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Effects of mechanical ventilation on platelet microparticles in bronchoalveolar lavage fluid
Diana K Mutschler1, Anders O Larsson, Samar Basu
1Department of Surgical Sciences, Faculty of Medicine, Uppsala University Hospital, Sweden.
Introduction:
Mechanical ventilation (MV) is considered to contribute to lung injury. Platelet membrane-derived microparticles (PMPs) are procoagulant and participate in the inflammatory process. The bronchoalveolar space could, besides plasma, be a site of origin of these microparticles. We evaluated the presence of these PMPs and two prostaglandin-derived metabolites in bronchoalveolar lavage fluid (BALF) regarding their possible relation to MV.
Materials And Methods:
Before and after 1 h of MV, PMPs and prostaglandin metabolites were analyzed, in BALF from 14 anesthetized pigs, by flow cytometry and RIA, respectively. Tracheal mucus from five humans was analyzed for PMPs at extubation after surgery.
Results:
Activated PMPs and prostaglandin metabolites were present in all BALF samples. The time needed to count 5000 cellular events was prolonged six-fold after 1 h of mechanical ventilation (p<0.001). The relative content of PMPs was constant in all samples. The PMPs were thrombogenic, i.e. they were fibrinogen, p-selectin and von Willebrand factor positive. Lavage did not per se affect the period necessary to count 5000 cellular events. PMPs in human tracheal mucus were in the same range as in the pig after 1 h of MV aiming at a PaCO(2) between 5.0 and 5.5 kPa.
Conclusions:
Activated PMPs are present in the pulmonary air-liquid interface. The prolongation of the time needed to count 5000 cellular events in BALF after MV indicates activation and adherence. Adherent microparticles bind neutrophils, which may aggravate pathological processes leading to pulmonary dysfunction. Evaluation of PMPs in BALF may be useful in evaluating strategies for lung-protective ventilator treatment.
Insights
Mechanical ventilation (MV) increases platelet-derived microparticles (PMPs) in the lungs, indicating activation and adherence. These findings suggest PMPs may worsen lung injury during ventilation.
Area of Science:
- Pulmonary Medicine
- Critical Care
- Hematology
Background:
- Mechanical ventilation (MV) is associated with lung injury.
- Platelet membrane-derived microparticles (PMPs) are procoagulant and involved in inflammation.
- The bronchoalveolar space may be a source of PMPs, in addition to plasma.
Purpose of the Study:
- To evaluate the presence of PMPs and prostaglandin metabolites in bronchoalveolar lavage fluid (BALF).
- To determine the relationship between PMPs in BALF and mechanical ventilation.
Main Methods:
- Analysis of PMPs and prostaglandin metabolites in BALF from 14 anesthetized pigs before and after 1 hour of MV using flow cytometry and RIA.
- Analysis of PMPs in tracheal mucus from five humans at extubation post-surgery.
Main Results:
- Activated PMPs and prostaglandin metabolites were detected in all BALF samples.
- Mechanical ventilation significantly prolonged the time to count cellular events in BALF, indicating activation and adherence.
- PMPs in pig BALF after MV were comparable to those in human tracheal mucus.
Conclusions:
- Activated PMPs are present at the pulmonary air-liquid interface.
- MV induces PMP activation and adherence in the lungs, potentially exacerbating inflammation and dysfunction.
- Monitoring PMPs in BALF could aid in developing lung-protective ventilation strategies.