title: A prospective evaluation of benzocaine-associated methemoglobinemia in human beings.
abstract: OBJECTIVE
  This study determined the frequency and severity of benzocaine-associated methemoglobinemia in routine clinical use.
  
  
  METHODS
  Prospective, crossover, convenience study.
  
  
  METHODS
  Gastroenterology clinic at a US Army medical center functioning as a community hospital and tertiary referral center.
  
  
  METHODS
  Healthy adult volunteers and patient volunteers undergoing an upper gastrointestinal endoscopic procedure.
  
  
  METHODS
  Baseline methemoglobin levels were measured. Subjects then received a 2-second spray of benzocaine to the oropharynx. Venous blood for methemoglobin analysis was collected 20, 40, and 60 minutes after benzocaine dosing and analyzed using a co-oximeter.
  
  
  RESULTS
  A statistically significant (P < .05) increase in methemoglobin level between baseline (0.8 +/- 0.2%) and 20-, 40-, and 60-minute measurements (0.9 +/- 0.2%) was identified using one-way analysis of variance followed by Fisher's protected least-squares difference.
  
  
  CONCLUSIONS
  A 2-second spray of 20% benzocaine applied to the oropharynx of human beings induces a statistically significant, but clinically insignificant, increase in methemoglobin levels.
authors.affiliation: Department of Emergency Medicine, Madigan Army Medical Center, Tacoma, Washington.
authors.forename: A T
authors.initials: AT
authors.lastname: Guertler
authors.forename: W A
authors.initials: WA
authors.lastname: Pearce
mesh_terms: D000328:Adult; D000336:Aerosols; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001566:Benzocaine / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D008706:Methemoglobin / Q000032:analysis; D008708:Methemoglobinemia / Q000097:blood / Q000139:chemically induced*; D008875:Middle Aged; D009960:Oropharynx; D011446:Prospective Studies; D013997:Time Factors
chemical_list: D000336:Aerosols; D008706:Methemoglobin; D001566:Benzocaine