Successful injury management is often dependent upon optimal pain control. Many injuries do not require procedural sedation or systemic analgesia, and emergency clinicians have used peripheral nerve blocks for several decades for these injuries. Nerve blocks deliver anesthetic to the nerve that corresponds to the sensory innervation of the area where the wound or injury is located. In the pediatric setting, some nerve block modalities require modification to the approach and techniques commonly used in adult patients due to the age and weight of the child, the ability of the patient to cooperate, and the ability of the emergency clinician to observe pain response. Peripheral nerve blocks have a high rate of success for effective local anesthesia and a low rate of complications, making them an attractive option for analgesia in the management of some injuries. This evidence-based review summarizes the advantages and disadvantages of peripheral nerve blocks, reviews commonly used local anesthetics, describes the landmark technique for the most common nerve blocks used in pediatric emergency medicine, and presents literature on ultrasound-guided technology.
Key words: pediatric nerve blocks, regional blocks, ultrasound-guided nerve blocks, pediatric nerve blocks, peripheral blocks
A 15-year-old previously healthy male presents to the emergency department via EMS after being assaulted in his neighborhood. The patient is in cervical spine immobilization and has blood-soaked gauze on his face. He is currently awake and complaining of pain in his face and left leg. He states that several people attacked him with fists and threw him onto an embankment. His vital signs are: heart rate, 110 beats/min; respiratory rate, 20 breaths/ min; blood pressure, 131/79 mm Hg; oxygen saturation, 99% on room air; and temperature, 36.4°C. On primary survey, the patient has a clear airway with no blood or lesions noted in the oral cavity, clear breath sounds, and good air entry throughout. He has strong peripheral and central pulses, with a 2-second capillary refill. The patient is alert and oriented to person, place, and time, and he has a Glasgow Coma Scale score of 15. You undress him fully and evaluate him for further injuries. He has a 3-cm stellate laceration extending 5 mm from the inferior border of the right eyelid to the medial aspect of the zygomatic process. He also has a 4-cm laceration extending from the right aspect of the lower lip, crossing the vermilion border to the right lateral aspect of the chin. There is a deformity above the left knee, with swelling and increased pain when manipulating the extremity. The femoral, popliteal, and pedal pulses are palpable, and sensation and motor strength are intact distal to the injury. After completing all necessary evaluations and concluding that the patient is stable for injury repair, you discuss the plan with the patient and his family members who have just arrived. The patient’s mother informs you that he has previously had an anaphylactic reaction to sedation for a dental procedure. She prefers that you do not sedate her son because she is fearful of another medication reaction. You exit the room to gather supplies for the wound repair and to call the orthopedic surgery consult. You begin to wonder: What is the most efficient way to provide safe analgesia to this patient? Due to the extent of the injuries, should I sedate him for the repairs? Which nerve block techniques and anesthetic can I use to anesthetize these injuries? How much of this anesthetic can I use in this patient? What are the anatomical landmarks I should be aware of for nerve block techniques? Will using ultrasound guidance improve the success of the nerve block?
Peripheral nerve blocks are commonly used in patients with lacerations, fractures, and other injuries when pain is expected during the management of the condition. Compared to local infiltration, nerve blocks are thought to prevent further wound distortion and allow for improved analgesia; additionally, they require a lower volume of anesthetic, reducing the risk of systemic toxicity.1,2 Traditionally, nerve blocks are performed using landmark-based techniques, but these are subject to errors from anatomical variability.2 More recently, the use of ultrasoundguided peripheral nerve blocks has been described in the literature. This issue of Pediatric Emergency Medicine Practice discusses the indications, contraindications, techniques, and cutting-edge technology available for peripheral nerve blocks through an examination of the current literature.
A literature search was performed using PubMed, using the search terms pediatric nerve blocks, regional blocks, ultrasound-guided nerve blocks, pediatric emergency nerve blocks, and peripheral blocks. A total of 369 articles from 1960 to the present were reviewed. The majority of the articles pertained to anesthesiology and chronic pain syndromes and were beyond the scope of this review. Abstracts were reviewed for relevance to the topic. Supporting articles were gathered from related articles and the reference lists of review articles. Textbooks pertaining to emergency medicine and anesthesia were used for the general guidelines of pediatric nerve blocks. Case reports, editorial views, and correspondence to the editors were largely excluded.
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report. To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study will be included in bold type following the references, where available. The most informative references cited in this paper, as determined by the author, will be noted by an asterisk (*) next to the number of the reference.