Meeting Reviews
Session VI: Regional Anesthesia for Patients with Congenital Heart Disease
By Ona Dachsangvorn, MD
This session was comprised of a talk discussing regional techniques for sternotomy and bypass, a PRO-CON debate regarding regional anesthesia in pediatric cardiac surgery, and a Q & A session.
Regional Anesthesia for Sternotomy and Bypass – Beyond the Epidural
Dr. Naveen Raj from Alder Hey Children's Hospital in Liverpool, England kicked off the session with his talk on "Regional Anesthesia for Sternotomy and Bypass – Beyond the Epidural". He described three regional techniques that are clinically relevant for sternotomy. Two posterior chest blocks are paravertebral block (PVB) and erector spinae plane block (ESPB). One anterior chest block discussed was the transversus thoracic plane block (TTP). He emphasized the pain pathway that should be considered for successful blocks, including T2-T6 intercostal nerves for sternotomy; visceral pain pathways from the heart, lungs, pleura, and pericardium (vagus nerve, phrenic nerve, sympathetic trunks), and drain sites coverage.
For paravertebral block, Dr. Raj explained relevant anatomy and described two approaches - the transverse in-plane approach and the paramedian longitudinal in-plane approach. He highlighted that anterior displacement of the pleura indicates successful injection into the desired space. In terms of efficacy and outcome, Dr. Raj pointed to a Cochrane review and a meta-analysis study showing equivalent analgesic efficacy between PVB and thoracic epidural in adult patients.
In these studies, patients receiving a PVB were shown to have better pulmonary functions, fewer complications, less postoperative nausea and vomiting, fewer occurrences of hypotension, and less urinary retention. It is also a good alternative for patients with contraindications to epidural, such as those needing systemic anticoagulation. To illustrate the safety, Dr. Raj shared a study by Vecchione (Anesth Analg 2016. 123: 1588-90) that showed no complications from single-shot PVB in 2390 thoracic PVBs performed in 871 children. PVB catheters in that study revealed one case of seizure and 13% minor catheter-related complications.
Looking specifically at PVB in pediatric cardiothoracic surgery, Dr. Raj shared two studies. Bendary et al (Ain-Shams Journal of Anesthesiology 2015; 08: 287-293) and Sahajanandan et al (Ann Card Anaesth 2021; 24: 24-29) illustrated that there was no hemodynamic instability in PVB groups. Furthermore, both studies showed a reduction in opioids and lower pain scores. At Dr. Ray’s institution, Alder Hey, over 150 single-shot PVBs have been performed each year since 2010. There were no major complications observed. Similar to Sahajanandan, slightly reduced heart rates and blood pressures were observed, but no inotropic infusions were used because of the block. In his experience, PVB added 10-15 minutes to anesthetic time.
Dr. Raj then explained relevant anatomy for erector spinae plane block (ESPB) and commented that the paramedian longitudinal technique is an easier approach compared to the transverse approach. The mechanism of action is still unknown, but it is theorized that local anesthetic ultimately makes its way into the paravertebral space. Dr. Raj recommended a review article, "Erector Spinae Plane Block: A Narrative Review with Systematic Analysis of the Evidence Pertaining to Clinical Indications and Alternative Truncal Blocks. (J Clin Anesth 2021; 68: 110063)."
In terms of efficacy, Nagaraja (Ann Card Anaesth 2018; 21: 323-327) illustrated that in adults, ESPB is comparable to C7-T1 epidural in terms of pain scores, opioid use, and ventilator and ICU duration. In pediatric cardiac surgery, Kaushal (Journal of Cardiothoracic and Vascular Anesthesia 2020; 34: 981-86) compared ESPB to no block and found that intraoperative fentanyl and time to extubation were similar. However, children in the ESPB group had greater time to first rescue analgesic dose and lower pain scores up to 10 hours post-operatively. Additionally, no complications were found in this study.
Next, Dr. Raj described the transversus thoracic plane block (TTPB), which was the only anterior chest block discussed. Similar to PVB and ESPB, TTPB can be performed in the transverse (intercostal approach) or longitudinal paramedian approach. For both approaches, the internal mammary artery is typically in the same plane as the TTPB. He highlighted three studies looking at TTPB in pediatric cardiac surgery, which showed decreased fentanyl use up to 24 hours, decreased time to extubation, and decreased pain scores with no complications.
Dr. Raj concluded that regional anesthesia has been shown to decrease opioid consumption, decrease postoperative pain scores, and potentially leads to early mobilization and decreased respiratory complications. Importantly, there have been negative studies; however, he emphasized that more studies are needed because sample sizes have been small and there has been no proof of local anesthetic spread in the target locations. Additionally, there has been no study highlighting the SIRS response. Lastly, he shared his current technique, which is bilateral PVB placed after central venous catheter insertion. His regimen included 1.5 mg/kg/side of ropivacaine followed by intravenous infusions of 0.5-1 mcg/kg/hr fentanyl and 1 mcg/kg/hr dexmedetomidine.
PRO-CON: Regional Anesthesia Should be Part of Multi-Modal Pain Management for Pediatric Cardiac Surgery
PRO: Dr. Ban C.H. Tsui, Director of Stanford Pediatric Regional Anesthesia; Director of Research, Adult Regional Anesthesia Division; Stanford University.
CON: Dr. Alexander Mittnacht, Vice-Chair and Associate Director, and Chief of Cardiac Anesthesia at Westchester Medical Center.
Dr. Ban Tsui described the pain pathway and explained that regional anesthetic techniques used for cardiothoracic surgeries aim at blocking the pain signal from sternotomy and chest tube sites through the intercostal nerves that reach the central neuraxial. Deep blocks such as spinal, epidural, and PVB can have both somatic and sympathetic blockade.
While erector spinae plane block provides somatic with a possible sympathetic blockade, peripheral blocks such as intercostal plane block, serratus anterior block, pectoral 1-2 blocks, transversus thoracic plane block, and parasternal block only provide somatic blockade. Since bleeding risk is a concern with more central nerve blocks in patients undergoing cardiothoracic surgery, posterior chest wall block such as the erector spinae plane block is very superficial and is a great alternative.
While Dr. Ban Tsui's team at Stanford is conducting an ongoing randomized control trial looking at ESPB in pediatric cardiothoracic patients, he pointed out that many studies consistently showed a reduction in opioid requirement in pediatric patients who received ESPB for cardiothoracic surgery. Aside from pain relief, he believes that intravenous lidocaine is a potent anti-inflammatory, anti-hyperalgesic, and gastrointestinal pro-peristaltic drug. He also mentioned current investigations of potential neuroprotective effects of lidocaine in cardiothoracic surgery. Therefore, Dr. Ban Tsui argued that the future of regional anesthesia has the potential to improve patient outcomes.
Dr. Alexander Mittnacht started the CON side by emphasizing that most studies to date are retrospective, non-blinded with a small number of subjects and have many confounders. Current evidence regarding effectiveness only showed a small difference in pain scores. They also illustrated incomplete blocks compared to intravenous or neuraxial.
Single-shot blocks have limited duration and are further limited by the inability to assess pain in small children. He mentioned a few studies that showed improved pain scores and cautioned about the clinical relevance of improving pain scores by 1-2 points or decreasing time to extubation by an hour. Additionally, current studies are not powered enough to illustrate that regional anesthesia in pediatric cardiac anesthesia is "safe". At best, we can say that no adverse events have been shown.
In considering whether to adopt a regional technique, one needs to consider many other factors. Most regional techniques require bilateral blocks, which can increase local anesthetic plasma levels. The time and complexity required to do the block may not make it efficient. Lastly, complications that have been reported in other settings include hematoma requiring evacuation, pneumothorax, and infection.
While Dr. Mittnacht presented the Con side, he stated that he provides regional anesthetic for his patients and believes that regional techniques should be part of multi-modal pain management for pediatric cardiac surgery.
Q & A Discussion
Moderators: Kelly A. Machovec, MD of Duke Children's Hospital and James Spaeth, MD of Cincinnati Children's Hospital
Speakers: Naveen Raj, MD, Ban C.H. Tsui, MD, and Alexander Mittnacht, MD.
Which Block?
Dr. Spaeth started the session by asking the panelists how they decide which blocks to use. Interestingly, each panelist prefers a different type of block. Dr. Raj answered that he prefers paravertebral blocks (PVB) as erector spinae plane blocks (ESPB) can be more variable in his experience. He also uses lateral transversus abdominis plane (TAP) block for chest tube drain sites. Dr. Mittnacht uses single-shot spinal or caudal anesthesia in all of the patients, with regionals as a supplement.
For instance, he uses ESPB for subaxillary incisions and surgeons infiltrate local anesthetics for sternotomies. He does not use any transversus thoracic plane blocks (TTPB) and has found serratus anterior blocks to be incomplete. Lastly, Dr. Ban Tsui prefaced that he practices regional anesthesia in both adults and pediatric patients. He uses ESPB with a catheter because it is far away from the surgical site, minimizing the risk of catheter-related surgical site infection. Additionally, it is a posterior peripheral block, placing it at lower risk of hematoma in cardiac patients who are lying supine during the procedure.
Which Drugs?
Dr. Raj uses ropivacaine, supplemented with intravenous fentanyl and dexmedetomidine infusions. Dr. Mittnacht uses caudal morphine at 25-50 mcg/kg for neonates and 100 mcg/kg for other children. He disclosed that he was a consultant for Exparel and uses liposomal bupivacaine routinely but has not observed that the block lasts as long as expected. Dr. Ban Tsui prefers lidocaine due to its titratability and the ability to measure blood concentration.
He also emphasized that regional anesthesia should not be considered as the sole analgesic agent. It does not provide as intense analgesia as epidural anesthesia and most children require sedation to keep lines and drains in place regardless of the analgesic level of the block. He suggested that we consider regional anesthetic as part of the multimodal pain control approach.
Single Shot vs Catheters?
Dr. Raj uses single shot as the spread from PVB catheters, as shown in multiple studies, is not as reliable as a single shot injection. Additionally, catheter placement requires separate scrubs, taking up valuable time. Importantly, postoperative opioid is frequently required to keep children from pulling on lines; therefore, minimal benefits are achieved from placing catheters.
At Stanford, Dr. Ban Tsui’s team places bilateral catheters expediently by using a parallel approach where the regional team works on blocks while the cardiac team works on lines. They can perform bilateral blocks in 20 minutes. To help with surgical buy-in, his regional team communicates directly with the cardiac ICU and manages the catheters in the ICU.
Dr. Mittnacht's team chose the more simplistic approach that does not require additional training by the PICU team. They primarily perform neuraxial single shots and use regional single shot blocks as supplements. They also use multimodal medications for postoperative pain management.
Weight or Age Cut Off?
Dr. Mittnacht performs regional techniques in neonates but does not place catheters. Currently, Dr. Ban Tsui's team only places fascial plane blocks in patients >10 kg to reduce the risk of local anesthetic toxicity. He stresses the importance of waiting for outcome improvements, such as neuroprotection or SIRS reduction, before deciding to place fascial plane blocks in smaller patients. He emphasized that performing a block simply to lower opioid requirement is not enough. Dr. Raj performs blocks on patients of all ages that are expected to wake up early; therefore, the only neonates receiving blocks are those undergoing coarctation repair and PDA ligation.
Complications/Pearls
The panel touched on complications from regionals, which were minimal. Dr. Ban Tsui mentioned transient numbness at the site after fascial plane catheter removals. None needed interventions. For posterior catheters, he places an antiseptic dressing after removal to minimize the risk of infection. When catheters are placed, the typical protocol is to remove them after chest tube removal. Dr. Mittnacht suggested limiting the dose of caudal morphine in neonates to 25-50 mcg/kg to minimize the risk of postoperative apnea.
What to Do with Bleeding?
The panelists were asked about bleeding at the injection site before cardiopulmonary bypass. Dr. Raj and Dr. Ban Tsui both agreed that PVB and ESPB are both outside of the vertebral column. They would not be concerned about hematoma leading to spinal cord compression.
While each expert preferred different types of blocks, they all agreed that most children require some sedative effects from opioids after cardiac surgery to minimize agitation, regardless of the success of the block. Therefore, one should not try to achieve an opioid-free anesthetic by using regional techniques. Rather, they emphasized the use of regional anesthesia as part of multimodal pain management.
