The effects of a modified deep serratus anterior plane block on surgical stress and perioperative neurocognitive disorders in elderly patients undergoing thoracic surgery: a randomized clinical study

Background: Perioperative stress response is an important risk factor for perioperative neurocognitive disorder (PND) in elderly patients. This study aimed to evaluate and compare the effects of a modified deep serratus anterior plane block (DSPB) combined with general anesthesia on surgical stress and PND in elderly patients undergoing thoracic surgery. Methods: A total of 66 patients undergoing thoracic surgery were randomly assigned to receive either a single-shot DSPB or local block after tracheal intubation using ropivacaine 0.5% (20 mL). The primary outcomes were the visual analog scale (VAS) scores at each time point. The secondary outcomes included the Montreal Cognitive Assessment (MoCA) score before surgery and after discharge from the hospital (or seventh day postoperatively), malondialdehyde (MDA), superoxide dismutase (SOD), and serum cortisol levels, drug consumption, vital signs, and blood gas analysis. Results: Ultimately, 60 patients were enrolled in the study. The VAS scores were significantly lower in the DSPB group than the local block group (all P<0.05). There was a statistically significant difference in the blood gas analysis index total carbon dioxide (TCO2) content (27.71±3.49 vs. 29.31±2.26 mmHg) between the two groups (P<0.05). The length of hospitalization was shorter in the DSPB group than the local block group (6.03±1.35 vs. 7.20±1.49 days), and the difference was statistically significant (P<0.05). There were no statistically significant differences between the two groups in terms of the MoCA scores before surgery and after hospitalization (or the seventh day postoperatively), stress indices, vital signs, bispectral index (BIS) value, blood gas analysis (except TCO2), and drug use during extubation at each time point (all P>0.05). Conclusions: Compared with the local block, the elderly patients undergoing thoracic surgery who received the DSPB had a superior analgesic effect, a lower VAS score, and shorter length of hospitalization. As a DSPB does not require ultrasound equipment, it is simpler and easier to operate than a local block, and is especially suitable for widespread implementation in small hospitals.