Rosen & Barkin's 5-Minute Emergency Medicine Consult (300 page)

• Metronidazole contraindicated in 1st trimester
  
• Albendazole, quinacrine, and tinidazole are contraindicated throughout pregnancy
  
• Use nitazoxanide instead
  
• If mild symptoms only, consider deferring treatment until late pregnancy or postpartum
  

• Immunocompromised patients at risk for disease that is refractory to standard drug regimens:
  
  • Try drug of a different class/mechanism or metronidazole + quinacrine for at least 2 wk
    

FOLLOW-UP

• Hypotension or tachycardia unresponsive to IV fluids
  
• Severe electrolyte imbalance
  
• Children with >10% dehydration
  
• Signs of sepsis/toxicity (rare in isolated giardiasis)
  
• Patients unable to maintain adequate oral hydration:
  
  • Extremes of age, cognitive impairment, significant comorbid illness
    

• Able to maintain adequate oral hydration
  
• Dehydration responsive to IV fluids
  

• Gastroenterology referral for diagnostic endoscopy if symptoms persist for >4 wk despite drug therapy
  
• Acquired lactose intolerance may develop and last for weeks to months
  
• Association with postinfectious fatigue syndrome
  

Diagnosis is the greatest challenge in this disease:

• Include giardiasis in the differential diagnosis of all patients with diarrhea:
  
  • Giardia
    occasionally reported in domestic water supply
    
  • Patients may not present with the classic history and risk factors to have giardiasis
    
  • 1 stool sample is frequently insufficient for diagnosis
    

• Escobedo AA, Almirall P, Alfonso M, et al. Treatment of intestinal protozoan infections in children.
  Arch Dis Child
  . 2009;94:478–482.
  
• Escobedo AA, Alvarez G, González ME, et al. The treatment of giardiasis in children: Single-dose tinidazole compared with 3 days of nitazoxanide.
  Ann Trop Med Parasitol
  . 2008;102:199–207.
  
• Escobedo AA, Cimerman S. Giardiasis: A pharmacotherapy review.
  Expert Opin Pharmacother
  . 2007;8:1885–1902.
  
• Huang DB, WhiteAC. An updated review on Cryptosporidium and Giardia.
  Gastroenterol Clin NorthAm
  . 2006;35:291–314.
  
• Kiser JD, Paulson CP, Brown C. Clinical inquiries. What’s the most effective treatment for giardiasis?
  J Fam Pract
  . 2008;57(4):270–272.
  
• Naess H, Nyland M, Hausken T, et al. Chronic fatigue syndrome after Giardia enteritis: Clinical characteristics, disability, and long-term sickness absence.
  BMC Gastroenterol.
  2012;12:13.
  
• Yoder JS, GarganoJW, Wallace RM, et al. Giardiasissurveillance–United States, 2009--2010.
  MMWR Surveill Summ.
  2012;61(5):13–23.
  

See Also (Topic, Algorithm, Electronic Media Element)

• Amebiasis
  
• Diarrhea, Adult
  

CODES

007.1 Giardiasis

BASICS

Disease characterized by elevation of intraocular pressure, optic neuropathy, and progressive loss of vision.

• Primary glaucoma:
  
  • Open-angle glaucoma:
    
    • Normal anterior chamber angle
      
    • Insidious onset with persistent rise in intraocular pressure
      
    • Most common type accounting for 90% of glaucomas in US
      
    • Leading cause of blindness in African Americans
      
    • Risk factors include African American, age >40 yr, family history, myopia, diabetes, and HTN
      
  • Acute angle-closure glaucoma:
    
    • Narrowing or closing of anterior chamber angle precluding natural flow of aqueous humor from posterior to anterior chamber of eye and through its filtering portion of trabecular meshwork
      
    • Usually abrupt onset with sudden increase in intraocular pressure
      
    • Risk factors include Asians and Eskimos, hyperopia, family history, increased age, and female gender
      
• Secondary glaucoma occurs from other diseases, including diseases of eye, trauma, and drugs:
  
  • Can be either open or closed angle
    
  • Drugs: Steroids, sertraline, bronchodilators, topiramate
    
  • Diseases: Neurofibromatosis, uveitis, neovascularization, and intraocular tumors
    
  • Trauma
    
  • Rapid correction of hyperglycemia
    

DIAGNOSIS

Classic descriptions:

• Open angle:
  
  • Painless and gradual loss of vision
    
• Closed angle:
  
  • Painful loss of vision with fixed midsized pupil
    

• Primary open-angle glaucoma:
  
  • Gradual reduction in peripheral vision or night blindness
    
  • Typically bilateral
    
  • Painless
    
• Primary angle-closure glaucoma:
  
  • Severe deep eye pain and ipsilateral headache often associated with nausea and vomiting
    
  • Decrease in visual acuity often described as visual clouding with halos surrounding light sources
    
  • Associated abdominal pain, which may misdirect diagnosis
    
  • Concurrent exposure to dimly lit environment such as movie theater
    
  • Use of precipitating medications:
    
    • Mydriatic agents: Scopolamine, atropine
      
    • Sympathomimetics: Pseudoephedrine, albuterol
      
    • Antihistamines: Benadryl, Antivert
      
    • Antipsychotics: Haldol
      
    • Phenothiazines: Compazine, Phenergan
      
    • Tricyclic antidepressants: Elavil
      
    • Sulfonamides: Topiramate
      

• Primary open-angle glaucoma:
  
  • Decreased visual acuity
    
• Primary angle-closure glaucoma:
  
  • Decreased visual acuity
    
  • Pupil is mid-dilated and nonreactive.
    
  • Corneal edema with hazy appearance
    
  • Conjunctival injection, ciliary flush
    
  • Firm globe to palpation
    

• Detailed ocular exam
  
• Visual acuity:
  
  • Hand movements typically all that is seen
    
• Tonometry:
  
  • Normal pressures are 10–21 mm Hg.
    
  • Primary open-angle glaucoma:
    
    • Degree of elevation can vary, but 25–30% of patients may have normal intraocular pressures.
      
  • Primary angle-closure glaucoma:
    
    • Any elevation is abnormal, but usually seen in ranges >40 mm Hg.
      
• Slit-lamp exam:
  
  • Evaluation of anterior chamber angle
    
  • Used to eliminate other possibilities in differential including corneal abrasion and foreign body
    

Directed toward workup of differential

Directed toward workup of differential

Gonioscopy:

• This is direct measurement of the angle of closure
  

• Cavernous sinus thrombosis
  
• Acute iritis and uveitis
  
• Retinal artery or vein occlusion
  
• Temporal arteritis
  
• Retinal detachment
  
• Conjunctivitis
  
• Corneal abrasion
  

TREATMENT