Annual Meeting Reviews
The Role of Regional Anesthesia in Pain Management
By Amy Beethe, MD
Department of Anesthesiology
Children’s Hospital & Medical Center
University of Nebraska Medical Center
Omaha, Nebraska
The Seventh Annual Society of Pediatric Pain Management conference was kicked off by a warm welcome from our president, Rita Agarwal, MD. This transitioned into the first session of the meeting: “The Role of Regional Anesthesia in Pain Management” which was a joint session with the American Society of Regional Anesthesia. The session was opened by Karen Boretsky, MD, who gave a talk entitled, “Neuroplasticity and Fast Learning: What are Children ‘Learning’ in the Perioperative Period?” Dr. Boretsky introduced the idea of synaptic plasticity where connections between nerve cells in the brain are not static but can undergo changes, resulting in learning.
For example, teenagers are designed to be risk takers. Their incomplete prefrontal cortex connections allow them to be risky enough to try new adventures that they learn from. Taking this exponential synaptic construction into consideration, pediatric patients become addicted “harder, stronger, and faster” when they are exposed to addictive medications early in life. Dr. Boretsky discussed that pediatric patients after surgery had on average a 4.8% likelihood of continued opioid use 12 months after his/her surgery, with colectomy being the highest risk surgery at 15.2%.
Dr. Boretsky then moved into the question of “Do babies ‘learn’ pain?” Early experiences of pain can have long lasting consequences on infants as proven by Dr. Anna Taddio et al where pain responses to vaccinations were stronger and more exaggerated in patients who had circumcisions performed without regional anesthesia. Likewise, placement of paravertebral nerve block catheters in infants undergoing surgical repair of long gap esophageal atresia resulted in a reduction in the total morphine equivalent and benzodiazepines received postoperatively. Consequently, these infants were able to be weaned off narcotics and benzodiazepines quicker than those infants without the paravertebral catheter infusions. Research in rats suggests that untreated pain in the neonatal period could have consequences in adulthood. While more research is needed on this topic, untreated pain in the pediatric population has the potential to cause long lasting effects.
Next to speak was Adrian Bosenberg, MD, who gave a lecture on “New Regional Aesthesia Blocks; Are They Worth the Hype?” After giving a historical synopsis of regional anesthesia over the years, Dr. Bosenberg discussed how it is critical to understand the anatomy of blocks and spinal nerves. With the anatomy freshly in the minds of the audience, the transversus abdominis plane (TAP) block was discussed. While this block could provide somatic analgesia, the desire for more coverage of the visceral anesthesia of the abdomen led to development of the quadratus lumborum (QL) blocks.
After understanding the anatomy, Dr. Bosenberg walked learners through the “shamrock sign” on ultrasound and where local anesthetic is ideally deposited with each of the three approaches to the QL block. The final block described was the erector spinae block. This block was first described in 2016 and has the advantage of multi-level dermatomal spread. After thorough anatomical explanation, Dr. Bosenberg explained that this block is simple and above all safe due to the anatomical distance from the spinal cord and lung pleura. After the summation of these three blocks, Dr. Bosenberg displayed a noteworthy table distinguishing spread, risk of neuraxial complications, local anesthetic systemic absorption risk, anesthetic coverage, and potential risks of each of the following blocks: erector spinae block, epidural, paravertebral, QL, and TAP blocks. Final answer: these blocks are worth the hype.
Michelle Kars, MD, gave her presentation on “Show Me the Study!! The Evidence You Need-Regional Anesthesia Decreases Opioid Consumption.” With her love of baseball as a lighthearted theme throughout this lecture, she laid out a strong argument for preemptive analgesia via regional block leading to a decreased postoperative pain, opioid exposure, and potential for chronic opioid use. She described how we should encourage all anesthesia colleagues to be proficient in regional anesthesia (RA) to reach the most patients. With all anesthesia providers being a member of the “block team”, standardization of surgical procedure to RA block becomes much easier.
Dr. Kars discussed four blocks that every anesthesiologist should know: rectus sheath block, quadratus lumborum (QL) block, pudendal nerve block, and erector spinae plane block. The first block that Dr. Kars discussed was the rectus sheath block. This block has been shown to provide opioid sparing analgesia for umbilical port placement for unperforated appendectomies resulting in decreased total intraoperative narcotic, decreased PACU narcotic, and overall decreased perioperative narcotic, as well as improved pain scores. She noted that at her institution, 17.8% of patients undergoing appendectomy due to unperforated appendicitis had opioid free hospital stays.
This transitioned into discussing the QL block, particularly for its effective use of analgesia for laparoscopic inguinal hernia repair. Not only did those patients who had a QL block receive less fentanyl (1.33 vs 0 mcg/kg), but the percentage of opioid free hospitalization was much higher (77.27% vs 6.67%). The last block described was the pudendal block as a safe alternative to caudal analgesia for hypospadias repair. The advantage of this block over the caudal block is the lack of motor blockade that occurs as well as minimal to no neuraxial risk. Her talk gave the audience the ammunition they need to refute surgical colleagues who believe that regional anesthesia is not worth the time.
The first session was concluded by a lecture entitled “Chloroprocaine: Don’t call it a Comeback” by Giorgio Veneziano, MD. With the risk of systemic toxicity in pediatric patients associated with ropivicaine/bupivacaine due to the multifactorial combination of; immature hepatic microsomal enzymes, decreased protein binding leading to more free drug, low body mass of pediatric patients, lack of the ability of pediatric patients to communicate premonitory symptoms of toxicity, and the high potential of arrhythmias/convulsions, chloroprocaine is a very attractive drug to pediatric anesthesia providers. With EDTA and sodium bisphosphate removed, which were the causative agents of chloroprocaine associated cauda equina syndrome and persistent back pain, chloroprocaine has become the ideal drug for infant epidurals. With a dose range of 1-1.5% of 2-chloroprocaine at 0.25-1.5 mL/kg/hr in an epidural,
Dr. Veneziano produced studies that demonstrated early post-operative extubation, lower opioid consumption compared to ropivicaine 0.1%, and median pain scores of 0/10 in infants undergoing abdominal surgery. On top of neuraxial analgesia, chloroprocaine has also been shown to be effective in peripheral nerve catheters and combine spinal-caudal catheter modalities. According to Dr. Veneziano the future is bright for chloroprocaine outside of neonatal/infant populations.
For instance, the use of chloroprocaine in peripheral nerve catheters is ideal in patients who are at risk of compartment syndrome. If concerns of compartment syndrome arise, the catheter can easily be shut off and the patient can be quickly evaluated due to the rapid drug metabolism. Other potential patient populations where chloroprocaine could be utilized are:
- Epidurals for the hemodynamically unstable patient due to its easily titratable nature;
- Chronic liver failure due to metabolism by plasma cholinesterases;
- Patients with limited respiratory reserve undergoing a brachial plexus blockade (idea being that chloroprocaine could be used as a test dose for phrenic nerve paralysis resulting in respiratory compromise).
Dr. Veneziano effectively argued that chloroprocaine has withstood the test of time with a bright future ahead.
