The pathology and biology of uremic pneumonitis

Uremic pneumonitis is included in the "adult respiratory distress syndrome". Diffuse alveolo-capillary damage, interstitial and intraalveolar edema, widespread atelectases, alveolar haemorrhages and pulmonary hyaline membranes are characteristic but not pathognomonic findings in uremic pneumonitits. Investigations showed that uremic pneumonitis results from diffuse permeability disorders of the alveolo-capillary permeability combined with an intrarenal or generalized consumption of coagulation factors, and a subsequent state of hypercoagulability. A comparative morphological and clinical analysis of 66 autopsy cases with severe uremia showed that neither the intensity of the urea retention nor the intensity of the creatinine retention correlate with the morphologic symptoms of uremic pneumonitis. Uremia may induce the basic alveolocapillary damage and the subsequent plasmatic leakage into the alveoli and alveolar ducts but uremia has obviously no influence on the simultaneous formation of pulmonary hyaline membranes and intraalveolar bleedings. Hyaline membranes and intraalveolar bleedings are the entire equivalents of the immediate procoagulative activity of the underlying diseases.