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Background Area under expiratory flow-volume curve (AEX) is a useful spirometric tool in stratifying respiratory impairment. The AEX approximations based on isovolumic flows can be used with reasonable accuracy when AEX is unavailable. We assessed here pre- to post-bronchodilator (BD) variability of AEX.sub.4 as a functional assessment tool for lung disorders. Methods The BD response was assessed in 4330 subjects by changes in FEV.sub.1, FVC, and AEX.sub.4, which were derived from FVC, peak expiratory flow, and forced expiratory flow at 25%, 50%, and 75% FVC. Newly proposed BD response categories (negative, minimal, mild, moderate and marked) have been investigated in addition to standard criteria. Results Using standard BD criteria, 24% of subjects had a positive response. Using the new BD response categories, only 23% of subjects had a negative response; 45% minimal, 18% mild, 9% moderate, and 5% had a marked BD response. Mean percent change of the square root AEX.sub.4 was 0.3% and 14.3% in the standard BD-negative and BD-positive response groups, respectively. In the new BD response categories of negative, minimal, mild, moderate, and marked, mean percent change of square root AEX.sub.4 was - 8.2%, 2.9%, 9.2%, 15.0%, and 24.8%, respectively. Conclusions Mean pre- to post-BD variability of AEX.sub.4 was < 6% and stratified well between newly proposed categories of BD response (negative, minimal, mild, moderate and marked). We suggest that AEX.sub.4 (AEX) could become a useful measurement for stratifying dysfunction in obstructive lung disease and invite further investigation into indications for using bronchodilator agents or disease-modifying, anti-inflammatory therapies., Author(s): Octavian C. Ioachimescu [sup.1] , James K. Stoller [sup.2] Author Affiliations: (1) grid.189967.8, 0000 0001 0941 6502, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, School of Medicine, [...]

Background Maximal consumption of oxygen (V[O.sub.2]max) during exercise is used in patients with chronic obstructive pulmonary disease (COPD) to stratify perioperative risk. However, the impact of therapeutic hyperoxia (i.e., use of supplemental oxygen to prevent hypoxemia during exercise) on V[O.sub.2]max and other ventilatory parameters during maximal exercise in the resting normoxic COPD population is poorly defined. Methods A randomized, double-blind crossover study was performed in which resting normoxic subjects (n = 16) with COPD underwent two standard symptom-limited, rampedprotocol bicycle ergometry cardiopulmonary exercise tests >5 days apart with Fi[O.sub.2] of 0.21 (control) and ~0.28 (therapeutic hyperoxia). V[O.sub.2]max and other ventilatory parameters were compared using a paired two-sample t-test. Results Therapeutic hyperoxia significantly increased V[O.sub.2]max (12.2 ± 2.9 vs. 13.6 ± 3.8 ml/kg/min, P = 0.03), partial pressure of end-tidal carbon dioxide, and oxygen saturation and significantly decreased VE-VC[O.sub.2] slope, but it did not affect exercise time, maximum watts achieved, maximum minute ventilation, or change in end-expiratory lung volume. Three of four subjects with V[O.sub.2]max Conclusions Therapeutic hyperoxia in a resting normoxic COPD population significantly improves V[O.sub.2]max and may change perioperative risk stratification by conventional criteria. Further studies are needed to determine if this change in stratification is appropriate. Keywords Chronic obstructive pulmonary disease * Hyperoxia * Maximal oxygen consumption * Exercise * Perioperative risk, Introduction Cardiopulmonary exercise tests (CPETs) are used to determine the etiology of reduced exercise tolerance and exertional dyspnea and are also helpful in perioperative risk assessment [1, 2]. Maximal consumption [...]