Clinical Observations on the Capillary Circulation

The direct observation of the capillary circulation in disease has long been the aim of many workers, interested in a variety of clinical and experimental problems.It is evident that the rest of the cardio- vascular system exists only to regulate the blood flow through the capillaries, for here takes place the exchange of gases necessary for internal respiration and the exchange of materials necessary for metab- olism.Any attempt to measure cardiovascular function is an indirect attempt to measure the efficiency of the capillary circulation.For example, blood pressure determinations are supposed to give some indi- cation of the peripheral blood flow, but as will be seen later, blood pressure is often a poor index of the state of the capillary circulation.Much work has been done experimentally upon so called capillary poisons, such as arsenic, etc., stimulating a clinical interest in many of the acute intoxications, especially those accompanied by skin reactions, such as occur after arsphenamin injections, diphtheria antitoxin, also occasionally after the injection of foreign proteins.In acute infections, suchas influenza, the sudden collapse is often attributed to a capillary intoxication.The disturbances of water balance in conditions like acute nephritis are by some supposed to be dependent upon an altera- tion of the permeability of capillary endothelium.In traumatic shock *This work was made possible by the clinical facilities offered by the Cleveland City Hospital.