Association Between Postresuscitation Partial Pressure of Arterial Carbon Dioxide and Neurological Outcome in Patients With Post–Cardiac Arrest Syndrome

Abstract

Background-Partial pressure of arterial CO 2 (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. 17 However, there is a paucity of clinical data on the subject of hypocapnia and hypercapnia during the post-ROSC period in adult patients. Specifically, it is unclear if exposure to hypocapnia and hypercapnia during the initial post-ROSC period is common and associated with neurological outcome.The objectives of this study were to determine the prevalence of hypocapnia and hypercapnia during the initial post-ROSC period and its association with neurological outcome among adult patients resuscitated from cardiac arrest. We hypothesized that hypocapnia and hypercapnia are common during the initial post-ROSC period and are both independently associated with poor neurological outcome. Methods SettingWe analyzed a prospectively compiled and maintained cardiac arrest registry at a single academic medical center, Cooper University Hospital in Camden, NJ. 18 We have prospectively collected data on all patients after cardiac arrest at our institution since 2009. We collect data pertaining to the index cardiac arrest event and outcomes consistent with the Utstein styl...

Letter by Eastwood et al Regarding Article, “Association Between Postresuscitation Partial Pressure of Arterial Carbon Dioxide and Neurological Outcome in Patients With Post–Cardiac Arrest Syndrome”

“…1 In our institution, the median number of arterial blood gas tests per patient is 9 (interquartile range, 7-10) during the first intensive care unit day, and our proportion of in-hospital cardiac arrest is only 35%, suggesting a much greater level of physiological monitoring and management of a very different population in Australian and New Zealand intensive care units. Moreover, mortality in the US cohort was 68% compared with 55.6% in Australia and New Zealand, and unfavorable neurological outcome was seen in 74% of survivors compared with only 35.3% of patients failing to be discharged home in Australia and New Zealand.…”

“…We read the article by Roberts and colleagues 1 with interest. Although we agree that hypocapnia has been demonstrated to be common and is a predictor of poor neurological outcome after cardiac arrest, we are concerned that the findings may lack external validity.…”

Can venous blood gas values be used instead of arterial blood gas values in respiratory alkalosis?

“…as an independent marker for poor neurologic function [17,18]. An independent relationship between duration of hypocapnia and poor functional results and symptomatic vasospasm was found in aneurismatic subarachnoid hemorrhage [19].…”

Response to Letter Regarding Article, “Association Between Postresuscitation Partial Pressure of Arterial Carbon Dioxide and Neurological Outcome in Patients With Post–Cardiac Arrest Syndrome”

“…1 In their letter, they raise concern that our results may reflect local practice and therefore should be interpreted with some caution. Our study was a single-center prospective study.…”