Postoperative orthostatic intolerance following fast-track unicompartmental knee arthroplasty: incidence and hemodynamics-a prospective observational cohort study.

BACKGROUND: Early postoperative mobilization is essential for early functional recovery but can be inhibited by postoperative orthostatic intolerance (OI). Postoperative OI is common after major surgery, such as total knee arthroplasty (TKA). However, limited data are available after less extensive surgery, such as unicompartmental knee arthroplasty (UKA). We, therefore, investigated the incidence of OI as well as cardiovascular and tissue oxygenation responses during early mobilization after UKA. METHODS: This prospective single-centre observational study included 32 patients undergoing primary UKA. Incidence of OI and cardiovascular and tissue oxygenation responses during mobilization were evaluated preoperatively, at 6 and 24 h after surgery. Perioperative fluid balance, bleeding, surgery duration, postoperative hemoglobin, pain during mobilization and opioid usage were recorded. RESULTS: During mobilization at 6 h after surgery, 4 (14%, 95%CI 4-33%) patients experienced OI; however, no patients terminated the mobilization procedure prematurely. Dizziness and feeling of heat were the most common symptoms. OI was associated with attenuated systolic and mean arterial blood pressure responses in the sitting position (all p < 0.05). At 24 h after surgery, 24 (75%) patients had already been discharged, including three of the four patients with early OI. Only five patients were available for measurements, two of whom experienced OI; one terminated the mobilization procedure due to intolerable symptoms. We observed no statistically significant differences in perioperative fluid balance, bleeding, surgery duration, postoperative hemoglobin, pain, or opioid usage between orthostatic intolerant and tolerant patients. CONCLUSIONS: The incidence of orthostatic intolerance after fast-track unicompartmental knee arthroplasty is low (~ 15%) and is associated with decreased orthostatic pressure responses. Compared to the previously described orthostatic intolerance incidence of ~ 40% following total knee arthroplasty, early orthostatic intolerance is uncommon after unicompartmental knee arthroplasty, suggesting a procedure-specific component. TRIAL REGISTRATION: Prospectively registered at ClinicalTrials.gov; registration number: NCT04195360, registration date: 13.12.2019.

Prevalence and associated factors of postoperative orthostatic intolerance at University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia, 2022: cross sectional study.

BACKGROUND: Postoperative orthostatic intolerance is an inability to maintain an upright position because of symptoms of cerebral hypoperfusion. It is a common problem in the early postoperative period and hinders early mobilization, however, there is limited information about factors associated with it. Thus, the main aim of this study was to determine the prevalence and identify factors associated with postoperative orthostatic intolerance. METHOD: Hospital based cross-sectional study was conducted from April 08 to July 20, 2022, at University of Gondar comprehensive Specialized Hospital. A semi-structured questionnaire containing sociodemographic variables and perioperative factors related to anesthesia and surgery was used for data collection. The presence of postoperative orthostatic intolerance during the first ambulation was evaluated with a standardized symptom checklist which contains symptoms of orthostatic intolerance. Binary logistic regression analysis was performed to assess factors associated with postoperative orthostatic intolerance. In multivariable regression, variables with P-value < 0.05 were considered statistically significant. RESULT: A total of 420 patients were included in this study with a response rate of 99.06%. Postoperative orthostatic intolerance was experienced in 254 (60.5%) participants. Being female (AOR = 2.27; 95% CI = 1.06-4.86), low BMI (AOR = 0.79; 95% CI = 0.71-0.95), ASA II and above (AOR = 3.34; 95% CI = 1.34-8.28), low diastolic blood pressure (AOR = 0.82; 95% CI = 0.88-0.99), general anesthesia (AOR = 3.26, 95% CI = 1.31-8.12), high intraoperative blood lose (AOR = 0.93, 95% CI = 0.88-0.99), high postoperative fluid intake (AOR = 2.09, 95% CI = 1.23-3.55), pain before ambulation (AOR = 1.99, 95% CI = 1.28-3.11) and pain during ambulation (AOR = 1.82, 95% CI = 1.23-2.69) were the significant factors associated with orthostatic intolerance. CONCLUSION: Our study revealed that postoperative orthostatic intolerance was experienced in nearly two-thirds of participants. During the time of ambulation, assessing patients for the presence of orthostatic intolerance is necessary to reduce the adverse effects of postoperative OI. In addition, maintaining preoperative normotension, reducing intraoperative blood loss and optimizing postoperative pain control is recommended to reduce the risk of postoperative orthostatic intolerance.

Orthostatic Intolerance-Type Events Following Hip and Knee Arthroplasty: A Systematic Review and Meta-Analysis.

BACKGROUND: Orthostatic intolerance (OI)-type events following hip and knee arthroplasty increase the risk of falls, hospital length of stay, and health-care costs. There is a limited understanding of the incidence of and risk factors for OI-type events in patients during the acute hospital stay. Our aim was to systematically review the incidence of and risk factors for OI-type events during the acute hospital stay following hip and knee arthroplasty. METHODS: A systematic review and meta-analysis of studies that investigated the incidence of and risk factors for OI-type events was undertaken. A comprehensive search was performed in MEDLINE, Embase, and CINAHL from their inception to October 2021. The methodological quality of identified studies was assessed using the modified version of the Quality in Prognosis Studies (QUIPS) tool. RESULTS: Twenty-one studies (14,055 patients) were included. The incidence was 2% to 52% for an OI event, 1% to 46% for orthostatic hypotension, and 0% to 18% for syncope/vasovagal events. Two studies reported female sex, high peak pain levels (>5 out of 10) during mobilization, postoperative use of gabapentin, and the absence of postoperative intravenous dexamethasone as risk factors. There was no consensus on the definition and assessment of an OI-type event. CONCLUSIONS: OI-type events are common during the acute hospital stay following hip and knee arthroplasty, and 4 risk factors have been reported for OI-type events. High-quality prospective cohort studies are required to systematically and reliably determine the incidence of and risk factors for OI-type events. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Orthostatic intolerance after fast-track knee arthroplasty: Incidence and hemodynamic pathophysiology.

BACKGROUND: Early postoperative mobilization can be hindered by orthostatic intolerance (OI) due to failed orthostatic cardiovascular regulation. The underlying mechanisms are not fully understood and specific data after total knee arthroplasty (TKA) are lacking. Therefore, we evaluated the incidence of OI and the cardiovascular response to mobilization in fast-track TKA. METHODS: This prospective observational cohort study included 45 patients scheduled for primary TKA in spinal anesthesia with a multimodal opioid-sparing analgesic regime. OI and the cardiovascular response to sitting and standing were evaluated with a standardized mobilization procedure preoperatively, and at 6 and 24 h postoperatively. Hemodynamic variables were measured non-invasively (LiDCO™ Rapid). Perioperative bleeding, fluid balance, surgery duration, postoperative hemoglobin, opioid use, and pain during mobilization were recorded. RESULTS: Eighteen (44%) and 8 (22%) patients demonstrated OI at 6 and 24 h after surgery, respectively. Four (10%) and 2 (5%) patients experienced severe OI and terminated the mobilization procedure prematurely. Dizziness was the most common OI symptom during mobilization at 6 h. OI was associated with decreased orthostatic responses in systolic, diastolic, mean arterial pressures, and heart rate (all p < .05), while severe OI patients demonstrated impaired diastolic, mean arterial pressures, heart rate, and cardiac output responses (all p < .05). No statistically significant differences in perioperative bleeding, fluid balance, surgery duration, postoperative hemoglobin, pain, or opioid use were observed between orthostatic tolerant and intolerant patients. CONCLUSION: Early postoperative OI is common following fast-track TKA. Pathophysiologic mechanisms include impaired orthostatic cardiovascular responses. The progression to severe OI symptoms appears to be primarily due to inadequate heart rate response.

The impact of orthostatic intolerance on early ambulation following abdominal surgery in an enhanced recovery programme.

BACKGROUND: The prevalence of orthostatic intolerance on the day of surgery is more than 50% after abdominal surgery. The impact of orthostatic intolerance on ambulation on the day of surgery has been little studied. We investigated orthostatic intolerance and walking ability after colorectal and bariatric surgery in an enhanced recovery programme. METHODS: Eighty-two patients (colorectal: n = 46, bariatric n = 36) were included and analysed in this prospective study. Walk tests for 2 min (2-MWT) and 6 min (6-MWT) were performed before and 24 h after surgery, and 3 h after surgery for 2-MWT. Orthostatic intolerance characterised by presyncopal symptoms when rising was recorded at the same time points. Multivariate binary logistic regressions modelling the probability of orthostatic intolerance and walking inability were performed taking into account potential risk factors. RESULTS: Prevalence of orthostatic intolerance and walking inability was, respectively, 65% and 18% 3-hour after surgery. The day after surgery, patients' performance had greatly improved: approximately 20% of the patients experienced orthostatic intolerance, whilst only 5% of the patients were unable to walk. Adjusted binary logistic regressions demonstrated that age (p = .37), sex (p = .39), BMI (p = .74), duration of anaesthesia (p = .71) and type of surgery (p = .71) did not significantly influence walking ability. CONCLUSION: Our study confirms that orthostatic intolerance was frequent (~ 60%) 3-hour after abdominal surgery but prevented a 2-MWT only in ~20% of patients. No risk factors for orthostatic intolerance and walking inability were evidenced.

Chronic Fatigue Syndrome and Cardiovascular Disease: JACC State-of-the-Art Review.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a medically unexplained illness characterized by severe fatigue limiting normal daily activities for at least 6 months accompanied by problems with unrefreshing sleep, exacerbation of symptoms following physical or mental efforts (postexertional malaise [PEM]), and either cognitive reports or physiological evidence of orthostatic intolerance in the form of either orthostatic tachycardia and/or hypocapnia. Although rarely considered to have cardiac dysfunction, ME/CFS patients frequently have reduced stroke volume with a significant inverse relation between cardiac output and PEM severity. Magnetic resonance imaging of ME/CFS patients compared with normal control subjects found significantly reduced stroke, end-systolic, and end-diastolic volumes together with reduced end-diastolic wall mass. Another cardiovascular abnormality is reduced nocturnal blood pressure assessed by 24-hour monitoring. Autonomic dysfunction is also frequently observed with postural orthostatic tachycardia and/or hypocapnia. Two consecutive cardiopulmonary stress tests may provide metabolic data substantiating PEM.

Orthostatic intolerance after bariatric surgery: A systematic review and meta-analysis.

There have been increased reports of orthostatic intolerance post-bariatric surgery. However, the prevalence, pathophysiology and long-term outcomes have not been well described. Therefore, we sought to summarize evidence of orthostatic intolerance after bariatric surgery. We conducted a systematic review using PubMed, Scopus, CINAHL, Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials (CENTRAL) to identify relevant articles from the date of inception until 1st April 2020. Study selection, data extraction and quality assessment of the included studies were performed independently by two reviewers. The findings of the included studies were narratively reported. When feasible, a meta-analysis was done to summarize the relevant results. We included 20 studies (n = 19 843 participants) reporting findings of 12 prospective cohort studies, 5 retrospective cohort studies, 2 cross-sectional studies and one randomized controlled trial. The 5-year cumulative incidence of orthostatic intolerance was 4.2% (one study). Common clinical presentations of orthostatic intolerance were lightheadedness, dizziness, syncope and palpitation. The pooled data suggested improvement in overall cardiac autonomic function (sympathetic and parasympathetic) post-bariatric surgery. In addition, a significant systolic blood pressure drop may reflect a reset of the balance between the sympathetic and parasympathetic nervous systems after weight loss in the pooled analysis. Existing literature on orthostatic intolerance post-bariatric surgeries was limited or of low quality, and larger studies are needed to know the true incidence of orthostatic intolerance post-bariatric surgeries and the pathophysiology. We found one study reporting the 5-years cumulative incidence of orthostatic intolerance post-bariatric surgeries as only 4.2%. This could challenge the idea of increased orthostatic intolerance prevalence post-bariatric surgeries. Registration The review protocol was registered at the International Prospective Register of Systemic Reviews PROSPERO (CRD42020170877).

Early Cerebral Hypoperfusion in Patients with Orthostatic Intolerance Without Tachycardia During Head-Up Tilt Test is Independent of Vasovagal Response.

BACKGROUND: Cerebral hypoperfusion before syncope has been shown in patients with chronic orthostatic intolerance (OI) without tachycardia, but it is unknown if an initial decrease of cerebral blood flow velocity (CBFv) could be related to the vasovagal response (VVR) to head-up tilt test (HUTT). OBJECTIVE: The objective of the study was to compare cardiovascular, cerebrovascular, and autonomic variables during HUTT in OI patients with or without a VVR. METHODS: We included 74 subjects (58% female, mean age 33 ± 12 years) who underwent a 30-min HUTT and were divided into three groups: OI with VVR positive (VVR+), OI without VVR negative (VVR-), and asymptomatic healthy subjects with negative HUTT (control group). Cardiovascular, cerebrovascular, and autonomic variables were assessed beat-to-beat during HUTT with a Task Force monitor and a trans-cranial Doppler. Mean values were evaluated at baseline and throughout the first 10 min of tilting. RESULTS: Cardiovascular variables were similar in the three groups. Systolic, diastolic, and mean CBFv were similar in VVR+ and VVR-, but both groups had lower CBFv than the control group. Systolic and diastolic CBFv decreased from baseline since min 1 in VVR+ and VVR- and since min 5 in the control group. The mean CBFv had a significant decrease since min 1 compared to baseline in all groups. Spectral indices of heart rate and blood pressure variability showed a similar autonomic response to HUTT in all groups. CONCLUSION: Patients with chronic OI without tachycardia have early postural cerebral hypoperfusion, regardless of the VVR during HUTT.

Orthostatic Intolerance after Bariatric Surgery: a Systematic Review.

Predisposing factors of new-onset orthostatic intolerance (OI) after bariatric surgery (BS) are unknown. The purpose of this study is to summarize current existing data on new-onset OI after BS. Materials and methods were considered for a search of articles that were published by the 30th of July 2020. A systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and in line with the protocol agreed by all authors was conducted. Of the 604 initially identified articles, four studies were found to match the established criteria and were extracted for eligibility. 83.3% were female. Hypertension, type 2 diabetes mellitus, and obstructive sleep apnea syndrome were the most frequently reported comorbidities. Surgical intervention such as revision, conversion, or reversal was not documented in these studies. Awareness of this issue must be raised due to the possibility of reduced quality of life and the risk of syncope.

The Effect of Orthostatic Hypotension Detected Pre-Operatively on Post-Operative Outcome.

BACKGROUND: Exacerbation of or new onset orthostatic hypotension in perioperative patients can occur. There is complex underlying pathophysiology with further derailment likely caused by acute cardiovascular changes associated with surgery. The implications for post-operative recovery are unclear, particularly in frail and older patients. We retrospectively explored patient notes for evidence of post-operative orthostatic intolerance in relation to pre-operative orthostatic hypotension. METHODS: Supine and 1-minute and 3-minute standing blood pressure measures obtained from adult patients before mainly general, orthopedic or uro/gynecology surgery were compared to post-operative outcome, specifically, evidence in patient notes about falls, feeling dizzy/unsteady and/or fearful to stand. Orthostatic hypotension was defined as a 20 mmHg or more and/or 10 mmHg or more fall in systolic and diastolic blood pressure, respectively, within ~3 minutes of standing after lying supine for an electrocardiogram. RESULTS: Whilst all patients included had a 1-minute standing blood pressure assessment (N = 170), 3-minute assessment was performed less commonly (N = 113). Nevertheless, one-quarter (23.5%; N = 40) of 170 patients had pre-operative orthostatic hypotension. This was not clearly explained by cardiac or neurological disease or by common medications, but did occur more frequently in older patients and in those aged 65 years or more with higher clinical frailty scale scores. The COVID-19 pandemic reduced the number of patients progressing to surgery within the planned study timescale (N = 143/170; 84.1%). Nevertheless, patients with orthostatic hypotension stayed longer in hospital post-operatively and were more likely to have an episode of fall, unsteadiness and/or dizziness documented (un-prompted) in their notes. CONCLUSIONS: These data provide further impetus for research into modifiable perioperative risk factors associated with orthostatic hypotension. These risks are not confined to those with a pre-existing dysautonomia diagnosis.

Risks of adverse events in patients with orthostatic intolerance undergoing surgery with general anesthesia.

INTRODUCTION: Orthostatic intolerance (OI) is a group of disorders characterized by symptoms that occur upon standing and resolve with recumbence. Although well established but not widely recognized, these diagnoses may create uncertainty for clinicians dealing with a patient affected by OI and requiring a surgical procedure. OBJECTIVES: To determine the rate of intra- and postoperative major adverse events in patients with OI undergoing surgery with general anesthesia. METHODS: The study was a retrospective study of patients with orthostatic intolerance who underwent surgery requiring general anesthesia from 1 January 2000 to 31 December 2018. RESULTS: A total 171 patients with OI underwent 190 surgeries. In patients with POTS and orthostatic-induced VVS, there were no major significant adverse events. There was one episode of AVNRT in a patient with POTS and one episode of bradycardia secondary to vasovagal reflex in a patient with orthostatic-induced VVS. Moreover, there were 13 (6.8%) episodes of postoperative hypotension. However, the majority of these episodes were related to bleeding, volume depletion or sepsis. All cases of hypotension responded well to appropriate therapy. In patients with OH, the rate of postoperative major adverse cardiac events was 4.7%, and the 30-day mortality rate was 6.1%. This is not significantly different from the calculated risk for patients without OH. There were no myocardial infarctions or deaths at 30 days in patients with POTS or orthostatic-induced VVS. CONCLUSION: Patients with OI may not experience higher rates of perioperative complications compared with patients without OI syndromes.

Symptom Score: A New Instrument to Assess Orthostatic Intolerance in Children and Adolescents.

OBJECTIVE: To develop an orthostatic intolerance symptom scoring system to assess orthostatic intolerance and then to compare the symptom score among different head-up tilt test responses. METHODS: 272 subjects (5-18 years) presenting with orthostatic intolerance symptoms finished questionnaire and head-up tilt test. According to head-up tilt test hemodynamic responses, the subjects were divided into head-up tilt test negative, vasovagal syncope, and postural tachycardia syndrome groups. RESULTS: We built up a symptom score according to the frequency of dizziness, headache, blurred vision, palpitations, chest discomfort, gastrointestinal symptoms, profuse perspiration, and syncope. The median score in postural tachycardia syndrome subjects was highest. A score of 2.5 for predicting vasovagal syncope yielded a sensitivity of 75.0% and specificity of 50.3%, a score of 5.5 for predicting postural tachycardia syndrome yielded a sensitivity of 69.7% and specificity of 72.0%. Furthermore, the median score in postural tachycardia syndrome subjects was significantly higher than that in head-up tilt test negative subjects with heart rate increment of 30-39 beats/min (P < .01). CONCLUSIONS: This suggests that the symptom score has some predictive value in head-up tilt test results, which can be served as a preliminary assessment instrument.

Screening for Orthostatic Intolerance in Symptomatic Children Presenting for Concussion Care.

Following concussion, children often experience nonspecific symptoms that overlap with those of other common pediatric conditions, including orthostatic intolerance (OI). The primary goal of this study was to evaluate OI in youth presenting for clinical care for concussion and reporting symptoms frequently observed in OI. Eighty-two of 114 patients aged 10 to 22 years endorsed symptoms based on 8 screening questions, and 24 of those 82 patients met criteria for OI based on an active standing test. No screening question generated clinically useful likelihood ratios for predicting OI. The prevalence of OI in this cohort is considerably higher than estimates in the general pediatric population, suggesting a link between concussion and OI. Future work is needed to evaluate the best method of testing for OI, the natural history of OI symptoms in youth with concussion, and the response to intervention in children with both concussion and OI.

A cluster analysis of serious adverse event reports after human papillomavirus (HPV) vaccination in Danish girls and young women, September 2009 to August 2017.

BackgroundSuspected adverse events (AE) after human papillomavirus (HPV) vaccines include postural orthostatic tachycardia syndrome (POTS), chronic fatigue syndrome (CFS), complex regional pain syndrome (CRPS) and symptoms including headache and orthostatic intolerance.AimWe aimed to identify phenotypes of AEs after HPV vaccination, defined as patterns of AE terms (signs, symptoms, diagnoses), and to evaluate if identified phenotypes reflected previously suspected symptomatology or heightened public concerns over HPV vaccine safety since 1 January 2015.MethodsWe conducted a retrospective observational study using latent class cluster analysis of all serious AE reports (n = 963) reported by females residing in Denmark between September 2009 and August 2017. Resulting clusters were characterised according to AE terms associated with POTS, CFS and CRPS before (September 2009-December 2014) and during (January 2015-August 2017) a time of heightened media activity regarding HPV vaccines.ResultsFour clusters of AE reports were distinguished. The most common symptoms were fatigue, dizziness and headache but their frequency varied among clusters. The majority of reports in one cluster were submitted during a period of heightened media activity, including an anomalous spike in submissions in December 2015; a high proportion of these reports included the symptoms cognitive disorder (78%), abdominal pain (77%), dysuria (60%) and sleep disorder (60%).ConclusionsNon-specific symptoms including headache, fatigue and dizziness feature prominently in serious AE reports from females in Denmark. Our analysis identified a cluster of reports, likely media stimulated, with a focus on symptoms of CFS and POTS.

Orthostatic intolerance in enhanced recovery laparoscopic colorectal resection.

BACKGROUND: Orthostatic hypotension (OH) and intolerance (OI) are common findings in the early postoperative period after major surgery and may delay early mobilization. The mechanism of impaired orthostatic competence and OI symptoms is not fully understood, and specific data after colorectal surgery with well-defined perioperative care regimens and mobilization protocols are lacking. The aim of this study was to investigate the prevalence, possible risk factors and the impact of OI in patients undergoing elective minimal invasive colorectal cancer resection. METHODS: A prospective single-centre study with an optimal enhanced recovery program and multimodal analgesic treatment. OI and OH were evaluated using a well-defined mobilization protocol preoperatively and 6 hour and 24 hour postoperatively. RESULTS: A total of 100 patients were included in the data analysis. The overall median length of stay was 3 days (1-38). OI was observed in 53% of the patients 6 hour postoperatively and in 24% at 24 hour. OI at 6 hour postoperatively was associated with younger age, lower BMI, and female gender. At 24 hour postoperatively, female gender and ASA class >1 was associated with OI. Opioid consumption and intravenous fluid during the first 24 hour was not associated with OI. Postoperative complications were equally observed between patients with and without OI. Although not statistically significant, patients with OI at 24 hour postoperatively had prolonged LOS (mean 4.0 vs 7.5 days, P = 0.069) compared with patients without OI. CONCLUSION: Postoperative orthostatic intolerance is a common problem during the first 24 hour following laparoscopic colorectal resection and may be followed by delayed recovery.

Changes in the augmentation index and postoperative orthostatic intolerance in orthopedic surgery: a prospective cohort study.

BACKGROUND: Postoperative orthostatic intolerance (OI) can be a major obstacle to early ambulation and its determinants are poorly understood. We aimed to study postoperative changes in vascular tone and their potential association with OI in various orthopedic surgical settings. METHODS: In this prospective cohort study, 350 patients undergoing total joint arthroplasty under neuraxial anesthesia or spine surgery under general anesthesia were enrolled. We determined the augmentation index (AI) as a measure of vascular tone and studied symptoms of OI using a validated questionnaire at various postoperative time points. RESULTS: The AI was significantly reduced postoperatively (at spinal resolution in patients with neuraxial anesthesia or two hours postoperatively in general anesthesia) compared with baseline values in all procedures and did not subsequently return to baseline throughout the postoperative period in the majority of patients [252/335 (75.2%); P < 0.001]. The majority [260/342 (76.0%); P < 0.001] of patients had postoperative symptoms of OI. Nevertheless, no association was found between postoperative change in AI from baseline and postoperative symptoms of OI. CONCLUSIONS: A significantly prolonged decrease in AI and symptoms of OI are common after orthopedic surgery. Nevertheless, an association between the two measures was not observed. While compensatory mechanisms may limit the influence of an AI decrease on symptoms of OI, more research is needed to understand the contributing factors and aid in the identification of patients at risk of OI.

Slower lower limb blood pooling in young women with orthostatic intolerance.

NEW FINDINGS: What is the central question of this study? Orthostatic stress is mostly caused by venous blood pooling in the lower limbs. Venous distension elicits sympathetic responses, and increased distension speed enhances the cardiovascular response. We examine whether lower limb blood pooling rate during lower body negative pressure is linked to orthostatic intolerance. What is the main finding and its importance? A similar amount of blood was pooled in the lower limb, but at a slower rate in women who developed signs of orthostatic intolerance. The difference in blood pooling rate increased with orthostatic stress and was most prominent at a presyncope-inducing level of lower body negative pressure. The findings have implications for the pathophysiology as well as treatment of orthostatic intolerance. Vasovagal syncope is common in young women, but its aetiology remains elusive. Orthostatic stress-induced lower limb blood pooling is linked with central hypovolaemia and baroreceptor unloading. Venous distension in the arm elicits a sympathetic response, which is enhanced with more rapid distension. Our aim was to study both the amount and the speed of lower limb pooling during orthostatic stress and its effects on compensatory mechanisms to maintain cardiovascular homeostasis in women with orthostatic intolerance. Twenty-seven healthy women, aged 20-27 years, were subjected to a lower body negative pressure (LBNP) of 11-44 mmHg. Five women developed symptoms of vasovagal syncope (orthostatic intolerant) and were compared with the remaining women, who tolerated LBNP well (orthostatic tolerant). Lower limb blood pooling, blood flow and compensatory mobilization of venous capacitance blood were measured. Lower body negative pressure induced equal lower limb blood pooling in both groups, but at a slower rate in orthostatic intolerant women (e.g. time to 50% of total blood pooling, orthostatic intolerant 44 ± 7 s and orthostatic tolerant 26 ± 2 s; P < 0.001). At presyncope-inducing LBNP, the mobilization of venous capacitance blood was both reduced (P < 0.05) and much slower in orthostatic intolerant women (P = 0.0007). Orthostatic intolerant women elicited blunted arterial vasoconstriction at low-grade LBNP, activating only cardiopulmonary baroreceptors, while orthostatic tolerant women responded with apparent vasoconstriction (P < 0.0001). In conclusion, slower lower limb blood pooling could contribute to orthostatic intolerance in women. Mobilization of venous capacitance blood from the peripheral to the central circulation was both slower and decreased; furthermore, reduced cardiopulmonary baroreceptor sensitivity was found in women who developed orthostatic intolerance. Further studies including women who experience syncope in daily life are needed.

Predictors of mortality, rehospitalization for syncope, and cardiac syncope in 352 consecutive elderly patients with syncope.

OBJECTIVES: To investigate the etiologies of syncope and predictors of all-cause mortality, rehospitalization, and cardiac syncope in consecutive elderly patients presenting with syncope to our emergency department. PARTICIPANTS: Participants were 352 consecutive patients aged 65 years or older with syncope admitted to hospital from the emergency department. DESIGN: Observational retrospective study. MEASUREMENTS: Review of medical records for history, physical examination, medications, and tests to determine causes of syncope. Cox stepwise logistic regression analysis was performed to identify significant independent prognostic factors for rehospitalization with syncope, all-cause mortality, and cardiac syncope. RESULTS: Of 352 patients, mean age 78 years, the etiology of syncope was diagnosed in 243 patients (69%). Vasovagal syncope was diagnosed in 12%, volume depletion in 14%, orthostatic hypotension in 5%, cardiac syncope in 29%, carotid sinus hypersensitivity in 2%, and drug overdose/others in 7% of patients. During a mean follow-up of 24 months, 10 patients (3%) were readmitted to the hospital for syncope and 39 (11%) died. Stepwise logistic regression analysis identified history of congestive heart failure (OR 5.18; 95% CI 1.23-21.84, P = .0257) and acute coronary syndrome (OR 5.95; 95% CI 1.11-31.79, P = .037) as independent risk factors for rehospitalization. Significant independent prognostic factors for mortality were diabetes mellitus (OR 2.08; 95% CI 1.09-3.99, P = .0263), history of smoking (OR 2.23; 95% CI 1.10-4.49, P = .0255), and use of statins (OR 0.37; 95% CI 0.19-0.72, P = .0036). Independent risk factors for predicting a cardiac cause of syncope were an abnormal electrocardiogram (OR 2.58; 95% CI 1.46-4.57, P = .0012) and reduced ejection fraction (OR 2.92; 95% CI 1.70-5.02, P < .001). The San Francisco Syncope Rule and Osservatorio Epidemiologico sulla Sincope nel Lazio scores did not predict mortality or rehospitalization in our study population. CONCLUSIONS: Significant independent risk factors for rehospitalization for syncope were congestive heart failure and acute coronary syndrome. Significant independent risk factors for mortality were diabetes mellitus, history of smoking, and use of statins (inverse association).