Cerebrovascular Physiology During Pediatric Extracorporeal Membrane Oxygenation: A Multicenter Study Using Transcranial Doppler Ultrasonography

Abstract

Objectives: To explore changes to expected, age-related transcranial Doppler ultrasound variables during pediatric extracorporeal membrane oxygenation.

Design: Prospective, observational, multicenter study.

Setting: Tertiary care PICUs.

Patients: Children 1 day to 18 years old requiring veno arterial extracorporeal membrane oxygenation.

Methods: Participants underwent daily transcranial Doppler ultrasound measurement of bilateral middle cerebral artery flow velocities. Acute neurologic injury was diagnosed if seizures, cerebral hemorrhage, or diffuse cerebral ischemia was detected.

Measurements and main results: Fifty-two children were enrolled and analyzed. In the 44 children without acute neurologic injury, there was a significant reduction in systolic flow velocity and mean flow velocity compared with predicted values over time (F [8, 434] = 60.44; p ≤ 0.0001, and F [8, 434] = 17.61; p ≤ 0.0001). Middle cerebral artery systolic flow velocity was lower than predicted on extracorporeal membrane oxygenation days 1-5, and mean flow velocity was lower than predicted on extracorporeal membrane oxygenation days 1-3. In the six infants less than 90 days old suffering diffuse cerebral ischemia, middle cerebral artery systolic flow velocity, mean flow velocity, and diastolic flow velocity from extracorporeal membrane oxygenation days 1-9 were not significantly different when compared with children of similar age in the cohort that did not suffer acute neurologic injury (systolic flow velocity F [8, 52] = 0.6659; p = 0.07 and diastolic flow velocity F [8, 52] = 1.4; p = 0.21 and mean flow velocity F [8, 52] = 1.93; p = 0.07). Pulsatility index was higher in these infants over time than children of similar age in the cohort on extracorporeal membrane oxygenation that did not suffer acute neurologic injury (F [8, 52] = 3.1; p = 0.006). No patient in the study experienced cerebral hemorrhage.

Conclusions: Flow velocities in the middle cerebral arteries of children requiring extracorporeal membrane oxygenation are significantly lower than published normative values for critically ill, mechanically ventilated, sedated children. Significant differences in measured systolic flow velocity, diastolic flow velocity, and mean flow velocity were not identified in children suffering ischemic injury compared with those who did not. However, increased pulsatility index may be a marker for ischemic injury in young infants on extracorporeal membrane oxygenation.