Clinical PaperRegional cerebral oxygen saturation after cardiac arrest in 60 patients—A prospective outcome study
Introduction
Prediction of neurological outcome in patients after cardiac arrest by biomarkers, clinical neurological examination and electrophysiological testing can be difficult and may partly be affected by targeted temperature management.1, 2, 3, 4, 5, 6 To enhance the power of early prognostication an integrated multimarker and clinical examination approach has been recommended in a recently published large review.7 This approach combined with novel techniques and new biomarkers might increase the precision of prognostication.8, 9 In general, post-hypoxic brain damage after cardiac arrest could be associated with changes in regional oxygen saturation (rSO2) of brain tissue following changes in oxygen consumption (CMRO2), cerebral blood flow (CBF) or cerebral blood volume (CBV). Both hyperoxygenation due to reduced cerebral oxygen consumption as well as hypooxygenation due to reduced cerebral blood flow could indicate hypoxic ischemic encephalopathy. Therefore, additional information for reliable outcome prediction may be gained by using continuous bedside near-infrared spectroscopy (NIRS) monitoring of frontal brain regional oxygen saturation.
The aim of our study was to improve the knowledge on changes in regional cerebral oxygen saturation after cardiac arrest and to evaluate continuous real-time, non-invasive cerebral oxygenation monitoring by NIRS for outcome prediction.
Section snippets
Material and methods
The local ethics committee of the Charité-Universitätsmedizin Berlin approved the study protocol and the study was registered (www.clinicaltrials.gov: NCT01531426). For all survivors a healthcare proxy was contacted to give written informed consent as all cardiac arrest survivors were unconscious on admission. Patients were enrolled between January 2012 and January 2013. Patients were included into the study during admission to ICU after cardiac arrest (n = 38 OHCA; n = 22 IHCA) without general
Results
A good outcome (CPC 1–2) was achieved in 23/60 (38%) patients, while 37/60 (62%) had a poor outcome (CPC 3–5). A coronary angiography after admission was performed in 35/60 patients after cardiac arrest and presumed myocardial infarction. Finally 30/35 patients were diagnosed with a coronary heart disease, a further 10 patients had a primary arrhythmia as cause of arrest.
Discussion
We prospectively evaluated continuous cerebral oxygenation saturation monitoring by NIRS for outcome prediction in a total of 60 patients after cardiac arrest. After successful resuscitation, median rSO2 is significantly lower during hypothermia treatment in patients with poor outcome as compared to patients with good outcome. The overlapping rSO2 ranges probably impair outcome prognostication by frontal brain rSO2. The cumulative subthreshold rSO2 of 50% was associated with poor outcome, but
Conclusion
Patients with good neurological outcome had higher median rSO2 levels compared to poor outcome patients after cardiac arrest. However, rSO2 ranges largely overlapped and reliable outcome prognostication by NIRS monitoring was not possible. Further studies could evaluate whether persistently very low rSO2 indicates poor outcome with high specificity. NIRS monitoring appears a promising tool for non-invasive continuous monitoring of cardiac arrest patients in the early post-resuscitation phase.
Conflicts of interest
This study received technical support (INVOS monitors and sensors) and financial support with a grant of 30.000€ by COVIDIEN (USA) to cover costs over the study period. The industrial sponsor had no influence toward the study protocol, inclusion of patients, final analyzing of the data and drafting of the manuscript. The study was investigator initiated.
C. Storm has received remuneration for presentations, travel costs and partial technical or material support from Philips, C.R. BARD, Zoll,
Acknowledgments
We would like to thank our ICU team, especially the nurses, for outstanding support during the study and a special thank you to our study nurse Astrid Caemmerer for her tireless support.
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