In 2020, breast cancer became the most common cancer worldwide. Treatment methods for
breast cancer include surgery, chemotherapy, and endocrine therapy, with surgery
remaining the primary treatment option. The emergence of neoadjuvant chemotherapy has
expanded the indications for breast cancer surgery, providing surgical opportunities for
patients with late-stage clinical staging and a strong desire for breast preservation.
Neoadjuvant chemotherapy has the effects of reducing tumor size, lowering clinical
staging, assessing the tumor's sensitivity to chemotherapy drugs, and inhibiting tumor
cell proliferation. However, chemotherapy, while treating the disease, also causes
numerous adverse reactions that directly or indirectly lead to sleep disturbances in
patients.
Sleep disturbances reduce cognitive function, immune function, and quality of life in
breast cancer chemotherapy patients, with an incidence of sleep disturbances during
chemotherapy reaching 80%. These patients, when undergoing surgery, are highly prone to
postoperative sleep disturbances (Postoperative Sleep Disturbance, PSD) due to factors
such as preoperative sleep disturbances, fear and anxiety about surgery, inflammatory
responses, and pain. This negatively impacts their recovery process.
PSD refers to changes in sleep structure and quality in the early postoperative period.
It is a clinical syndrome characterized by disturbances in the sleep-wake rhythm
following surgery, leading to abnormal sleep quality or sleep behavior, usually
manifesting as reduced rapid eye movement (REM) sleep, prolonged wakefulness, and
fragmented sleep. There is no unified standard for the duration of PSD, as it varies
according to disease type, surgical procedure, and individual differences. Generally, it
occurs within a short time after surgery, such as 1-3 days postoperatively. PSD
significantly affects the postoperative circadian rhythm, pain levels, inflammatory
responses, cognitive function, and cardiovascular outcomes, leading to prolonged recovery
time. Clinically, both pharmacological and non-pharmacological interventions are used,
with pharmacological treatments primarily involving benzodiazepines, which increase sleep
duration and reduce sleep latency. Studying short-term sleep disturbances helps identify
and reduce postoperative complications, such as delirium, infections, and cardiovascular
events, thus accelerating recovery, improving patient safety, and promoting
multidisciplinary collaboration. However, there is limited research on the preventive
improvement of sleep quality.
Esketamine, a non-competitive N-methyl-D-aspartate receptor (NMDA) antagonist, is the
right-handed isomer of ketamine. It shares a similar pharmacological mechanism with
ketamine, but its potency is higher. The most important effect of esketamine is its
ability to inhibit the NMDA receptor-mediated glutamate entry into the GABA nervous
system, causing excitability changes in the cortex and limbic system, ultimately leading
to loss of consciousness. Sub-anesthetic doses of esketamine (0.5 mg/kg, 40-minute
intravenous infusion) have been shown to produce rapid and sustained antidepressant
effects in patients with treatment-resistant major depressive disorder (MDD).
Additionally, intravenous administration of esketamine at 0.2-0.4 mg/kg (single infusion
over 40 minutes) has demonstrated rapid and potent antidepressant effects in the
treatment of refractory depression. Apart from its antidepressant effects, esketamine has
been proven to improve sleep disturbances in patients with MDD and sleep issues,
suggesting that esketamine has potential as a treatment for sleep disorders. Some studies
indicate that the antidepressant effect of esketamine is related to the neurobiological
structure of wakefulness, sleep, and circadian rhythms. Animal studies also suggest that
esketamine can modulate the NF-κB signaling pathway and oxidative stress, inhibiting the
release of downstream inflammatory factors, thereby reducing surgical-induced
inflammatory damage and playing an anti-anxiety, antidepressant role to improve
postoperative recovery quality. However, it remains unclear whether continuous low-dose
infusion of esketamine during surgery can reduce the incidence of PSD. This study aims to
investigate the impact of continuous infusion of esketamine during surgery on
postoperative sleep quality in patients undergoing modified radical mastectomy for breast
cancer.