Efficacy of Perioperative Opioid Sparing Techniques on Time to Initiation of Chemotherapy

Enhanced recovery after surgery (ERAS) has become the standard of perioperative care for patients undergoing oncologic surgery. Multimodal and regional anesthetic techniques to reduce postoperative pain and opioid requirements are a key component of ERAS. Epidural analgesia was considered standard in early ERAS protocols. however, it is labor-intensive, requires close postoperative follow-up, and may exacerbate hemodynamic instability. Long-acting intrathecal (IT) opioid use in oncologic surgery has been described as an equianalgesic technique to epidural analgesia with an improved safety profile, although both have the potential for neurological complications and respiratory depression9. Quadratus lumborum (QL) block is an alternative opioid sparing technique to neuraxial analgesia for abdominal surgery. QL blocks can provide similar pain coverage as an epidural with decreased hemodynamic instability. However, it is limited by its relatively short duration of effect, which ranges from 6 to 12 h. Another method employed is the transversus abdominis plane block. One of the advantages of this technique is that it does not depend on a separate service to perform like ITM and QL as it is commonly performed by the surgeon during surgery. However, unlike the QL block which has been shown to spread to the lumbar plexus and even thoracic paravertebral space providing both somatic and visceral analgesia, TAP blocks only provide somatic analgesia coverage. TAP blocks are still frequently performed by oncologic surgeons though the long term success compared to QL and ITM blocks is unclear. Most research looking into the efficacy of these techniques has been aimed at studying their effects on pain scores, opioid requirements, and opioid related adverse drug events. Time to initiation of adjuvant chemotherapy (AC) following oncologic surgery is an important predictor of survivability that has not yet been considered in QL vs. IT comparison studies. Two meta-analyses demonstrated that postponing the postoperative AC was associated with poor survival in colorectal cancer patients. Results from Biagi et al. showed that every 4 weeks delay result in a 14% decrease of overall survival (OS). Similarly, Guetz's study indicated that delaying the initiation of AC for \> 8 weeks after operation significantly decreased OS. In pancreatic and colorectal cancer, several factors are involved in this metric. One of the more common factors in this patient population is gastrointestinal complications including ileus. Some of these complications can be affected by perioperative opioid consumption.