To describe the prevalence of heparin-induced thrombocytopenia (HIT) in patients on extracorporeal membrane oxygenation (ECMO) and to explore ways to improve the diagnostic accuracy of the HIT enzyme-linked immunosorbent assay (ELISA). Retrospective review of all patients needing ECMO between September 2011 and September 2020 who underwent evaluation for HIT while on ECMO. The diagnosis of HIT required a confirmatory serotonin release assay (SRA). Various break points for the optical density (OD) that defines a positive HIT ELISA were examined to estimate their utility as screening tests for HIT. Patient outcomes served as a secondary endpoint. Among 417 ECMO patients, 162 (38.8%) had a HIT ELISA. Of these, 114 (70.4%) had a subsequent SRA. Although the HIT ELISA was positive at an OD ≥ 0.4 in 1/3 rd of subjects, only 15 subjects met criteria for HIT by SRA. Hence, the prevalence of HIT equaled 3.6%. At an OD ≥ 0.4 the ELISA had both poor specificity (71.7%) and accuracy (74.6%). Changing the definition of the ELISA to an OD ≥ 1.2 improved both specificity and accuracy with only a limited impact on sensitivity. Nearly 60% of those with HIT developing during ECMO died. HIT is infrequent in persons requiring ECMO. However, HIT remains associated with substantial mortality. The HIT ELISA as currently implemented performs poorly as a screening test and likely results in the unnecessary overuse of alternatives to unfractionated heparin. Altering the definition of a positive OD improves the HIT ELISA’s accuracy.

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Introduction: EVALI has been a new crisis affecting the country over the last 6 months. There have been numerous reports indicating pulmonary injury tied to e-cigarette use, particularly with tetrahydrocannabinol (THC) products. Case: A 24-year-old male with a history of intermittent asthma came to the ED due to subacute shortness of breath, diffuse pleuritic chest pain, and productive cough. He was at another ED 2 days prior with a 5-day history of fevers, chills, dyspnea, nausea and was discharged home the same day with oral antibiotics, prednisone, ondansetron, and albuterol. His dyspnea did not improve so he came to the ED. On admission his respiratory rate was 22 breath/minute, SpO2 98% on 10L of oxygen, heart rate 107/minute; other vitals were within the normal range. The respiratory exam was notable for bilateral wheezing. Labs notable for leukocytosis, Arterial blood gas (on 4L oxygen) showed hypoxemia with pH 7.44, pO2 66mmHg, pCO2 42mmHg and HCO3 25. Chest x-ray showed patchy airspace opacity and Computed tomography showed patchy geographic ground-glass opacities scattered throughout both lungs in a peripheral distribution. He admitted to having a 7-month history of 'vaping' THC products obtained from a friend, roughly 4 times a week. His most recent use was a week prior to admission. Bronchoscopy with bronchoalveolar lavage was done which found mild neutrophilic predominance, no malignant cells, no increased eosinophils, normal CD4/CD8 ratio, and no subsequent organism growth. The respiratory viral panel was negative, sputum culture found no growth of infectious organisms, rheumatologic workup, and HIV testing was negative. He was treated with a 5day course of IV antibiotics, oral prednisone for 8 days and kept on 4-6L of oxygen via nasal cannula. Clinically, his symptoms improved over time, and he was discharged on hospital day 8 with a prednisone taper and no home oxygen. Discussion: This is the first recognized confirmed case of EVALI in the District of Columbia. This case fits the emerging profile in terms of having gastro-intestinal symptoms before the onset of respiratory symptoms and having improvement with prednisone. These cases are challenging to diagnose and treat in outpatient and inpatient settings due to their novelty, lack of clear imaging pattern and wide range of severity of illness. Of interest, the patient identified 'DANK vapes' as one of the most recent brands he used. This is consistent with reports of black-market sourced products, usually counterfeit, as being a possible culprit for EVALI.

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