Abstract
BackgroundIn patients with aneurysmal subarachnoid hemorrhage (SAH), an association between hypocapnia and poor clinical outcomes has been reported. However, the optimal arterial carbon dioxide tension (PaCO2) remains unknown. The present retrospective study aimed to examine the association of abnormal PaCO2 levels with neurological outcomes and investigate the optimal target PaCO2 level in patients with SAH.MethodsWe retrospectively selected consecutive adult patients hospitalized in the intensive care unit (ICU) for SAH between January 2009 and April 2017. Univariate and multivariate analyses were performed to identify the independent predictors of unfavorable neurological outcomes (i.e., modified Rankin scale score of 3–6 on hospital discharge).ResultsAmong 158 patients with SAH, 73 had unfavorable neurological outcomes. During the first 2 weeks in the ICU, the median number of PaCO2 measurements per patient was 43. The factors significantly associated with unfavorable neurological outcomes were age, Hunt and Kosnik grade, maximum lactate levels during the first 24 h, and maximum (odds ratio [OR], 1.12; 95% confidence interval [CI], 1.03–1.21; p < 0.01) and minimum PaCO2 levels (OR, 0.81; 95% CI, 0.72–0.92; p < 0.01). Receiver operating characteristic curve analysis revealed that the cutoff range of PaCO2 was 30.2–48.3 mmHg. Unfavorable neurological outcomes were noted in 78.8% of patients with PaCO2 levels outside this range and in 22.8% of patients with PaCO2 levels within this range.ConclusionsBoth the maximum and minimum PaCO2 levels during ICU management in patients with SAH were significantly associated with unfavorable neurological outcomes. Further prospective studies are required to validate our findings and explore their clinical implications. Our findings may provide a scientific rationale for these future prospective studies.
Highlights
In patients with aneurysmal subarachnoid hemorrhage (SAH), an association between hypocapnia and poor clinical outcomes has been reported
The patient medical records were reviewed after receiving approval from the institutional review board, and the study was performed in accordance with the ethical standards established in the Control of Arterial carbon dioxide tension (PaCO2) levels in patients with SAH in the intensive care unit (ICU) arterial blood gas (ABG) analyses, including PaCO2, were routinely performed every 6 h during the first 2 weeks in the ICU, and additional measurements were obtained by critical care physicians as needed
Association between PaCO2 levels and unfavorable neurological outcomes We found that 78.8% of patients with a maximum PaCO2 of > 48.3 mmHg and a minimum PaCO2 of < 30.2 mmHg had unfavorable neurological outcomes, whereas only 22.8% of patients who did not have either of these PaCO2 levels had unfavorable neurological outcomes (Fig. 4)
Summary
In patients with aneurysmal subarachnoid hemorrhage (SAH), an association between hypocapnia and poor clinical outcomes has been reported. The present retrospective study aimed to examine the association of abnormal PaCO2 levels with neurological outcomes and investigate the optimal target PaCO2 level in patients with SAH. A previous systematic review demonstrated abnormal PaCO2 levels to be associated with poor clinical outcomes in patients with traumatic brain injury (TBI), post-cardiac arrest patients, and stroke patients [13]; PaCO2 control in the intensive care unit (ICU) can greatly influence the management of patients with SAH. The association between hypercapnia (defined as PaCO2 > 45 mmHg) and neurological outcomes in patients with SAH has not been examined
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