Articles: respiratory-distress-syndrome.
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Critical care medicine · Oct 1991
Multicenter Study Clinical TrialAirway pressure release ventilation during acute lung injury: a prospective multicenter trial.
To evaluate the feasibility of airway pressure release ventilation (APRV) in providing ventilatory support to patients with acute lung injury of diverse etiology and mild-to-moderate severity. ⋯ APRV is a feasible alternative to conventional mechanical ventilation for augmentation of alveolar ventilation in patients with acute lung injury of mild-to-moderate severity.
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Alterations in right ventricular (RV) performance are critical to the cardiac dysfunction witnessed in adult respiratory distress syndrome (ARDS), septic shock (SS), and as a consequence of positive end-expiratory pressure (PEEP) administration during mechanical ventilation. The authors review evidence for right heart dysfunction in these circumstances. In ARDS, an increase in RV afterload with the onset of pulmonary artery hypertension is the predominant factor promoting RV dysfunction. ⋯ The application of PEEP during mechanical ventilation can potentiate alterations in RV preload, afterload, and/or contractility, all of which promote RV dysfunction and compromise left ventricular filling. As RV dysfunction may seriously affect global myocardial performance in all of these settings, the clinician must identify that RV function is impaired, discern the contributing mechanism, and select an appropriate therapeutic regimen targeted at addressing this predominant mechanism. Assessment and management strategies are described.
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Am. Rev. Respir. Dis. · Sep 1991
Effects of positive end-expiratory pressure on alveolar recruitment and gas exchange in patients with the adult respiratory distress syndrome.
The effects of different levels of positive end-expiratory pressure (PEEP) (zero to 15 cm H2O) on the static inflation volume-pressure (V-P) curve of the respiratory system and on gas exchange were studied in eight patients with the adult respiratory distress syndrome (ARDS). Alveolar recruitment with PEEP was quantified in terms of recruited volume, i.e., as difference in lung volume between PEEP and zero end-expiratory pressure (ZEEP) for the same static inflation pressure (20 cm H2O) from the V-P curves obtained at the different PEEP levels. ⋯ The results suggest that: (1) in some patients with ARDS the V-P curves determined on ZEEP exhibit an upward concavity reflecting progressive alveolar recruitment with increasing inflation volume, and PEEP results in alveolar recruitment (range of recruited volume at 15 cm H2O of PEEP: 0.11 to 0.36 L); (2) in other patients with ARDS the V-P curves on ZEEP are characterized by an upward convexity, and PEEP results in a volume displacement along this curve without alveolar recruitment and with enhanced risk of barotrauma; (3) the PEEP-induced increase in arterial oxygenation is significantly correlated to the recruited volume but not to the changes in static compliance. The shape of the static inflation V-P curves on ZEEP allows the prediction of alveolar recruitment with PEEP.
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Comparative Study
The value of portable chest roentgenography in adult respiratory distress syndrome. Comparison with computed tomography.
In 17 patients with adult respiratory distress syndrome, we used data derived from computed tomographic (CT) scan densitometric analysis to validate the value of portable chest roentgenograms in objectively estimating the amount of pulmonary edema. Chest roentgenograms and CT scans were taken in the same ventilatory conditions (apnea at 10 cm H2O of positive end-expiratory pressure [PEEP]); blood gas samples and hemodynamic parameters were collected at the same time. Roentgenographic analysis was undertaken by independent observers using two standardized scoring systems proposed in the literature. ⋯ Both the roentgenographic scoring systems showed direct correlation with the pulmonary impairment as detected by CT scan densitometric analysis (CT number, percentage of nonaerated tissue, lung weight, and excess tissue mass; p less than 0.01) and inverse relation with the percentage of normally aerated tissue (p less than 0.01). We also found a relationship between roentgenographic scores and the impairment in gas exchange as detected by shunt fraction (p less than 0.05). We conclude that standardized reading of portable chest roentgenograms by means of scoring tables is a valuable tool in estimating the amount of pulmonary edema in a patient with adult respiratory distress syndrome.