Lung
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Review Comparative Study
Pulse oximetry versus arterial blood gas specimens in long-term oxygen therapy.
Portable pulse oximeters are now widely available for the assessment of arterial oxygenation, and the U. S. Medicare program considers saturation readings to be acceptable substitutes for arterial PO2 in selecting patients for long-term oxygen therapy (LTOT). ⋯ Pulse oximetry cannot detect hypercapnia or acidosis. For these and other reasons, pulse oximetry should not be used in initial selection of patients for LTOT, as a substitute for arterial blood gas analysis in the evaluation of patients with undiagnosed respiratory disease, during formal cardiopulmonary exercise testing, or in the presence of an acute exacerbation. Pulse oximetry is an important addition to the clinician's armamentarium, however, for titrating the oxygen dose in stable patients, in assessing patients for desaturation during exercise, for sleep studies, and for in-home monitoring.
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Dyspnea--an unpleasant or uncomfortable awareness of breathing or need to breathe--is a common symptom of patients with cardiopulmonary disease. Although often thought of as a single symptom, dyspnea probably subsumes many sensations. Experimental conditions used to induce dyspnea are characterized by discrete groups or clusters of descriptive phrases. ⋯ Evidence is gathering that the sensations of dyspnea are modified by information from a variety of receptors throughout the respiratory system. The sense of effort, although still important in the breathlessness associated with mechanical loads, is insufficient to explain the dyspnea arising from a number of experimental and clinical conditions. As our understanding of the interactions between effort and afferent information from the respiratory system grows, new therapeutic interventions to alleviate dyspnea are likely to follow.
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The effects of a 10-week inspiratory muscle training (IMT) program at home were compared to IMT during a 10-week pulmonary rehabilitation program (PR) in 40 COPD patients with a ventilatory limitation of the exercise capacity. IMT was performed with a target-flow resistive device; the generated mouth pressure as well as the duty cycle were imposed. The mean age of the patients was 59, the mean FEV1 was 48% of predicted. ⋯ In the PR + IMT group, however, Wmax, VO2,max, walking distance, and ADL scores improved significantly after the training period. Walking distance and ADL scores showed a significantly greater improvement in the PR + IMT group than in the IMT group. It is concluded that both isolated IMT and PR + IMT in COPD patients with a ventilatory limitation have a beneficial effect on inspiratory muscle strength, but PR + IMT improves the physical exercise capacity significantly more than IMT alone.
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Diaphragmatic weakness implies a decrease in the strength of the diaphragm. Diaphragmatic paralysis is an extreme form of diaphragmatic weakness. Diaphragmatic paralysis is an uncommon clinical problem while diaphragmatic weakness, although uncommon, is probably frequently unrecognized because appropriate tests to detect its presence are not performed. ⋯ In this review we outline an approach we have found useful in attempting to determine a specific cause. Most frequently the cause is either a phrenic neuropathy or diaphragmatic myopathy. Often the neuropathy or myopathy affects other nerves or muscles that can be more easily investigated to determine the specific pathologic basis, and, by association, it is presumed that the diaphragmatic weakness or paralysis is secondary to the same disease process.