RESUMO
BACKGROUND: Digoxin is a widely prescribed drug for congestive heart failure and atrial fibrillation. Digoxin has a narrow therapeutic index and toxicity can develop quite easily. Digoxin immune fab (DIF) is an effective treatment for toxicity, however there are limited studies characterizing its impact on clinical outcomes in real-world clinical practice. OBJECTIVES: The aim of this study was to identify factors and healthcare outcomes associated with digoxin immune fab (DIF) treatment in patients with confirmed/suspected digoxin toxicity. METHODS: An IRB-approved retrospective chart review of digoxin toxic patients (2011-2020) presenting at an academic healthcare system was conducted. Demographic and clinical data were collected. Patients were stratified by DIF treatment versus non-DIF treatment. DIF utilization patterns (appropriate, use when not indicated, or underutilized) were determined using pre-defined criteria. Severe digoxin toxicity was defined as having one or more of the following: mental status disturbances, antiarrhythmic therapy, acute renal impairment or dehydration, serum digoxin concentration (SDC) > 4 ng/mL, or serum K+ > 5 mEq/mL. Logistic multivariable regression analysis evaluated factors associated with DIF use. All statistical analyses were performed in R version 4.1. RESULTS: Data from 96 patients (non-DIF treated group = 49; DIF treated group = 47) were analyzed. DIF was used appropriately in 70 patients (73%), underutilized in 19 (20%), and administered to 7 (7%) patients when it was not indicated. Several clinical parameters differentiated the DIF from the non-DIF group (p < 0.05) including higher mean SDC (3.41 ± 1.63 vs 2.87 ± 1.17), higher mean potassium (5.33 ± 1.48 vs 4.55 ± 0.87), more toxicity severity (85% vs 49%), and more likely to require cardiac pacing (26% vs 4%). Digoxin toxicity resolved sooner in the DIF group (coefficient - 0.702, 95% CI - 1.137 to - 0.267) (p < 0.01) and they had shorter intensive care unit lengths of stay (12.4 ± 20.3 vs 24.4 ± 28.7 days; p = 0.018). The all-cause mortality rate in patients appropriately managed with DIF therapy versus those patients where DIF was underutilized was 11% and 21%, respectively. CONCLUSIONS: Based on our study population, DIF therapy appears to be beneficial in limiting duration of toxicity and intensive care unit lengths of stay in digoxin toxic patients. Although DIF was appropriately utilized in most cases, there was a relatively high proportion of cases in which DIF treatment was either underutilized or not indicated.
RESUMO
BACKGROUND: Historically, the first step in treating cyanide (CN-) toxicity utilized antidotes to induce methemoglobinemia. This is concerning in patients who are already hypoxemic or have elevated carboxyhemoglobin. Hydroxocobalamin (OHCbl) is now the first-line antidote for CN- toxicity and is not known to induce methemoglobinemia. We observed elevated methemoglobin (MetHb) levels in several patients treated with OHCbl and sought to investigate the incidence of MetHb formation following administration of OHCbl. METHODS: Chart review: A single-center, retrospective case series of patients who received 5 or 10 g of hydroxocobalamin from 01/01/2011 through 04/30/2019. Data was analyzed using descriptive statistics. In-vitro study: Discarded blood was separated into whole blood and plasma samples. OHCbl and normal saline was added to reach 0×, 1×, 2×, and 4× peak therapeutic concentrations and analyzed at times 0, 2, and 4 h after administration. RESULTS: Chart review: Twenty-seven cases of OHCbl administration were identified. The median age was 53 years (IQR 38 - 64) and 20 (74.1%) were male. Exposure to a house fire or smoke inhalation was the reason for OHCbl administration in 21 (77.8%) patients. Five (18.5%) patients received 10 g of OHCbl while the rest received 5 g. Six (22.2%) patients developed methemoglobinemia, all after 5 g OHCbl administration; four had been exposed to fire and smoke, two received the medication for severe acidosis of unknown etiology not related to fire or smoke. The median peak level was 7.1% (IQR 2.2 - 16.4%) at a median time of 11.4 h post-administration. Two patients received methylene blue (MB), neither responded. Death occurred in 17 (63%) cases. In-vitro study: We observed a dose dependent elevation in total hemoglobin but did not detect any increase in MetHb. CONCLUSION: We observed a noteworthy temporal association between the formation of methemoglobinemia and the administration of hydroxocobalamin. This does not appear to be an artifact of the CO-oximeters. This could have profound implications for patients who are already hypoxemic or have impaired oxygen carrying capacity from carboxyhemoglobin.