The American review of respiratory disease
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Am. Rev. Respir. Dis. · Oct 1992
Randomized Controlled Trial Comparative Study Clinical TrialOxygen may improve dyspnea and endurance in patients with chronic obstructive pulmonary disease and only mild hypoxemia.
Oxygen (O2) has been reported to improve exercise tolerance in some patients with chronic obstructive pulmonary disease (COPD) despite only mild resting hypoxemia (PaO2 greater than 60 mm Hg). To confirm these prior studies and evaluate potential mechanisms of benefit, we measured dyspnea scores by numeric rating scale during cycle ergometry endurance testing and correlated the severity of dyspnea with right ventricular systolic pressure (RVSP) measured by Doppler echocardiography during a separate supine incremental exercise test. Both sets of exercise were performed according to a randomized double-blind crossover protocol in which patients breathed compressed air or 40% O2. ⋯ Duration of exercise increased on 40% O2 from 10.3 +/- 1.6 to 14.2 +/- 1.5 min (p = 0.005), and the rise in dyspnea scores was delayed. Oxygen delayed the rise in RVSP with incremental exercise in all patients and lowered the mean RVSP at maximum exercise from 71 +/- 8 to 64 +/- 7 mm Hg (p less than 0.03). Improvement in duration of exercise correlated with decrease in dyspnea (r2 = 0.66, p = 0.001) but not with decreases in heart rate, minute ventilation, or RVSP.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. Rev. Respir. Dis. · Sep 1992
Comparative StudyAdaptations of the peripheral circulation to PEEP.
The purpose of this study was to determine the role of changes in the parameters of venous return on the homeostatic adaption to the application of PEEP. We studied 13 dogs anesthetized with alpha-chloralose, intubated, and ventilated. We measured central venous pressure (CVP), arterial pressure (Pao) and cardiac output by thermal dilution. ⋯ The rise in MCFP matched the rise in CVP so that the pressure gradient for venous return did not change. However, there was also an increase in the resistance to venous return, which resulted in a lower cardiac output than expected for the rise in MCFP. In conclusion, homeostatic adjustments to PEEP included a decrease in vascular capacitance, which is partially offset by a rise in the resistance to venous return.
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Am. Rev. Respir. Dis. · Sep 1992
Case ReportsImproved diaphragmatic function after surgical plication for unilateral diaphragmatic paralysis.
We studied pulmonary function tests, maximal voluntary ventilation, arterial blood gases, and respiratory muscle strength and recruitment pattern in a 37-yr-old symptomatic man before and after surgical plication for a left unilateral diaphragmatic paralysis. After plication, FVC, FEV1, TLC and FRC increased, whereas residual volume remained unchanged. Arterial PO2 improved from 70 to 87 mm Hg. ⋯ This indicates more effective diaphragmatic recruitment after the procedure. We conclude that surgical plication may be of benefit to patients with symptomatic unilateral diaphragmatic paralysis. The improvement is due to improved respiratory muscle function.
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Am. Rev. Respir. Dis. · Sep 1992
Effect of positive end-expiratory pressure on right ventricular function in humans.
The effect of positive end-expiratory pressure (PEEP) on right ventricular (RV) function in humans is complex. Previous studies have been limited in their interpretation by not defining either pericardial pressure (Ppc) or RV volumes. Accordingly, we measured RV volumes and pressures and Ppc as PEEP was increased from zero to 15 cm H2O in 12 patients after thoracotomy, using a pulmonary arterial catheter equipped with a rapid responding thermistor that allowed measurement of RV ejection fraction (ef), while Ppc was measured via a pericardial balloon catheter. ⋯ Similarly, there was no relation between Ppa and ESV when either mean or peak Ppa values relative to Ppc were used. The relations between EDV and both SV and RVef were weak (r = 0.54 and 0.55, respectively). RVef varied inversely with ESV (r = -0.77), although it showed no relation to transmural peak Ppa (r = 0.28).(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. Rev. Respir. Dis. · Sep 1992
Case ReportsPulmonary edema associated with salt water near-drowning: new insights.
In this case report we describe the clinical and laboratory findings of a man who nearly drowned after aspirating a large quantity of seawater. The aspiration of salt water, which is strongly hypertonic with respect to plasma, resulted in severe pulmonary edema, both from the quantity of aspirated seawater and the osmotically driven ultrafiltrate of plasma that accumulated in the air spaces. ⋯ In addition, the magnesium concentration was markedly elevated because of the aspiration of magnesium-containing seawater, which may have diagnostic importance for near-drowning in salt water. The data from this case provide evidence for well-preserved alveolar epithelial barrier function after aspiration of large quantities of hypertonic salt water.