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1.  Reference values for the 6-minute walk test in healthy children and adolescents in Switzerland 
Background
The six-minute walk test (6MWT) is a simple, low tech, safe and well established, self-paced assessment tool to quantify functional exercise capacity in adults. The definition of normal 6MWT in children is especially demanding since not only parameters like height, weight and ethnical background influence the measurement, but may be as crucial as age and the developmental stage. The aim of this study is establishing reference values for the 6MWT in healthy children and adolescents in Switzerland and to investigate the influence of age, anthropometrics, heart rate, blood pressure and physical activity on the distance walked.
Methods
Children and adolescents between 5–17 years performed a 6MWT. Short questionnaire assessments about their health state and physical activities. anthropometrics and vitals were measured before and after a 6-minute walk test and were previously defined as secondary outcomes.
Results
Age, height, weight and the heart rate after the 6MWT all predicted the distance walked according to different regression models: age was the best single predictor and mostly influenced walk distance in younger age, anthropometrics were more important in adolescents and females. Heart rate after the 6MWT was an important distance predictor in addition to age and outreached anthropometrics in the majority of subgroups assessed.
Conclusions
The 6MWT in children and adolescents is feasible and practical. The 6MWT distance depends mainly on age; however, heart rate after the 6MWT, height and weight significantly add information and should be taken into account mainly in adolescents. Reference equations allow predicting 6-minute walk test distance and may help to better assess and compare outcomes in young patients with cardiovascular and respiratory diseases and are highly warranted for different populations.
doi:10.1186/1471-2466-13-49
PMCID: PMC3750631  PMID: 23915140
6-minute walk test; Healthy children; Exercise physiology; Exercise testing; Predicted equation; Reference value
2.  Lung Function and Breathing Pattern in Subjects Developing High Altitude Pulmonary Edema 
PLoS ONE  2012;7(7):e41188.
Introduction
The purpose of the study was to comprehensively evaluate physiologic changes associated with development of high altitude pulmonary edema (HAPE). We tested whether changes in pulmonary function and breathing pattern would herald clinically overt HAPE at an early stage.
Methods
In 18 mountaineers, spirometry, diffusing capacity, nitrogen washout, nocturnal ventilation and pulse oximetry were recorded at 490 m and during 3 days after rapid ascent to 4559 m. Findings were compared among subjects developing HAPE and those remaining well (controls).
Results
In 8 subjects subsequently developing radiographically documented HAPE at 4559 m, median FVC declined to 82% of low altitude baseline while closing volume increased to 164% of baseline (P<0.05, both instances). In 10 controls, FVC decreased slightly (to 93% baseline, P<0.05) but significantly less than in subjects with HAPE and closing volume remained unchanged. Sniff nasal pressure was reduced in both subjects with and without subsequent HAPE. During nights at 4559 m, mean nocturnal oxygen saturation dropped to lower values while minute ventilation, the number of periodic breathing cycles and heart rate were higher (60%; 8.6 L/min; 97 cycles/h; 94 beats/min, respectively) in subjects subsequently developing HAPE than in controls (73%; 5.1 L/min; 48 cycles/h; 79 beats/min; P<0.05 vs. HAPE, all instances).
Conclusion
The results comprehensively represent the pattern of physiologic alterations that precede overt HAPE. The changes in lung function are consistent with reduced lung compliance and impaired gas exchange. Pronounced nocturnal hypoxemia, ventilatory control instability and sympathetic stimulation are further signs of subsequent overt HAPE.
Registration
ClinicalTrials.gov identifier: NCT00274430
doi:10.1371/journal.pone.0041188
PMCID: PMC3400591  PMID: 22829927
3.  Pulmonary hypertension in patients with Martorell hypertensive leg ulcer: a case control study 
Respiratory Research  2012;13(1):45.
Background
Martorell hypertensive ischemic leg ulcer (Martorell ulcer) is characterized by distinct alterations in the arteriolar wall of subcutaneous vessels, leading to progressive narrowing of the vascular lumen and increase of vascular resistance. These changes are similar to the alterations observed in pulmonary arterioles in patients with chronic pulmonary hypertension (PH). This study was aimed to assess an association between the two disorders.
Methods
In this case–control study, 14 patients with Martorell ulcer were clinically assessed for the presence of pulmonary hypertension using transthoracic Doppler echocardiography. Data from patients were compared to 28 matched hypertensive controls.
Results
Systolic pulmonary arterial pressure (sPAP) in patients with Martorell ulcer was significantly higher than in the control group (33.8 ± 16.9 vs 25.3 ± 6.5 mmHg, p = 0.023); the prevalence of pulmonary hypertension was 31% (5/14) in patients and 7% (2/28) in controls (p = 0.031). No differences were seen in left heart size and function between patients and controls.
Conclusion
This study provides first evidence that subcutaneous arteriolosclerosis, the hallmark of Martorell ulcer, is associated with PH. These findings suggest that patients with Martorell leg ulcer might be at significant risk to develop elevated pulmonary arterial pressure. Patients with leg ulcers who present with dyspnea should be evaluated by echocardiography for the presence of pulmonary hypertension.
doi:10.1186/1465-9921-13-45
PMCID: PMC3471016  PMID: 22686459
Pulmonary hypertension; Echocardiography; Martorell ulcer
4.  Successful pregnancy in pulmonary arterial hypertension associated with systemic lupus erythematosus: a case report 
Introduction
Pulmonary arterial hypertension is a complication of systemic lupus erythematosus. Mortality in pregnant patients with pulmonary arterial hypertension related to connective tissue disease is as high as 56%. The authors report the first case of a successful maternal-fetal outcome in a pregnant patient with systemic lupus erythematosus-associated pulmonary arterial hypertension treated with sildenafil and inhaled iloprost during pregnancy and until several weeks after caesarean section.
Case presentation
The case presented is of a 29-year-old woman with systemic lupus erythematosus and associated severe pulmonary arterial hypertension. Vasodilator therapy with bosentan and sildenafil, immunosuppressive therapy with prednisone, hydroxychloroquine and azathioprine and oral anticoagulation (phenprocoumon) had normalized her right ventricular over right atrial pressure when she was diagnosed in her 5th week of pregnancy. The teratogenic drugs bosentan and phenprocoumon were stopped, the latter replaced by low molecular weight heparin. During the 35th week, a slight increase in pulmonary pressure was found. Therapy with inhaled iloprost was established. A caesarean section was performed in the 37th week and a healthy baby was delivered. The patient remained stable until 11 weeks after delivery, when an increase in right ventricular over right atrial pressure was noted. Bosentan was reintroduced and prednisone and azathioprine doses were increased. The patient has remained stable until the present time.
Conclusion
Pulmonary arterial hypertension has been considered a contraindication for pregnancy. Novel vasodilator therapy, combined with immunosuppressants in this patient with systemic lupus erythematosus, may "cure" pulmonary arterial hypertension and permit pregnancy with successful outcome. However, postpartum exacerbation of systemic lupus erythematosus and pulmonary arterial hypertension have to be considered.
doi:10.4076/1752-1947-3-7255
PMCID: PMC2726506  PMID: 19830150
5.  Bone Mineral Density and Secondary Hyperparathyroidism in Pulmonary Hypertension 
Background:
Low bone mineral density (BMD) is common in chronic lung diseases and associated with reduced quality of life. Little is known about BMD in pulmonary hypertension (PH).
Methods:
Steroid-naïve patients with PH (n=34; 19 idiopathic, 15 chronic thromboembolic) had BMD measured by DXA at the time of diagnostic right heart catheterization. Exercise capacity, quality of life and various parameters related to PH severity and bone metabolism were also assessed. 24 patients with left heart failure (LHF) were similarly assessed as controls.
Results:
The prevalence of osteopenia was high both in PH (80%) and in controls with LHF (75%). Low BMD was associated with lean body mass, age, lower BMI, impaired exercise capacity and in PH with higher pulmonary vascular resistance. Serum parathyroid hormone (PTH) was elevated and considerably higher in PH than in LHF (above normal, in 55 vs 29%). Secondary hyperparathyroidism was not related to impaired renal function but possibly to low vitamin D status.
Conclusions:
Osteopenia is common in PH and in chronically ill patients with LHF. Osteopenia is associated with known risk factors but in PH also with disease severity. Preventive measures in an increasingly chronic ill PH population should be considered. Secondary hyperparathyroidism is highly prevalent in PH and might contribute to bone and possibly pulmonary vascular disease. Whether adequate vitamin D substitution could prevent low BMD in PH remains to be determined.
doi:10.2174/1874306400903010053
PMCID: PMC2684713  PMID: 19461899
Pulmonary hypertension; chronic thromboembolic pulmonary hypertension; hyperparathyroidism; osteopenia; osteoporosis; left heart failure.
6.  Caveolin-1 Expression and Hemodynamics in COPD Patients 
Caveolin-1 is a regulator of both intracellular calcium homeostasis and endothelial nitric oxide synthase and may play a pathogenetic role in pulmonary hypertension. In the present study, we aimed to investigate the correlations between pulmonary hemodynamics and vessel morphology including the expression of Caveolin-1 in pulmonary arterioles from patients with chronic obstructive pulmonary disease (COPD) who underwent lung-volume reduction surgery. Staining and subsequent analysis was performed on paraffin-embedded lung tissue from COPD patients (n = 12). Pulmonary arteries with an external diameter of 100-500µm were analysed. Immunhistochemistry with antibodies against caveolin-1 was performed and intensity was assessed. Morphometric data were obtained by using computer-assisted imaging software. The findings were quantified and correlated to hemodynamic data obtained by right-heart catheterization. In COPD patients with pulmonary hypertension (n = 5), the expression of caveolin-1 within the medial smooth muscle cell layer was found to be increased, whereas the intimal caveolin-1 was more prominently expressed in COPD patients with normal pulmonary pressures (n = 7). The ratio between these expression patterns was positively correlated to the mean pulmonary artery pressure. Similar findings were observed for the ratio between intimal and medial thickness as well as for the expression of smooth muscle actin (SMA).
Taken together, the expression of caveolin-1 within medial smooth muscle cells of pulmonary arteries in patients with COPD is associated with pulmonary hypertension. Our results thus emphasize a potential novel player in the pathogenesis of COPD-associated pulmonary hypertension.
doi:10.2174/1874306400903010073
PMCID: PMC2703474  PMID: 19572028
Caveolin-1; chronic obstructive pulmonary disease (COPD); morphometry; pulmonary hypertension.

Results 1-6 (6)