Cerebral Blood Flow Hemispheric Asymmetry in Comatose Adults Receiving Extracorporeal Membrane Oxygenation

Abstract

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.

Cerebral Autoregulation: A Target for Improving Neurological Outcomes in Extracorporeal Life Support

“…Various methods have been used to measure CA in ECMO patients. These methods include NIRS-derived rSO 2 [11,[33][34][35][46][47][48], oxyhemoglobin concentration [49], and total hemoglobin concentration [50], in addition to TCD-derived [51] and DCS-derived [42,52] CBF. Of note, each of these methods is used to derive a unique CA index, none of which is a gold standard.…”

“…Early studies identified an association between the incidence of right-sided cerebral injury and carotid artery cannulation [81][82][83][84]. However, asymmetric cerebral perfusion has also been reported in a mixed population of adults on both VV and VA ECMO, none of whom underwent carotid artery cannulation [52]. The role of carotid artery cannulation in lateralized cerebral damage and neurological injury remains to be elucidated, as many other investigations have failed to identify this association [66,75,77,[85][86][87][88][89][90][91].…”

“…CA disruption has also been associated with lower ipsilateral CBF following carotid artery ligation in newborn lambs [70]. However, impaired CA has also been associated with asymmetric CBF in adults undergoing VA ECMO, none of whom had carotid artery cannulation [52]. Therefore, it is possible that impaired CA in the face of variable systemic blood pressure may play a more causative role in asymmetric perfusion and subsequent neurological injuries than cannulation site alone.…”

Neuromonitoring of Pediatric and Adult Extracorporeal Membrane Oxygenation Patients: The Importance of Continuous Bedside Tools in Driving Neuroprotective Clinical Care

“…This study showed similarities in the detection of high hemispheric asymmetry in comatose patients on ECMO between TCD and DCS. 92…”

“…This study showed similarities in the detection of high hemispheric asymmetry in comatose patients on ECMO between TCD and DCS. 92 Furthermore, DCS may be used to identify CA disruptions, potentially indicating impending brain injury. A prospective feasibility study used DCS and FD-DOS to measure CBF, hemoglobin concentrations, and optical scattering in nine neonates on ECMO.…”