Mannitol versus mannitol with hypertonic saline for brain relaxation during craniotomies using ultra-sonographic optic nerve sheath diameter

Background This study compared the effect of conventional doses of mannitol alone versus combined lower doses of mannitol-hypertonic saline on brain debulking during elective craniotomies.Patients and methods Sixty participants aged 18–60 years, ASA class I or II, who were scheduled for elective supratentorial brain tumor surgery, were randomly separated into 2 equal groups. Group (M) received 5 ml/kg of 20% mannitol at the onset of the surgical incision over 15 min. Group (MH) received 2.5 ml/kg of 20% mannitol plus 2.5 ml/kg 3% hypertonic saline (HTS) at the onset of the surgical incision over 15 min. Optic nerve sheath diameter (ONSD), brain relaxation score, serum lactate, electrolytes, and surgeon’s satisfaction were measured.Results Both groups yielded similar results concerning demographic and tumor characteristics. The Optic nerve sheath diameter (ONSD) was considerably lower in group MH compared to group M just before and immediately after dural incision (p = <0.001, and 0.001) respectively. The brain relaxation was considerably more adequate in group MH when compared to group M (p = 0.001). Group MH showed significant elevation in serum sodium, chloride, and osmolarity at 60 min and at the end of surgery with negligible changes at 12- and 24-hrs postoperatively. Moreover, group M showed a significant increase in serum potassium and lactate at 60 min and at the end of surgery, with insignificant change at 12- and 24-hrs postoperatively. Surgeons were more noteworthy satisfied in group MH.Conclusion Optic nerve sheath was comparable to brain relaxation score (BRS) for assessing the brain relaxation. In comparison to mannitol alone, lower prescribed doses of mannitol in combination with hypertonic saline (HTS) have provided better intraoperative brain debulking, clinically accepted electrolyte changes, and more surgeons’ satisfaction during supratentorial brain tumor surgery.