. We hypothesized that four 20-s pauses during the first 3. min of standard CPR would improve post resuscitation cardiac and neurological function, in a porcine model of prolonged untreated cardiac arrest. Methods: 18 female farm pigs, intubated and isoflurane anesthetized had 15. min of untreated ventricular fibrillation followed by standard CPR (SCPR). Nine animals were randomized to receive PC with four, controlled, 20-s pauses, during the first 3. min of CPR (SCPR. +. PC). Resuscitated animals had echocardiographic evaluation of their ejection fraction after 1 and 4. h and a blinded neurological assessment with a cerebral performance category (CPC) score assigned at 24 and 48. h. All animals received 12. h of post resuscitation mild therapeutic hypothermia. Results: SCPR. +. PC animals had significant improvement in left ventricular ejection fraction at 1 and 4. h compared to SCPR (59 ± 11% vs 35 ± 7% and 55 ± 8% vs 31 ± 13% respectively, p<0.01). Neurological function at 24. h significantly improved with SCPR. +. PC compared to SCPR alone (CPC: 2.7 ± 0.4 vs 3.8 ± 0.4 respectively, p=0.003). Neurological function significantly improved in the SCPR. +. PC group at 48. h and the mean CPC score of that group decreased from 2.7 ± 0.4 to 1.7 ± 0.4 (p<0.00001). Conclusions: Ischemic postconditioning with four 20-s pauses during the first 3. min of SCPR improved post resuscitation cardiac function and facilitated neurological recovery after 15. min of untreated cardiac arrest in pigs.