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FNB decreased pain, hospital stay in pediatric patients undergoing arthroscopic knee surgery
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Postoperative pain remains a significant problem in the pediatric surgical population and is related to not only prolonged recovery times, but also the need for inpatient admission. As such, there is a desire among pediatric surgeons and anesthesiologists to implement techniques that reduce postoperative pain and limit opiate-related adverse effects. Regional anesthesia is a broad term, encompassing many techniques that ultimately render an area of a patient’s body insensate. Surgeries of the lower extremity, including arthroscopic knee surgeries, are particularly well suited for regional anesthesia.
Caudal epidural blockade remains the most common regional anesthetic technique in pediatric patients. In small children, a caudal block is a safe and easy way of providing analgesia below the level of the umbilicus. While pediatric patients undergoing arthroscopic knee surgeries may greatly benefit from regional anesthesia, they are frequently unilateral procedures performed in older children, making caudal epidural block difficult and impractical. Ultrasound guided femoral nerve blockade (FNB) is an additional option which is also safe and easy to perform in an older pediatric population; and capable of providing more directed analgesia.
Change in protocol
For these reasons, in 2010 we began supplementing general anesthesia for arthroscopic knee surgeries with a FNB and noticed significant improvement in postoperative pain as well as a decrease in the need for hospital admission. Since that time, our regional anesthesia program has grown significantly, and FNB for arthroscopic knee surgeries have become routine at our institution. The period between 2009 and 2011 provided us with a unique time to perform a retrospective analysis, comparing those patients receiving a FNB in addition to general anesthesia with those receiving general anesthesia alone. During this time, 376 patients underwent arthroscopic knee surgery at our institution. Of these, 131 patients received a FNB with general anesthesia and 245 had general anesthesia alone. When comparing the groups as a whole, we found that patients in the FNB group required significantly less rescue doses of opioid, had lower postoperative recovery room pain scores and had shorter time to hospital discharge.
Figure 1. After a sterile preparation, the ultrasound probe is placed along the inguinal crease to begin scanning for the femoral nerve.
Figure 2. After the anatomy has been identified, the block needle is placed in plane with the ultrasound probe.
Images: Schloss B and colleagues
When looking specifically at ACL reconstruction (the most painful procedure of the cohort), we found a significantly lower need for inpatient admission following this procedure, with 72% requiring admission when given a FNB compared to 95% requiring admission with general anesthesia alone. A more recent analysis of our data shows that three out of 120 patients (2.5%) undergoing ACL reconstruction have required admission in 2013. Therefore, admission rates for ACL reconstructions have decreased from 95% to 2.5% in a matter of 3 years with the implementation of a successful regional anesthesia program.
After a formal, verbal pre-block time out, we perform the FNB in the operating room after general anesthesia has been induced. While the patient is in the supine position, a high-frequency linear ultrasound probe is placed in the inguinal crease, perpendicular to the femoral nerve (Figure 1). The nerve is identified immediately lateral to the femoral artery, appearing as a hyperechoic triangular structure. A sterile 22-gauge, 2-inch needle is inserted in plane with the transducer, in a lateral to medial fashion, toward the femoral nerve. The authors prefer an in-plane approach, allowing visualization of the needle tip at all times. A distinctive pop is typically felt as the needle passes through the fascia iliaca (Figure 2). With proper placement adjacent to the femoral nerve, needle aspiration is attempted to detect inadvertent vascular access (Figure 3). After negative aspiration, 0.2 mL/kg to 0.5 mL/kg of 0.5% ropivacaine is injected under constant ultrasound visualization. Performance of the block is immediately followed by surgical time-out and preparation.
Application for ACL reconstruction
Given the decreased admission rates and high patient satisfaction, our practice has continued to evolve beyond single-shot FNB. Those patients undergoing ACL reconstruction with a hamstring autograft routinely receive a mid-thigh sciatic nerve block in addition to a FNB. We believe this additional block is a large contributing factor to same day discharge after surgery. In addition, select patients have been receiving femoral nerve catheters, which are inserted during the block process. These catheters are secured and attached to a disposable elastomeric pump, providing a constant local anesthetic infusion for approximately 2 days to 3 days. Patients are discharged to home with their catheter, which the patient and/or parent can easily remove at a specified time.
Figure 3. The anatomy of the femoral nerve (lateral), femoral artery (middle) and femoral vein (medial) as well as the trajectory of the needle placement for an effective block are seen.
During the preoperative consent process, patients are counseled on muscle weakness, the areas of the leg that will be numb, as well as the need to begin oral pain medication as they notice the block receding (typically 12 hours to 15 hours following a single-shot FNB). A discussion of appropriate postoperative expectations, and emphasizing the need to “stay ahead” of the pain with oral medication, helps to ensure a positive experience for patients and parents. For those with femoral nerve catheters, the pain service makes a daily follow-up phone call until the catheter removal.
Another consideration is operating room time. When performed by an experienced anesthesiologist, we have found that a single-shot FNB can be placed in fewer than 5 minutes; with a sciatic nerve block adding an additional 5 minutes. Longer times can be expected when blocks are performed by trainees or with catheter placements. To offset this additional time, we will frequently induce anesthesia and place the blocks in adjacent induction room as the previous surgical case is completed and the room is being cleaned.
In conclusion, we have found the implementation of a regional anesthesia program can improve patient outcomes and prevent unnecessary hospital admission. Although such services may increase manpower and equipment needs, we have found that these costs are offset by earlier hospital discharge and the decreased need for eventual hospital admission. Such services can only be provided by a cooperative effort among various departments including anesthesiology, orthopedic surgery, and nursing. Thorough planning prior to instituting such a program is key to ensuring its success.
References:
Fortier J. Can J Anaesth. 1998;doi:10.1007/BF03012088.
Markakis DA. Anesthesiol Clin North Amer. 2000;18:355-381.
Schloss B. J Pediatr Orthop. 2014;doi:10.1097/BPO.0000000000000113.
For more information:
Brian Schloss, MD, Tarun Bhalla, MD, David Martin, MD; and Joseph D. Tobias, MD, can be reached at Department of Anesthesiology and Pain Medicine. Kevin Klingele, MD, can be reached at Department of Orthopedic Surgery. All are at Nationwide Children’s Hospital and The Ohio State University Medical Center, Columbus, Ohio; email: klingele.1@osu.edu.