Table of Contents

 

1. Abstract
2. Case Presentation
3. Introduction
4. Critical Appraisal Of The Literature
5. Pathophysiology
6. Emergency Department Evaluation
   1. Physical Examination
7. Treatment
   1. Possible Complications Of Nerve Blocks
   2. Epinephrine Use
   3. Calculating Dosages
   4. Face And Head Nerve Blocks
      1. Infraorbital Block
      2. Supraorbital And Supratrochlear Blocks
      3. Mental Block
      4. Great Auricular Nerve Block
   5. Upper Extremity Nerve Blocks
      1. Digital Blocks
      2. Wrist Blocks
         • Wrist Block, Radial Nerve
         • Wrist Block, Ulnar Nerve
      3. Elbow Blocks
         • Elbow Block, Median Nerve
         • Elbow Block, Radial Nerve
         • Elbow Block, Ulnar Nerve
      4. Axillary Block (Brachial Plexus)
   6. Lower Extremity Nerve Blocks
      1. Femoral Blocks
         • Femoral Nerve Block
      2. Fascia Iliaca Compartment Block
      3. Ankle/Foot Blocks
         • Posterior Tibial Nerve
         • Sural Nerve
         • Superficial Peroneal Nerve
         • Deep Peroneal Nerve
         • Saphenous Nerve
   7. Other Blocks
      1. Bier Block (Intravenous Regional Anesthesia)
      2. Penile Block
         • Penile Block, Subcutaneous Ring Block
         • Penile Block, Dorsal Penile Nerve Block
         • Penile Block, Subpubic Block
8. Special Circumstances
9. Controversies And Cutting Edge
   1. Use Of Ultrasound In Nerve Blocks
      1. Complications For Ultrasound-Guided Nerve Blocks
      2. Techniques And Approaches To Ultrasound-Guided Nerve Blocks
         • Improving Image Quality
         • Needle Positioning Techniques
   2. Use Of The Nerve Stimulator In Nerve Blocks
10. Disposition
11. Summary
12. Time- And Cost-Effective Strategies
13. Risk Management Pitfalls For Pediatric Nerve Blocks
14. Case Conclusion
15. Clinical Pathway For Analgesia In Injured Children
16. Tables and Figures
    1. Table 1. Amide Anesthetics
    2. Table 2. Ester Anesthetics
    3. Table 3. Diagnoses And Indications For Consideration Of Nerve Blocks
    4. Table 4. Common Pediatric Regional Nerve Block Anesthetic Volumes
    5. Figure 1. Supraorbital And Supratrochlear Block
    6. Figure 2. Mental Nerve Block
    7. Figure 3. Great Auricular Nerve Block
    8. Figure 4. Diamond Field Block
    9. Figure 5. Dorsal Approach Digital Block
    10. Figure 6. Tumescent Digital Block
    11. Figure 7. Innervation Of The Hand
    12. Figure 8. Median Nerve Block At The Wrist
    13. Figure 9. Landmarks Of The Ankle
    14. Figure 10. Nerve Blocks At The Ankle
    15. Figure 11. Pre-Nerve Block Ultrasound Image
    16. Figure 12 Post-Nerve Block Ultrasound Image
17. References

Abstract

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

Case Presentation

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?

Introduction

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.

Critical Appraisal Of The 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.

Risk Management Pitfalls For Pediatric Nerve Blocks

1. “The child wouldn't tolerate the block procedure.” Children may not tolerate procedures due to high anxiety levels. Utilizing a child life specialist, distraction techniques, or anxiolytics may help the child tolerate the procedure.
2. “I couldn’t tell if the nerve was properly blocked because the child couldn’t communicate.” There are a variety of behavioral response assessments and pain scales that can help determine whether the patient is feeling discomfort or if the block has successfully anesthetized the area.
3. “I wasn’t sure of the correct method for the nerve block, so I decided to try local infiltration instead.” Taking the time to review the techniques for nerve blocks can potentially decrease the amount of anesthetic used, the time required to anesthetize the area, and the distortion caused by local infiltration.
4. “I sedated the girl with a femur fracture for portable radiographs because she couldn’t tolerate the manipulation.” Sedating a patient will not guarantee decreased pain with manipulation; however, a nerve block will anesthetize the area and allow for more appropriate imaging of an awake and alert patient in the radiology suite without the antecedent risks of procedural sedation. The duration of nerve blocks may also allow subsequent repair with a single dose of anesthetic compared to possible repeat doses of sedating medications.
5. “I decided to use lidocaine without epinephrine because it had a lower dose and therefore posed less risk of toxicity.” Epinephrine is recommended because it will allow for vasoconstriction in the area and a longer duration of anesthetic. If there is a dosing concern, then the concentration of anesthetic should be lowered and a nerve block should be considered.
6. “I didn't do a nerve block because I was afraid I would puncture a vessel and cause further damage.” While it is possible to puncture a vessel while performing a nerve block, simple pressure to the area will create hemostasis and the procedure can be attempted again. Using ultrasound may assist in avoiding vessels and may decrease the rate of complications.
7. “Using the ultrasound machine requires too many hands. I did the nerve block by landmarks alone.” If there are no available personnel to assist in the procedure, simply reviewing the anatomy of the area with ultrasound may assist in the initial placement and direction of your needle.
8. “I didn’t do a nerve block because they have a high risk for causing permanent nerve damage.” Done properly, nerve blocks have a low rate of complications and can successfully produce analgesia and anesthesia.
9. “Nerve blocks can only be used for laceration repair.” Nerve blocks can be successfully used in the management of many types of injuries, including fracture and dislocation reduction, foreign body removal, incision and drainage of abscesses, and wound management.
10. “I tried to ‘spread out’ the maximum dose of anesthetic via local infiltration to repair this wound.” Inadequate analgesia caused by “spreading out” local infiltration can make proper injury repair more difficult. A smaller dose of anesthetic used in a nerve block can produce adequate anesthesia to aid in wound management.

Tables and Figures

References

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.

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