The Peculiarities of Six-Minute Walk Test in Patients with Chronic Obstructive Pulmonary Disease, Some with Normal Weight and Some Overweight

Background: The combination of chronic obstructive pulmonary disease (COPD) and overweight/obesity is a common clinical situation in modern healthcare. The objective of this study was to conduct a comparative analysis of exercise tolerance in normal body weight (NBW) and overweight patients with COPD in the 6MWT using the original device for cardiorespiratory analysis and a method for assessing the cardiorespiratory condition. Methods and Results: The study included 194 patients with COPD. The patients were divided into two groups. Group 1 consisted of 96 COPD patients with NBW: 77(80.21%) men and 19(19.79%) women aged 41 to 73 years (mean age of 63.33 ± 8.44 years). Group 2 consisted of 98 overweight COPD patients: 74(75.51%) men and 24(24.49%) women aged 55 to 71 (mean age of 64.84 ± 5.46 years). To assess tolerance to physical activity and to objectify the functional status of patients, the 6MWT was used and carried out according to generally accepted principles. The distance covered in 6 minutes (6MWD) was measured in meters and compared with the proper 6MWD(i). The developed device for cardiorespiratory analysis was used to obtain the most accurate 6MWT result. All patients in the study groups underwent an analysis of the composition of the body by the bioelectrical impedance method using a fat mass analyzer BC-555 (Tanita Corporation, Tokyo, Japan). The percentages of fat, water, muscle mass (MM), and bone mass were evaluated. The average value of the 6MWD/6MWD(i) ratio in COPD patients with NBW was significantly lower than in COPD patients with overweight (P=0.0121). Before the test, the study groups did not differ in the level of SpO2. However, according to the results of comparative analysis, this parameter was significantly lower in patients with NBW immediately after the 6MWT (P=0.0000), which, along with a lower value of the distance traveled as a percentage of the proper value in Group 1 patients, may indicate a lower tolerance to physical activity in COPD patients with NBW than in patients with overweight. In COPD patients with NBW, the percentage of fat and MM were significantly lower than in COPD patients with overweight (P=0.0000 in both cases). There was a direct correlation between 6MWD and body mass index (r=0.56, P=0.003) and between 6MWD and MM percentage (r=0.59, P=0.016). Conclusion: Higher exercise tolerance is found in overweight COPD patients than in COPD patients with NBW. This phenomenon can be explained to some extent by the compositional components of the body, in particular, by a significantly lower percentage of lean MM in patients with NBW

Changes of the Antarctic ozone hole : controlling mechanisms, seasonal predictability, and evolution

The ozone hole changes considerably from one year to the next. It varies between conditions in which springtime ozone is strongly depleted to others in which ozone is only weakly depleted. Those changes are shown to closely track anomalous planetary wave forcing of the residual circulation. The strong coherence with planetary wave forcing is consistent with similar coherence of springtime temperature, which modulates Polar Stratospheric Cloud (PSC). By controlling the lifetime of PSC, anomalous wave forcing determines the net activation of chlorine and bromine and, hence, springtime depletion of ozone during individual years. The strong coherence with planetary wave forcing affords long-range predictability. It supports a seasonal forecast of springtime depletion, which, through the ozone mass deficit, perturbs ozone across much of the Southern Hemisphere during subsequent months of summer. Conditioned upon wintertime wave structure, a hindcast of springtime depletion faithfully predicts the anomalous ozone observed. A reliable forecast of tropospheric planetary waves would thus enable springtime depletion to be predicted. The current evolution of Antarctic ozone is dominated by dynamically-induced changes. Representing its climate variability, those large changes obscure the more gradual evolution of springtime depletion, like that associated with the decline of chlorine. The strong dependence on planetary wave forcing, however, enables dynamically-induced changes of ozone to be identified accurately. Removing them unmasks the secular variation of Antarctic ozone, the part coherent over a decade and longer. Independent of dynamically-induced changes, that component discriminates to changes associated with stratospheric composition. It reveals a gradual but systematic rebound over the last decade. The upward trend is shown to be robust, significant at the 99.5% level. Uncertainty in this trend is thus small enough to make the probability of it arising through chance alignment of error less than 0.5%. The discriminated component mirrors the decline of effective stratospheric chlorine, representing a gradual return of springtime ozone toward its level in 1980 of 10-15%. It enables Antarctic ozone to be tracked relative to changes of chlorine, CO₂, and other features of climate more reliably than is otherwise possible.11 page(s