Abstract
This chapter reviews the thankfully rare but critical topic of local anesthetic systemic toxicity in children. The authors discuss the incidence, presentation and differential diagnosis related to local anesthetic toxicity. The chapter discusses the prevention and treatment of local anesthetic toxicity which is crucial knowledge for providers performing regional anesthesia in children.
A nine-year-old, 35 kg boy presents for an open reduction and internal fixation of a right lateral condyle fracture. The patient has a past medical history of headaches presenting with nausea and vomiting. The main provoking factor is anxiety. The alleviating factors for the headaches are bed rest and caffeine. The parents provide consent for general anesthesia with regional anesthesia for pain management. He complains of a headache that seems to improve after intravenous midazolam is given. He is positioned for an ultrasound-guided supraclavicular block. Following negative aspiration, 10 mL of 0.5% ropivacaine is injected. He is resting comfortably in the holding area. After 30 minutes, the patient complains that his headache has returned and he begins to feel nauseous. He begins stuttering and cannot formulate sentences and begins to seize prior to entering the operating room.
What Is the Differential Diagnosis?
It is important to differentiate this patient’s migraine from local anesthetic toxicity. The patient began having headaches that seemed to reflect his past medical history of having terrible migraines. Although the needle aspiration was negative upon placement of the supraclavicular block and a significant amount of time had passed prior to the onset of symptoms, local anesthetic toxicity cannot be ruled out. The patient has a past medical history that confounds the diagnosis even under direct ultrasound guidance and visualization.
What Is Local Anesthetic Systemic Toxicity (LAST) and When Does It Occur?
LAST can occur in any patient at any location of local anesthetic placement. Pregnant patients, young patients, and patients with preexisting hypoxia and/or respiratory acidosis are at highest risk for developing LAST. LAST most commonly occurs during an intravascular injection of local anesthetic. However, even the correct placement of anesthetic can cause systemic toxicity. Factors that affect LAST include: concurrent medications, patient risk factors, location and technique of the block, total anesthetic dose, timeliness of detection, and adequacy of treatment.
What Is the Incidence of LAST?
The location of the block is a significant risk factor for patients developing LAST. Supraclavicular and interscalene blocks have shown an incidence of 79 of 10,000 patients developing LAST symptoms in one institution. LAST is more likely to occur in infants compared to adults because of the infant’s low protein binding and low intrinsic clearance of local anesthetics. As most infants and children have blocks performed under general anesthesia, the central nervous system manifestations of LAST, such as seizures, are not seen as commonly.
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