Effect of pre-infusion of hypertonic saline on postoperative delirium in geriatric patients undergoing shoulder arthroscopy: a randomized controlled trial

Background Neuroinflammation may be a potential mechanism of postoperative delirium (POD) in geriatric patients, and hypertonic saline (HS) has immunomodulatory properties. The purpose of this study was to investigate whether HS could reduce the incidence of POD in elderly patients and its effect on neutrophil activation and inflammatory cytokine expression. Methods We studied the effect of pre-infusion of 4 mL/kg 3% hypertonic saline vs. 4 mL/kg 0.9% normal saline on POD in patients undergoing shoulder arthroscopy in a prospective, randomized, double-blind, controlled trial. Neutrophil surface molecules (CD11b, CD66b and CD64) were analyzed by flow cytometry. Circulating concentrations of inflammatory factors IL-1β, IL-6, TNF-α and neurological damage factor S100β were assessed by enzyme immunoassay. The Confusion Assessment Method-Chinese Revision (CAM-CR) was applied for the assessment of POD 1–3 days after surgery. Results The incidence of POD in group H was significantly lower than that in group N (7.14% vs 26.83%, P = 0.036). The expression levels of inflammatory cytokines ( IL-6 and TNF-α) and neutrophil surface markers (CD11b and CD66b) were significantly lower in group H than in group N at 24 h after surgery ( P = 0.018, P < 0.001, P < 0.001, P = 0.024). There were no significant differences in postoperative pain, nausea and vomiting, infection, phlebitis, and patients satisfaction between the two groups. Conclusion Pre-infusion of HS can reduce the incidence of POD and the immune-inflammatory response. Trial registration Chinese Clinical Trial Registry (14/4/2022, registration number: ChiCTR2200058681.