The American review of respiratory disease
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Am. Rev. Respir. Dis. · Sep 1987
Randomized Controlled Trial Comparative Study Clinical TrialA prospective study of lung water measurements during patient management in an intensive care unit.
We prospectively evaluated a protocol that included extravascular thermal volume (ETV) as a measure of extravascular lung water (EVLW) instead of pulmonary artery wedge pressure (Ppaw) measurements to guide the hemodynamic management of 48 critically ill patients. Patients were randomized to either a protocol management (PM), or to a routine management (RM) group. In the RM group, EVLW measurements were unknown to the primary care physicians. ⋯ Mortality for the groups as a whole was similar, but was significantly better (p less than 0.05) for PM patients with initially high EVLW and normal Ppaw (predominantly patients with sepsis or the adult respiratory distress syndrome). For both groups, patients with an initial EVLW greater than 14 ml/kg had a significantly greater mortality than did those with a lesser amount of EVLW: 13 of 15 (87%) versus 13 of 32 (41%), p less than 0.05. We conclude that management based on a protocol using EVLW measurements is safe, may hasten the resolution of pulmonary edema, and may lead to improved outcome in some critically ill patients.
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Am. Rev. Respir. Dis. · Sep 1987
Pressure-volume curve of total respiratory system in acute respiratory failure. Computed tomographic scan study.
To investigate the relationship between lung anatomy and pulmonary mechanics in acute respiratory failure (ARF), 20 patients with ARF underwent computerized tomography (CT) at 3 levels of positive end-expiratory pressure (PEEP) (5, 10, and 15 cm H2O). The static pressure-volume curve of the total respiratory system and the lung volumes (helium dilution method) were also measured. By knowing the lung volumes and analyzing the CT number frequency distribution, a quantitative estimate of normally aerated, poorly aerated, and nonaerated lung tissue was obtained at each level of PEEP. ⋯ No relationship was found between the compliances and the poorly aerated and nonaerated tissue. The specific compliance was in the normal range, whereas the amount of recruitment was related to the ratio of inflation compliance to starting compliance. Our data suggest that (1) the pressure-volume curve parameters in ARF investigate only the residual healthy zones of the lung and do not directly estimate the "amount" of disease (poorly or nonaerated tissue), (2) the pressure-volume curve may allow an estimate of the anatomic recruitment, and (3) the residual normally aerated zones of the ARF lung seem to maintain a normal intrinsic elasticity.
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Am. Rev. Respir. Dis. · Sep 1987
Effect of acute diaphragm paralysis on ventilation in awake and sleeping dogs.
The mechanisms responsible for hypoventilation during rapid-eye-movement (REM) sleep in patients with diaphragmatic weakness are not clear. Therefore, we studied the effects of unilateral (UDP) and bilateral (BDP) diaphragmatic paralysis on ventilation during wakefulness (W), slow-wave sleep (SWS), and REM sleep. Studies were performed in 3 trained dogs in which small silicone cuffs had been implanted surgically around the phrenic nerves. ⋯ In contrast, during REM sleep, VI was decreased by an average of 21% mainly because of a fall in tidal volume, and PACO2 increased by 2.4 mm Hg compared with that during the intact state. Furthermore, addition of extra dead space to the breathing circuit, which was well tolerated in intact dogs, led to a progressive increase in PACO2 during BDP and to arousal from sleep. The findings indicate that acute BDP does not impair ventilation during quiet W or SWS, but reduces ventilation during REM sleep, supporting the concept that during REM sleep maintenance of ventilation is critically dependent on diaphragmatic compensation for intercostal and accessory muscle inhibition.