The American review of respiratory disease
-
Am. Rev. Respir. Dis. · Feb 1992
Flow and volume dependence of respiratory system flow resistance in patients with adult respiratory distress syndrome.
Using a simple and rapid technique, we studied the flow and volume dependence of the total resistance of the respiratory system (Rrs) in six patients with ARDS. At any given inflation volume, Rrs decreased progressively with increasing flow (V) according to the following hyperbolic function: Rrs = a/V + b, where a and b are constants. At any fixed inflation flow, Rrs increased progressively with increasing inflation volume. ⋯ The flow and volume dependence of Rrs found in the patients with ARDS is qualitatively similar to that previously observed in normal anesthetized paralyzed subjects. In ARDS, however, Rrs was considerably greater than in the normal subjects, indicating that besides a low respiratory compliance ARDS is characterized by a high flow resistance. This mainly reflects increased effective flow resistance of the pulmonary and chest wall tissues, although airway resistance is also higher than normal.
-
Am. Rev. Respir. Dis. · Feb 1992
Resolution of laryngeal injury following translaryngeal intubation.
Translaryngeal intubation (TLI) causes mucosal ulcerations of the vocal cords and posterior laryngeal commissure. Usually these ulcers heal by primary reepithelialization, but occasionally laryngeal granulomas or strictures develop at these ulcer sites. The incidence of granuloma and stricture formation and the variables influencing abnormal laryngeal healing following TLI are not well understood. ⋯ Laryngeal symptoms, particularly hoarseness, resolved as the larynx healed. Performance of tracheostomy, age, TLI for more than 10 days, and severe laryngeal injury at extubation did not influence the median time to resolution of laryngeal abnormalities. Abnormal laryngeal healing following TLI is uncommon but is not exacerbated by prolonged TLI (more than 10 days), severe laryngeal injury at extubation, or performance of a tracheostomy.
-
Am. Rev. Respir. Dis. · Feb 1992
Multicenter Study Clinical TrialThe lung health study: airway responsiveness to inhaled methacholine in smokers with mild to moderate airflow limitation. The Lung Health Study Research Group.
As part of a multicenter clinical trial (Lung Health Study), methacholine inhalation challenge testing was performed in 5,877 current cigarette smokers, ages 35 to 59 yr (mean 48.5 +/- 6.8 yr), with borderline to moderate airflow limitation (FEV1/FVC ratio 63.0 +/- 5.5). The test was successfully completed in 96.4% of subjects, of whom 63% were male and 95.9% were white. Symptomatic reactions to methacholine were rarely severe enough to require evaluation by a trial physician. ⋯ By contrast, among women, AHR was not significantly associated with chronic cough and/or phlegm (p greater than 0.05) or a past history of asthma or hay fever (p greater than 0.1) and was only weakly related to wheeze and current asthma (p = 0.04), as well as to cigarette pack-years (p = 0.044). These results indicate that most continuing smokers with functional evidence of early chronic obstructive pulmonary disease have nonspecific AHR that is strongly related to gender and baseline lung function and, to a lesser extent, to respiratory symptoms. The reason for the striking effect of gender on AHR in early chronic obstructive pulmonary disease is unclear but cannot be attributed to male-female differences in age, cigarette use, presence of asthma, or baseline degree of airflow obstruction.
-
Am. Rev. Respir. Dis. · Jan 1992
Metabolism of exogenously administered surfactant in the acutely injured lungs of adult rabbits.
Acute lung injury was induced in adult rabbits with a subcutaneous injection of N-nitro-so-N-methylurethane (NNNMU). Clearance of saturated phosphatidylcholine (Sat. PC) from a treatment dose of exogenous surfactant (100 mg/kg) in the injured lungs of these rabbits was similar to normal, control rabbits when measured 24 h after treatment. ⋯ In vivo functional studies of these aggregates were performed by intratracheal injection into surfactant-deficient preterm rabbits. Large aggregates from normal adult rabbits given surfactant had superior functional properties than did the surfactant used for treatment alone, which in turn was better than large aggregates isolated from NNNMU-injured rabbits treated with surfactant. This indicates that the alveolar environment influenced the function of the exogenously administered surfactant differently in normal and injured rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)
-
Am. Rev. Respir. Dis. · Jan 1992
Clinical TrialProportional assist ventilation. Results of an initial clinical trial.
The response to proportional assist ventilation (PAV) was tested in four normal subjects during heavy exercise and in five ventilator-dependent patients recovering from assorted medical disorders. The apparatus consisted of a rolling-seal piston coupled to a motor that generated pressure in proportion to inspired flow and inspired volume, with the gains adjusted such that the proportionality between airway pressure (Paw) and instantaneous patient-generated pressure (Pmus) was approximately 1:1 (i.e., machine-amplified patient effort by a factor of 2). Normal subjects responded to PAV by decreasing their own effort, as judged from esophageal pressure, such that the changes in ventilation and breathing pattern were rather small (VE: 64.8 +/- 3.6 during PAV versus 56.0 +/- 4.3, p less than 0.01; VT: 2.39 +/- 0.24 versus 2.02 +/- 0.17, p less than 0.05; f: 27.5 +/- 1.9 versus 28.0 +/- 2.2, NS). ⋯ After a period of observation during synchronized intermittent mechanical ventilation (SIMV) the patient was switched to PAV and maintained on it for 1 to 3 h. No patient had to be replaced on SIMV because of discomfort or deterioration in any of the monitored variables. During PAV peak airway pressure was less than half the value observed with the IMV breaths (16.6 +/- 2.4 versus 35.4 +/- 3.4 cm H2O, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)