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The role of the polymorphonuclear leukocyte in the pathogenesis of the adult respiratory distress syndrome

University of British Columbia

This study was designed to follow up a chance observation in patients with an admission white blood cell (WBC) count showing an absolute lymphocytosis and relative neutropenia that changed to a lymphopenia and neutrophilia within 24 hours. As 15 of the 20 patients were admitted following trauma, we examined this association further by reviewing charts of 69 patients who had sustained stab wounds to the chest and abdomen. A prospective study involving 40 patients in the Intensive Care Unit was also undertaken because of the related hypothesis that the Adult Respiratory Distress Syndrome (ARDS) is associated with sequestration of complement activated polymorphonuclear leukocytes (PMN) by the lung. These studies show that trauma is frequently associated with a lymphocytosis and relative neutropenia. In cases where ARDS did develop, the onset of respiratory failure was associated with a profound fall in the circulating PMN count. To test the hypothesis that these leukocyte changes were due to catecholamine release and sequestration of PMN within the pulmonary micro-vasculature, we studied the effects of epinephrine infusion, lowered cardiac output and complement activation on WBC uptake and release from the dog lung. The data show that pulmonary blood flow has a marked effect on the uptake and release of WBC by the lung but has no effect on differential counts. Epinephrine infusion increases circulating WBC counts but also does not alter differential counts. In contrast, activation of the complement cascade alters differential values by causing preferential sequestration of PMN. We conclude that trauma is frequently associated with a lymphocytosis and relative neutropenia and speculate that this phenomenon is due to a combination of catecholamine release and sequestration of PMN within pulmonary and systemic microvasculatures. The findings that a profound fall in PMN counts occurs prior to the onset of ARDS and after activation of the complement pathway with cobra venom factor support the hypothesis that complement activated PMN play a role in the pathogenesis of ARDS. These data also suggest that prospective leukocyte counts may be a useful predictor with respect to determining which patients will develop this syndrome.

Text

2010-05-26

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http://hdl.handle.net/2429/25058

Pathology

University of British Columbia

Graduate