Blood and blood vessel wall changes induced by decompression sickness in dogs

Healthy female dogs of mixed breed were anesthetized with pentobarbital sodium and given 51Cr-labeled autologous red blood cells and 125I-labeled anticanine vessel wall fiber (collagen and elastin) antibody. The anesthetized dogs were exposed to the equivalent of a 220-ft dive on air for 40-45 min (descent rate 75 ft/min, ascent rate 60 ft/min). The animal's condition was adjusted by additional shorter and/or shallower dives. Four dogs had mild decompression sickness (DCS), and seven had severe DCS judged by electrocardiogram. Three of the seven died before completion of the experiment. Permeability of the endothelial sheet of jugular veins and carotid arteries to the tracer (125I-gamma-globulin) was significantly increased in animals with severe but not mild DCS. There was slight hemoconcentration (increased capillary and venular permeability). Scanning electron microscopy showed that the endothelium was grossly intact with no evidence of mechanical damage, but giant cells (derived from monocytes) frequently adhered to the endothelium. Leukocytes and platelets adhered occasionally. Fibrin monomer was found in the plasma. Thus DCS is accompanied by endothelial cell alteration and limited blood cell adhesion to vessel walls in addition to activation od the clotting mechanism.