The influence of lidocaine topical anesthesia during transesophageal echocardiography on blood methemoglobin level and risk of methemoglobinemia

Abstract

Methemoglobinemia is a relatively rare, but potentially life-threating medical condition, which may be induced by application of topical anaesthetic agents commonly used during endoscopic procedure. The aim of our study was to assess the influence of lidocaine used prior to transesophageal echocardiography (TEE) on the blood level of methemoglobin in vivo. Additionally we attempted to establish the occurrence rate of clinically evident lidocaine-induced methemoglobinemia on the basis of data collected in our institution. We retrospectively analyzed patient records from 3,354 TEEs performed in our echocardiographic laboratory over the course of 13 years in search for clinically evident methemoglobinemia cases. Additionally, 18 consecutive patients referred for TEE were included in the prospective part of our analysis. Blood samples were tested before and 60 min after pre-TEE lidocaine anesthesia application. Information concerning concomitant conditions and pharmacotherapy were also obtained. In 3,354 patients who underwent TEE in our institution no cases of clinically evident methemoglobinemia occurred. In the prospective part of the study, none of 18 patients [16 (89 %) men, mean age 63 ± 13] was diagnosed with either clinical symptoms of methemoglobinemia or exceeded normal blood concentration of methemoglobin. Initial mean methemoglobin level was 0.5 ± 0.1 % with mild, statistically (but not clinically) significant rise to 0.6 ± 0.1 % after 60 min (p = 0.02). Among the analyzed factors only the relation between the proton pump inhibitors intake and methemoglobin blood level rise was identified as statistically relevant (p = 0.03). In adults, pre-TEE lidocaine anesthesia with recommended dosage results in significant increase in methemoglobin blood level, which however does not exceed normal values and does not result in clinically evident methemoglobinemia.

Methemoglobinemia incidence after the application of lidocaine for small surgical procedures

“…[13] Under normal conditions, blood MetHb levels should be less than 1.5%. [7,13] If MetHb values are more than 5% g/dL, cyanosis can be observed. When the MetHb value is greater than 40%, an increase in cyanosis, respiratory distress, dizziness, headache, tachycardia, weakness, nausea, vomiting, lethargy, or syncope may be observed.…”

“…[5] There are case reports of methemoglobinemia due to lidocaine in infants and adults in the literature, although they are rare. [6,7] Therefore, we performed a cross-sectional study to determine the incidence of methemoglobinemia after the application of lidocaine for small surgical procedures in an emergency department.…”

Benzocaine-induced methaemoglobinaemia in an adolescent with sepsis

“…Benzocaine still is commonly used as a topical oropharyngeal anaesthetic prior to routine inpatient and outpatient endoscopic procedures such as transoesophageal echocardiography (TEE) and bronchoscopies, dental procedures in the hospital. Benzocaine-induced methaemoglobinaemia after transoesophageal echocardiogram had been described in adult literature with few case reports but extremely rare in children and adolescents 5–9…”

Methemoglobinemia: A Life-threatening Complication of Topical Pharyngeal Anesthetics

“…Topical pharyngeal anesthetics such as benzocaine are used in conjunction with moderate sedation to increase patient comfort during esophagogastroduodenoscopy (EGD). Topical pharyngeal anesthetics can cause methemoglobinemia, which is a rare and life-threatening complication [1]. We present a case of a 22year-old healthy female with no known co-morbidities who developed symptoms of shortness of breath following the use of topical anesthesia for EGD and was subsequently diagnosed with methemoglobinemia based on her arterial blood gas and methemoglobin levels.…”