The incidence of nephrolithiasis in pediatric patients is increasing by 6%-10% annually, leading to increased cases of severe renal colic pain (1). A number of oral and intravenous (IV) medications are used to treat the pain including nonsteroidal anti-inflammatory drugs, opioids (e.g., fentanyl or morphine), hydration, calcium channel blockers, alpha blockers, and phosphodiesterase inhibitors. However, parenteral opioids are used in 72% of adults who presented to emergency departments (EDs) with renal colic (2). In the pediatric population, 56% of adolescents also receive opioids for renal colic, which portends an increased risk for persisting opioid dependence and even overdose (3). Erector spinae plane nerve block (ESPB) is an increasingly used tool of long-acting analgesia with a favorable safety profile that can potentially reduce opioid consumption, provide prolonged analgesia, and be performed at bedside without sedation. With the ever-increasing use of point-of-care ultrasound (US), emergency physicians are expanding their use of US-guided regional anesthesia. ESPB has many clinical analgesia applications, including rib fractures, thoraco-abdominal surgery, pancreatitis, herpes zoster, or nephrolithiasis. Previous literature has primarily focused on the use of ESPB in adults, suggesting a potential need for application to pediatric emergency medicine. In this case report, we present an example of an adolescent presenting with refractory pain due to confirmed renal colic who experienced significant improvement in his pain following a US-guided ESPB at bedside in the ED.

A previously healthy, 12-year-old boy presented to the ED complaining of nausea and vomiting in the setting of right-sided abdominal pain rated as a 10/10 Numerical Rating Scale (NRS), which had started suddenly several hours prior to the presentation. The boy’s weight and height were 57.2 kg (88th percentile) and 157.5 cm (65th percentile), respectively, making a body mass index of 23.1 kg/m² (92nd percentile). The initial vital signs were as follows: blood pressure value, 127/89 mmHg; heart rate, 78 beats/minute; respiratory rate, 18 breaths/minute; temperature, 35.7 °C; and alert with acute ill appearance. On examination, he was noted to have abdominal tenderness isolated to the right lower quadrant, without rebound, guarding, or rigidity. There were no cardiopulmonary abnormalities. His laboratory studies showed a white blood cell count, 12,200/μL; blood urea nitrogen, 5 mg/dL; and creatinine, 0.4 mg/dL, with otherwise normal laboratory findings.

In the ED, he initially received 4 mg of IV morphine and 4 mg of IV ondansetron, which minimally relieved his symptoms. Given a high suspicion of appendicitis as a differential diagnosis, a computed tomography scan was performed, showing a right-sided 2 mm-sized ureterovesical stone with mild to moderate hydronephrosis with no evidence of appendicitis or free air. Subsequently, he received 1 dose of 15 mg IV ketorolac, and his father consented to an ESPB given the ongoing renal colic rated as 8/10 NRS. The ESPB was performed 2.5 and 1 hours after the administration of morphine and ketorolac, respectively. It was performed utilizing a 1-5 MHz curvilinear transducer (PX cart; FujiFilm Sonosite) by an emergency physician using 30 mL of RECK^TM (QuVaPharma), a patented premade 50-mL syringe stocked by the institution (Fig. 1) (4). The 30 mL included ropivacaine 123 mg, epinephrine 0.25 mg, clonidine 0.04 mg, and ketorolac 15 mg. He was discharged 30 minutes after the ESPB was performed with pain at 5/10 NRS. There was no 48-hour return to the ED for analgesia.

Although ESPB is a relatively new tool of analgesia, it has been growing in popularity among emergency physicians due to its efficacy, safety, and relative easiness to perform. There are a growing number of possible indications, which have been insufficiently studied in pediatric populations, including renal colic, chest surgery, laparotomy, nephrectomy, chest tube placement, cholecystectomy, inguinal hernia repair, orchiopexy, hip surgery, herpes zoster, pancreatitis, rib fractures, or palliative care (5). As interest and research in the ESPB grow, more indications are likely to be identified.

ESPB is performed at different levels along the thoracic or lumbar spines, and causes a sensory blockade of the dorsal and ventral rami of the sympathetic ganglion (Fig. 1B) (6,7). Subsequently, a curvilinear transducer is used to obtain a transverse view of the spinous process and both transverse processes (TPs) at the T5-T7 levels (Fig. 1A). With a patient in the prone position (Fig. 2), a 22-gauge (3.5-inch) needle is introduced in a lateral to medial trajectory under the direct sonographic visualization until the needle tip makes a contact with any point along the distal half of ipsilateral TP (Figs. 3, 4). The needle is then retracted 2-3 mm and hydro-dissection is performed to confirm the needle tip position along the TP, deep to the erector spinae muscles and superficial to the periosteum of the TP. Then, 20-30 mL of a selected anesthetic solution is injected with an aspiration every 5-10 mL. The needle is then removed, and the patient is placed into a position of comfort. A common pitfall is to inject the anesthetics into the belly of the muscles rather than into the fascial plane, which may result in decreased efficacy. Informed consent for the procedure is required given the potential complications including bleeding, local anesthetic toxicity, vascular injury, short-term numbness or weakness, and pneumothorax, which can occur at 0.22% (8,9).

This case exemplifies a potential tool of analgesia for refractory renal colic using point-of-care US. ESPB is advantageous in that it may reduce the use of opioid or the need for hospitalization for IV analgesia, or provide rapid and adequate analgesia within 12-24 hours after the block. However, there are limitations to the modality to consider. The first limitation is a skill and training requirement. In our ED, to perform nerve blocks, emergency physicians should complete a 1-year emergency US fellowship with dedicated hands-on training and simulation. While the skill set is within the scope and ability of most emergency physicians, it requires intentional education and skill maintenance. The other limitation is the requirement of cost and time. The procedure requires a spinal needle, extension tubing, 3-way stopcock, 50-mL syringe, sterile gloves, skin cleaning solution, and a sterile US transducer cover. While none of these items are particularly expensive, they are added costs. In a crowded ED, time is likely a barrier to using this technique. With experience, this procedure takes 10-15 minutes, and relief is typically noted within 20 minutes of the injection.

In conclusion, this case report indicates an effective option for analgesia in pediatric renal colic that is refractory to opioids. ESPB provided the case patient with timely analgesia and discharge with no complications reported. Additional studies are required to draw conclusions about whether ESPB can make a significant reduction in hospital length of stay or adjunctive use of opioids, or whether it is feasible in the pediatric population.