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.

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.