Prognostic Value of Computed Tomography Score in Patients After Extracorporeal Cardiopulmonary Resuscitation

Jeong-Am Ryu; Young Hwan Lee; Chi Ryang Chung; Yang Hyun Cho; Kiick Sung; Kyeongman Jeon; Gee Young Suh; Taek Kyu Park; Joo Myung Lee; Minjung Kathy Chae; Jeong-Ho Hong; Sei Hee Lee; Hyoung Soo Kim; Jeong Hoon Yang

Disclosures

Crit Care. 2018;22(323) 

In This Article

Discussion

In the present study, we evaluated whether ASPECTS with some modifications could be used to predict neurological outcomes in patients after ECPR. Major findings of this study are as follows:

  1. Brain CT could be helpful for predicting neurological outcomes of post-cardiac arrest patients after ECPR.

  2. ASPECTS and its modifications were feasible and reliable for predicting neurological outcomes of post-cardiac arrest patients after ECPR.

  3. The predictive performance of mASPECTS for poor neurological outcome was better than that of ASPECTS or ASPECTS-b.

  4. In multivariable analysis, ischemic cardiac cause of arrest and mASPECTS were significant predictors of poor neurologic outcomes in ECPR patients.

Neuroimaging studies such as brain CT, brain magnetic resonance imaging, and magnetic resonance spectroscopy after conventional CPR have been performed.[1] Brain CT scans might be particularly helpful for predicting neurological outcomes after ECPR. However, brain magnetic resonance imaging is an expensive and time-consuming procedure. It cannot be performed immediately, because ECMO equipment is used for patients receiving ECPR.[22] In addition, sedative medications and neuromuscular blockade are commonly used in comatose CPR survivors. They might confound outcome prediction after cardiac arrest.[23] Some clinical signs and examinations such as motor response to noxious stimuli, corneal reflex, caloric testing, and EEG might also be confounded by sedation.[1,23] Therefore, brain CT might be more helpful for predicting neurological outcome in ECPR patients under sedation. However, data on prognostic markers of brain CT for neurological outcomes after ECPR are limited.[17,24]

Some changes visualized by brain CT have been associated with hypoxic-ischemic cerebral insult. They are useful for predicting poor neurological outcome after cardiac arrest.[5–7,25] Especially, loss of the boundary between gray matter and white matter and cortical sulcal effacement on brain CT are associated with hypoxic-ischemic brain damage and poor outcome after cardiac arrest.[5–7,25] These changes are also useful for predicting poor neurological outcomes after ECPR.[7] However, identification of these signs might depend on the abilities of each investigator. In addition, these changes are not quantifiable. Therefore, an objective and quantifiable tool is needed to identify hypoxic-ischemic lesions. ASPECTS is a widely used screening tool to quantify the extent of ischemic hypodensity or hypoattenuation in ischemic stroke. ASPECTS and its modifications might be able to explain the quantitative association between cerebral insult following hypoxic-ischemic injury after cardiac arrest and neurological outcome.[9,10] In conventional CPR, ASPECT with some modifications could be used to estimate early neurologic outcomes in post-cardiac arrest patients.[6,9,10]

Selective vulnerability has been reported for hypoxic-ischemic injury in previous studies. The middle lamina of the cortex, caudate nucleus, putamen, globus pallidus, thalami, and Purkinje cells might be at particular risk owing to highly metabolically active tissue.[26,27] Eventually, cortex, basal ganglia, and the cerebellum are areas vulnerable to hypoxic-ischemic injury after cardiac arrest. In the present study, the performance of mASPECTS for predicting poor neurological outcome was better than ASPECTS-b. Although ASPECTS-b can estimate hypoxic-ischemic lesions in bilateral MCA regions (MCA territorial cortex, subcortex, and basal ganglia), mASPECTS can estimate lesions in bilateral regions of ACA, PCA, and the cerebellum as well as MCA regions of ASPECTS-b. Therefore, mASPECTS can better detect cortical lesions by hypoxic-ischemic insult than ASPECTS-b. In addition, cortical lesions seem to be more relevant to neurological outcomes after ECPR than those of subcortex/basal ganglia or the brainstem/cerebellum. These findings suggest that mASPECTS is more useful than ASPECTS or ASPECT-b for predicting neurological outcomes in patients after ECPR.

This study has several limitations. First, the CPC score was retrospectively determined on the basis of medical records. Second, the nonrandomized nature of the registry data might have resulted in selection bias. Although brain CT was performed within 48 hours following ECPR, a major limitation of this study might be that the CT was performed at different time settings. However, in ROC curves for the prediction of poor neurological outcome using CT scores, AUCs of CT scores were not significantly different between within and after median CT scan intervals in this study. Third, brain CT scan was performed by two different scanners, which might have resulted in bias. Fourth, selection bias might have been an influence because we excluded 26 non-survived patients for whom we could not exactly define neurological status at discharge. We added the result including these 26 patients to compare with the results excluding these patients in Additional file 2. Last, a limited number of patients received targeted temperature management. The methods used were decided by each intensivist. They varied according to conditions and situations.

Supplementary Figure 1.

mASPECTS according to neurological outcome. Bar is presented to median with interquartile range. There was significant difference in mASPECTS according to neurological outcome (p < 0.001) and it was tested by the Kruskal-Wallis test among groups. Bars of the same color indicate non-significant differences between groups base on the Mann-Whitney U test. The patients of confirmed brain death had lowest mASPECT scores (2.0 [0 – 24.0]) among the neurological outcome groups. Especially, mASPECTSs of patients died of brain death were lower compared with those of patients die of other causes (2.0 [0 – 24.0] vs. 24.0 [21.0 – 27.0], p = 0.02). In addition, mASPECTSs were not significant difference between patients with CPC 3 – 4 and patients died of causes other than brain death (p = 0.884). mASPECTS, modified Alberta stroke program early computed tomography score; CPC, Cerebral Performance Categories.

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