(279) - Differential effect of paravertebral block in mastectomy patients: Phenotyping using preoperatively determined psychosocial and psychophysical characteristics

Abstract

Surgical injury represents a physiological and psychological stressor, and how an individual experiences and responds to this stressor is determined by their unique biology, psychology, and environment. Previous studies have shown that individual variation in psychosocial and psychophysical characteristics may help predict short- and long-term pain during recovery. What is less well known is whether preoperative phenotyping can help predict differential response to interventions in the perioperative period. In this prospective observational study of women undergoing partial or total mastectomy, which used careful phenotyping of psychosocial (pain catastrophizing scale, anxiety, depression) and psychophysical (pressure pain threshold, temporal summation of mechanical pinprick at non-surgical sites) traits at baseline, we assessed pain in the surgical area and impact on function using the breast cancer pain questionnaire and verbal rating scale at rest and with movement. Of patients who had total mastectomy approximately 45% received a bilateral paravertebral block (PVB) as part of their anesthetic. PVB resulted in lower reported pain and administered perioperative morphine equivalents. Interestingly, the difference in pain score was more pronounced for those who reported high preoperative pain catastrophizing (P = .017), than those who reported lower pain catastrophizing (P = .052). Moreover, despite being a small group (10%), patients who reported painful aftersensations (PAS) after a train of weighted pinpricks on preoperative testing (P = .06) gained as much or more analgesic benefit from PVB as the larger group of those not reporting PAS (P = .047). These studies suggest that enrichment of interventional studies with high risk patients may allow more efficient testing of analgesics, but also that phenotyping patients may help track and predict their differences in responsiveness to a given perioperative analgesic strategy. Understanding the psychosocial and psychophysical profile of patients before surgery may help guide the personalized application of perioperative preventive interventions.