[Correlation between postoperative decrement of hematocrit and osmolarity in neurosurgical patients]

After neurosurgical treatment, surgeons sometimes observe decreased hematocrit (Ht), though fluid as well as blood transfusions were properly given during and after surgery. This study was performed to investigate the effects of osmotic change on the decrease in Ht.

Subjects were 153 patients who underwent neurosurgical treatment. Group 1: 39 patients with parasellar tumor. Group 2: 35 patients with anterior cerebral aneurysm. Group 3: other 79 patients with brain tumor or aneurysm except Group 1 and 2. As the controls, 50 patients undergoing intraabdominal operations. During the pre- and postoperative course, blood examination (Ht, RBC, blood glucose, BUN, electrolyte and blood gases), measurements of osmotic pressure (of serum, urine and cerebrospinal fluid), and checks of blood and water balance and vital signs were performed.

As compared with the control group in which Ht decreased clearly but slightly, the neurosurgically-treated groups showed marked decreases in Ht on the 2nd to 4th day after surgery. Of them, groups 1 and 2 showed more prominent decreases. On the 1st to 4th day after surgery, serum sodium levels of groups 1, 2 and 3 increased more clearly than that of the control group. Urine volumes of groups 1 and 2 were larger during one postoperative week, and cases of diabetes insipidus were included. No significant difference was found in water balance and urinary osmotic pressure. Relationships between the serum osmotic pressure and serum sodium content, cerebrospinal fluid osmotic pressure and serum sodium content, and cerebrospinal fluid and serum osmotic pressure were seen. We lay stress on the inverse correlation between the decrease in Ht and the time-course of serum osmotic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)