Abstract WP350: Pumping Against Gravity - Cardiac Function Affects Fluctuations in Cerebral Blood Flow Caused by Head Position Change in Acute Ischemic Stroke

Introduction: Acute ischemic stroke (AIS) patients often have the head-of-bed (HOB) elevated to 300 while in the Emergency Department (ED). Flat HOB positioning has been shown to impact cerebral flow. Whether this holds true in undifferentiated, ED stroke patients is unknown. Hypothesis: We tested the hypothesis that 00 HOB positioning improves middle cerebral artery (MCA) mean flow velocity (MFV) in AIS compared to 300. We secondarily tested the hypothesis that lower cardiac output (CO) is associated with greater fluctuation of MFV. Methods: This was a quasi-experimental study with repeat measurements of MCA MFV at 300 and 00 HOB position. Patients > 18 years presenting to the ED within 12 hours of symptom onset and a NIHSS ≥ 4 were eligible. After applying non-invasive monitoring of mean arterial pressure (MAP) and CO, an investigator used transcranial Doppler to obtain bilateral MCA MFV at 300 and 00 HOB position. If a signal was unobtainable on the ischemic side, the contralateral MFV was used for ana...