TRANSCRANIAL DOPPLER ASSESSMENT OF THE CEREBRAL-CIRCULATION DURING POSTPRANDIAL HYPOTENSION IN THE ELDERLY

Objective: The aim of the present study was to evaluate whether alterations in postprandial hemodynamics in the elderly were associated with changes in cerebral perfusion assessed by transcranial Doppler ultrasonography. Design: Time series, ie, post-intervention compared to pre-intervention with no-intervention controls. Participants: Ten elderly institutionalized subjects (4 women, 6 men, mean age 84.9 years). Three subjects had a history of syncope. Setting: A 725-bed academic long-term care facility. Intervention: A 400-kcal mixed meal. Measurements: Heart rate, blood pressure, and blood flow velocity in the middle cerebral artery by transcranial Doppler recording, before the test meal and at 5-minute intervals for 60 minutes afterwards. Results: Systolic, diastolic, and mean arterial blood pressure declined significantly from baseline between 30 and 55 minutes after the meal (P < 0.05, ANOVA); however, maximum and mean blood flow velocity did not change. The pulsatility index (end diastolic to peak systolic amplitude divided by mean velocity) increased significantly (P < 0.05, ANOVA) between 30 and 55 minutes after the meal, suggesting increased arteriolar resistance. There were no significant changes in blood pressure, blood flow velocity, and pulsatility index during a control study conducted with four subjects under identical conditions but without a meal. Conclusions: The results of this study suggest a small, unexpected increase in resistance of the intracranial circulation following a meal in elderly people with postprandial hypotension. Although the clinical significance of this finding is not known, the occurrence of postprandial arteriolar vasoconstriction may lead to cerebral ischemia during periods of marked blood pressure decline.