The American review of respiratory disease
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Am. Rev. Respir. Dis. · Jan 1987
Comparative StudyRespiratory symptoms and lung function in habitual heavy smokers of marijuana alone, smokers of marijuana and tobacco, smokers of tobacco alone, and nonsmokers.
To evaluate the possible pulmonary effects of habitual marijuana smoking with and without tobacco, we administered a detailed respiratory and drug use questionnaire and/or lung function tests to young, habitual, heavy smokers of marijuana alone (n = 144) or with tobacco (n = 135) and control subjects of similar age who smoked tobacco alone (n = 70) or were nonsmokers (n = 97). Mean amounts of marijuana and/or tobacco smoked were 49 to 57 joint-years marijuana (average daily number of joints times number of years smoked) and 16 to 22 pack-years of tobacco. ⋯ We noted significant worsening effects of marijuana but not to tobacco on specific airway conductance and airway resistance (tests of mainly large airways function) in men and of tobacco but not of marijuana on carbon monoxide diffusing capacity and on closing volume, closing capacity, and the slope of Phase III of the single-breath nitrogen washout curve (tests reflecting mainly small airways function) (p less than 0.03, two-way ANCOVA). No adverse interactive effects of marijuana and tobacco on lung function were found.
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Am. Rev. Respir. Dis. · Jan 1987
Comparative StudyTreatment of respiratory failure during sleep in patients with neuromuscular disease. Positive-pressure ventilation through a nose mask.
Severe nocturnal hypoxemia may occur in patients with respiratory muscle weakness caused by neuromuscular disorders. Negative pressure ventilators may be partially effective in these patients but can cause upper airway obstructive apneas. We examined the effectiveness of positive pressure ventilation through a nose mask in preventing nocturnal hypoxemia and compared it with negative pressure systems. ⋯ Negative pressure ventilation appears to contribute to upper airways obstruction during REM sleep as evidenced by cessation of air flow, reduced chest wall movements, falls in arterial oxyhemoglobin saturation, and hypercapnia. With treatment, daytime PaO2 improved from a mean of 70 to 83 mm Hg, and PaCO2 decreased from a mean of 61 to 46 mm Hg. We conclude that nasally applied positive pressure ventilation is a highly effective method of providing nocturnal assisted ventilation because it stabilizes the oropharyngeal airway.
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Am. Rev. Respir. Dis. · Dec 1986
Comparative StudyThe pattern of breathing during successful and unsuccessful trials of weaning from mechanical ventilation.
We prospectively examined the pattern of breathing in patients being weaned from mechanical ventilation: one group (n = 10) underwent a successful weaning trial and were extubated, whereas another group (n = 7) developed respiratory failure and required the reinstitution of mechanical ventilation. During the period of ventilator support, minute ventilation (VI), tidal volume (VT), and respiratory frequency (f) were similar in the 2 groups. After discontinuation of the ventilator, VI remained similar in the 2 groups, but VT was lower and f was higher in the patients who failed the trial compared with those who were successful, 194 +/- 23 and 398 +/- 56 ml (p less than 0.001), respectively, and 32.3 +/- 2.3 and 20.9 +/- 2.8 breaths/min (p less than 0.001), respectively. ⋯ Eighty-one percent of the variance in PaCO2 was accounted for by the pattern of rapid, shallow breathing. During weaning, resting respiratory drive (reflected by mean inspiratory flow, VT/TI) and fractional inspiratory time (TI/Ttot) were similar in the 2 groups. The patients in the failure group showed significant increases in VT/TI, 265 +/- 27 to 328 +/- 32 ml/s (p less than 0.01), and VI, 5.82 +/- 0.53 to 7.32 +/- 0.52 L/min (p less than 0.01), from the beginning to the end of the weaning trial; VT and f showed no further change.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. Rev. Respir. Dis. · Oct 1986
Mechanisms of paradoxical rib cage motion in patients with chronic obstructive pulmonary disease.
Paradoxical motion of the rib cage is well recognized in patients with chronic obstructive pulmonary disease (COPD); most often this is seen in the lateral dimension (Hoover's sign), but paradoxical indrawing of the lower sternum during inspiration has also been described. We have examined the possible mechanisms of these abnormalities by relating rib cage motion (using magnetometers) to the changes in pleural (Ppl), abdominal (Pab), and transdiaphragmatic (Pdi) pressures in 13 patients with COPD and hyperinflation who had previously documented abnormal rib cage motion. During tidal breathing, Pab became more negative in early inspiration in 11 of the 13 patients. ⋯ Five of the 13 patients showed indrawing of the sternum in early inspiration, and in 4, the abnormal motion was confined to the lower sternum, with qualitatively normal motion at the angle of Louis. In these 4 patients, the peak distortion coincided with the nadir of Pab in early inspiration. In all 5 patients, an increase in Pab during expiration suggested expiratory muscle contraction, and this was associated with a paradoxical increase in the anteroposterior diameter of the rib cage.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. Rev. Respir. Dis. · Sep 1986
Estimating the probability of malignancy in solitary pulmonary nodules. A Bayesian approach.
Decisions about managing solitary pulmonary nodules often involve estimates of the likelihood that the nodule is malignant. We used Bayes' theorem to devise a simple scheme for estimating the likelihood that a solitary pulmonary nodule is malignant based on the diameter of the nodule, the patient's age and history of cigarette smoking, and data on the overall prevalence of malignancy in solitary nodules. This method may improve the accuracy of estimating the likelihood of malignancy for individual patients with solitary pulmonary nodules.