Chest
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Flow in the upper airway wall induces significant error in estimating respiratory impedance by the standard forced oscillation technique in subjects with airway obstruction and may be minimized by oscillating pressure around the subject's head (head generator technique). The aim of this study was to determine whether the latter improves the power of forced oscillations in detecting airway response to bronchodilators in children. Seventy-five children with airway obstruction were studied (ages 5.5 to 15 years old). ⋯ Finally, delta %Crs was more specific (72 vs 67%) and more sensitive (68 vs 52%) with standard than with head generator. The overall incidence of false results was lower with the head generator than with the standard generator for resistance and lower with the standard generator than with the head generator for fn and compliance. Thus, the head generator improves the diagnostic power of the forced oscillation resistance in establishing the reversibility of airway obstruction, but parameters derived from the reactance may have better diagnostic value with the standard method.
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Inflammatory cytokines have been related to the development of adult respiratory distress syndrome (ARDS), shock, and multiple organ dysfunction syndrome (MODS). We tested the hypothesis that unfavorable outcome in patients with ARDS is related to the presence of a persistent inflammatory response. For this purpose, we evaluated the behavior of inflammatory cytokines during progression of ARDS and the relationship of plasma inflammatory cytokines with clinical variables and outcome. ⋯ Our findings indicate that unfavorable outcome in acute lung injury is related to the degree of inflammatory response at the onset and during the course of ARDS. Patients with higher plasma levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 on day 1 of ARDS had persistent elevation of these inflammatory cytokines over time and died. Survivors had lesser elevations of plasma inflammatory cytokines on day 1 of ARDS and a rapid reduction over time. Plasma IL-1 beta and IL-6 levels were consistent and efficient predictors of outcome.
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A number of echocardiographic clues of pericardial tamponade have been described, but their accuracy in patients with pulmonary hypertension has not been well elucidated. Four echocardiographic clues of pericardial tamponade, namely, right atrial collapse (RAC), right ventricular diastolic collapse (RVDC), marked (> 40%) respiratory variation in transmitral Doppler flow velocity ("flow velocity paradoxus [FVP]"), and inferior vena cava plethora (IVCP) were prospectively evaluated in 32 patients with large pericardial effusions. Of 12 patients with pulmonary hypertension, 6 had invasively determined evidence of tamponade and 6 did not; of 20 patients without pulmonary hypertension, 11 had tamponade and 9 did not. ⋯ Although all predictive accuracies were lower in patients with pulmonary hypertension, statistically significant decreased predictive accuracy was found only with FVP (p < 0.05). Interestingly, IVCP had the best predictive accuracy among patients with pulmonary hypertension. Our findings suggest that despite somewhat decreased accuracy in patients with pulmonary hypertension, traditional echocardiographic clues for pericardial tamponade may be useful.
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Mixed venous oxygen saturation (SvO2) is a physiologic parameter reflecting cardiac output (CO) and tissue oxygen utilization. An implantable oxygen sensor incorporated in a right ventricular pacing lead has been developed to assess the feasibility of ambulatory monitoring of SvO2 to predict cardiorespiratory parameters. Eight patients with a mean age of 62 +/- 2 years and sinoatrial disease received an SvO2-driven dual-chamber rate-adaptive pacemaker capable of continuous SvO2 measurement. ⋯ Doppler-derived CO was significantly correlated with CO estimated from SvO2 measured (r = 0.8 +/- 0.1, p < 0.05) and is expressed as 46x derived CO +300. Although continuous SvO2 sensing was originally developed to increase pacing rate during exercise, its use can be extended for monitoring cardiopulmonary performance on an ambulatory basis. This may be useful as a direct assessment of cardiopulmonary status in diseased states and also as an objective means to evaluate cardiac response to medical therapy in patients with heart failure.