A comparison of the effect of 0.9% saline versus balanced salt solution (plasma-lyte a) on acid base equilibrium, serum osmolarity and serum electrolytes in supratentorial neurosurgical procedures requiring craniotomy

Introduction: The most commonly used isoosmolar fluid in neurosurgery is 0.9% saline (308 mosm/L) which has a high chloride content (154 mmol/L), and is known to produce acidosis. Balanced salt solutions, e.g. Plasmalyte A, are isoosmolar (294 mosm/L), contain additional electrolytes, have less chloride content (98 mmol/L) and are stated to produce less acid base disturbances. Our aim was to study the effects of plasma-Lyte A (Baxter healthcare (India) pvt Ltd.) on acid base balance, serum osmolarity and serum electrolytes in neurosurgical procedures. Methods: In this prospective study, 70 Subjects were randomly allocated to two groups, to receive either 0.9% saline as the sole intravenous fluid (Group N) or Plasma-Lyte A (Group P). Arterial Blood Gas Samples were analysed at regular intervals and the variables noted were: serum osmolarity, pH, base deficit or excess, chloride, lactate, sodium, potassium, calcium, and glucose levels. The data was analysed statistically by student’s T test (continuous) and chi-square test (categorical) using NCSS software version 9.0. Results: Towards the end of the surgery, pH was found to be low in the normal saline group (7.334 ± 0.05 and 7.275 ± 0.05) as compared to the plasmalyte group (7.402 ± 0.03 and 7.406 ± 0.03), this difference being statistically highly significant (p<0.0001). The difference in base deficit was also highly significant at the same time intervals. (Group N -2.474 ± 1.169 and -3.682 ± 2.12, Group P-1.046 ± 0.831 and -1.438 ± 1.093, p<0.0001). Chloride levels were significantly higher in the normal saline group at different time intervals (112.8 ± 8.002 and 102.57 ± 6.17), (115.77 ± 9.84 and 103.63 ± 5.2) and (117.194 ± 10.7 and 103.15 ± 4.95) (p value<0.0001). Serum electrolytes and serum osmolarity were found to be comparable in both the groups at all time intervals. Conclusion: Plasmalyte A is a better alternative to 0.9% saline as intravenous fluid in neurosurgical procedures as it produces lesser acidosis and maintains serum chloride levels.