scholarly journals Fick principle and exercise pulmonary hemodynamic determinants of the six-minute walk distance in pulmonary hypertension

2020 ◽  
Vol 10 (3) ◽  
pp. 204589402095757
Author(s):  
Phillip Joseph ◽  
Rudolf K.F. Oliveira ◽  
Roza B. Eslam ◽  
Manyoo Agarwal ◽  
Aaron B. Waxman ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Oxygen Delivery ◽  
Walk Distance ◽  
Right Heart ◽  
Fick Principle ◽  
Six Minute Walk Test ◽  
Pulmonary Hemodynamic ◽  
Minute Walk Distance ◽  
Minute Walk ◽  
Hemodynamic Determinants

The six-minute walk test is widely used to assess the severity and prognosis of pulmonary hypertension. However, the pathophysiology underlying a compromised six-minute walk distance is incompletely characterized. The purpose of this study is to evaluate the Fick principle and pulmonary hemodynamic determinants of the six-minute walk distance in patients with suspected pulmonary hypertension. Twenty-nine patients were retrospectively studied and underwent a right heart catheterization for the evaluation of suspected pulmonary hypertension. With the pulmonary artery catheter in place, patients were moved to a treadmill and completed a six-minute walk test. Fick cardiac output and indices of right heart afterload were calculated using continuous measurements of pulmonary vascular pressures, gas exchange, and mixed venous blood samples. Fifteen subjects who walked ≤ 348 m were compared to 14 subjects who walked > 348 m. Systemic oxygen delivery was impaired in six-minute walk distance ≤ 348 m compared to six-minute walk distance > 348 m (15.2 ± 6.2 vs. 23.2 ± 6.8 mL/kg/min, p < 0.01). Impaired oxygen delivery was due to a depressed cardiac index and decreased cardiac reserve demonstrated by the change in the stroke volume index (3.0 ± 14 vs. 17 ± 15 mL/min/m2, p = 0.02). The six-minute walk distance positively correlated with oxygen delivery ( r = 0.501, p = 0.006) and inversely correlated with oxygen extraction ( r = 0.369, p = 0.049). A decreased six-minute walk distance was associated with an increased total pulmonary resistance ( r = 0.502, p = 0.006) and pulmonary vascular resistance ( r = 0.530, p = 0.003). In patients with suspected pulmonary hypertension, a decreased six-minute walk distance is due to compromised oxygen delivery, decreased cardiac reserve, and increased right ventricular afterload.

Review of the Latest Published Research

2013 ◽  
Vol 11 (4) ◽  
pp. 157-158
Keyword(s):  
Computed Tomography ◽  
Pulmonary Hypertension ◽  
Clinical Context ◽  
Walk Distance ◽  
Published Research ◽  
Minute Walk Distance ◽  
Minute Walk

Summaries and commentaries from the section editors and invited reviewers present a clinical context for practitioners' application of the latest published research relevant to the care of patients with pulmonary hypertension. In this issue, Kelly Chin discusses the role of computed tomography and 6-minute walk distance in the diagnosis of pulmonary hypertension patients.

The Effect of Inhaled Nitric Oxide on 6-Minute Walk Distance in Patients With Pulmonary Hypertension

CHEST Journal ◽  
1998 ◽  
Vol 114 (1) ◽  
pp. 70S-72S ◽  
Author(s):  
S. Parsons ◽  
D. Celermajer ◽  
E. Savidis ◽  
O. Miller ◽  
I. Young
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Inhaled Nitric Oxide ◽  
Walk Distance ◽  
Minute Walk Distance ◽  
Minute Walk

scholarly journals Improvement of the Six-Minute Walk Test in Children with Sickle Cell Disease over Time

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1085-1085
Author(s):  
Geoffrey Bourg ◽  
Laurence Dedeken ◽  
Phu-Quoc Le ◽  
Laurence Rozen ◽  
Safiatou Diallo ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Hemoglobin Level ◽  
Walk Test ◽  
Cell Disease ◽  
Walk Distance ◽  
Six Minute Walk Test ◽  
Clinical Events ◽  
Minute Walk Distance ◽  
Minute Walk ◽  
Over Time

Abstract The six-minute walk test (6MWT) was introduced in adults and children suffering from pulmonary or cardio-vascular conditions to assess their sub-maximal functional exercise capacity. In sickle cell disease (SCD), a reduced 6-minute walk distance was observed in adults with chronic pain, hip avascular necrosis and osteopenia ; and in children with low hemoglobin level, low fetal hemoglobin, a baseline elevated TRV. In a previous study (Dedeken et al., PLoS One 2014), we also showed that abnormal 6MWT was significantly associated with the presence of silent infarct. The aim of our study is to explore the evaluation of the 6MWT over time and to confirm the correlation with the cerebral vasculopathy in a larger cohort. This study was conducted at Hôpital Universitaire des Enfants Reine Fabiola (Brussels, Belgium) and included SCD children older than 6 years, regularly followed between 2011 and 2017 and who had at least two 6MWT. The age-standardized predicted value of the 6-minute walk distance (6MWD) was established as reported by Geiger. The 6MWT was considered as normal if the 6MWD was more than 80% of the age-standardized predicted value. Baseline hematological values, clinical events, cerebro-vascular disease, cardio-pulmonary parameters and disease-modifying treatment (DMT) were compared between those with normal and abnormal 6MWT and according to the 6MWD and between the 1st and the 2nd 6MWT overtime. 118 patients have been assessed twice and had at first evaluation a 6MWD of 90.6% (Range 49-119%), with an abnormal test found in 5.1%. The characteristics of the patients are detailed in the Table 1. The changes of the 6MWD and the biological data over time are detailed in Table 2. After 4 years of follow-up, 77.1% of patients were treated with Hydroxyurea (HU) and 16.6% patients were chronically transfused. In parallel with the increased HU prescribing rate, we have observed a significant increase of the Hb and the MCV and a decrease of reticulocytes and hemolysis parameters. The first 6WMT was performed at the median age of 10.3 years and the last one at the median age of 14.1 years. The median 6MWD increased over time including for non-chronically transfused patients. Girls performed less well in the 6MWT (93% for girls vs. 95.7% for boys; P = 0.03). Acute chest syndrome was significantly more frequent in boys (62%) compare to girls (38.7%). Nevertheless, no other differences were founded between boys and girls regarding biological values, clinical events or DMT. 26.5% of our patients have silent infarcts at a median age of 14.6 years. The 6MWD was the same in patients with and without silent infarcts (92.5% vs. 95% ; P=0.17) even when chronically transfused patients were excluded (94% vs. 95% ; P= 0.20). Patients with silent infarcts have a significant lower hemoglobin level and higher reticulocytes count, neutrophils count, LDH and MCV. In conclusion, the 6MWD observed in our cohort characterized by a very high rate of HU treatment is much higher than published in others series and improved over time. With only 5% of SCD patients having a 6MWD < 80% of the normal predicted value at last evaluation, we were not able anymore to confirm a correlation between the presence of silent infracts and abnormal 6MWT. Disclosures No relevant conflicts of interest to declare.

scholarly journals Pulmonary Hemodynamics and Six-Minute Walk Test Outcomes in Patients with Interstitial Lung Disease

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Osamu Nishiyama ◽  
Ryo Yamazaki ◽  
Hiroyuki Sano ◽  
Takashi Iwanaga ◽  
Yuji Higashimoto ◽  
...  
Keyword(s):  
Interstitial Lung Disease ◽  
Lung Disease ◽  
Walk Test ◽  
Walk Distance ◽  
Right Heart ◽  
Pulmonary Hemodynamics ◽  
Physiological Variables ◽  
Six Minute Walk Test ◽  
Right Heart Catheter ◽  
Minute Walk

Background. Six-minute walk test (6MWT) has 3 measurement outcomes, which are walk distance, desaturation, and symptom. The aim of this study was to examine whether routinely measured right-heart catheter (RHC) data correlate with 6MWT outcomes in patients with interstitial lung disease (ILD).Methods. Between June 2010 and December 2012, consecutive patients with ILD who underwent evaluation, including pulmonary function test, hemodynamic studies with right-heart catheter, and 6MWT as routine general practice, were recruited. Correlates of 3 outcomes of 6MWT were examined to reveal significant predictors.Results. Forty-six patients consisting of 20 with idiopathic pulmonary fibrosis, 14 with collagen vascular disease associated ILD, and 12 with other idiopathic interstitial pneumonia were recruited (mean % predicted FVC:76.7±17.1%). Several physiological variables, including mean pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR), were correlated with each 6MWT outcome. Stepwise multivariate regression analyses showed that % predicted FVC and % predicted DLco were independent predictors of walk distance (r2=0.35,p=0.0002). For SpO2at the end of 6MWT, % predicted DLco and PVR were selected as independent predictors (r2=0.46,p<0.0001). For dyspnea at the end of 6MWT, % predicted DLco was only one predictor (r2=0.18,p=0.005).Conclusion. Mean PAP had little impact on 6MWT outcomes in ILD patients who were nonselectively recruited, although PVR was one of predictors of desaturation.

Pulmonary Hypertension in Sickle Cell Disease: Cardiopulmonary Evaluation and Response to Chronic Phosphodiesterase 5 Inhibitor Therapy.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 235-235 ◽  
Author(s):  
Roberto F. Machado ◽  
Sabrina E. Martyr ◽  
Anastasia Anthi ◽  
Gregory J. Kato ◽  
Lori A. Hunter ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Functional Capacity ◽  
Cell Disease ◽  
Walk Distance ◽  
Jet Velocity ◽  
Minute Walk Distance ◽  
Minute Walk ◽  
Tricuspid Regurgitant Jet Velocity

Abstract Pulmonary hypertension (PH) is a risk factor for mortality in Sickle Cell Disease, but it is unclear whether pulmonary hypertension is a marker or a direct cause of mortality. To better understand the pathophysiology of pulmonary hypertension in patients with sickle cell disease we performed evaluations of cardiopulmonary function in sickle cell disease patients with pulmonary hypertension (n= 15, mean age = 41 ± 2.4 years, males = 7, HbSS = 15, mean Hb = 8.3 ± 0.2 g/dl, mean tricuspid regurgitant jet velocity = 3.2 ± 0.11 m/s) compared to matched controls with sickle cell disease without pulmonary hypertension (n=11, mean age=40.2 ± 2.5 years, males=4, HbSS=11, mean Hb=8.5 ± 0.3 g/dl, mean tricuspid regurgitant jet velocity = 2.28 ± 0.07 m/s). To evaluate if specific therapy for pulmonary hypertension has any impact on systolic pulmonary artery pressure (PAP), estimated by tricuspid regurgitant jet velocity (TRJ), and functional capacity, measured by six-minute walk test (a well validated surrogate of functional capacity and response to therapy in patients with other causes of pulmonary hypertension), we treated 14 patients with sickle cell disease and pulmonary hypertension (mean age = 40 ± 2.5 years, males = 3, HbSS = 14, mean Hb = 8.8 ± 0.6 g/dl, mean TRJ = 3.4 ± 0.1 m/s) with sildenafil for at least three months. When compared to controls pulmonary hypertension patients had lower maximal oxygen consumption (VO2 max (% predicted), +PH: 44 ± 4, −PH: 55 ± 4; P=0.41), walked shorter six-minute walk distance (meters, +PH: 308.5 ± 53.8, −PH: 427.1 ± 44.6; P=0.03), demonstrated greater degree of interstitial lung disease by chest CT (P &lt; 0.05), and more perfusion impairments measured by ventilation perfusion scan (P &lt; 0.05). Six-minute walk distance correlated directly with maximal oxygen consumption (R=0.6; P=0.01), and inversely with mean pulmonary arterial pressure (R= −0.5; P=0.03) and tricuspid regurgitant jet velocity (R= −0.6;P=0.002), suggesting that the test is an adequate surrogate of functional capacity and response to therapy in pulmonary hypertension patients with sickle cell disease. Chronic treatment with sildenafil (up to 100 mg TID) decreased pulmonary arterial pressure (PAP mmHg, baseline: 50 ± 4.4, sildenafil: 41 ± 2.5; P=0.04) and increased six-minute walk distance (meters, baseline: 394 ± 31, sildenafil: 476 ± 26: P= 0.02). Sildenafil was well tolerated with only 2 patients stopping the drug due to headaches. We also observed 3 episodes of transient eyelid edema not requiring discontinuation of drug. Priapism was not observed in the 3 males treated (2 on exchange transfusion therapy, 1 with erectile dysfunction). In conclusion, we find that in patients with sickle cell disease, 1) pulmonary hypertension, though relatively mild, is associated with severe impairments in cardiopulmonary function, 2) traditional markers of functional capacity such as six-minute walk test can be utilized in this population as a therapeutic endpoint for clinical trials, 3) and therapy with sildenafil seems to have a favorable impact on pulmonary pressures and functional capacity.

Hemolysis-Associated Elevation in Tricuspid Regurgitation Velocity Predicts Reduction in Six-Minute Walk Distance After Two Years of Follow up in Children and Adolescents with Sickle Cell Disease.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 574-574
Author(s):  
Victor R. Gordeuk ◽  
Lori Luchtman-Jones ◽  
Andrew D. Campbell ◽  
Sohail R Rana ◽  
Mehdi Nouraie ◽  
...  
Keyword(s):  
Steady State ◽  
Sickle Cell Disease ◽  
Children And Adolescents ◽  
Sickle Cell ◽  
Cell Disease ◽  
Walk Distance ◽  
Six Minute Walk Test ◽  
Minute Walk Distance ◽  
Minute Walk

Abstract Abstract 574 Background. Elevated tricuspid regurgitation velocity (TRV) as determined by echocardiography correlates with elevated systolic pulmonary artery pressure and is associated with increased morbidity and mortality in adults with sickle cell disease. The importance of elevated TRV in children and adolescents with sickle cell disease is not known. The Pulmonary Hypertension and the Hypoxic Response in SCD (PUSH) study is an ongoing, longitudinal and observational multicenter study of children with sickle cell disease. Methods. Baseline echocardiography and six-minute walk test were performed prospectively in 361 children and adolescents with sickle cell disease at steady state and then repeat studies were performed in 209 after a median of 22 months of follow up (range 10 months to 36 months), also at steady state. A hemolytic component was derived by principal component analysis of baseline values for reticulocyte count, lactate dehydrogenase, aspartate aminotransferase and total bilirubin. Results. TRV or six-minute walk test were measured at both baseline and follow-up in 193 patients. Twenty-one of these 193 patients had elevated TRV of 2.60 m/sec or higher at baseline. Elevated baseline TRV was associated with high hemolytic rate in 15 patients, defined as hemolytic component above the median for the population studied, and with lower hemolytic rate in six patients. Elevated baseline TRV with high hemolytic rate predicted elevated TRV at follow up (odds ratio 7.7; 95% confidence interval [CI] 2.5 to 24.2; P <0.001) but elevated baseline TRV with lower hemolytic rate did not (odds ratio 1.6; 95% CI 0.2 to 14.1; P = 0.7). Elevated baseline TRV with high hemolytic rate also predicted a decline in the six-minute walk distance by 10% or more at follow-up (hazard ratio 3.9; 95% CI 1.4 to 10.7; P = 0.009). In contrast, higher cardiac output as measured by the left ventricular end diastolic dimension z-score was associated with reduced risk for a decline in the walk distance (hazard ratio 0.7; 95%CI 0.6 to 0.9; P = 0.006). Conclusion. Steady-state TRV elevation in association with a high hemolytic rate occurs on screening in about 8% of children and adolescents with sickle cell disease and is predictive of elevated TRV and reduced six-minute walk distance after approximately two years of follow. Such children may be at risk for adverse clinical consequences of pulmonary hypertension as young adults. Further studies are indicated to identify the molecular mechanisms and to develop appropriate medical management for children and adolescents with this complication. Disclosures: No relevant conflicts of interest to declare.

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