Survival from hospital discharge to one year after out-of-hospital cardiac arrest: a comparison of standard CPR versus active compression-decompression CPR plus an impedance threshold device [abstract]
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Background. Little is known about the impact of the method of cardiopulmonary resuscitation (CPR) on long-term survival following out-of-hospital cardiac arrest. A recent National Institutes of Health–funded multicenter prospective randomized clinical trial, the ResQTrial, compared standard CPR (S-CPR) versus active compression–decompression CPR plus the use of an impedance threshold device (ACD+ITD). ACD+ITD was associated with a relative 53% increase in survival to hospital discharge with favorable neurologic function for subjects with a cardiac arrest of presumed cardiac etiology, compared with SCPR. Using data from all patients randomized to one of these two methods of CPR from this trial, we tested the hypothesis that ACD+ITD would improve the likelihood of survival from the time of hospital discharge to one year after cardiac arrest. Methods. A total of 1,335 adult patients with nontraumatic out-of-hospital cardiac arrest were enrolled in the S-CPR group and 1,403 in the ACD+ITD group; 134 patients versus 165 patients, respectively, survived to hospital discharge. A Kaplan-Meier analysis was performed for all patients known to be discharged alive from the hospital. Data up to one year after the cardiac arrest were obtained from patient records, patient interviews, and public records. Results. Fewer patients in the S-CPR group survived to hospital discharge with modified Rankin score (MRS) ¡Â3 (5.7% vs. 7.9%, p = 0.03), but the demographic characteristics of survivors were similar between groups. Starting with 100% survival at hospital discharge, survival decreased in both groups over time, but more notably in the S-CPR group. Six months after cardiac arrest, survival rates were 77% in the S-CPR group and 88% in the ACD+ITD group. After 365 days, survival rates were 72% in the S-CPR group and 83% in the ACD+ITD group (log base rank p-value = 0.014). Conclusions. The survivors to hospital discharge in the ResQTrial who were treated with ACD+ITD CPR had an absolute 11% greater likelihood of surviving to 365 days after cardiac arrest compared with the patients treated with S-CPR. These data support the hypothesis that increased perfusion during CPR, obtained with the use of ACD+ITD CPR, results in a significantly higher likelihood of long-term survival, regardless of etiology of the nontraumatic cardiac arrest.