American Society of Regional Anesthesia and Pain Medicine February 2015 - (Page 17)

Optimal Postcesarean Delivery Pain Management O ne-third of deliveries in the United States are by cesarean. Anesthesiologists must consider the long-term consequences of exposure to major surgery and postoperative pain in this large group of patients. A survey of pregnant women showed that the most pressing fear among parturients is pain during and after cesarean delivery.1 Previous studies have shown that tissue trauma from surgery is a common cause of chronic pain and disability, particularly among women.2 In a multicenter trial, Eisenach et al found the severity of acute postpartum pain was independently associated with the risk of developing chronic postpartum pain and depression, regardless of mode of delivery.3 These findings underscore the importance of carefully addressing postcesarean delivery pain. In 2006, the American Society of Anesthesiologists Task Force on Obstetric Anesthesia recommended neuraxial opioids (usually intrathecal or epidural morphine) as an important mainstay for postcesarean analgesia;4 however, some parturients are not candidates for neuraxial opioid and, in most patients, a multimodal approach allows for lower opioid doses and fewer adverse effects. In this article, we will highlight treatment strategies that may help anesthesiologists provide patients with optimal postcesarean analgesia. TRANSVERSUS ABDOMINIS PLANE BLOCK The transversus abdominis plane (TAP) block involves injection of a large volume of local anesthetic into the plane between the internal oblique and transversus abdominis muscles and can provide postoperative analgesia for abdominal surgery. Techniques include a landmarkassisted approach and several ultrasound-guided approaches, including anterior obliquesubcostal, mid-axillary, and posterior approaches. The pattern of spread of local anesthetic differs depending on the site of injection, and this may have important implications for the efficacy of the block.5 Compared to placebo, TAP blocks have been shown to decrease postcesarean pain scores and morphine consumption for up to 48 hours postoperatively in women receiving standard spinal anesthesia without intrathecal opioids. Samir Patel, MD Instructor Cynthia A. Wong, MD Professor and Vice-Chair Department of Anesthesiology Northwestern University Feinberg School of Medicine Chicago, Illinois Section Editors: Brian Harrington, MD, and Steven Orebaugh, MD contrast, the IT saline/TAP bupivacaine group had the highest morphine consumption at 24 hours. These findings suggest that TAP blocks do not offer analgesic benefit over IT morphine, nor do they supplement analgesia from IT morphine in the setting of multimodal analgesia. A 2012 systematic review and meta-analysis analyzed five randomized controlled trials (RCT) comparing TAP blocks with placebo in cesarean deliveries.7 The trials were stratified based on whether or not intrathecal morphine was used as part of the analgesic regimen. The primary outcome was IV morphine consumption during the first 24 hours; pain scores and opioid-related adverse effects were secondary outcomes. TAP block reduced the mean 24-hour morphine consumption if IT morphine was not used. VAS pain scores (10-cm line) were reduced by 0.8 cm, and the incidence of opioid-related adverse effects was reduced as well. In contrast, there were no differences in primary or secondary outcomes when the TAP block was used in conjunction with IT morphine. Thus, TAP blocks provide analgesic benefit to patients in the setting of a multimodal regimen that does not include IT morphine. These blocks are best reserved for patients who are not candidates for neuraxial morphine, including women who receive general anesthesia and perhaps those who have breakthrough pain following IT morphine. "A multimodal analgesic approach is likely the best approach for optimal postcesarean pain management." A 2011 trial addressed whether a TAP block augmented analgesia in parturients who received intrathecal morphine analgesia.6 Subjects undergoing elective cesarean delivery were randomized to receive intrathecal (IT) morphine or saline and a TAP block with either 2 mg/kg bupivacaine or saline (four groups). All patients received a standard multimodal postpartum analgesic regimen. The primary outcome was pain with movement assessed with a visual analogue scale (VAS). The groups that received IT morphine had the lowest pain scores with movement and the lowest morphine consumption at 6 hours after delivery. In Of concern are studies that suggest the plasma concentrations of local anesthetics injected during a TAP block may approach levels consistent with local anesthetic systemic toxicity.8 Indeed, seizures American Society of Regional Anesthesia and Pain Medicine 2015 17 3

Table of Contents for the Digital Edition of American Society of Regional Anesthesia and Pain Medicine February 2015

In Memoriam : Alon Palm Winnie, M.D., ASRA Founding Father
President’s Message
Editorial
40th Annual Regional Anesthesiology and Acute Pain Medicine Meeting
Resident and Fellow Events at the 2015 Spring Meeting
How We Do It: Managing an Acute and Perioperative Pain Medicine (APPM) Service at the University of Florida
Ketamine—an Old Drug with New Tricks
Optimal Postcesarean Delivery Pain Management
Palliative Care and Pain Medicine—Beyond Intrathecal Pumps and Opioids
Scientist Spotlight—Dr. Guy Weinberg, Trailblazer in Patient Safety

American Society of Regional Anesthesia and Pain Medicine February 2015