The American review of respiratory disease
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Am. Rev. Respir. Dis. · Oct 1982
The effect of positive end-expiratory pressure on functional residual capacity: role of prostaglandin production.
It has been shown that lung distension can generate prostaglandins. To test the hypothesis that there may be a prostaglandin-mediated peripheral (alveolar duct) bronchodilator effect contributing to the increase in functional residual capacity (FRC) observed with positive end-expiratory pressure (PEEP), we applied PEEP to 8 beagle dogs at 2, 5, 5, 7.5, and 10 cm H2O, and measured FRC at each level and immediately after cessation of PEEP. This experiment was then repeated after the intravenous administration of indomethacin 10 mg/kg. ⋯ Furthermore, FRC initially failed to return to baseline immediately after cessation of PEEP but did so after indomethacin. We conclude that endogenous prostaglandin production of PEEP but did so after indomethacin. We conclude that endogenous prostaglandin production may be partially responsible for the elevation of FRC with PEEP.
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Am. Rev. Respir. Dis. · Sep 1982
Comparative StudyComparison of intraesophageal balloon pressure measurements with a nasogastric-esophageal balloon system in volunteers.
Recently, an esophageal balloon incorporated into a nasogastric tube was designed that allowed measurement of intraesophageal pressure. To define the performance of this nasogastric-esophageal balloon (NG-EB) system, comparative measurements were made with a standard esophageal balloon while subjects were in the sitting, supine, and left lateral decubitus and right lateral decubitus positions. ⋯ For both balloon systems, CL showed no significant difference between sitting and right lateral decubitus positions. Results from this study indicate that the NG-EB system acceptably reflects esophageal balloon pressure measurements and should be useful in estimating lung and chest wall mechanics in acutely ill patients requiring mechanical ventilation.
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Am. Rev. Respir. Dis. · Jul 1982
Randomized Controlled Trial Clinical TrialEffect of chest physiotherapy on the removal of mucus in patients with cystic fibrosis.
We studied the effectiveness of some of the components of a physiotherapy regimen on the removal of mucus from the lungs of 6 subjects with cystic fibrosis. On 5 randomized study days, after inhalation of a 99mTc-human serum albumin aerosol to label primarily the large airways, the removal of lung radioactivity was measured during 40 min of (a) spontaneous cough while at rest (control), (b) postural drainage, (c) postural drainage plus mechanical percussion, (d) combined maneuvers (postural drainage, deep breathing with vibrations, and percussion) administered by a physiotherapist, (e) directed vigorous cough. Measurements continued for an additional 2 h of quiet rest. ⋯ We conclude that in cystic fibrosis, vigorous, regimented cough sessions may be as effective as therapist-administered physiotherapy in removing pulmonary secretions. Postural drainage, although better than the control maneuver, was not as effective as cough and was not enhanced by mechanical percussion. Frequent, vigorous self-directed cough sessions are potentially as useful as more complex measures for effective bronchial toilet.
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Am. Rev. Respir. Dis. · Jul 1982
The oxygen cost of breathing in patients with cardiorespiratory disease.
We measured the oxygen cost of breathing (VO2resp) in 13 patients with cardiorespiratory disease requiring artificial ventilation as the difference between the oxygen consumption during spontaneous respiration (VO2tot) and that during artificial ventilation (VO2nonresp). Average VO2tot was 312 +/- 90 ml/min (mean +/- 1 SD), whereas VO2nonresp was 246 +/- 38 ml/min (p less than 0.01). Average VO2resp was 75 +/- 82 ml/min (range, 8 to 286), representing 24% of VO2tot or 8.7 +/- 8.9 ml O2/L ventilation. ⋯ The VO2resp had an exponential relationship with FEV1 (r = 0.97) in 6 patients who had had prior spirometry. Because minute ventilation was normal in our patients (8.8 +/- 2.2 L/min), the elevated VO2resp represented an increase in the work of breathing as well as a decrease in the efficiency of the respiratory muscles. These results suggest that, where O2 transport is compromised, artificial ventilation may release substantial quantities of oxygen for use by other body systems.