Alteration of pressure-volume characteristics due to different types of edema induction in isolated rabbit lungs

Procoagulant activity in bronchoalveolar lavage of severely traumatized patients--relation to the development of acute respiratory distress

In a prospective study in severely traumatized patients, procoagulant activity (PCA) was determined in bronchoalveolar lavage fluids (BAL). Bronchoscopy with lavage was serially performed during the first 15 days after injury (in total 148 samples of 25 patients). PCA was measured as recalcification times in the absence or presence of excess phosphatidylethanolamine and translated into procoagulant unit equivalents using standard thromboplastin. The data were correlated to the extent of respiratory failure in the injured patients and were compared to PCA in 29 lavage samples obtained from 10 healthy control subjects. A several-fold increase in BAL PCA was noted in all trauma victims, evident already within the first 24 h after injury. A progressive rise in PCA occurred from the 4th posttraumatic day and was highly significantly more pronounced in patients developing serious respiratory failure than in those with only mild pulmonary dysfunction. Significant correlations were noted between PCA increase and alveolar protein-leakage, granulocyte-influx and surfactant alterations, however with correlation coefficients not surpassing 0.55. We conclude that a marked increase in procoagulant activity occurs in severely injured patients, which may favour alveolar fibrin deposition and is related to the development of acute respiratory failure.

Pulmonary surfactant-associated protein A enhances the surface activity of lipid extract surfactant and reverses inhibition by blood proteins in vitro

Although a monolayer of dipalmitoylphosphatidylcholine, the major component of pulmonary surfactant, is thought to be responsible for the reduction of the surface tension at the air-liquid interface of the alveolus, the participation of unsaturated and anionic phospholipids and the three surfactant-associated proteins is suggested in the generation and maintenance of this surface-active monolayer. We have examined the effects of surfactant-associated protein A (SP-A) purified from bovine lavage material on the surface activity of lipid extract surfactant (LES), an organic extract of pulmonary surfactant containing all of the phospholipids and SP-B and SP-C, but lacking SP-A. Measurements of the surface tension during dynamic compression were made on a pulsating bubble surfactometer. Addition of SP-A to LES reduces the number of pulsations required to attain surface tensions near zero at minimum bubble radius. This increase in surface activity is dependent upon the presence of Ca2+ in the assay mixture. Maximal enhancement is observed at or below 1% of the lipid concentration (w/w). The addition of two blood proteins, fibrinogen and albumin, at physiological concentrations to LES causes severe inhibition of surface activity. Addition of SP-A in the presence of Ca2+ completely counteracts the inhibition by fibrinogen. The amount of SP-A required for full reversal of this inhibition was less than 0.5% of the lipid concentration. Complete reversal of inhibition by albumin was also observed, even though there was a approximately 5000-fold molar excess of inhibitor. Addition of lysophosphatidylcholine also inhibits LES; however, SP-A has no effect on this inhibition.

Effect of corticosteroids on lung volume-pressure curves in bleomycin-induced lung injury in the rat

In this study we investigated changes in volume-pressure curves at various stages after bleomycin induced lung injury (6 h, and 3, 7, and 28 days) and tested the ability of steroids to influence these changes. The most significant decreases in volume-pressure curves were observed at 3 days post bleomycin, a time point that correlates to the peak period of inflammation. Steroids as drugs of high antiinflammatory potency were used in order to modulate the inflammatory response and possibly the volume-pressure curve changes observed during the natural course of bleomycin induced lung injury. Dexamethasone treatment significantly inhibited the decreases in volume pressure curves observed at 3 days post bleomycin, whereas methylprednisolone did not. Also both steroids significantly inhibited inflammation as measured by histological evaluation and the presence of cells in the bronchoalveolar lavage fluid.

Correlation of changes in pulmonary surfactant phospholipids with compliance in bleomycin-induced pulmonary fibrosis in the rat

Qualitative and quantitative analysis was performed on phospholipids isolated from bronchoalveolar lavage fluid during the development of pulmonary fibrosis in the rat. A single transtracheal injection of 2.0 units of bleomycin was administered to rats to induce lung injury. Animals were killed at 0, 3, 7, 14, 30, and 120 days after bleomycin treatment. Total lipid phosphorus in BAL from animals given bleomycin increased from 1.6 mumol/lung in normal animals to 3.2 mumol/lung at 14 and 30 days. The increase in phospholipids was primarily in phosphatidylcholine with minor increases in phosphatidylinositol and phosphatidylethanolamine. These quantitative changes were accompanied by qualitative changes that included an increase in the percentage of total phosphatidylcholine, disaturated phosphatidylcholine, and phosphatidylinositol. In contrast, the percentage of phosphatidylglycerol was significantly reduced. Plasma phospholipid analysis indicated that these alterations were not due to plasma contamination. The functional significance of the phospholipid changes was assessed by comparing air- and saline-filled compliance measurements at similar times after bleomycin. Abnormal compliance measurements were observed at 3, 7, and 14 days after bleomycin. At 3 and 7 days the predominant compliance defect was at the air-liquid interface; however, at 14 days, when phospholipids were significantly elevated, the defect was primarily due to tissue components.(ABSTRACT TRUNCATED AT 250 WORDS)