American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Jun 2000
Oxygenation response to a recruitment maneuver during supine and prone positions in an oleic acid-induced lung injury model.
Prone position and recruitment maneuvers (RM) are proposed as adjuncts to mechanical ventilation to open up the lung and keep it open. We studied the oxygenation response to a RM (composed of a 30-s sustained inflation at 60 cm H(2)O airway pressure) performed in prone and supine positions in dogs after oleic acid- induced lung injury using an inspired O(2) fraction of 0.60. In one group (n = 6) first supine then prone positions were examined after a RM at 8 cm H(2)O and 15 cm H(2)O of positive end-expiratory pressure (PEEP). ⋯ Prone positioning after supine position always improved oxygenation, whereas the decrement in Pa(O(2)) was relatively small when dogs were returned to the supine position. Oxygenation improved in both groups after a RM, and the improvement was sustained (after 15 min) in the prone position at 8 cm H(2)O of PEEP, but 15 cm H(2)O of PEEP was required in supine position. Our results suggest that a RM improves oxygenation more effectively with a decreased PEEP requirement for the preservation of the oxygenation response in prone compared with supine position.
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Am. J. Respir. Crit. Care Med. · Jun 2000
Effect of unplanned extubation on outcome of mechanical ventilation.
Unplanned extubation is a major complication of translaryngeal intubation, but its impact on mortality, duration of mechanical ventilation (MV), length of intensive care unit (ICU) and hospital stay, and need for ongoing hospital care has not been adequately defined. We performed a case-control study in a tertiary-care medical ICU, comparing 75 patients with unplanned extubation and 150 controls matched for Acute Physiology and Chronic Health Evaluation II score, presence of comorbid conditions, age, indication for MV, and sex. Forty-two (56%) patients required reintubation after unplanned extubation (74% immediately, 86% within 12 h). ⋯ We conclude that unplanned extubation is not associated with increased mortality when compared with that of matched controls, although it does result in prolonged MV, longer ICU and hospital stay, and increased need for chronic care. These effects are due exclusively to patients who fail to tolerate unplanned extubation. Although successfully tolerated unplanned extubation decreased the duration of weaning trials, it had no other measurable beneficial impact on outcome.
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Am. J. Respir. Crit. Care Med. · Jun 2000
Randomized Controlled Trial Clinical TrialInhaled furosemide greatly alleviates the sensation of experimentally induced dyspnea.
Furosemide is known to influence the activity of vagally mediated mechanoreceptors in the airways. Because vagal afferent fibers may play an important role in modulation of the sensation of dyspnea, it is possible that inhaled furosemide may modify the sensation of dyspnea. In a double-blind, randomized, crossover study, we compared the effect of inhaled furosemide on dyspneic sensation with that of placebo. ⋯ Total breathholding time after inhalation of furosemide (median, 93 [interquartile range, 78 to 112]s) was prolonged compared with the total breathholding time after placebo inhalation (67 [47-74]s). We also found that respiratory discomfort during loaded breathing after inhalation of furosemide develops more slowly and is less than that observed after inhalation of placebo. Our findings indicate that inhaled furosemide greatly alleviates the sensation of dyspnea induced experimentally by breathholding and by a combination of resistive loading and hypercapnia.
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Am. J. Respir. Crit. Care Med. · Jun 2000
Role of the heart in the loss of aeration characterizing lower lobes in acute respiratory distress syndrome. CT Scan ARDS Study Group.
In the acute respiratory distress syndrome (ARDS), lower lobes appear essentially non-aerated in contrast to upper lobes whose aeration can be preserved in some patients. The aim of this study was to assess the mechanical compression exerted by the heart on lower lobes in patients with ARDS. Fourteen healthy volunteers and 38 patients with ARDS free of left ventricular failure were studied. ⋯ The enlargement of the heart was mainly related to a left cardiac protrusion and the pressure exerted by the left heart on the lower lobes was higher in patients with ARDS than in healthy volunteers (8 +/- 3 g. cm(-)(2) versus 6 +/- 1 g. cm(-)(2), p < 0.01). As a consequence, the faction of gas represented 62% of the left lower lobes in healthy volunteers and 12% only in patients with ARDS. The present study demonstrates that apart from the already known anteroposterior and cephalocaudal gradients of pressure depending on the lung weight and abdominal pressure, the heart plays an important role in the dramatic loss of aeration characterizing lower lobes of patients with ARDS lying in the supine position.
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Am. J. Respir. Crit. Care Med. · Jun 2000
Randomized Controlled Trial Clinical TrialThe effect of glutathione and N-acetylcysteine on lipoperoxidative damage in patients with early septic shock.
Both the hyperproduction of oxygen free radicals (OFR) and the weakening of natural scavenging mechanisms have been implicated as contributors to multiple organ failure in septic shock. This study examined whether the antioxidants glutathione (GSH) and N-acetyl-L-cysteine (NAC) play a protective role against damage by OFR in early septic shock. We randomly entered 30 patients with septic shock into one of three groups within 24 h of diagnosis. ⋯ The decrease in peroxidative indexes was even more marked in Group C. Clinical scores in this group were also significantly improved. In conclusion, the administration of high doses of NAC added to GSH significantly decreased the peroxidative stress of patients with septic shock.