Postprandial hypotension: simple treatment but difficulties with the diagnosis.

OVER the past two decades, a growing amount of work on postprandial hypotension has been published. Postprandial hypotension has now been recognized as a very common clinically relevant disorder in elderly persons (1,2). In healthy elderly persons, meal-induced decreases in blood pressure are common but mostly asymptomatic (2). Elderly persons with hypertension have an increased frequency of postprandial hypotension. Patients with heart failure, syncope, or Parkinson’s disease; patients on dialysis; and persons with autonomic dysfunction tend to have worse postprandial hypotension (2–5). In these patients, the prevalence of postprandial hypotension ranges from 40% to more than 80%. Postprandial hypotension was also highly prevalent in very old depressed patients. Treatment with nortriptyline or paroxetine did not affect postprandial blood pressure responses and symptoms (6). In hospital and institutionalized populations, the prevalence of postprandial hypotension in elderly persons is higher than that in the community because of the higher frequency of comorbid conditions and diseases and the increased number of medications, which all may have effects on blood pressure regulation. Nearly all elderly nursing home residents experience postprandial hypotension (7). In almost 40% of these residents, systolic blood pressure decreases more than 20 mmHg within 75 minutes of eating a meal (7,8). Postprandial hypotension is probably more common than is orthostatic hypotension. In this issue of the Journal, Vloet and colleagues provide further evidence that in elderly patients admitted to hospitals postprandial hypotension is extremely common. In 85 consecutive frail geriatric patients, 67% had postprandial hypotension and 52% were diagnosed with orthostatic hypotension (9). Eighty-one percent of the patients had either postprandial hypotension or orthostatic hypotension. It has been reported that orthostatic hypotension and postprandial hypotension occur frequently but not necessarily together in geriatric patients suggesting different pathophysiological mechanisms (2). The basic mechanisms by which postprandial hypotension is produced remain uncertain (2,10). Clearly the extent of postprandial splanchnic hyperemia is an important factor (11,12). The other major factors appear to be impairments in baroreflex function, inadequate postprandial increases in cardiac output, and inadequate sympathetic nervous system compensation (2). Our current understanding of postprandial hypotension is limited by the absence of a standardized clinically meaningful definition. Jansen and Lipsitz (2) defined postprandial hypotension, analogous to orthostatic hypotension, as a decline of 20 mmHg or more in systolic blood pressure within 2 hours following the start of a meal or when the absolute level of systolic blood pressure following a meal falls below 90 mmHg, and preprandial systolic blood pressure is over 100 mmHg. Postprandial hypotension occurs both in the sitting and supine position and can be found at all meal times. Although not found in all studies, it appears that postprandial hypotension is more prevalent and more profound in the morning. In this issue of the Journal, Vloet and colleagues (13) show that postprandial hypotension was most prevalent in the morning and least prevalent in the evening. In addition, test meals at dinnertime induced significantly shorter postprandial hypotensive periods, and these patients had almost no symptoms compared to those at breakfastor lunchtime. Also, Puisieux and colleagues (14) showed that elderly persons admitted to a geriatric short stay department for evaluation of falls and syncope had a higher prevalence of postprandial hypotension at breakfast time than at other times. Because it is most likely that postprandial hypotension occurs after breakfast, evaluation of meal-related blood pressure decreases should be performed in the morning. The timing of the fall in postprandial systolic blood pressure is variable for each person. The time period of measuring blood pressure to detect postprandial hypotension should be at least 90 minutes. Apparent postprandial decreases in blood pressure can be found almost immediately after a meal with a nadir in blood pressure as early as 15 minutes following the meal in approximately 15% of patients. Postprandial blood pressure usually reaches a nadir within 30–60 minutes in 70% of patients. However, in the remaining 15% of patients, decreases in systolic blood pressure are apparent as late as 75 minutes following the meal (2). Including the rest period of at least 10 minutes for preprandial blood pressure measurements, the total time of a meal test takes at least 2 hours, making these tests quite time-consuming. This might be a reason that meal tests for the evaluation of postprandial hypotension are not always included in the geriatric assessment. Postprandial hypotension is easily detectable by manual or automatic blood pressure measurements. Ambulatory blood pressure monitoring is a valuable and useful method to investigate mealrelated blood pressure changes in elderly patients (9,14). Only a few studies have used ambulatory blood pressure monitoring. There is no standard definition for postprandial