Effect of neck compression on sodium excretion in subjects with congestive heart failure.

Previous studies on normal subjects have shown that neck compression causes increased urinary excretion of sodium in the sitting position, but has little or no effect in the recumbent position. In the present study, patients with congestive heart failure have exhibited no increase in urinary sodium excretion after neck compression. P REVIOUS studies" 2 have shown that the decline in sodium excretion which occurs in the sitting position, as compared with recumbency, can be partially but not completely prevented by compression of the neck. Neck compression of the same subjects in the horizontal and head-down (Tren-delenburg) positions had little or no effect. Also, removal of small amounts of blood from sitting subjects caused reduction of sodium excretion which could be prevented by compression of the neck.3 These observations wrere interpreted as indicating the existence of a central homeostatic mechanism which regulates the volume of extracellular fluid by altering sodium excretion, and is apparently activated by changes in the volume of body fluids rather than by changes in cardiac output. The present study was performed to learn whether such a mechanism is active in patients with congestive heart failure. METHODS Four patients in congestive heart failure were studied. None had recently received mercurial diuretics. Each subject came to the laboratory in the fasting state, and ingested 200 ml. of 0.14 per cent sodium chloride every 30 minutes. Urine was collected at hourly intervals for a period of nine hours, and one small chocolate bar was consumed every two hours. Serum sodium analyses were done at the beginning and end of the studies. These observations will be reported later. Experiments dealing with compression of the neck 88 were conducted in the same manner but were performed a few days later. A blood pressure cuff was wrapped around the subject's neck and sustained at a pressure of 20 mm. Hg. Sodium analyses were done according to the method described by Mosher and co-workers4 using the flame photometer. RESULTS Since the results were essentially similar for all four subjects, they are presented as averages in figure 1. For the purpose of comparison , similar observations made on normal subjects2 are also presented. Urine Volume. This function increased shortly after the subjects began to drink the dilute sodium chloride solution. Diuresis attained a peak at the end of the second hour in the normal subjects, but the congestive heart failure patients did not show maximal …