Effect of acute dose of caffeine on cardiovascular autonomic responses in healthy subjects.

The effect of acute dose of caffeine (4 mg kg-1) on cardiovascular autonomic responses were studied in 10 healthy subjects. Standard cardiovascular reflex tests were used during which heart rate and blood pressure were continuously measured. Each subject was tested twice in a random order, with and without prior use of caffeine. It was found that immediate heart rate responses following standing up were lower under influence of caffeine. Blood pressures were systematically, although non-significantly, higher and blood pressure responses in isometric handgrip test stronger when caffeine was used before testing. It is suggested that caffeine should not be used before autonomic testing. This is especially important when the test(s) are performed for research purposes or in order to study the blood pressure responses. If the tests are made for diagnostic purposes the following rules should be adopted: (1) if the subject has used caffeine before testing but all heart rate responses are within normal ranges, it can be assumed that the subject does not have cardiac parasympathetic neuropathy and retesting is not necessary: (2) if the patient has used caffeine before testing and the results suggest presence of autonomic neuropathy, the patient must be retested without the prior use of caffeine.

RCT Entities:   Population Interventions Outcomes