Design
cognitive impairment
ENDOCRINE DISEASES, MINOR, DISEASES
This study was a prospective randomized controlled trial performed at the General Hospital of Ningxia Medical University from 10/03/2022 to 28/12/2022. 90 female patients aged 45–75 years, with American Society of Anesthesiologists (ASA) physical status I or II, undergoing MRM were enrolled in this study. MRM was defined as the removal of the entire breast, including the skin, areola, nipple, and most axillary lymph nodes with preservation of the pectoralis major and minor muscles. Patients complicated with severe diseases including severe heart, lung, liver, kidney, or endocrine diseases, cognitive impairment, currently on sedative opioids or sleep-aid medication (benzodiazepines), use of anti-depression medications (such as: tricyclic, tetracyclic antidepressants or selective serotonin reuptake inhibitors) were excluded. Using a computer-generated random number table, all participants were randomly allocated to either the control or the S-ketamine group following a 1:1 ratio. The group allocation was concealed in sealed and opaque envelopes, which was opened by the anesthesiologist after the patient entered the operation room. The study medications were prepared by an attending anesthetist so that the designated researcher was blinded to the intervention.