[The effect of small doses of 7.5% NaCl on brain bulk during elective craniotomies]

In 16 patients (ASA I i II) aged 16-76 years (48 +/- 15; mean +/- SD) operated on because of intracranial expanding mass, the effect of hypertonic saline (7.5%--1 ml/kg b.w.) on brain bulk (BB) was evaluated. Patients were anaesthetised with a slight hypocarbia (PaCO2 = 33.3 +/- 3.5 mmHg). BB was scored after opening the dura (T0) and 15 min. (T15) after hypertonic saline (HS) infusion. Five points BB scale was used. Brain bulk reduction (D BB) was calculated as a difference: BB15-BB0. Tomographic signs of intracranial expansion (TSIE) in preoperative CT were scored using the scale from 5 to 15 points assessing (1 to 3 points) the size of mass lesion, the size of perifocal oedema, midline shift, displacement of ventricles and basal cisterns compression. Systolic (SBP), diastolic (DBP) blood pressures and heart rate (HR) were monitored. Serum natrium (SNa), kalium (SK) and osmolarity (Sosm) were measured at T0, T15 and Tp0 (one hour after operation). Student's t-test, Wilcoxon test and Spearman correlation were used for statistical analysis. P < 0.05 was considered as statistically significant. HS caused significant decrease in BB (p = 0.002). In 12 patients with a solid brain tumor a negative correlation between BB and TSIE was found (r = -0.68). A slight but significant decreases in SBP and DBP at Tp0 and T15 as well as decrease in HR due to HS were stated. SNa and Sosm increased at T15 and reminded elevated at Tpo. We can conclude that 7.5% saline in a dose of 1 ml/kg b.w. reduces brain bulk during craniotomy in patients with supratentorial mass lesions. In patients with a solid brain tumor this effect correlates negatively with a size of expanding mass. A slight changes in blood pressure and heart rate due to HS as well as moderate decrease in SK are within limits of clinical acceptance.