testing the parasympathetic nervous system
Last reviewed 01/2018
The integrity of the parasympathetic nervous system can be shown by:
- the Valsalva manoeuvre: as the arterial blood pressure rises, the heart rate will fall inversely due to a baroreceptor reflex response.
- pressure on carotid sinus or eyeball will produce reflex bradycardia; caution must be exercised as myocardial infarction can be precipitated.
- drugs: antimuscarinics such as atropine, scopolamine and tropicamide will inhibit vagal activity with consequent manifestation of sympathetic effects e.g. pupillary dilation.