Chest
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Respiratory rate is a sensitive clinical parameter in a multitude of pulmonary diseases, especially in the critical care setting. In order to validate the routine recording of the respiratory rate in the intensive care unit, we compared the values obtained from the nursing records with the breathing frequency continuously recorded by a prototype microprocessor system using respiratory inductive plethysmography. We found a significant (greater than or equal to 20 percent) error in the staff's monitoring of respiratory rate one third of the time. In addition, we demonstrated the ease and reliability of using this prototype system as a continuous, noninvasive, long-term respiratory monitor in the intensive care unit.
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Randomized Controlled Trial Clinical Trial
Positive end-expiratory pressure following coronary artery bypass grafting.
Pulmonary dysfunction commonly follows open heart surgery. To evaluate the effects of positive end-expiratory pressure (PEEP) upon the course and severity of impaired oxygen transfer and roentgenographic evidence of atelectasis after coronary artery bypass grafting (CABG), we randomly assigned 44 patients to positive pressure ventilation and 0, 5, or 10 cm H2O PEEP. Study groups did not differ with respect to preoperative P(A-a)O2 or time on cardiopulmonary bypass. ⋯ Roentgenographic atelectasis scores did not differ on the fifth postoperative day. Five days after CABG, P(A-a)O2 exceeded preoperative P(A-a)O2 (29 +/- 1 vs 18 +/- 1 mm Hg, p less than .001), although the roentgenographic distances from hemidiaphragm to lung apex were unchanged (21.2 +/- 0.9 vs 22.0 +/- 0.9 cm). We conclude that routine PEEP improves pulmonary oxygen transfer but, once discontinued, PEEP offers no sustained beneficial effect upon impaired oxygen transfer or roentgenographic evidence of atelectasis following CABG.
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We examined the relationship between pulmonary density, measured with computerized tomography, and pulmonary mechanics (static pulmonary volume; pulmonary resistance) in 39 normal subjects (20 nonsmokers and 19 smokers). Pulmonary density decreased with increasing static elastic recoil pressure, and smokers consistently showed higher pulmonary density than nonsmokers. Pulmonary density, measured at full inspiration, correlated inversely with total lung capacity. ⋯ The study shows that pulmonary density is related to the mechanical properties of the lung in normal subjects. Increased pulmonary density appears to be a sensitive indicator of pulmonary damage induced by smoking. Further studies of the relationship between pulmonary density and pulmonary mechanics in disease seem warranted.