Abstract:
Background. Whether lying-flat improves blood flow in patients with acute ischemic
stroke (AIS) is unknown. Our aim was to investigate if lying-flat ‘changes’ cerebral
blood flow velocities (CBFV) assessed by transcranial Doppler (TCD) in AIS patients.
Methods. In a multicenter cluster clinical trial, we randomly assigned patients within 12
hours from onset of a neurological deficit due to cerebral ischemia of the anterior
circulation to lying-flat or upright head positioning. The primary outcome was a change
of 8cm/sec or more in mean CBFV on TCD to the middle cerebral artery at 1 and 24
hours post-randomization, adjusted for imbalance in baseline variables. Secondary
outcomes included serious adverse events (SAEs) and physical functioning at 90 days.
Results. Ninety-four of 304 patients screened were recruited. The primary outcome
occurred in 11 (26%) of 43 patients in the lying-flat group and in 6 (12%) of 51 in the
upright group at 1 hour (adjusted odds ratio, 3.81; 95% CI, 1.07 to 13.54), and in 23
(53%) and 18 (36%) patients in these respective groups at 24 hours (adjusted odds ratio,
3.04; 95% CI, 1.08 to 8.53). There were no between-group differences in SAEs,
including pneumonia, heart failure or mortality, nor in functional outcome at three
months (adjusted common odds ratio, 1.38; 95% CI 0.64 to 3.00).
Conclusion. The lying-flat head position was associated with a significant increase in
CBFV at one and 24 hours within the ipsilateral hemisphere of anterior circulation AIS,
without serious safety concerns.
