High-intensity exercise does not protect against orthostatic intolerance following bedrest in 55- to 65-yr-old men and women.

Prolonged bedrest provokes orthostatic hypotension and intolerance of upright posture. Limited data are available on the cardiovascular responses of older adults to head-up tilt following bedrest, with no studies examining the potential benefits of exercise to mitigate intolerance in this age group. This randomized controlled trial of head-down bedrest (HDBR) in 55- to 65-yr-old men and women investigated if exercise could avert post-HDBR orthostatic intolerance. Twenty-two healthy older adults (11 female) underwent a strict 14-day HDBR and were assigned to either an exercise (EX) or control (CON) group. The exercise intervention included high-intensity, aerobic, and resistance exercises. Head-up tilt-testing to a maximum of 15 minutes was performed at baseline (Pre-Bedrest) and immediately after HDBR (R1), as well as 6 days (R6) and 4 weeks (R4wk) later. At Pre-Bedrest, three participants did not complete the full 15 minutes of tilt. At R1, 18 did not finish, with no difference in tilt end time between CON (422 ± 287 s) and EX (409 ± 346 s). No differences between CON and EX were observed at R6 or R4wk. At R1, just 1 participant self-terminated the test with symptoms, while 12 others reported symptoms only after physiological test termination criteria were reached. Finishers on R1 protected arterial pressure with higher total peripheral resistance relative to Pre-Bedrest. Cerebral blood velocity decreased linearly with reductions in arterial pressure, end-tidal CO2, and cardiac output. High-intensity interval exercise did not benefit post-HDBR orthostatic tolerance in older adults. Multiple factors were associated with the reduction in cerebral blood velocity leading to intolerance.

Effects of Vitamin D Supplementation on Orthostatic Hypotension: Results From the STURDY Trial.

BACKGROUND: Vitamin D3 supplementation is considered a potential intervention to prevent orthostatic hypotension (OH) based on observational evidence that vitamin D levels are inversely associated with OH. With data from The Study to Understand Fall Reduction and Vitamin D in You (STURDY), a double-blind, randomized, response-adaptive trial, we determined if higher doses of vitamin D3 reduced risk of OH. METHODS: STURDY tested the effects of higher (1,000+ IU/day, i.e., 1,000, 2,000, and 4,000 IU/day combined) vs. lower-dose vitamin D3 (200 IU/day, comparison) on fall risk in adults ages 70 years and older with low serum 25-hydroxyvitamin D (25(OH)D, 10-29 ng/ml). OH was determined at baseline, 3, 12, and 24 months by taking the difference between seated and standing blood pressure (BP). OH was defined as a drop in systolic or diastolic BP of at least 20 or 10 mm Hg after 1 minute of standing. Participants were also asked about OH symptoms during the assessment and the preceding month. RESULTS: Among 688 participants (mean age 77 [SD, 5] years; 44% women; 18% Black), the mean baseline systolic/diastolic BP was 130 (19)/67 (11) mm Hg, serum 25(OH)D was 22.1 (5.1) ng/ml, and 2.8% had OH. There were 2,136 OH assessments over the maximum 2-year follow-up period. Compared with 200 IU/day, 1,000+ IU/day was not associated with seated, standing, or orthostatic BP, and it did not lower risk of OH or orthostatic symptoms. CONCLUSIONS: These findings do not support use of higher doses of vitamin D3 supplementation as an intervention to prevent OH. CLINICAL TRIALS REGISTRATION: Trial Number NCT02166333.

In adults with hypertension, more- vs. less-intensive BP-lowering treatment reduces orthostatic hypotension.

SOURCE CITATION: Juraschek SP, Hu JR, Cluett JL, et al. Effects of intensive blood pressure treatment on orthostatic hypotension: a systematic review and individual participant-based meta-analysis. Ann Intern Med. 2020. [Epub ahead of print.] 32909814.

Prevention and Management of Supine Hypertension in Patients With Orthostatic Hypotension.

BACKGROUND: Orthostatic hypotension (OH) is a potentially debilitating condition caused by dysfunction of the autonomic nervous system, which is essential for the physiologic response to orthostatic posture. In addition to OH, autonomic dysfunction may also be associated with the development of concurrent supine hypertension (SH). AREAS OF UNCERTAINTY: This paradoxical effect speaks to the complexity of the pathogenesis of autonomic disease and greatly complicates management of these patients. Clinicians are faced with a dilemma because aggressive treatment of orthostatic intolerance can worsen supine hypertension and attempts to control supine hypertension can worsen orthostatic intolerance. DATA SOURCES: Systematic review of the published literature. PREVENTION OF SUPINE HYPERTENSION: Patients should aim to avoid known stressors, perform physical maneuvers (eg, slowly getting up from bed, sleeping with head of bed elevated), manage underlying related conditions (eg, diabetes mellitus), and exercise. MANAGEMENT OF SUPINE HYPERTENSION: With failure of conservative management, patients may advance to pharmacologic therapy. It is important to understand the underlying suspected etiology of the syndrome of supine hypertension and OH (SH-OH) to select promising pharmacologic agents. This article reviews medical treatment options to work toward achieving a better quality of life for patients afflicted with this disease. Although clonidine and beta-blockers can be used to treat hypertension without causing significant hypotension, midodrine, pyridostigmine, and droxidopa may be helpful in preventing OH. CONCLUSION: The etiology and severity of autonomic dysfunction vary widely between patients, suggesting a need for an individualized treatment approach. Achieving perfect blood pressure control is not a realistic goal. Rather, treatment should be aimed at improving the patient's quality of life and decreasing their risk of injury and organ damage.

Plantar Myofascial Mobilization: Plantar Area, Functional Mobility, and Balance in Elderly Women: A Randomized Clinical Trial.

OBJECTIVE: The purpose of this study was to evaluate the effects of plantar myofascial mobilization (PMM) on the plantar area, balance, and functional mobility of elderly women. METHODS: In this randomized, single-blind, placebo-controlled clinical trial, elderly women with maintained independent orthostatism were recruited from the community and randomly separated into a PMM group (MG = 15), a placebo group (PG = 13), or a control group (control group = 14). Vigorous PMM and soft PMM were performed in the MG and PG, respectively, for 5 days with a rest day between each. The measures of plantar area, single leg stance test with open eye and closed eye, and timed up-and-go test were performed pre-PMM, immediately post-PMM, and on the last day of the protocol. The control group only underwent evaluation before and on the last day of the protocol. The sample size was calculated, and, for quantitative variables, a mixed analysis of variance was used for repeated measurements (split plot), followed by the Bonferroni post hoc test. The results were analyzed in 2 ways: 3 groups at 2 moments (pre, last day), and 2 groups at 3 moments (pre, post, last day). RESULTS: Forty-two elderly women with mean age of 69.03 ± 3.32 years were included in the study. The vigorous MMP showed a statistically significant increase in the plantar area of the right foot (3 groups: P = .49) and single leg stance test with open eye time (2 groups: P = .002; 3 groups: P = .001), and a decrease in the timed up-and-go time (2 groups: P = .04; 3 groups: P = .0001). CONCLUSION: The vigorous PMM showed increases of the plantar area and promoted beneficial effects on functional mobility and body balance.

Preventing Exercise-Associated Collapse Using Online Runner Education: A Randomized, Controlled Trial.

OBJECTIVE: To determine whether online exercise-associated collapse (EAC) prevention education decreases medical tent EAC visits among first-time marathoners. DESIGN: A prospective controlled study, with age- and sex-stratified randomization, evaluated rates of medical tent diagnosed EAC among runners randomized to the intervention group and intervention participants, compared with a control group. SETTING: Grandma's Marathon Medical Tent in Duluth, MN, June 2016. PARTICIPANTS: Runners in the 2016 Grandma's Marathon who never previously ran a marathon (n = 2943), randomized into control (n = 1482) and intervention (n = 1461) groups. Intervention participants opened the EAC prevention video (n = 590). INTERVENTIONS: Online EAC education included an introductory webpage and 5-minute professional video describing EAC and prevention. MAIN OUTCOME MEASURES: Medical tent visit with EAC diagnosis. RESULTS: Intervention participants had no decreased likelihood of EAC, compared with controls [odds ratio (OR), 0.88, 95% confidence interval (CI), 0.46-1.69]. Exercise-associated collapse occurred less frequently in those with longer race times (OR, 0.58, 95% CI, 0.43-0.79). Intervention participation was associated with longer race times (OR, 1.12, 95% CI, 1.10-1.23). CONCLUSIONS: Those opening the EAC prevention video and controls had similar EAC rates. Slower running speed was associated with lower EAC rates. Video viewing was a predictor of slower running pace.

Impaired orthostatic blood pressure stabilization and reduced hemoglobin in chronic kidney disease.

Impaired orthostatic blood pressure (BP) stabilization is prevalent in patients with chronic kidney disease (CKD) and is associated with adverse outcomes. We aimed to test the hypothesis that reduced hemoglobin is an important contributor to orthostatic intolerance in CKD in the present study. This study included 262 patients with non-dialysis-dependent CKD. Seated and standing BP was measured, and orthostatic BP reduction was calculated for both systolic BP (∆ SBP) and diastolic BP (∆ DBP). The association between orthostatic BP reduction and hemoglobin was determined by multiple linear regression models. We also performed mediation analysis to test to what extent the effect of renal dysfunction on impaired orthostatic BP stabilization can be explained by reduced hemoglobin. The mean age of the patients was 57.7 (±14.5) years, and 61.5% were male. Both ∆ SBP and ∆ DBP correlated negatively with estimated glomerular filtration rate (eGFR). With adjustment for age and sex, hemoglobin level was negatively associated with ∆ SBP (ß = -1.4, SE = 0.4, P < .001) and ∆ DBP (ß = -0.6, SE = 0.2, P = .009). The associations remained significant with further adjustment for additional covariates. When eGFR was introduced as a covariate, it did not eliminate the significance (both P < .05). The associations remained essentially unchanged in a sensitivity analysis excluding those with concurrent erythropoietin use. Mediation analysis demonstrated that reduced hemoglobin accounted for 35.4% (P = .004) of the effect of eGFR on ∆ SBP and 47.7% (P = .032) on ∆ DBP. Our study suggests that reduced hemoglobin is a potentially important contributor to the development of orthostatic hypotension in CKD.

High compression leg bandaging prevents seated postural hypotension among elderly hospitalized patients.

Postural hypotension (PH) is a very common and often symptomatic disorder among elderly hospitalized patients. Little is known about measures for preventing previously unknown PH in this population. We evaluated the effectiveness of high compression leg bandaging in preventing seated PH during the initial phase of ambulation, among elderly inpatients without a history of PH. We compared the occurrence of seated PH between patients who were bandaged (n = 100) and unbandaged (n = 100). The rate of seated PH was significantly lower in the bandaged than the unbandaged group (27% vs. 51%, p < 0.001, relative risk reduction 47%, and the number of patients needed to treat 4.2). On multivariate analysis, not wearing leg bandaging was one of the variables most significantly associated with eventual occurrence of PH (p = 0.002, odds ratio 2.65, and 95% confidence interval 1.42-4.97). We conclude that during ambulation of elderly inpatients, high compression leg bandaging is beneficial to prevent seated PH.

[Hypotensions in the elderly: Clinical and therapeutic features]. / Hypotensions du sujet âgé : aspects cliniques et thérapeutiques.

Hypotension and especially very low diastolic blood pressure could be an at-risk situation in very old and frail patients and in those with coronary heart disease. Chronic hypotension in people with heart failure is an indicator of poor prognosis and hinders the management of therapy. Orthostatic hypotension is a decrease in blood pressure>20mmHg for systolic and/or>10mmHg for diastolic within 3minutes after transition from supine to upright. Orthostatic hypotension may be symptomatic or not. The search for orthostatic hypotension is part of the clinical examination of elderly patients with hypertension, falling, diabetes and or polymedication. First intention treatment aims to correct modifiable modifying factors and to limit the circulatory consequences of orthostatism by elastic venous compression.

Effect of pre-operative methylprednisolone on orthostatic hypotension during early mobilization after total hip arthroplasty.

BACKGROUND: Orthostatic hypotension (OH) and intolerance (OI) are common after total hip arthroplasty (THA) and may delay early mobilization. The pathology of OH and OI includes a dysregulated post-operative vasopressor response, by a hitherto unknown mechanism. We hypothesized that OI could be related to the inflammatory stress response which is inhibited by steroid administration. Consequently, this study evaluated the effect of a pre-operative high-dose methylprednisolone on OH and OI early after THA. METHODS: Randomized, double-blind, placebo-controlled study in 59 patients undergoing elective unilateral THA with spinal anesthesia and a standardized multimodal analgesic regime. Patients were allocated (1 : 1) to pre-operative intravenous (IV) methylprednisolone (MP) 125 mg or isotonic saline (C). OH, OI and cardiovascular responses to sitting and standing were evaluated using a standardized mobilization protocol pre-operatively, 6, and 24 h after surgery. Systolic and diastolic arterial pressure and heart rate were measured non-invasively (Nexfin® ). The systemic inflammation was monitored by the C-reactive protein (CRP) response. RESULTS: At 6 h post-operatively, 11 (38%) versus 11 (37%) patients had OH in group MP and group C, respectively (RR 1.02 (0.60 to 1.75; P = 1.00)), whereas OI was present in 9 (31%) versus 13 (43%) patients (RR 0.76 (0.42 to 1.36; P = 0.42)), respectively. At 24 h post-operatively, the prevalence of OH and OI did not differ between groups, though CRP levels were significantly reduced in group MP (P < 0.001). CONCLUSION: Pre-operative administration of 125 mg methylprednisolone IV did not reduce OH or OI compared with placebo despite a reduced inflammatory response.

The effect of oral intake during the immediate pre-colonoscopy time period on volume depletion in patients who receive sodium picosulfate.

Sodium picosulfate, used in combination with magnesium oxide and citric acid for bowel cleansing, can result in dehydration. We investigated whether enhanced carbohydrate fluid intake pre-colonoscopy could mitigate this effect. We enrolled 398 elective colonoscopy patients in a prospective, controlled, single-blinded study. The control group (n=194) fasted routinely (minimum seven hours) whilst the treatment group (n=197) drank 1,200 ml carbohydrate solution leading up to admission (up until two hours pre-colonoscopy). On admission a patient survey was completed, and urine specific gravity obtained. Supine blood pressure and pulse rate were measured, and repeated within three minutes of standing. The carbohydrate group had reduced symptoms and signs of dehydration, including thirst (34% versus 65%, P <0.001), dry mouth (45% versus 59%, P=0.008), dizziness (10% versus 20%, P=0.010), lower mean urine specific gravity (1.007 versus 1.017, P <0.001), lower incidence of orthostatic hypotension (2.6% versus 11%, P <0.001), and lower mean erect pulse rate (78 versus 81 /minute, P=0.047). The postural change in systolic blood pressure was less in the treatment group (mean -0.4 mmHg, median -1 mmHg [interquartile range, IQR -7 to 7]) than in the control group (mean -4.1 mmHg, median -1 mmHg [IQR -12 to 3], P=0.028). These findings indicate that hydration with carbohydrate solution in patients taking sodium picosulfate has clinical benefit.

[Hypertension en orthostatic hypotension during use of monoamine oxidase (MAO) inhibitors]. / Hypertensie en orthostatische hypotensie bij gebruik van monoamine-oxidase(MAO)-remmers1.

Monoamine oxidase (mao) inhibitors are antidepressants with potentially severe side-effects. For this reason, the registration of this drug was suspended for some time when safer alternatives became available. However, mao inhibitors can be very effective in cases where depression has proved to be treatment resistant. Consequently, last year tranylcypromine was re-registered for use in the Netherlands. Since mao inhibitors have been used only sporadically in the Netherlands over the last few years, health professionals have only limited knowledge about the side-effects. On the basis of a recent case, we discuss the two most important side-effects of using mao inhibitors, namely hypertension and orthostatic hypotension. We discuss the possible causes and suggest ways on which these two side-effects can be prevented, or treated, should they arise.

Standing Up Slowly Antagonises Initial Blood Pressure Decrease in Older Adults with Orthostatic Hypotension.

BACKGROUND: Orthostatic hypotension (OH) is common in older adults and associated with increased morbidity and mortality, loss of independence and high health-care costs. Standing up slowly is a recommended non-pharmacological intervention. However, the effectiveness of this advice has not been well studied. OBJECTIVES: The aim of this study was to investigate whether standing up slowly antagonises posture-related blood pressure (BP) decrease in a clinically relevant population of geriatric outpatients. METHODS: In this cross-sectional study, 24 community-dwelling older adults referred to a geriatric outpatient clinic and diagnosed with OH were included. BP was measured continuously during 3 consecutive transitions from supine to standing position during normal, slow and fast transition. RESULTS: The relative BP decrease at 0-15 s after slow transition was significantly lower than after normal transition (p = 0.003 for both systolic BP and diastolic BP) and fast transition (p = 0.045 for systolic BP; diastolic BP: non-significant). The relative diastolic BP decrease at 60-180 s after normal transition was significantly lower than after fast transition (p = 0.029). CONCLUSION: Standing up slowly antagonises BP decrease predominantly during the first 15 s of standing up in a clinically relevant population of geriatric outpatients diagnosed with OH. Results support the non-pharmacological intervention in clinical practice to counteract OH.

Droxidopa for orthostatic hypotension: a systematic review and meta-analysis.

OBJECTIVE: The systematic review and meta-analysis aims to determine the efficacy and safety of droxidopa in the treatment of orthostatic hypotension, following its recent approvals in the United States. METHODS: MEDLINE, EMBASE, PubMed, Cochrane Controlled Trials Register, Web of Science, ProQuest, and the WHO Clinical Trials Registry were searched. Studies were included if they randomized adults with orthostatic hypotension to droxidopa or to control, and outcomes related to symptoms, daily activity, blood pressure, or adverse events. Data were extracted independently by two reviewers. Risk of bias was judged against the Cochrane risk of bias tool and quality of evidence measured using Grading of Recommendations Assessment, Development and Evaluation criteria. A fixed-effects model was used for pooled analysis. RESULTS: Of 224 identified records, four studies met eligibility, with a pooled sample size of 494. Study duration was between 1 and 8 weeks. Droxidopa was effective at reducing dizziness [mean difference -0.97 (95% confidence interval -1.51, -0.42)], overall symptoms [-0.52 (-0.98, -0.06)] and difficulty with activity [-0.86 (-1.34, -0.38)]. Droxidopa was also effective at improving standing SBP [3.9 (0.1, 7.69)]. Rates of adverse events were similar between droxidopa and control groups, including supine hypertension [odds ratio 1.93 (0.87, 4.25)]. CONCLUSION: Droxidopa is well tolerated and effective at reducing the symptoms associated with neurogenic orthostatic hypotension without increasing the risk of supine hypertension. REGISTRATION: PROSPERO ID CRD42015024612.

Orthostatic Hypotension and Elevated Resting Heart Rate Predict Low-Energy Fractures in the Population: The Malmö Preventive Project.

BACKGROUND: Autonomic disorders of the cardiovascular system, such as orthostatic hypotension and elevated resting heart rate, predict mortality and cardiovascular events in the population. Low-energy-fractures constitute a substantial clinical problem that may represent an additional risk related to such autonomic dysfunction. AIMS: To test the association between orthostatic hypotension, resting heart rate and incidence of low-energy-fractures in the general population. METHODS AND RESULTS: Using multivariable-adjusted Cox regression models we investigated the association between orthostatic blood pressure response, resting heart rate and first incident low-energy-fracture in a population-based, middle-aged cohort of 33 000 individuals over 25 years follow-up. The median follow-up time from baseline to first incident fracture among the subjects that experienced a low energy fracture was 15.0 years. A 10 mmHg orthostatic decrease in systolic blood pressure at baseline was associated with 5% increased risk of low-energy-fractures (95% confidence interval 1.01-1.10) during follow-up, whereas the resting heart rate predicted low-energy-fractures with an effect size of 8% increased risk per 10 beats-per-minute (1.05-1.12), independently of the orthostatic response. Subjects with a resting heart rate exceeding 68 beats-per-minute had 18% (1.10-1.26) increased risk of low-energy-fractures during follow-up compared with subjects with a resting heart rate below 68 beats-per-minute. When combining the orthostatic response and resting heart rate, there was a 30% risk increase (1.08-1.57) of low-energy-fractures between the extremes, i.e. between subjects in the fourth compared with the first quartiles of both resting heart rate and systolic blood pressure-decrease. CONCLUSION: Orthostatic blood pressure decline and elevated resting heart rate independently predict low-energy fractures in a middle-aged population. These two measures of subclinical cardiovascular dysautonomia may herald increased risks many years in advance, even if symptoms may not be detectable. Although the effect sizes are moderate, the easily accessible clinical parameters of orthostatic blood pressure response and resting heart rate deserve consideration as new risk predictors to yield more accurate decisions on primary prevention of low-energy fractures.

[Orthostatic hypotension in elderly: a case-control study]. / Hypotension orthostatique chez le sujet âgé : une étude cas-témoins.

Orthostatic hypotension is common in the elderly and is often associated with increased morbidity and mortality. Compression bandages are recommended as a first-line treatment but there is little evidence of their efficacy in literature. A case-control study involving 52 patients was carried out to test the efficacy of the bandages. In the group with orthostatic hypotension, compression improved the symptoms without correcting the blood pressure readings.

Effect of discontinuation of antihypertensive medication on orthostatic hypotension in older persons with mild cognitive impairment: the DANTE Study Leiden.

BACKGROUND: the relationship between antihypertensive medication and orthostatic hypotension in older persons remains ambiguous, due to conflicting observational evidence and lack of data of clinical trials. OBJECTIVE: to assess the effect of discontinuation of antihypertensive medication on orthostatic hypotension in older persons with mild cognitive impairment. METHODS: a total of 162 participants with orthostatic hypotension were selected from the Discontinuation of Antihypertensive Treatment in Elderly people (DANTE) Study. This randomised clinical trial included community-dwelling participants aged ≥75 years, with mild cognitive impairment, using antihypertensive medication and without serious cardiovascular disease. Participants were randomised to discontinuation or continuation of antihypertensive treatment (ratio 1:1). Orthostatic hypotension was defined as a drop of at least 20 mmHg in systolic blood pressure and/or 10 mmHg in diastolic blood pressure on standing from a seated position. Outcome was the absence of orthostatic hypotension at 4-month follow-up. Relative risks (RR) were calculated by intention-to-treat and per-protocol analyses. RESULTS: at follow-up, according to intention-to-treat analyses, of the 86 persons assigned to discontinuation of antihypertensive medication, 43 (50%) were free from orthostatic hypotension, compared with 29 (38%) of the 76 persons assigned to continuation of medication [RR 1.31 (95% confidence interval (CI) 0.92-1.87); P = 0.13]. Per-protocol analysis showed that recovery from orthostatic hypotension was significantly higher in persons who completely discontinued all antihypertensive medication (61%) compared with the continuation group (38%) [RR 1.60 (95% CI 1.10-2.31); P = 0.01]. CONCLUSION: in older persons with mild cognitive impairment and orthostatic hypotension receiving antihypertensive medication, discontinuation of antihypertensive medication may increase the probability of recovery from orthostatic hypotension.

Reconstructive surgery and patients with spinal cord injury: Perioperative considerations for the plastic surgeon.

BACKGROUND: Patients with spinal cord injury (SCI) requiring reconstructive surgery, particularly for pressure ulcers, are ubiquitous in Plastic and Reconstructive Surgery practices. Much of the current literature focuses on operative techniques, antibiotic indications, sitting protocols, and dressing and bedding choices. METHODS: This paper reviews normal neuroanatomy, outlines changes in neurophysiology observed in spinal cord injury, and addresses concepts related to perioperative care that are highly relevant but often under-emphasised. RESULTS: Vascular disturbances such as autonomic dysreflexia and orthostatic hypotension are dangerous phenomena occurring in this patient population that, if not properly recognised and treated, may result in complications such as haematoma, flap loss, inadequate tissue perfusion, and death. The management of spasticity, deep venous thrombosis, and perioperative pain are also relevant and discussed in this paper. CONCLUSION: A basic understanding of these concepts is essential for the Plastic Surgeon involved in the care of patients with SCI and pressure ulcers, particularly before and after debridement or reconstruction.

Oral Midodrine Hydrochloride for Prevention of Orthostatic Hypotension during Early Mobilization after Hip Arthroplasty: A Randomized, Double-blind, Placebo-controlled Trial.

BACKGROUND: Early postoperative mobilization is essential for rapid recovery but may be impaired by orthostatic intolerance (OI) and orthostatic hypotension (OH), which are highly prevalent after major surgery. Pathogenic mechanisms include an insufficient postoperative vasopressor response. The oral α-1 agonist midodrine hydrochloride increases vascular resistance, and the authors hypothesized that midodrine would reduce the prevalence of OH during mobilization 6 h after total hip arthroplasty relative to placebo. METHODS: This double-blind, randomized trial allocated 120 patients 18 yr or older and scheduled for total hip arthroplasty under spinal anesthesia to either 5 mg midodrine hydrochloride or placebo orally 1 h before mobilization at 6 and 24 h postoperatively. The primary outcome was the prevalence of OH (decrease in systolic or diastolic arterial pressures of > 20 or 10 mmHg, respectively) during mobilization 6 h after surgery. Secondary outcomes were OI and hemodynamic responses to mobilization at 6 and 24 h. RESULTS: At 6 h, 14 (25%; 95% CI, 14 to 38%) versus 23 (39.7%; 95% CI, 27 to 53%) patients had OH in the midodrine and placebo group, respectively, relative risk 0.63 (0.36 to 1.10; P = 0.095), whereas OI was present in 15 (25.0%; 15 to 38%) versus 22 (37.3%; 25 to 51%) patients, relative risk 0.68 (0.39 to 1.18; P = 0.165). At 24 h, OI and OH prevalence did not differ between groups. CONCLUSIONS: Preemptive use of oral 5 mg midodrine did not significantly reduce the prevalence of OH during early postoperative mobilization compared with placebo. However, further studies on dose and timing are warranted since midodrine is effective in chronic OH conditions.