BackgroundThe 1-minute sit-to-stand (STS) test could be valuable to assess the level of exercise tolerance in chronic obstructive pulmonary disease (COPD). There is a need to provide the minimal important difference (MID) of this test in pulmonary rehabilitation (PR).MethodsCOPD patients undergoing the 1-minute STS test before PR were included. The test was performed at baseline and the end of PR, as well as the 6-minute walk test, and the quadriceps maximum voluntary contraction (QMVC). Home and community-based programs were conducted as recommended. Responsiveness to PR was determined by the difference in the 1-minute STS test between baseline and the end of PR. The MID was evaluated using distribution and anchor-based methods.ResultsForty-eight COPD patients were included. At baseline, the significant predictors of the number of 1-minute STS repetitions were the 6-minute walk distance (6MWD) (r=0.574; P<10−3), age (r=−0.453; P=0.001), being on long-term oxygen treatment (r=−0.454; P=0.017), and the QMVC (r=0.424; P=0.031). The multivariate analysis explained 75.8% of the variance of 1-minute STS repetitions. The improvement of the 1-minute STS repetitions at the end of PR was 3.8±4.2 (P<10−3). It was mainly correlated with the change in QMVC (r=0.572; P=0.004) and 6MWD (r=0.428; P=0.006). Using the distribution-based analysis, an MID of 1.9 (standard error of measurement method) or 3.1 (standard deviation method) was found. With the 6MWD as anchor, the receiver operating characteristic curve identified the MID for the change in 1-minute STS repetitions at 2.5 (sensibility: 80%, specificity: 60%) with area under curve of 0.716.ConclusionThe 1-minute STS test is simple and sensitive to measure the efficiency of PR. An improvement of at least three repetitions is consistent with physical benefits after PR.

Background: Sit-to-stand tests (STST) have recently been developed as easy-to-use field tests to evaluate exercise tolerance in COPD patients. As several modalities of the test exist, this review presents a synthesis of the advantages and limitations of these tools with the objective of helping health professionals to identify the STST modality most appropriate for their patients. Method: Seventeen original articles dealing with STST in COPD patients have been identified and analysed including eleven on 1min-STST and four other versions of the test (ranging from 5 to 10 repetitions and from 30 s to 3 min). In these studies the results obtained in sit-to-stand tests and the recorded physiological variables have been correlated with the results reported in other functional tests. Results: A good set of correlations was achieved between STST performances and the results reported in other functional tests, as well as quality of life scores and prognostic index. According to the different STST versions the processes involved in performance are different and consistent with more or less pronounced associations with various physical qualities. These tests are easy to use in a home environment, with excellent metrological properties and responsiveness to pulmonary rehabilitation, even though repetition of the same movement remains a fragmented and restrictive approach to overall physical evaluation. Conclusions: The STST appears to be a relevant and valid tool to assess functional status in COPD patients. While all versions of STST have been tested in COPD patients, they should not be considered as equivalent or interchangeable.

Parasympathetic respiratory control and nonautonomic mechanisms may influence the HF-peak shift during strenuous exercise. HRV and the usual indexes of sympathetic activity do not accurately reflect changes in autonomic modulation during exhaustive exercise.

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Using simultaneous nitric oxide and carbon monoxide lung transfer measurements (T LNO and T LCO ), the membrane transfer capacity (D m ) and capillary lung volume (V c ) as well as the dimensionless ratio T LNO /T LCO can be calculated. The significance of this ratio is yet unclear. Theoretically, the T LNO /T LCO ratio should be inversely related to the product of both lung alveolar capillary membrane (μ) and blood sheet thicknesses (K ). NO and CO transfers were measured in healthy subjects in various conditions likely to be associated with changes in K and/or μ. Experimentally, deflation of the lung from 7.4 to 4.8 l decreased the T LNO /T LCO ratio from 4.9 to 4.2 (n = 25) which was consistent mainly with a thickening of the blood sheet. Compared with continuous negative pressure breathing, continuous positive pressure breathing increased this ratio suggesting a thinning of the capillary sheet. It was also observed with 12 healthy subjects that slight haemodilution that may thicken the blood sheet decreased the T LNO /T LCO ratio from 4.85 to 4.52. In conclusion, the T LNO /T LCO ratio is related to the thickness of the alveolar blood barrier. This ratio provides novel information for the analysis of the diffusion properties. Diffusion of gases between the alveolar space of the lung and blood is usually described with Roughton and Forster's model (Forster et al. 1957). In this model, key factors affecting gas transfer include two components: (a) the membrane which is supposed to be homogenous and characterized by its conductance (D m ) and (b) the product of red cell conductance for a given gas (θ ) and pulmonary capillary volume (V c ). D m is considered to be an independent variable to V c .In order to calculate D m and V c the NO/CO transfer method (T LNO /T LCO ) was introduced in the lung function testing of humans in 1987 (Guénard et al. 1987). As the in vivo conductance of NO in blood is very high, the only limitation to its transfer through the barrier is the membrane. CO transfer (T LCO ) depends on D m , V c and haemoglobin concentration. T LCO also varies with pulmonary capillary oxygen tension since θ CO is inversely proportional to this pressure. The ratio of NO to CO transfer (T LNO /T LCO ) should therefore provide some insight into the relative properties of the membrane and capillaries.The surface area of the alveolar membrane and capillary are identical or closely related and by consequence, D m and V c should be directly correlated. The hypothesis of this study is based on the assumption that V c and D m are dependent parameters.Under this assumption, this study is designed to identify the significance of the T LNO /T LCO ratio through both theoretical and experimental approaches with the expectations that the new model would be relevant for physiological or clinical purposes. Specifically, we have shown that the T LNO /T LCO ratio is independent of membrane surface area and inversely proportional to the product of alveolar membrane and capillary blood layer thicknesses. Methods Theoretica...