Assessment of gas compression and lung volume during air stacking maneuver.

PURPOSE: We reasoned that the application of positive pressure through air stacking (AS) technique could cause gas compression and the absolute lung volumes could be estimated. The aim of this study was to estimate the amount of gas compression (ΔV comp) during AS in healthy subjects positioned at 45° trunk inclination and verify if the simultaneous measurements of chest wall volume changes (ΔV CW), by optoelectronic plethysmography, and changes in lung volume (ΔV ao), by pneumotachograph, combined with pressure variation at the airways opening (ΔP ao) during AS are able to provide reliable data on absolute lung volumes. METHODS: Twenty healthy subjects (mean age 23.5 ± 3.8 years) were studied during a protocol that included slow vital capacity and AS maneuvers. V comp was calculated by subtracting ΔV ao and ΔV CW occurring during AS and total lung capacity (TLC) was estimated by applying Boyle-Mariote's law using V comp and ΔP ao. RESULTS: During AS, 0.140 ± 0.050 L of gas was compressed with an average ΔP ao of 21.78 ± 6.18 cmH2O. No significant differences between the estimated TLC (-0.03 ± 3.0% difference, p = 0.6020), estimated FRC (-2.0 ± 12.4% difference, p = 0.5172), measured IC (1.2 ± 11.2% difference, p = 0.7627) and predicted values were found. CONCLUSION: During AS, a significant gas compression occurs and absolute lung volumes can be estimated by simultaneous measurements of ΔV CW, ΔV ao and ΔP ao.

Potential effect of 6 versus 12-weeks of physical training on cardiac autonomic function and exercise capacity in chronic obstructive pulmonary disease.

BACKGROUND: Exercise is an important part of chronic obstructive pulmonary disease (COPD) treatment. However, it is not know about the minimum effective time of physical training that could beneficially modify the cardiac autonomic modulation (CAM) and exercise capacity in these patients. AIM: To contrast the potential effects of a physical training program (PTP), for 6 versus 12 weeks, on CAM by linear and nonlinear heart rate variability (HRV) indices and exercise capacity in COPD patients. DESIGN: Prospective randomized controlled trial. SETTING: Outpatient pulmonary rehabilitation. POPULATION: Twenty moderate-to-severe COPD patients were randomly assigned to either a training group (N.=10) or a control group (N.=10). METHODS: HRV at rest and during submaximal test was determined by linear (rMSSD and SDNN) and non-linear indices (SD1, SD2 and sample entropy [SE]). In addition, key responses were obtained during cardiopulmonary exercise testing (CPET), the walking distance (WD) during the six minute walking test and submaximal constant speed testing (CST). PTP consisted of 30 minutes of aerobic exercise training on a treadmill, 3 times per week at 70% of CPET peak speed rate. Patients were evaluated on baseline, 6 and 12 weeks. RESULTS: Significant improvements in HRV indices, WD, as well as, other physiological responses were observed after 6 weeks of the PTP and maintained until 12 weeks (P<0.05). However, after 12 weeks, the SD1 index demonstrated an additional improvement compared with 6 weeks (P<0.05). Peak oxygen uptake and dioxide carbon production improved only after 12 weeks (P<0.05). Interestingly, the 6th week-baseline delta (6th week-baseline) of WD, SDNN and SE were significantly higher than 12th week-6th week delta (P<0.05). CONCLUSION: These results indicate that beneficial changes on cardiac autonomic modulation in conjunction with improvement in submaximal functional capacity occur in the first 6 weeks of PTP in moderate to severe COPD. CLINICAL REHABILITATION IMPACT: Short-term rehabilitation (6 weeks) is an effective sufficient time to beneficially modify important outcomes as cardiac modulation and exercise capacity in COPD patients.

Avaliação clínica da capacidade do exercício em pacientes com doença pulmonar obstrutiva crônica: [revisão] / Clinical assessment of exercise capacity in patients with chronic obstructive pulmonary disease: [review]

CONTEXTUALIZAÇÃO: A doença pulmonar obstrutiva crônica (DPOC) se caracteriza por ser uma afecção multissistêmica que leva a uma diminuição na tolerância ao exercício do paciente pneumopata. Atualmente, a Fisioterapia Respiratória dispõe de uma grande variedade de testes validados que tem como característica a sua simplicidade, praticidade e baixo custo. OBJETIVO: Descrever os testes de campo mais utilizados em pacientes com DPOC para avaliar a capacidade de exercício e a atividade física, assim como alguns testes que potencialmente poderiam ser adotados na avaliação clínica destes pacientes. CONCLUSÕES: Para poder justificar a qualidade do trabalho do profissional de Fisioterapia Respiratória, deve-se incorporar os testes utilizados e validados internacionalmente. Além disso, é importante escolher o teste mais adequado para medir a capacidade do exercício e, sobretudo, realizar um seguimento cuidadoso da evolução do paciente.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterized as a multisystemic disease that reduces patient's tolerance to exercise. Nowadays, a great variety of validated tests are available for use in Respiratory Physical Therapy that are simple, practical and inexpensive. OBJECTIVE: To describe the tests most used in patients with COPD to evaluate their exercise capacity and physical activity, along with some tests that potentially could be adopted for clinical evaluations in such patients. CONCLUSIONS: To be able to justify the professional quality of the respiratory physical therapists' work, tests that have been used and validated internationally must be incorporated. Moreover, it is important to choose the most appropriate tests for measuring exercise capacity and, above all, to perform a careful follow-up of the patient.