Key result
Head-up tilt enhanced vascular responses to neck suction in controls (from 0.04 to -1.01 %.mmHg-1, P<0.001) but had no effect in patients with low orthostatic tolerance (from -0.3 to -0.3 %.mmHg-1).
Why the study?
Does head-up tilting alter carotid baroreceptor reflex sensitivity differently in subjects with varying orthostatic tolerance?
Observational
Does head-up tilting alter carotid baroreceptor reflex sensitivity differently in subjects with varying orthostatic tolerance?
Failure to increase carotid baroreceptor/vascular resistance reflex sensitivity during orthostatic stress may explain poor orthostatic tolerance in patients with posturally related syncope.
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Impaired baroreflex adaptation during tilt may underlie syncope susceptibility; hypothesis-generating and requires prospective validation before clinical use.
Cooper et al. (2002) conducted an observational in Suspected posturally related syncope and low orthostatic tolerance. Head-up tilt and carotid baroreceptor loading/unloading vs. Supine rest was evaluated on Responses of R-R interval and forearm vascular resistance to loading and unloading of carotid baroreceptors. Head-up tilt enhanced vascular responses to neck suction in controls (from 0.04 to -1.01 %.mmHg-1, P<0.001) but had no effect in patients with low orthostatic tolerance (from -0.3 to -0.3 %.mmHg-1).
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