Key result
Brief mild hypotension triggers sympathetically-mediated tachycardia in lambs, but severe hypotension reverses it in fetuses.
Why the study?
Reflex heart rate responses to hypotension and their autonomic control in fetal and newborn lambs were not fully characterized.
Does autonomic blockade alter reflex heart rate responses to hypotension in fetal and newborn lambs?
Population
Chronically instrumented fetal (n=4) and newborn (n=4) lambs
Comparison
Responses to brief hypotension with and without sympathetic beta-adrenergic, cholinergic, and total autonomic blockade
Design
Preclinical study
Authors
Loading...
Should not alter neonatal hypotension management; extends developmental autonomic physiology and leaves open human translation.
Does autonomic blockade alter reflex heart rate responses to hypotension in fetal and newborn lambs?
The study demonstrates distinct patterns of autonomic reflex heart rate control in response to hypotension between fetal and newborn lambs.
Walker et al. (2009) studied Hypotension (n=8). Autonomic blockade (propranolol and/or atropine) vs. Unblocked state was evaluated on Reflex heart rate response to hypotension. Brief hypotensive stimuli caused sympathetically-mediated tachycardia during mild hypotension in both fetal and newborn lambs, but severe hypotension reversed this response in fetal lambs.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: