Moderators: Malgorzata Lutwin-Kawalec, MD, Dinesh K Choudhry, MD, FRCA. Institution: Nemours/AI DuPont Hospital for Children, Wilmington, DE

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1 PBLD Table # 17 A teenager with Factor V Leiden and pectus excavatum for a Nuss procedure: navigating recommendations for testing, perioperative risk of thrombosis and post-operative pain management. Moderators: Malgorzata Lutwin-Kawalec, MD, Dinesh K Choudhry, MD, FRCA Institution: Nemours/AI DuPont Hospital for Children, Wilmington, DE Goals: 1. Upon completion of this learning activity, participants should be able to understand the patophysiology of Factor V Leiden coagulopathy 2. Upon completion of this learning activity, participants should be able to identify risk factors known to provoke thrombosis in children 3. Upon completion of this learning activity, participants should be able to identify patients with Factor V Leiden that may require perioperative anticoagulation 4. Upon completion of this learning activity, participants should be able to discuss some available strategies for dealing with post-operative pain after a minimal access pectus excavatum repair with a Nuss procedure. Case History: GL is a 13-year-old, 52 kg, 5 7 Caucasian male with pectus excavatum deformity who presents for a Nuss procedure (minimal access semi-permanent insertion of metal bars in order to reduce chest deformity and refashion the contour of the growing thorax). Patient s mother was diagnosed with Factor V Leiden (FVL) thrombophilia six months ago after an episode of lower extremity deep venous thrombosis. GL has multiple family members with FVL and history of clots but has never been tested. He is otherwise healthy and has never had anesthesia before. What is Factor V Leiden coagulopathy? What s its pathophysiology? Are all patients symptomatic? What s the usual presentation? Does it predominantly cause arterial or venous thrombosis? What s the most common site? What personal or family history should make you suspect the diagnosis? Is it more prevalent in certain ethnic groups? What pediatric age groups are at highest risk of developing acute thrombotic events? Are you concerned and would you like any tests or consults before proceeding? What tests are currently available to diagnose FVL? If genetic testing is done, does it make any difference if the patient is a homo- or heterozygote? Why? What questions would you ask the consulting hematologist?

2 Case History (continued): GL s surgery was postponed until he underwent necessary testing and was identified to be a FVL heterozygote. Now he is back, seems really anxious and would like to know what his risk of getting clots is and what factors increase this risk during and after the procedure. He is even considering not having the procedure done at all, but admits that his chest deformity is causing him more and more psychological discomfort. What are you going to tell the patient and his parents in regards to GL s thrombotic risk? Is thrombotic risk in an otherwise healthy child with a single thrombotic defect high? What prothrombotic risk factors is GL likely to be exposed to during and after Nuss procedure? What are some of long-term complications of pediatric venous thromboembolism? Is prophylactic anticoagulation indicated? What are some of specific fears that teenage patients might have before surgery and anesthesia? What are some of the techniques available to alleviate anxiety in teenagers having surgery? Case History (continued): After your discussion with the patient and his family, answering the questions, explaining the anesthesia plan and using some evidence-based techniques to alleviate GL s anxiety, GL decides to proceed with the surgery. He undergoes an uneventful general anesthetic with compression stockings for DVT prophylaxis. Upon emergence from anesthesia, he starts complaining of severe pain. What is pectus excavatum deformity? How common is it? What are the most common indications for pectus correction? How do you assess severity of the deformity? What is Nuss procedure? Since this is a minimally invasive technique, is it painful? What are the available strategies for post-operative pain management after Nuss procedure? What are the pros and cons of these strategies?

3 Discussion: FVL thrombophilia is characterized by a poor anticoagulant response to activated protein C (APC) and an increased risk for venous thromboembolism (VTE). Deep venous thrombosis is the most common VTE with legs being most common site. Resistance to APC is caused by a single base substitution, adenosine for guanosine at position 1691, which codes for a glutamine substitution for arginine at amino acid 506 in the mutated factor V (Factor V Leiden). This mutated protein is inactivated at rate approximately 10 times slower than normal factor V and persists longer in the circulation causing increased thrombin generation and a mild hypercoagulable state. FVL is suspected in children with a history of DVT or pulmonary embolism, and in children with a personal or family history of recurrent thrombosis. The diagnosis is made either using a coagulation screening test such as activated protein C resistance assay or by DNA analysis of F5 gene which encodes factor V. In adults, the risk of VTE is increased 3 - to 7 fold in heterozygotes and 18- to 80-fold in homozygotes. VTE is far less common in children but the prevalence of thrombotic disorders in children with thrombosis is higher than in a corresponding adult population. The neonates and teenagers at the greatest risk. Even though most children with FVL are asymptomatic and do not require modifications in perioperative management, our patient should be tested to either rule out or confirm coagulopathy and for counseling purposes. If the coagulation screening test is positive, genetic testing is recommended to identify if the patient is a hetero- or homozygote. Hematology consult would be helpful to determine the need for anticoagulation. The thrombosis risk in an otherwise healthy child with a single thrombotic defect is very low. A combination of risk factors is necessary to provoke thrombosis in children including congenital coagulopathy (Factor V Leiden, MTHFR, deficiency of protein C, S or anthithrombin), acquired hypercoagulability (surgery, trauma, prolonged immobilization, malignancy, chemotherapy, organ transplantation, severe illness) and placement of central venous catheter. Pectus excavatum is the commonest chest wall anomaly in humans, occurring in approximately 1 in every 400 births, males being affected 5 times more often than females. The indication for correction is primarily cosmetic. During this procedure rigid metal bars are placed transthoracically beneath the sternum for a period of time until permanent remodeling of the chest wall has occurred. Postoperative pain is significant and multimodal analgesia is usually used. A thoracic epidural (TE) has historically been the superior regional anesthesia technique for this procedure. Although effective and safe, this technique may be associated with problems such as hypotension, upper extremity weakness or tingling, failed or one-

4 sided epidural, Horner syndrome, and in rare but serious cases an epidural hematoma or abscess. Patient controlled analgesia (PCA) has also been used but multiple reviews have shown superior pain relief with TE compared to PCA, resulting in lower postoperative pain scores in conjunction with greater wellbeing. Other forms of regional anesthesia include bilateral paravertebral catheters and bilateral continuous chest wall catheters. In a recent retrospective study of 20 adolescent males undergoing Nuss procedure, Hall Burton et al reported that bilateral paravertebral nerve block catheters resulted in equivalent opioid consumption and pain scores when compared to TE (Paediatr Anaesth, 2014). There are ongoing clinical trials comparing the efficacy of continuous chest wall catheter infusions to TE. Also, there is a multicenter trial underway (SPAIN) to evaluate management techniques adopted by various institutions and their outcome. REFERENCES: 1. Young G. Impact of Inherited Thrombophilia on Venous Thromboembolism in Children. Circulation 2008;118: Donahue B. Factor V Leiden and Perioperative Risk. Anesthesia & Analgesia 2004;98: Kujovich J. Factor V Leiden Thrombophilia. Gene Reviews NCBI Bookshelf 2010/ 4. Gerotziafas GT. Risk factors for venous thromboembolism in children. Int Angiol 2004; 23(3): Protopapas A. Perioperative data on the Nuss procedure in children with pectus excavatum: independent survey of the first 20 years data. Journal of Cardiothoracic Surgery 2008, 3:40 6. Mavi J. Update on Postoperative Pain Management following Pectus Excavatum Repair. SOJ Anesthesiology and Pain Management 2014, 1, St Peter SD, Weesner KA, Sharp RJ, Sharp SW, Ostlie DJ, Holcomb GW 3rd. Is epidural anesthesia truly the best pain management strategy after minimally invasive pectus excavatum repair? J Pediatr Surg 2008; 43: Hall Burton DM, Bortesky KR. A comparison of paravertebral nerve block catheters and thoracic epidural catheters for postoperative analgesia following the Nuss procedure for pectus excavatum repair. Pediatric Anaesth 2014; 24:

5 9. Bogert JN, Potter DD, Moir CR, Dawit Haile D, Wilder RT. Patientcontrolled analgesia-based pain control strategy for minimally-invasive pectus excavatum repair. Surg Pract 2013; 17: