Overview
Definition:
Peripheral nerve blocks in pediatrics involve the targeted injection of local anesthetic near specific nerves to provide localized analgesia and anesthesia for procedures such as laceration repair, minimizing systemic absorption and associated side effects compared to infiltration anesthesia.
Epidemiology:
Lacerations are common pediatric emergencies, with estimates suggesting millions of visits to emergency departments annually for this reason
The choice of anesthesia, including nerve blocks, significantly impacts patient comfort and procedural success
Many pediatric patients require procedures necessitating local anesthesia, making nerve blocks a valuable technique.
Clinical Significance:
Effective pain management during laceration repair is crucial in pediatric patients to reduce anxiety, improve cooperation, and enhance the patient and caregiver experience
Peripheral nerve blocks offer advantages such as prolonged analgesia, reduced systemic toxicity, and avoidance of distortion of the wound site, which can be particularly beneficial for complex or deep lacerations.
Age Considerations
Infants:
Neonates and infants have unique physiological differences affecting pharmacokinetics and pharmacodynamics of local anesthetics, requiring careful dose calculation and monitoring for systemic toxicity
They may also have limited ability to vocalize discomfort, necessitating keen observation.
Toddlers Preschoolers:
This age group often experiences significant anxiety and fear associated with medical procedures
Clear communication, distraction techniques, and rapid, effective anesthesia are paramount
Nerve blocks, when performed efficiently, can facilitate a smoother experience.
School Aged Adolescents:
Older children and adolescents can often understand the procedure better and may tolerate longer block procedures if well-explained
They can also articulate pain levels more effectively
Involvement in decision-making can be beneficial.
Pharmacokinetics:
Immature hepatic and renal function in neonates can lead to prolonged elimination of local anesthetics
Reduced plasma protein binding in infants can increase the free fraction of anesthetic, potentially increasing toxicity risk
Dosages must be adjusted accordingly.
Clinical Presentation
Chief Complaint:
Parental concern regarding an injury, often presenting with visible bleeding, deformity, or pain associated with a laceration.
Associated Symptoms:
Pain, swelling, and potential signs of infection if the laceration is not fresh
For deeper lacerations, assessment for underlying tissue, tendon, or nerve damage is essential.
Patient History:
Mechanism of injury, time since injury, any contamination, prior tetanus immunization status, and known allergies to medications, particularly local anesthetics.
Diagnostic Approach
History Taking:
Detailed history focusing on the mechanism of injury, wound characteristics (depth, length, location, contamination), and patient’s pain level
Obtain immunization history and any relevant medical comorbidities.
Physical Examination:
Thorough visual inspection of the laceration, assessing depth, extent, and presence of foreign bodies
Evaluate for neurovascular compromise distal to the injury, including sensation, motor function, and capillary refill
Palpate for crepitus.
Investigations:
Typically not required for simple lacerations
Imaging (X-ray) may be indicated if a radiopaque foreign body is suspected or if there is concern for underlying fracture
Wound cultures are reserved for heavily contaminated or infected wounds.
Differential Diagnosis:
Other traumatic soft tissue injuries, avulsions, degloving injuries, crush injuries, and penetrating trauma
The primary differential diagnosis for anesthesia technique is infiltration vs
nerve block.
Common Nerve Blocks For Lacerations
Digital Nerve Blocks:
For injuries to fingers and toes
Typically performed using a dorsal approach at the base of the digit, circumferentially injecting local anesthetic around the neurovascular bundles
Lidocaine 1% or bupivacaine 0.25% are commonly used
Maximum dose considerations are crucial, especially in infants.
Supraorbital Nerve Block:
For lacerations of the forehead and anterior scalp
Anesthetizes the supraorbital nerve
Injected just above the orbital rim, medial to the supraorbital notch
Bupivacaine or lidocaine can be used.
Infraorbital Nerve Block:
For lacerations of the lower eyelid, cheek, and upper lip
Targets the infraorbital nerve as it exits the infraorbital foramen
A needle is inserted below the orbital rim, directed superiorly and medially towards the foramen
Requires careful technique to avoid intraorbital injection.
Auricular Nerve Blocks:
For lacerations of the ear
Involves blocking the greater auricular nerve (posterior aspect) and possibly the auriculotemporal nerve (anterior aspect)
Injections are made around the mastoid process and anterior to the tragus.
Intercostal Nerve Blocks:
For lacerations of the chest wall
Blocks typically performed paravertebrally at the appropriate dermatome
Requires precise anatomical knowledge and sterile technique.
Management
Anesthesia Choice:
The choice between local infiltration and peripheral nerve blocks depends on the location, depth, and extent of the laceration, as well as patient age, cooperation, and anticipated pain
Nerve blocks are often preferred for digit, hand, and foot lacerations, or those requiring extensive manipulation.
Preparation:
Ensure appropriate resuscitation if needed
Obtain informed consent from parents/guardians
Prepare sterile equipment, including syringes, needles of appropriate gauge (e.g., 25-30G for pediatric blocks), local anesthetic with or without epinephrine (epinephrine generally avoided in digits, ears, and penis), and antiseptic solution.
Block Procedure:
Perform the block using sterile technique
Aspirate before injecting to avoid intravascular injection
Inject slowly
For pediatric patients, consider distraction techniques, such as video or play, during the procedure
Adequate time must be allowed for the block to take effect (typically 5-15 minutes).
Wound Care:
After successful anesthesia, irrigate the wound thoroughly with saline
Debride any devitalized tissue
Repair the laceration using appropriate sutures or staples
Apply a sterile dressing
Provide post-procedure pain management instructions to caregivers.
Complications
Early Complications:
Nerve injury (paresthesia, nerve damage), hematoma formation, local anesthetic systemic toxicity (LAST) with CNS or cardiovascular effects, infection, and failure of the block.
Late Complications:
Chronic pain, neuroma formation, scar formation
Prolonged sensory or motor deficits are rare but possible.
Prevention Strategies:
Meticulous sterile technique, correct anatomical landmarks, aspiration before injection, judicious dosing, and slow injection
Using ultrasound guidance can improve accuracy and reduce complications
Careful patient selection and monitoring are essential.
Key Points
Exam Focus:
Dosing of local anesthetics based on weight (mg/kg) and maximum recommended doses
Understanding the anatomy of nerves targeted for common pediatric laceration sites
Recognizing signs and symptoms of local anesthetic systemic toxicity (LAST)
Indications for nerve blocks versus infiltration.
Clinical Pearls:
Always aspirate before injection to prevent intravascular administration
Use the lowest effective concentration of local anesthetic
Consider adding bicarbonate to lidocaine to reduce injection pain
For digit blocks, avoid epinephrine
If a block fails, consider repeat attempt or alternative anesthesia (e.g., infiltration, procedural sedation).
Common Mistakes:
Incorrect dosing, especially in neonates and infants
Injection into blood vessels
Failure to allow adequate time for block onset
Insufficient anesthetic volume
Not adequately assessing neurovascular status pre- and post-block.