Management of Rodenticide Poisoning Associated with Synthetic Cannabinoids

Treatment

In the ED, the case was discussed with the Illinois Poison Control Center. The patient was diagnosed with coagulopathy likely due to anticoagulant poisoning. He was immediately treated with 10 mg of IV vitamin K, a fixed dose of 2,000 units of 4-factor prothrombin complex concentrate, and 4 units of fresh frozen plasma. His INR improved to 1.42 within several hours. He received 5 mg of IV metoprolol for uncontrolled AF and was admitted to the intensive care unit (ICU) for further care.

In the ICU the patient was started on oral vitamin K 50 mg tid for ongoing treatment of coagulopathy due to concern for possible rodenticide poisoning associated with very long half-life. This dose was then decreased to 50 mg bid. He was given IV fluid resuscitation with normal saline and started on rate control for AF with oral metoprolol. His heart rate improved. An echocardiogram showed new cardiomyopathy with an ejection fraction of 25% to 30%. Given basilar infiltrates and 1 episode of low-grade fever, he was started on ceftriaxone for possible community-acquired pneumonia. The patient was started on cholestyramine to help with washout of the possible rodenticide. No endoscopic interventions were performed.

The patient was transferred to an inpatient telemetry floor 24 hours after admission to the ICU once his tachycardia and bleeding improved. He did not require transfusion of packed red blood cells. In the ICU his INR had ranged between 1.62 and 2.46 (down from > 20 in the ED). His hemoglobin dropped from 13.3 g/dL on admission to 12 g/dL on transfer from the ICU, before stabilizing around 11 g/dL on the floor. The patient’s heart rate required better control, so metoprolol was increased to a total daily dose of 200 mg on the telemetry floor. Oral digoxin was then added after a digoxin load for additional rate control, as the patient remained tachycardic. Twice a day the patient continued to take 50 mg vitamin K. Cholestyramine and ceftriaxone were initially continued, but when the INR started increasing again, the cholestyramine was stopped to allow for an increase to more frequent 3-times daily vitamin 50 mg K administration (cholestyramine can interfere with vitamin K absorption). According to the toxicology service, there was only weak evidence to support use of cholestyramine in this setting.

Given his ongoing mild hemoptysis, the patient received first 1 unit, and then another 4 units of FFP when the INR increased to 3.96 despite oral vitamin K. After FFP, the INR decreased to 1.93 and subsequently to 1.52. A CT of the chest showed patchy ground-glass densities throughout the lungs, predominantly at the lung bases and to a lesser extent in the upper lobes. The findings were felt to represent pulmonary hemorrhage given the patient’s history of hemoptysis (Figure 2).

The patient’s heart rate control improved, and he remained hemodynamically stable. A thyroid function test was within normal limits. Lisinopril was added to metoprolol and digoxin given his newly diagnosed cardiomyopathy. The patient was observed for a total of 4 days on the inpatient floor and discharged after his INR stabilized around 1.5 on twice daily 50 mg vitamin K. The patient’s hematuria and hematochezia completely resolved, and hemoptysis was much improved at the time of discharge. His hemoglobin remained stable. The anticoagulant poisoning panel came back positive for difenacoum and brodifacoum. Given the long half-lives of these 2 substances, the patient required ongoing high-dose vitamin K therapy.
The patientwas seen 2 days and 9 days after hospital discharge by his primary care physician. He had no recurrence of bleeding. His INR had a slight upward trend from 1.50 to 1.70, so his vitamin K dose was increased to twice daily 60 mg vitamin K. A subsequent visit documented a follow-up INR of 1.28 on this higher dose. Six weeks after hospital discharge a repeat echocardiogram showed a recovered ejection fraction of 50% to 55%. A cardiology consult suggested that cardiomyopathy was largely tachycardia-induced and that with control of the ventricular rate, the cardiac function had recovered.

The patient has remained in AF at all follow-up visits. The INR normalized by 6 weeks after hospital discharge, and the dose of vitamin K slowly was tapered with close monitoring of the INR. Vitamin K was tapered for about 6 months after his initial presentation, and the patient was started on a direct oral anticoagulant (DOAC) for anticoagulation when the INR remained stable off vitamin K. He subsequently underwent a transesophageal echocardiogram followed by an attempt at direct current (DC) cardioversion; however, he did not remain in sinus rhythm, and is being continued on anticoagulation and rate control for his AF.