EFFECT OF 5-PERCENT ALBUMIN SOLUTION ON SODIUM-BALANCE AND BLOOD-VOLUME AFTER SUBARACHNOID HEMORRHAGE

OBJECTIVE: Subarachnoid hemorrhage (SAH) predisposes patients to exces sive natriuresis and volume contraction. We studied the effects of pos toperative administration of 5% albumin solution on sodium balance and blood volume after SAH. We also sought to identify physiological vari ables that influence renal sodium excretion after SAH. METHODS: Forty- three patients with acute SAH were randomly assigned to receive hyperv olemia or normovolemia treatment for a period of 7 days after aneurysm clipping. In addition to a base line infusion of normal saline soluti on (80 ml/hr), 250 ml of 5% albumin solution was administered every 2 hours for central venous pressure (CVP) values of less than or equal t o 8 mm Hg (hypervolemia group, n = 19) or less than or equal to 5 mm H g (normovolemia group, n = 24). RESULTS: Both groups demonstrated rela tive volume expansion in base line measurements. The hypervolemia grou p received significantly more total fluid, sodium, and 5% albumin solu tion than did the normovolemia group and had higher CVP values and ser um albumin levels tall P < 0.02). Cumulative sodium balance was even i n the hypervolemia group and persistently negative in the normovolemia group, because of sodium losses that occurred on Postoperative Days 2 and 3 (P = 0.03). In a multiple-regression analysis of all patients, 24-hour sodium balance correlated negatively with glomerular filtratio n rate (GFR) and positively with serum albumin levels, after correctio n for sodium intake (P < 0.0001). Hypervolemia therapy seemed to parad oxically lower GFR (P = 0.10) and had no effect on blood volume, which declined by 10% in both groups. Pulmonary edema requiring diuresis oc curred in only one patient in the hypervolemia group. CONCLUSION: Supp lemental 5% albumin solution given to maintain CVP values of > 8 mm Hg prevented sodium and fluid losses but did not have an impact on blood volume in our patients, who were hypervolemic in base line measuremen ts. The natriuresis that occurs after SAH may be mediated in part by e levations of GFR. In addition to acting as a colloid volume expander, 5% albumin solution lowers the GFR and promotes renal sodium retention after SAH. These properties may limit the amount of total fluid requi red to maintain a given CVP value and hence may minimize the frequency of pulmonary edema.