A Study of Capillary Permeability in Experimental Burns and Burn Shock Using Radioactive Dyes in Blood and Lymph.

The integrity of the capillary membrane is essential to the maintenance of the circulation in a normal animal. Increased loss of plasma colloids through the capillary wall may be an important factor in the development of a pathologic state. In recent years, interest has centered upon abnormal capillary permeability, and local changes in permeability have been demonstrated in areas of trauma and burn. A generalized increase in capillary permeability has been postulated in shock, but the evidence is conflicting. Known to occur when histamine is injected intravenously (1), it might take place in other types of shock and has been suggested as a reason for the irreversibility of late shock. The tissue anoxia that occurs as a result of prolonged low blood pressure and decreased blood flow in shock could result in an increase in capillary permeability which would not be limited to the site of injury. Direct quantitative measurement of capillary permeability presents technical difficulties because of the microscopic character of the spaces involved. Several workers, including Krogh (2) and Landis (3), have succeeded in experimental animals in observing directly through a dissecting microscope the passage of dyes, particulate matter, and blood cells out of the capillary into the extravascular space. Landis (3), using a micro-pipette, has been able to measure capillary pressure in both animals and man. Such observations, while demonstrating that under experimental conditions the capillary wall is permeable to large molecules and even particulate matter, have not shown to what extent, in the intact animal with capillaries undisturbed by