Rosen & Barkin's 5-Minute Emergency Medicine Consult (457 page)

• Activated charcoal: 1–2 g/kg PO
  
• Cyproheptadine: 4–8 mg PO/nasogastric tube q1–4h until therapeutic response; max. daily dose: 0.5 mg/kg (peds: 0.25 mg/kg/d; max. 12 mg/d; safety not established age <2 yr)
  
• Dextrose: D50W 1–2 amp (50–100 mL or 25–50 g) (peds: D25W 2–4 mL/kg) IV push (IVP)
  
• Diazepam: 5–10 mg (peds: 0.1 mg/kg slowly) increments IVP
  
• Lorazepam: 1–2 mg increments IVP
  
• Nitroprusside: 0.3–10 μ/kg/min IV
  
• Norepinephrine: 2-4 μ/kg/min (peds: 0.05–0.1 μ/kg/min) IV
  
• Phentolamine: 5 mg (peds: 0.05–0.2 mg/kg/dose) increments IVP
  
• Sodium bicarbonate: Bolus 1–2 mEq/kg IVP; adult infusion: 3 amp (50 mEq per amp) sodium bicarbonate in 1,000 mL D5W at 2–3 mL/kg/h IV
  
• Vecuronium: 0.1 mg/kg IVP
  

FOLLOW-UP

• All MAOI overdose patients require admission to a monitored unit for 24 hr.
  
• ICU admission for seriously ill patients
  

• Resolved mild hypertensive syndrome or resolved mild serotonin syndrome may be discharged after several hours of ED observation.
  

Intentional overdoses should receive a psychiatry consult for suicide attempt.

Following significant MAOI toxicity, medications need to be reassessed to prevent future crises.

• Delayed onset of 6–12 hr prior to symptoms
  
• Linezolid and methylene blue are MAOIs.
  
• Phentolamine is contraindicated in MAOI overdose secondary to unopposed β-agonist.
  

• Boyer EW, Shannon M. The serotonin syndrome.
  New Engl J Med
  . 2005;352:1112–1120.
  
• Brush DE, Bird SB, Boyer EW. Monoamine oxidase inhibitor poisoning resulting from Internet misinformation on illicit substances.
  J Toxicol Clin Toxicol
  . 2004;42:191–195.
  
• Gillman PK. Monoamine oxidase inhibitors, opioid analgesics and serotonin toxicity.
  Br J Anaesth
  . 2005;95:434–441.
  
• Oates JA, Sjoerdsma A. Neurologic effects of tryptophan in patients receiving a monoamine oxidase inhibitor.
  Neurology
  . 1960;10:1076–1078.
  
• Ramsay RR, Dunford C, Gillman PK. Methylene blue and serotonin toxicity: Inhibition of monoamine oxidase A (MAO A) confirms a theoretical prediction.
  Br J Pharmacol
  . 2007;152:946–951.
  

See Also (Topic, Algorithm, Electronic Media Element)

Sympathomimetic Poisoning

CODES

969.01 Poisoning by monoamine oxidase inhibitors

BASICS

• Results in most cases from infection with the Epstein–Barr virus (EBV) (a herpesvirus):
  
  • Non-EBV causes of infectious mononucleosis (IM):
    
    • Cytomegalovirus (CMV)
      
    • Adenovirus
      
    • Hepatitis A
      
    • Herpesvirus 6
      
    • HIV
      
    • Rubella
      
    • Toxoplasma gondii
      
    • Group A β-hemolytic streptococci
      
• >90% of adults on serologic testing demonstrate prior infection with EBV:
  
  • Most do not recollect specific IM symptoms
    
• Mode of transmission is close or intimate contact particularly with saliva from “shedders” who may or may not be symptomatic:
  
  • Nickname “kissing disease”
    
  • Viral shedding in saliva can persist intermittently for life
    
  • May occur after transfusions/transplants
    
• Incubation period: 4–6 wk
  
• Immunologic response:
  
  • T-cells response:
    
    • T-cell response is responsible for an elevated absolute lymphocyte count and the associated clinical symptoms and complications
      
    • Subtype of the T-cell lineage, cytotoxic CD8 cells (Downey cells), contain eccentrically placed and lobulated nuclei with vacuolated cytoplasm: The “atypical lymphocytes” seen on differential
      
  • B-cell response:
    
    • EBV infects and replicates in B-cells
      
    • B-cells are then transformed into plasmacytoid cells that secrete immunoglobulins
      
    • IgM antibody secreted: The heterophile antibody which is reactive against red cell antigens
      
• Mortality from IM is rare, but may occur due to the following complications:
  
  • Airway edema
    
  • Neurologic complications
    
  • Secondary bacterial infection
    
  • Splenic rupture
    
  • Hepatic failure
    
  • Myocarditis
    
• EBV infection has also been strongly linked to African Burkitt lymphoma and nasopharyngeal carcinoma
  

• In children <4 yr, infection with EBV is often asymptomatic
  
• In children who do become symptomatic, there is propensity toward atypical presentations:
  
  • Neutropenia, pneumonia, and varied rashes
    
  • Mesenteric lymphadenopathy and splenomegaly can cause the illness to present with abdominal pain and be confused with appendicitis.
    
  • Infants and toddlers can present with only irritability and failure to thrive so must be considered when no other source can be identified
    

DIAGNOSIS

• Typically an insidious onset over several days to weeks but may be abrupt onset
  
• Prodromal fatigue, malaise, arthralgias, and myalgias with a biphasic or “waxing and waning” course
  
• Prominent or “worst ever” sore throat and fever. Airway edema may be reported as difficulty breathing or respiratory distress.
  
• Swollen lymph nodes
  
• Headache
  
• Significant abdominal pain is uncommon but when present should raise concern about marked splenic enlargement or splenic rupture.
  
• Varied rashes can be seen in 18–34% of children and adolescents (not associated with antibiotics)
  
• Administration of ampicillin or amoxicillin in patients with IM is associated with development of a rash
  

• Malaise and/or fatigue (90–100%)
  
• Pharyngitis (65–85%) and tonsillar enlargement
  
• Fever (80–95%)
  
• Eyelid edema (15–35%)
  
• Symmetric tender lymphadenopathy (100%)
  
• Hepatomegaly (15–25%)
  
• Splenomegaly (50–60%)
  
• Nonspecific rashes
  
• Morbilliform rash can be seen if the patient has been given ampicillin or amoxicillin:
  
  • Typically develops 5–9 days after the onset of antibiotic therapy (should not be interpreted as a penicillin allergy)
    
• Petechia can occur on the skin or at the junction between the hard and the soft palate.
  
• Complications found on exam:
  
  • Airway compromise due to edema (1–5%)
    
  • Severe abdominal tenderness may be due to splenic rupture (may also cause referred pain to left shoulder)
    
  • Jaundice (∼5%) due to hepatitis or hepatic failure
    
    • Hepatitis is the most common complication
      
  • Neurologic findings consistent with:
    
    • Encephalitis or cerebellitis
      
    • Aseptic meningitis
      
    • Guillain–Barré syndrome
      
    • Optic neuritis
      
    • Bell palsy
      
• Anemia (palor): May be due to hemolytic anemia, thrombocytopenia, agranulocytosis, hemophagocytic lymphohistiocytosis (HLH)
  
• Orchitis
  
• Neck tenderness and/or limited range of motion due to pain: Secondary bacterial soft tissue infection such as retropharyngeal or peritonsillar abscesses
  
• Signs of shock: May be due to dehydration or a secondary anaerobic sepsis