A more effective alternative to the 6-minute walk test for the assessment of functional capacity in patients with pulmonary hypertension.

BACKGROUND: The prognosis of Pulmonary Hypertension (PH) is directly correlated with the functional capacity (FC). The most common FC test is the 6-Minute Walk Test (6MWT), however, there is evidence to suggest that the 6MWT does not reflect the real FC in PH patients. AIM: To compare physiological responses among three field walk tests and cardiopulmonary exercise testing (CPET) in patients with pulmonary hypertension (PH), and to determine the determinants of distance walked in the field walk tests. DESIGN: Cross sectional study. SETTING: Outpatient clinic. POPULATION: 26 volunteers (49.8±14.6 years), WHO functional class II-III and a mean pulmonary artery pressure of 45 mmHg. METHODS: Patients underwent three field walk test: 6MWT, incremental shuttle walk test (ISWT), and endurance shuttle walk test (ESWT) and CPET on different, non-consecutive days. The main outcome measures were heart rate and perception of effort at the peak of exercise. RESULTS: The ISWT achieved maximum levels of effort without significant difference in any physiologic response compared to CPET. The physiological responses during ISWT were significantly higher than 6MWT and ESWT responses. CONCLUSIONS: The ISWT produced the greatest physiologic response of the field tests safely for which reason it appears to be the most effective test to assess FC of PH patients. CLINICAL REHABILITATION IMPACT: The self-paced characteristic of the 6MWT and lower physiologic responses compared to the CPET were the main reason for this test to be classified as submaximal in PH patients. The physiological responses during the ESWT were significantly lower than other field tests highlighting the need for more research on this test and other field test in PH patients.

Evaluation of autonomic modulation of lung function and heart rate in children with cystic fibrosis.

The autonomic nervous system (ANS) plays an important role in modulating bronchial smooth muscle contractility, which is altered in cystic fibrosis (CF). A convenient approach to probe ANS regulation is the quantitative analysis of heart rate variability (HRV). The purpose of this study was to evaluate ANS regulation in children with CF and to investigate the influence of colonization by Pseudonomas aeruginosa via assessment of HRV in colonized CF (CCF) children and noncolonized CF (NCCF) children. Sixteen children with CF (7 CCF and 9 NCCF) and seven healthy age-matched control children were enrolled in the study. Heart rate was recorded for 10 min at rest in the supine and standing positions and HRV analysis was carried out using autoregressive spectral analysis. The CCF group was characterized by lower forced expiratory volume than NCCF, indicating an impairment of respiratory function. The HRV parameters further confirmed the possible sympathetic overactivity in CCF. Children with CF exhibited hyperactivity of the sympathetic nervous system. In particular, the CCF group presented a greater impairment of ANS modulation. Both CCF and NCCF children showed lower supine vagal activation in the HRV indices related to sympathetic activation and reduction of indices indicating vagal activity with the postural change from supine to standing when compared to the NCCF group.