American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Feb 1998
Clinical TrialRespective and combined effects of prone position and inhaled nitric oxide in patients with acute respiratory distress syndrome.
Inhaled nitric oxide (NO) and prone position (PP) are two of the new therapeutics proposed in the setting of acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate the hemodynamic and respiratory effects of NO and prone position in patients with ARDS. Fourteen patients, sedated, paralyzed, and ventilated using volume-control mode, were prospectively investigated. ⋯ The association of NO with PP (T4) resulted in a significant improvement in PO2/FI(O2) (261 +/- 98 mm Hg) when compared with T0, T1, and T3. Analysis of variance showed a significant and additive effect of NO and PP on both PO2/FI(O2) (p < 0.000) and shunt fraction (QS/QT) (p < 0.01). Since the association of NO with PP presents additive effects on oxygenation, this association can be proposed for the treatment of ARDS.
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Am. J. Respir. Crit. Care Med. · Feb 1998
Time course evolution of ventilatory responses to inspiratory unloading in patients.
Inspiratory muscle unloading decreases ventilatory drive. In this study, we examined the time course of this effect in patients with chronic obstructive pulmonary disease receiving two modes of ventilatory support: pressure support ventilation (PSV), during which each cycle was assisted, and biphasic positive airway pressure (BIPAP), set up in such a manner that one spontaneous breath took place between two consecutive pressure-assisted breaths. The first breath following the switch from spontaneous breathing to PSV was associated with an increase in tidal volume (VT) and a drop in mean transdiaphragmatic pressure (mean Pdi) and inspiratory work (WI) performed per liter but with unchanged values of esophageal occlusion pressure at 100 ms (Pes 0.1), diaphragmatic electrical activity (EMGdi), and WI performed by breath. ⋯ During the subsequent breaths of PSV, Pes 0.1, EMGdi, and WI performed per breath decreased progressively up to the sixth to eighth breaths, and VT returned to pre-PSV values. We conclude that in patients with chronic obstructive pulmonary disease the decrease in ventilatory drive associated with PSV takes place from the first breath onwards but requires six to eight breaths to be fully achieved. During BIPAP, as a consequence of the kinetics of the PSV-induced downregulation of ventilatory drive, assisted breaths following spontaneous breaths are characterized by an enhanced inspiratory efficiency.
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Am. J. Respir. Crit. Care Med. · Feb 1998
Analyses of the NRAMP1 and IFN-gammaR1 genes in women with Mycobacterium avium-intracellulare pulmonary disease.
Mycobacterium avium-intracellulare (MAI) pulmonary disease causes substantial morbidity in a population of older, HIV-negative women without preexisting lung disease. The cause for disease susceptibility in these patients is unknown, although their relative phenotypic homogeneity suggests the existence of a common, subtle immune deficiency. An investigation was undertaken to determine if these patients have a defect in their natural resistance-associated macrophage protein (NRAMP1) or interferon gamma receptor 1 (IFN-gammaR1) genes. ⋯ In the NRAMP1 promoter microsatellite, 3 of 8 patients were heterozygous for a dinucleotide sequence insertion, as were 10 of 22 controls. None of the patients had either of the two known IFN-gammaR1 mutations. In conclusion, in women with MAI pulmonary disease, there is no evidence for a genetic defect in NRAMP1 or IFN-gammaR1 to correlate with disease.
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Am. J. Respir. Crit. Care Med. · Feb 1998
Histological indications of a progressive snorers disease in an upper airway muscle.
The etiology of upper airway collapsibility in patients with snoring and obstructive sleep apnea (OSA) remains unclear. Local muscular abnormalities, including neurogenic lesions, could be a contributory factor. The aim of this study was to histologically evaluate the hypothesis of a progressive snorers disease. ⋯ The subjects were also divided into three groups according to their type of nocturnal breathing, i.e., nonsnorers, patients with < 20%, and patients with > or = 45% obstructive breathing. These groups correlated significantly with the degree of abnormality and pathological fiber-size spectra. In conclusion, these results support the hypothesis of a progressive local neurogenic lesion, caused by the trauma of snoring, as a possible contributory factor to upper airway collapsibility.