Fig. 1: Position changes during the 90° tilt-test.
From: Cerebrovascular responses to a 90° tilt in healthy neonates
In our 90° tilt-test, neonates were first in a supine (0°) position (a) for 2-min and tilted (over 1–2 s) to a sitting (90°) position (b) for an additional 2-min. We ensured neonates were not slouched or hunched when being tilted. In the supine position, the heart and brain are of equal height from the ground. In the sitting position, the brain is higher than the heart, resulting in orthostatic stress from gravitational forces. c Image of an actual neonatal study participant in the “snuggle-up” during the supine position (permission obtained from the parents).
