At. Guertler et Wa. Pearce, A PROSPECTIVE EVALUATION OF BENZOCAINE-ASSOCIATED METHEMOGLOBINEMIA IN HUMAN-BEINGS, Annals of emergency medicine, 24(4), 1994, pp. 626-630
Study objective: This study determined the frequency and severity of b
enzocaine-associated methemoglobinemia in routine clinical use. Design
: Prospective, crossover, convenience study. Setting: Gastroenterology
clinic at a US Army medical center functioning as a community hospita
l and tertiary referral center. Participants: Healthy adult volunteers
and patient volunteers undergoing an upper gastrointestinal endoscopi
c procedure. Interventions: Baseline methemoglobin levels were measure
d. Subjects then received a 2-second spray of benzocaine to the oropha
rynx. Venous blood for methemoglobin analysis was collected 20, 40, an
d 60 minutes after benzocaine dosing and analyzed using a co-oximeter.
Results: A statistically significant (P<.05) increase in methemoglobi
n level between baseline (0.8+/-0.2%) and 20-, 40-, and 60-minute meas
urements (0.9+/-0.2%) was identified using one-way analysis of varianc
e followed by Fisher's protected least-squares difference. Conclusion:
A 2-second spray of 20% benzocaine applied to the oropharynx of human
beings induces a statistically significant, but clinically insignific
ant, increase in methemoglobin levels.