***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Postpr and ial hypotension is an important clinical condition that predisposes to syncope , falls , angina , and cerebrovascular events . The magnitude of the fall in blood pressure after meals depends on enteric glucose availability . We hypothesized that acarbose , an & agr;-glucosidase inhibitor that decreases glucose absorption in the small intestine , would attenuate postpr and ial hypotension . Acarbose or placebo was given 20 minutes before a st and ardized meal in 13 patients with postpr and ial hypotension in the setting of autonomic failure ( age : 65±2.64 years ; body mass index : 25±1.08 kg/m2 ; supine plasma norepinephrine : 110±26.6 pg/mL ) . Four patients were studied in a single-blind protocol and 9 patients in a double-blind , r and omized , crossover fashion . Patients were studied supine , and blood pressure , heart rate , and neuroendocrine parameters were obtained at baseline and for 90 minutes after meal intake . After adjusting for potential confounders , acarbose significantly attenuated the postpr and ial fall in systolic and diastolic blood pressures by 17 mm Hg ( 95 % CI : 7 to 28 ; P=0.003 ) and 9 mm Hg ( 95 % CI : 5 to 14 ; P=0.001 ) , respectively . Furthermore , acarbose effectively reduced plasma levels of insulin , a known vasodilator , by 11 & mgr;U/mL ( 95 % CI : 5 to 18 ; P=0.001 ) compared with placebo . After adjusting for insulin levels , the attenuation of postpr and ial hypotension by acarbose remained significant , indicating that additional mechanisms contribute to this effect . In conclusion , 100 mg of acarbose successfully improved postpr and ial hypotension  in patients with severe autonomic failure . This effect is not explained solely by a reduction in insulin levels Postpr and ial hypotension occurs commonly in patients with autonomic failure and may be due to attenuation of the normal sympathetic nervous system activation in response to meal ingestion . In a r and omized , double-blind , placebo-controlled study , we investigated the therapeutic effect of the norepinephrine precursor 3,4-DL-threo-dihydroxyphenylserine ( DL-DOPS ) on this condition . We measured blood pressure , heart rate , forearm vascular resistance , and plasma DL-DOPS and norepinephrine in 11 patients with autonomic failure .  DL-DOPS attenuated the postpr and ial fall in blood pressure . This was associated with an increase in plasma norepinephrine and forearm vascular resistance .  DL-DOPS therapy did not change the postpr and ial increase in heart rate . There was a trend toward increased supine hypertension associated with DL-DOPS treatment . This study shows that DL-DOPS is a promising treatment for postpr and ial hypotension and provides support for the hypothesis that postpr and ial hypotension is , at least in part , due to decreased activation of the sympathetic nervous system . NEUROLOGY 1996;47 : 1414 - 1 . The aim of this study was to determine the effects of caffeine on haemodynamic and neurohumoral responses to meal ingestion in elderly patients with a history of symptomatic postpr and ial hypotension . 2 . Postpr and ial hypotension is a common disorder of blood pressure regulation in the elderly , associated with falls and syncope . The pathophysiological mechanism is thought to be related to impaired vascular compensation for splanchnic blood pooling after a meal . Since caffeine inhibits vasodilatory adenosine receptors in the splanchnic circulation , we postulated that caffeine would reduce splanchnic blood pooling and prevent the development of postpr and ial hypotension . 3 . We conducted a r and omized , double-blind , placebo-controlled , cross-over study in nine elderly patients [ age 76 + /- 9 ( SD ) years ] with histories of symptomatic postpr and ial hypotension . St and ardized 1674kJ liquid meals with 250 mg of caffeine or placebo were given on two occasions , at least 1 week apart . Blood pressure , heart rate , forearm vascular resistance ( by venous occlusion plethysmography ) , and plasma caffeine and catecholamine levels were measured . Cardiac and splanchnic blood volume were determined by radionuclide scans . 4 . By 30 min after both caffeine and placebo meal studies , supine mean arterial blood pressure fell significantly ( P = 0.006 ) by 31 + /- 7 and 19 + /- 6 mmHg , respectively ( mean + /- SEM , between group difference was not significant ) . Heart rate , cardiac output and splanchnic blood volume increased significantly , but to a similar extent , after caffeine and placebo .  Forearm vascular resistance was unchanged after both meals . 5 . Oral caffeine given with a meal does not reduce splanchnic blood pooling nor prevent postpr and ial hypotension in symptomatic elderly patients Objective To investigate the effects of the somatostatin analogue octreotide , which inhibits the release of various peptides , on 24-h ambulatory blood pressure profiles in subjects with primary ( idiopathic ) autonomic failure due to sympathetic denervation , and in particular to determine whether octreotide reduces daytime hypotension and whether it causes or accentuates nocturnal hypertension . Subjects and methods Eighteen subjects with primary autonomic failure , confirmed by detailed physiological and biochemical autonomic tests , were studied in a r and omized manner on two occasions , with and without octreotide treatment ( 1 μg/kg body weight subcutaneously , twice a day at 0800 and 1800 h ) . Blood pressure was measured using the SpaceLabs 90207 system . This was connected at 0900 h with programmed recordings at 30-min intervals until 2300 h and at 60-min intervals until the next morning . There were additional subject-initiated recordings after 5 min each of lying , sitting and st and ing four times during the day , while sitting after lunch at noon and while st and ing following walking in the evening . Additional analyses included calculation of cumulative sum (cusum)-derived parameters and construction of cusum plots . Results After octreotide treatment , the overall mean daytime systolic/diastolic blood pressure ( mmHg ) was raised ( 123 ± 2/77 ± 1 without treatment versus 128 ± 2/79 ± 1 with treatment ) . There was a reduction in postural ( supine versus st and ing : from 96 ± 3/62 ± 3 without treatment to 106 ± 5/67 ± 4 with treatment ) , postpr and ial ( 107 ± 3/65 ± 2 to 122 ± 5/75 ± 4 ) and exertion-induced ( 96 ± 5/61 ± 5 to 113 ± 6/71 ± 5 ) hypotension . Symptoms of hypotension were reduced by octreotide . Nocturnal blood pressure was lower after octreotide ( 139 ± 3/84 ± 1 versus 129 ± 3/78 ± 2 ) . Analyses with the cusum technique further demonstrated blood pressure recovery during the day , with a reduction in the magnitude of change at night after octreotide treatment . Conclusions In primary autonomic failure , 24-h ambulatory blood pressure profiles and cusum analyses indicate that octreotide has beneficial effects in reducing postural , postpr and ial and exertion-induced hypotension , without causing or increasing nocturnal hypertension 1 . Postpr and ial hypotension is now recognized as an important clinical problem , particularly in the elderly and in patients with autonomic dysfunction . The mechanisms responsible are poorly understood ; however , impaired regulation of splanchnic blood flow and the release of gastrointestinal hormones appear to be important . The effect of gastric emptying on the magnitude of the postpr and ial fall in blood pressure has not been evaluated . 2 . The aim of this study was to determine whether there is a relationship between changes in blood pressure and the rate of gastric emptying after ingestion of 75 g of glucose in patients with non-insulin-dependent diabetes mellitus ( NIDDM ) and both young and older normal subjects . Sixteen patients with recently diagnosed NIDDM , median age 57 ( 39 - 79 ) years , 10 ' young ' subjects with a median age of 23 ( 19 - 26 ) years and nine ' older ' subjects , median age 48 ( 40 - 68 ) years , were measured simultaneously for gastric emptying of 75 g of glucose in 350 ml of water blood pressure and blood glucose concentrations , commencing at approximately 10.00 hours after an overnight fast . Measurements of blood pressure were made in the sitting position immediately before glucose ingestion and at 15 min intervals up to 180 min . 3 . Gastric emptying of glucose was not significantly different between the three groups [ 50 % emptying time ( T50 ) : 95 + /- 7.3 min in patients with NIDDM compared with 120 + /- 13.2 min in the ' young ' group and 97 + /- 8.1 min in the ' older ' group ] . There was a significant fall in mean blood pressure after the glucose load in the patients with NIDDM ( P < 0.0001 ) and the ' older ' normal subjects ( P < 0.05 ) , but not the ' young ' normal subjects . Postpr and ial hypotension ( fall in systolic blood pressure > or = 20 mmHg ) was evident in seven ( 44 % ) patients with NIDDM and three ( 33 % ) ' older ' normal subjects . The area under the change in mean blood pressure curve was related significantly to the gastric emptying T50 ( r = 0.67 , P < 0.005 ) in the patients with NIDDM , but not in either control group . 4 . In conclusion , in patients with recently diagnosed NIDDM the fall in blood pressure after an oral glucose load is ( i ) greater than in both young and older normal subjects and ( ii ) related to the rate of gastric emptying In a double-blind placebo-controlled study , we examined the effect of caffeine pretreatment on the haemodynamic and humoral changes after a st and ardized breakfast in 15 healthy elderly subjects ( mean age 75.4 + /- 6.6 years ) . After placebo , the prepr and ial blood pressure did not change and the postpr and ial blood pressure declined by a maximum of 6.1 % . After oral ingestion of 250 mg caffeine , 60 min before breakfast , the prepr and ial blood pressure increased by 12.5 % . Although the decrease of the postpr and ial blood pressure was not altered , blood pressure remained above its basal value . The increase in plasma noradrenaline after the meal was similar in the placebo and the caffeine tests . Plasma adrenaline decreased after placebo ( -19 % ) but did not change after caffeine . Thus , despite the unchanged decrease of the postpr and ial blood pressure , the prepr and ial pressor effect of caffeine prevented the decline of the postpr and ial blood pressure below its baseline value . The clinical relevance of this finding has still to be determined 1 . A postpr and ial fall in blood pressure ( BP ) in older men and women increases the risks of falls and impaired cerebral perfusion . Postpr and ial hypotension has been suggested to be greater in hypertensive subjects , particularly in those on antihypertensive medication Postpr and ial hypotension occurs frequently in diabetes ; the fall in blood pressure is greatest after ingestion of carbohydrate , particularly glucose and , in type 2 diabetes , is related to the rate of gastric emptying . The aim of this study was to determine whether slowing of gastric emptying by guar gum reduces the fall in blood pressure after oral glucose in patients with type 2 diabetes . Eleven type 2 patients managed by diet alone , age 61.9 ± 1.3 years , had measurements of gastric emptying , blood pressure , blood glucose , and serum insulin on two occasions after ingestion of 300 ml water containing 50 g glucose , with or without 9 g guar gum . The magnitude of the fall in blood pressure was less ( P < 0.05 ) and gastric emptying slower ( P < 0.05 ) after guar  . Blood glucose ( P < 0.05 ) and serum insulin ( P < 0.01 ) concentrations were lower after guar . The magnitude of the fall in systolic blood pressure was related to gastric emptying of glucose at 30 min on the control day ( r = 0.67 , P < 0.05 ) . We conclude that guar gum attenuates the fall in blood pressure after oral glucose in patients with type 2 diabetes mellitus , presumably by slowing glucose absorption OBJECTIVE To determine whether slowing of gastric emptying and glucose absorption with guar gum would reduce the fall in blood pressure after an oral glucose load in older subjects . DESIGN A r and omized , experimental , cross-over study . SETTING Department of Nuclear Medicine , Royal Adelaide Hospital , Adelaide , SA , Australia . PARTICIPANTS Ten healthy subjects , 
    Output:
    
RESULTS Thirteen articles reporting 12 studies ( 1 study was reported in 2 articles ) demonstrated that caffeine ( 5 studies ) ; acarbose ; 3,4-DL-threo-dihydroxyphenylserine ; guar gum ( 3 studies ) ; and octreotide ( 2 studies ) statistically attenuated the postpr and ial reduction in BP .
For symptomatic participants , there was improvement with acarbose but none with caffeine .
Drug interventions can attenuate postpr and ial reductions in BP , but they may not necessarily be effective in people with symptomatic PPH