Postprandial haemodynamic changes: a source of bias in cardiovascular research affected by its own methodological bias.

The effects of heart rate and systolic and diastolic blood pressure of eating a 3100 kJ cold meal were assessed in eight young normal subjects studied in a randomised and balanced crossover study. Blood pressure was measured simultaneously and in the same arm by auscultation of the fossa cubitalis (Korotkoff I, IV, and V), by an automated device with a microphone over the brachial artery (equivalent to Korotkoff I and V), and by graphical analysis of these microphone signals (equivalent to Korotkoff I and IV). Eating caused a rise in mean heart rate, a small rise in systolic blood pressure, and a decrease in diastolic blood pressure, which was overestimated when Korotkoff V rather than Korotkoff IV endpoints were considered. Both the automated device and the graphical analysis yielded acceptable overall quantitative agreement with the auscultatory method. Both alternative methods allowed similar postprandial blood pressure trends to be detected, but the quantitative agreement in estimating the postprandial effects was far less optimal. Eating therefore was shown to cause changes that might distort and confuse the interpretation of cardiovascular data in studies in which subjects are allowed to eat. This source of bias itself appeared to be affected by its own methodological bias.

RCT Entities:   Population Interventions Outcomes