The American review of respiratory disease
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Am. Rev. Respir. Dis. · Aug 1986
Lack of bacterial aerosols associated with heat and moisture exchangers.
Contaminated condensate might serve as a source for cross infection. Heat and moisture exchangers (HME) are devices that humidify inspired gases, which pass through a hygroscopic felt pad surrounded by a cellulose sponge housed in a plastic case. In our study, we used a Servo 150 HME in place of a cascade humidifier in mechanical ventilator circuits. ⋯ In a second study, HMEs contaminated with either Staphylococcus aureus or Pseudomonas aeruginosa (at 10(3), 10(5), or 10(8) organisms/ml) were connected to an Andersen Air Sampler to simulate a ventilator circuit. Bacterial aerosols were not generated, with the exception of 2 to 4 bacteria recovered after contamination with 10(8) bacteria. The HME can provide humidification for mechanically ventilated patients with little risk of generating respirable bacterial aerosols.
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Am. Rev. Respir. Dis. · Aug 1986
Independent influence of reversibility of air-flow obstruction and nonspecific hyperreactivity on the long-term course of lung function in chronic air-flow obstruction.
We evaluated factors that might influence the course of lung function after 2 to 21 yr of follow-up in 81 nonallergic patients with chronic air-flow obstruction (CAO) and considerable lung function impairment (initial forced expiratory volume in one second as a percentage of inspiratory slow vital capacity (FEV1 % VC) ranging from 40 to 55% and increasing less than 15% after the administration of the anticholinergic bronchodilator thiazinamium). A more favorable rate of change in FEV1 was associated with less pack-years of smoking, less nonspecific hyperreactivity, and a higher degree of reversibility of air-flow obstruction, when expressed as the increase in FEV1 as a percentage of the predicted minus prebronchodilator FEV1 value. ⋯ However, the possibility that interval therapy may ultimately produce the same results cannot be excluded. It seems to be important to stop smoking, both for the sake of its negative influence on the course of FEV1 and for the fact that a beneficial influence of bronchodilating therapy may become even more apparent.
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Am. Rev. Respir. Dis. · Jul 1986
Factors affecting bronchial blood flow through bronchopulmonary anastomoses in dogs.
Most of the bronchial arterial blood flow (Qbr) drains through bronchopulmonary anastomoses into the pulmonary circulation, and the remainder goes into the systemic venous system via the bronchial veins. We studied the relationship between blood flow through bronchopulmonary anastomoses, and alveolar pressure and pulmonary vascular pressures as well as hydrostatic pressure in the bronchial veins in 10 adult dogs. The pulmonary artery and vein of the experimental left lower lobes (LLL) of open-chested, anesthetized dogs were isolated and connected to reservoirs. ⋯ The mean anastomotic Qbr was 4.4 +/- 1.1 (mean +/- SEM) ml/min and it decreased by 23 and 39% when alveolar pressure was raised from 5 cm H2O to 10 and 20 cm H2O respectively (p less than 0.05). Approximately 75% of the total anastomotic Qbr was collected from the pulmonary venous reservoir at all alveolar pressures. When both pulmonary artery and venous pressures were increased higher than the alveolar pressure (zone III), azygos snaring increased the anastomotic Qbr by 13 and 31% at alveolar pressures of 10 and 20 cm H2O, respectively (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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In an attempt to assess the action of the sternocleidomastoid muscles on the human rib cage, we studied the pattern of rib cage motion in 2 patients with complete transection of the upper cervical cord. Measurements of rib cage motion were obtained with magnetometers and chest roentgenograms, and concentric needle electrodes were used to record the electromyograms (EMG) of various respiratory muscles. Spontaneous quiet breathing elicited a large amount of phasic inspiratory EMG activity not only in the sternocleidomastoids, but also in the trapezii, platysma, mylohyoid, and sternohyoid muscles. ⋯ During spontaneous inspiration both patients showed a clear-cut decrease in lower rib cage transverse diameter, and they both had a cranial displacement of the sternum and an increase in upper rib cage anteroposterior diameter that was disproportionately larger than the increase in lower rib cage anteroposterior diameter. Radiographic measurements confirmed these deformations but also demonstrated that the upper rib cage transverse diameter increased rather than decreased with inspiration. These results indicate that: (1) Patients with high tetraplegia use many neck muscles in addition to the sternocleidomastoids to breathe; (2) The synchronous contraction of these muscles acts to pull the sternum cranially, expands the upper rib cage, and causes paradoxical inward displacement of the lateral walls of the lower rib cage; (3) As in dogs, the motion of the upper rib cage in humans is more tightly linked to the sternum than that of the lower rib cage.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. Rev. Respir. Dis. · Jun 1986
Assessment of lung injury in the adult respiratory distress syndrome using multiple indicator dilution curves.
To assess its usefulness as an index of lung injury in critically ill patients with respiratory failure, the lung microvascular permeability surface area product for urea (14C-PSu) was measured using a multiple radioisotopic indicator dilution technique in 10 patients with the adult respiratory distress syndrome (ARDS) and in a control population of 5 patients without ARDS. The mean values for 14C-PSu and for extravascular lung water (EVLW) were both significantly elevated in patients with ARDS compared with those in control patients (14C-PSu: 18.7 +/- 4.4 versus 7.6 +/- 0.7, p less than 0.05; EVLW: 676 +/- 55 versus 269 +/- 53, p less than 0.001); 14C-PSu and EVLW were significantly correlated (R = 0.52, p less than 0.001). In the patients with ARDS, 14C-PSu and oxygenation, assessed as the alveolar-arterial oxygen difference, did not appear to be correlated. ⋯ These data suggest that measurement of 14C-PSu in critically ill patients is a clinically applicable parameter that reflects the degree of microvascular injury in groups of patients. However, our study did not indicate a clear advantage of 14C-PSu over EVLW in assessing lung injury in this patient population. The variability in 14C-PSu control patients also suggests that directional changes in 14C-PSu, as a measure of changes in the degree of lung microvascular dysfunction, should be interpreted with caution.