No abstract

No abstract

Extracorporeal membrane oxygenation (ECMO) is a form of cardiopulmonary bypass that provides life-saving support to critically ill patients whose illness is progressing despite maximal conventional support. Use in adults is expanding, however neurological injuries are common. Currently, the existing brain imaging tools are a snapshot in time and require high-risk patient transport. Here we assess the feasibility of measuring diffuse correlation spectroscopy, transcranial Doppler ultrasound, electroencephalography, and auditory brainstem responses at the bedside, and developing a cerebral autoregulation metric. We report preliminary results from two patients, demonstrating feasibility and laying the foundation for future studies monitoring neurological health during ECMO.

Peripheral veno-arterial extracorporeal membrane oxygenation (ECMO) artificially oxygenates and circulates blood retrograde from the femoral artery, potentially exposing the brain to asymmetric perfusion. Though ECMO patients frequently experience brain injury, neurologic exams and imaging are difficult to obtain. Diffuse correlation spectroscopy (DCS) non-invasively measures relative cerebral blood flow (rBF) at the bedside using an optical probe on each side of the forehead. In this study we observed interhemispheric rBF differences in response to mean arterial pressure (MAP) changes in adult ECMO recipients. We recruited 13 subjects aged 21–78 years (7 with cardiac arrest, 4 with acute heart failure, and 2 with acute respiratory distress syndrome). They were dichotomized via Glasgow Coma Scale Motor score (GCS-M) into comatose (GCS-M ≤ 4; n = 4) and non-comatose (GCS-M > 4; n = 9) groups. Comatose patients had greater interhemispheric rBF asymmetry (ASYMrBF) vs. non-comatose patients over a range of MAP values (29 vs. 11%, p = 0.009). ASYMrBF in comatose patients resolved near a MAP range of 70–80 mmHg, while rBF remained symmetric through a wider MAP range in non-comatose patients. Correlations between post-oxygenator pCO2 or pH vs. ASYMrBF were significantly different between comatose and non-comatose groups. Our findings indicate that comatose patients are more likely to have asymmetric cerebral perfusion.

ObjectivePatients with acute lung or heart failure can experience hypoxic ischemic brain injury resulting in neurovascular unit (NVU) dysfunction. The NVU couples brain activity and perfusion. Extracorporeal membrane oxygenation (ECMO) is used for refractory lung and/or heart failure and often necessitates sedation, obfuscating neurological assessments. We hypothesized that combining cerebral electrographic activity and perfusion monitoring can detect brain injury in adults undergoing ECMO.MethodsFast Fourier transformation was used to identify fast (α+β) and slow (δ) power bands from cEEG. Diffuse correlation spectroscopy (DCS) measured blood flow index (BFI), a surrogate of perfusion, daily in adults undergoing ECMO. Correlations between α+β/δ ratio (ABDR) and BFI were compared between patients who were grouped into brain-injured and uninjured groups by neurologic exam and neuroimaging findings.ResultsTen patients (21-78 years old, five females, five brain-injured) underwent cEEG and DCS monitoring. Sixty-eight monitoring sessions (average 127 minutes/session) were analyzed. ABDR-BFI correlation was significantly higher in uninjured patients than brain-injured ones. Sedation did not significantly impact CBF-power band correlation.ConclusionsBrain-injured patients exhibited significantly less correlation between brain activity and perfusion, possibly as a result of NVU dysfunction.SignificanceABDR-BFI correlation can be measured continuously and noninvasively at the bedside and may represent a marker of NVU dysfunction.HighlightsQuantitative EEG and diffuse correlative spectroscopy can be used to measure markers of brain injury noninvasively, continuously, and at the bedside.Decreased ABDR-BFI correlation may be a marker of neurovascular decoupling in patients with hypoxic ischemic brain injury.ABDR-BFI correlation may be independent of analgosedation, which is used heavily in patients undergoing ECMO.