Effect of inhalation of peppermint essential oil aromatherapy on postoperative delirium in old patients following major lower limb joint arthroplasty surgery: A randomized controlled trial.

BACKGROUND

Postoperative delirium (POD), a serious complication in elderly patients following major surgery, is strongly associated with increased morbidity and mortality. While peppermint essential oil (PEO) demonstrates cognitive-enhancing and neuroprotective properties, its efficacy in reducing POD incidence remains unclear. This study aims to evaluate the impact of inhaled PEO aromatherapy on POD incidence within 3 days after major lower limb arthroplasty (THA/TKA) in patients aged ≥65 years.

METHODS

A total of 178 elderly patients scheduled for THA/TKA were randomized to either the PEO group (n = 89) or normal saline (NS) group (n = 89). The primary endpoint was POD incidence within 3 days postoperatively. Secondary endpoints included: delirium severity, duration, and subtype; pain scores at rest and during activity within postoperative 3 days; anxiety scores within 2 days post-surgery; adverse event incidence; neutrophil-to-lymphocyte ratio (NLR); and hospital length of stay.

RESULTS

All 178 patients completed the trial (median age 70 years; 98 women [55.1 %]). The PEO group showed significantly lower POD incidence within 3 days postoperatively (7.9 % vs 19.1 %; risk ratio 0.412, 95 % confidence interval [CI] [0.179, 0.944], risk difference -0.112, 95 % CI [-0.215, -0.014], P = 0.048), with reduced pain scores (rest/activity) within the first 3 postoperative days and lower anxiety scores within the first 2 postoperative days (all P < 0.05) compared to the NS group.

CONCLUSION

Inhalation of PEO aromatherapy significantly reduces POD incidence within 3 days post-surgery and alleviates postoperative pain and anxiety in elderly patients undergoing major lower limb arthroplasty.