Distribution and Suspected Causes of Methemoglobinemia at an Academic Medical Center
Description
Supplementary file 1: Data for methemoglobin concentrations in whole blood specimens performed at the University of Iowa Hospitals and Clinics from May 1, 2009 to June 22, 2023. The data elements for the “All Values” tab (which contains all methemoglobin values in the above timeframe) include: deidentified patient number, legal sex in the electronic medical record, patient age in years at time of methemoglobin measurement (greater than 89 years expressed as ">89"), location type (outpatient or inpatient) for where methemoglobin measurement was made, quantitative methemoglobin value (%), methemoglobin category (0.0-3.0%, 3.1-4.9%, 5.0-9.9%, and 10+%), and pediatric/adult at time of testing (pediatric defined as < 18 years old). The data elements for the “Episodes with MetHb >=3.1%” field (which contains only those episodes of care with a methemoglobin concentrations of 3.1% or higher) include: deidentified patient number, legal sex in the electronic medical record, patient age in years at time of methemoglobin measurement (greater than 89 years expressed as ">89"), location type (outpatient or inpatient) for where methemoglobin measurement was made, methemoglobin cause category from chart review, highest quantitative methemoglobin value (%) during episode of care, methemoglobin category (0.0-3.0%, 3.1-4.9%, 5.0-9.9%, and 10+%), pediatric/adult (pediatric defined as < 18 years old), asymptomatic during episode (yes/no), cardiovascular symptoms during episode (yes/no), cough during episode (yes/no), cyanosis during episode (yes/no), death during episode of care (yes/no), dizziness and/or loss of balance during episode (yes/no), edema during episode (yes/no), fatigue during episode (yes/no), gastrointestinal pain during episode (yes/no), nausea/vomiting during episode (yes/no), respiratory difficulties during episode (yes/no). Supplementary file 2: Data for methemoglobin concentrations in whole blood specimens performed at the University of Iowa Hospitals and Clinics from January 1, 1996 to April 30, 2009. The data elements for the “All Values” tab (which contains all methemoglobin values in the above timeframe) are the same as the “All Values” tab in Supplemental file 1. The data elements for the “Episodes with MetHb >=10.0%” field contain only those episodes of care with a methemoglobin concentrations of 10.0% or higher. Data elements are the same as those in the “Episodes with MetHb >=3.1%” tab in Supplemental file 1.
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Steps to reproduce
This study was conducted with ethical approval from the University of Iowa Institutional Review Board as a retrospective study with waiver of informed consent (protocols #202101499 and 202306426). We utilized electronic medical record reporting tools (Epic Reporting Workbench) to retrieve all whole blood methemoglobin measurements from January 1, 1996 to June 22, 2023 [1]. This search was for any methemoglobin analysis performed on a patient for clinical purposes. The present study did not influence test ordering, analysis, clinical management for any patient. Demographic data collected included age at time of testing, legal sex, and clinical location at time of testing (e.g., emergency department, inpatient unit, outpatient clinic). Detailed chart review was performed for all patients who had a methemoglobin level of 3.1% of higher between May 2009 and June 2023, and all patients who had methemoglobin level of 10.0% or higher prior to May 2009. The more limited review of the data prior to May 2009 reflected the incompleteness of medication administration records in older dates resulting from incompleteness of data import from the previous electronic medical record. Chart review focused on the most likely cause of methemoglobinemia during an episode of care (emergency department visit, inpatient encounter, outpatient clinic appointment, laboratory monitoring). Data regarding clinical signs and symptoms of methemoglobinemia was also collected from the medical record within temporal proximity to the abnormal laboratory value. For purposes of classification by methemoglobin level, the highest methemoglobin level during an episode was used. During the retrospective timeframe of analysis, the main blood gas analyzers used were Radiometer ABL800 FLEX or ABL90 FLEX models (Radiometer, Inc., Copenhagen, Denmark). Recognized causes of methemoglobinemia from prior published studies included: amyl or isobutyl nitrite, benzocaine, bupivacaine, contaminated food with high nitrates, dapsone, gastroenteritis (infants), lidocaine, nitric oxide (iatrogenic), nitroglycerin, phenazopyridine, primaquine, sepsis, smoke inhalation, sodium nitrite, sodium nitroprusside, sulfasalazine, and trimethoprim-sulfamethoxazole. Reference: [1] M.D. Krasowski, B.A. Ford, J.S. Klutts, C.S. Jensen, A.S. Briggs, R.A. Robinson, L.A. Bruch, N.J. Karandikar, Using Focused Laboratory Management and Quality Improvement Projects to Enhance Resident Training and Foster Scholarship, Acad Pathol 4 (2017) 2374289517722152. https://doi.org/10.1177/2374289517722152.