Association between postresuscitation partial pressure of arterial carbon dioxide and neurological outcome in patients with post-cardiac arrest syndrome.

BACKGROUND: Partial pressure of arterial CO2 (Paco(2)) is a regulator of cerebral blood flow after brain injury. Recent guidelines for the management of cardiac arrest recommend maintaining Paco(2) at 40 to 45 mm Hg after successful resuscitation; however, there is a paucity of data on the prevalence of Paco(2) derangements during the post-cardiac arrest period and its association with outcome. METHODS AND RESULTS: We analyzed a prospectively compiled and maintained cardiac arrest registry at a single academic medical center. Inclusion criteria are as follows: age ≥18, nontrauma arrest, and comatose after return of spontaneous circulation. We analyzed arterial blood gas data during 0 to 24 hours after the return of spontaneous circulation and determined whether patients had exposure to hypocapnia and hypercapnia (defined as Paco(2) ≤30 mm Hg and Paco(2) ≥50 mm Hg, respectively, based on previous literature). The primary outcome was poor neurological function at hospital discharge, defined as Cerebral Performance Category ≥3. We used multivariable logistic regression, with multiple sensitivity analyses, adjusted for factors known to predict poor outcome, to determine whether post-return of spontaneous circulation hypocapnia and hypercapnia were independent predictors of poor neurological function. Of 193 patients, 52 (27%) had hypocapnia only, 63 (33%) had hypercapnia only, 18 (9%) had both hypocapnia and hypercapnia exposure, and 60 (31%) had no exposure; 74% of patients had poor neurological outcome. Hypocapnia and hypercapnia were independently associated with poor neurological function, odds ratio 2.43 (95% confidence interval, 1.04-5.65) and 2.20 (95% confidence interval, 1.03-4.71), respectively. CONCLUSIONS: Hypocapnia and hypercapnia were common after cardiac arrest and were independently associated with poor neurological outcome. These data suggest that Paco(2) derangements could be potentially harmful for patients after resuscitation from cardiac arrest.

Multiple organ dysfunction after return of spontaneous circulation in postcardiac arrest syndrome.

OBJECTIVES: Recent guidelines for the treatment of postcardiac arrest syndrome recommend optimization of vital organ perfusion after return of spontaneous circulation to reduce the risk of postresuscitation multiple organ injury. However, the prevalence of extracerebral multiple organ dysfunction in postcardiac arrest patients and its association with in-hospital mortality remain unclear. DESIGN: Single-center, prospective observational study. SETTING: Urban academic medical center. PATIENTS: Postcardiac arrest patients. Inclusion criteria were as follows: age older than 17 years, nontrauma cardiac arrest, and comatose after return of spontaneous circulation. INTERVENTIONS: We prospectively captured all extracerebral components of the Sequential Organ Failure Assessment score over the first 72 hours after return of spontaneous circulation. The primary outcome measure was in-hospital mortality. We used multivariate logistic regression to determine if multiple organ dysfunction (defined as the highest extracerebral Sequential Organ Failure Assessment score) was an independent predictor of death, after adjustment for the presence of cerebral injury (defined as not following commands at any point over 0-72 hr). MEASUREMENTS AND MAIN RESULTS: We enrolled 203 postcardiac arrest patients; 96% had some degree of extracerebral organ dysfunction and 66% had severe dysfunction in two or more extracerebral organ systems. The most common extracerebral organ failures were cardiovascular (i.e., vasopressor dependence) and respiratory (i.e., oxygenation impairment). The highest extracerebral Sequential Organ Failure Assessment score over 72 hours had an independent association with in-hospital mortality (odds ratio 1.95 [95% CI, 1.15-3.29]). Of the individual organ systems, only the cardiovascular and respiratory Sequential Organ Failure Assessment scores had an independent association with in-hospital mortality. CONCLUSIONS: The results of this study support the hypothesis that extracerebral organ dysfunction is common and associated with mortality in postcardiac arrest syndrome. This association appears to be driven by postresuscitation hemodynamic dysfunction and oxygenation impairment. Further research is needed to determine the value of hemodynamic and oxygenation optimization as a part of treatment strategies for patients with postcardiac arrest syndrome.