The phenomenon of respiratory failure in shock: the genesis of "shock lung"

Shock lung and diffuse alveolar damage pathological and pathogenetic considerations

Diffuse alveolar damage may be caused by any one or more of a large number of injurious agents. While the etiology may be diverse, the pathology is relatively uniform ranging from an acute exudative phase characterized by protein-rich interstitial and alveolar edema, through to a reactive subacute proliferative phase characterized by interstitial fibroplasia and collagenization together with granular pneumocyte hyperplasia. Interstitial inflammation is a variable feature and of course mixed exudative and proliferative features are common. In the clinically overt adult respiratory distress syndrome, the mortality is formidable. The pathogenesis is damage to endothelial cells and membranous pneumocytes. This may be caused by direct chemical action or indirectly through the mediation of oxidizing free radicles or leukotrienes. In diffuse alveolar damage associated with shock, recent work suggests mediation of the cellular injury via complement activation following tissue injury, with the major pathology being due to lysosomal enzyme damage from phagocytes chemotactically attracted to the lung. Etiological factors in diffuse alveolar damage are numerous and details of appropriate primary therapy are therefore diverse. The pathogenesis and pathology are however relatively uniform, calling for uniform supportive therapeutic measures of the clinical adult respiratory distress syndrome.

Occurrence of pulmonary insufficiency in abdominal trauma

The alteration of pulmonary function in 35 patients with abdominal trauma admitted to the Trauma ICU of Oska University Hospital were studied. A fall of PaO2 reaching the lowest level on the third post-traumatic day, incomplete recovery even on the seventh posttraumatic day and of longer duration was remarkable in comparison to those seen after elective abdominal surgery. Thirty two patients recovered without need of particular respiratory control but remaining three died with progressive decrease of PaO2 in spite of the intensive respiratory care. The hypoxia seen in the fatal cases was irresponsive to the administration of 100 per cent O2 with mechanical ventilation. Therefore, increase in intrapulmonary shunt was likely to be responsible for their fatal course.