We measured lung mechanics in seven healthy males during acute isocapnic hypoxia (PAO2 = 40-50 Torr; PACO2 = 38-42 Torr). Hypoxia was accompanied by increases in total lung capacity (mean increase +/- SD; 0.40 +/- 0.24 liters; P less than 0.005) functional residual capacity (0.34 +/- 0.25 liters; P less than 0.01) and residual volume (0.56 +/- 0.44 liters; P less than 0.02) in all subjects. Specific conductance of the lung decreased during hypoxia (P less than 0.02). The static deflation pressure-volume curve of the lung was shifted upward during hypoxia in all subjects. Resting end-expiratory recoil pressure of the lung was slightly, but not significantly lower during hypoxtic expiratory lung compliance was greater during hypoxia (0.39 +/- 0.04 l/cmH2O) than control measurements (0.31 +/- 0.05 l/cmH2O; P less than 0.005). No change was noted in dynamic lung compliance. All changes in lung mechanics were reversed within three minutes of reoxygenation. We conclude that acute isocapnic hypoxia increases total lung capacity in man and suggest that this may be due to the effect of hypoxia on the airways and pulmonary circulation.
Ventilatory responses to isocapnic hypoxia, with and without an inspiratory elastic load (12.1 cmH2O/l), were measured in seven healthy subjects using a rebreathing technique. During each experiment, the end-tidal PCO2 was held constant using a variable-speed pump to draw gas from the rebreathing bag through a CO2 absorbing bypass. Studies with and without the load were performed in a formally randomized order for each subject. Linear regressions for rise in ventilation against fall in SaO2 were calculated. The range of unloaded responses was 0.74-1.38 1/min per 1% fall in SaO2 and loaded responses 0.71-1.56 1/min per 1% fall in SaO2. Elastic loading did not significantly alter the ventilatory response to progressive hypoxia (P greater than 0.2). In all subjects there was, however, a change in breathing pattern during loading, whereby increments in ventilation were attained by smaller tidal volumes and higher frequencies than in the control experiments. These results support the hypothesis previously proposed in our studies of resistive loading during progressive hypoxia, that a similar control pathway appears to be involved in response to the application of loads to breathing, whether ventilation is stimulated by hypoxia or hypercapnia.
The complexities of cancer treatment present a myriad of life-altering impacts for patients. These impacts can be addressed only if health care systems have been designed to detect and address all of these challenges. One significant, but often hidden, challenge is distress. This reaction to the myriad obstacles that cancer presents can impact the quality of life, and influence outcomes, of patients with cancer. Health systems have been slow to address these problems, and a prime example is the implementation of a distress screening and management system. This case study summarizes distress screening in a community oncology clinic compared to a Department of Veterans Affairs (VA) oncology clinic. The community clinic responded to accreditation and grant-driven initiatives, whereas the VA responded to mental health and integrated primary care initiatives. This case study explores the history and the ongoing challenges of distress screening in these community-based health care systems.
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