Dabigatran deliberate overdose: two cases and suggestions for laboratory monitoring.

CONTEXT: Dabigatran etexilate (dabigatran) is a direct thrombin inhibitor anticoagulant agent. There is limited information about the changes in coagulation profile and outcomes in overdose. A monoclonal antibody has been developed to neutralize the anticoagulant effect of dabigatran. Case reports describe enhanced clearance of dabigatran by haemodialysis as an intervention to prevent haemorrhagic complications - however, the threshold for initiating haemodialysis is not well defined in an asymptomatic patient with normal renal function. CASE DETAILS: Two patients presented following deliberate dabigatran overdoses. A 55-year-old woman ingested 10 × 150 mg dabigatran. A 21-year-old woman with a history of systemic lupus erythematosus and pulmonary embolus ingested 100 × 110 mg dabigatran. Both were admitted to the intensive care unit and managed expectantly. Serial coagulation tests normalized over 60 h. The half-life of dabigatran was not prolonged following overdose, being calculated between 7 and 11 h in each case. There was positive correlation between international normalized ratio (INR), prothrombin time (PT) and activated partial thromboplastin time (aPTT) with plasma dabigatran levels. CONCLUSION: There is limited experience with dabigatran overdoses. Normal aPTT, PT and INR assays 12 h following deliberate ingestion indicate that the drug concentration is not high. Individual risk assessment of bleeding risk needs to be formulated for each patient and expectant management is reasonable in the presence of normal renal function and absent risk factors for bleeding.

Randomized controlled trial of intravenous antivenom versus placebo for latrodectism: the second Redback Antivenom Evaluation (RAVE-II) study.

STUDY OBJECTIVE: Latrodectism is the most important spider envenomation syndrome worldwide. There remains considerable controversy over antivenom treatment. We aimed to investigate whether antivenom resulted in resolution of pain and systemic effects in patients with latrodectism who received standardized analgesia. METHODS: In a multicenter randomized placebo-controlled trial of redback spider antivenom for latrodectism, 224 patients (>7 years) with a redback spider bite and severe pain, with or without systemic effects, were randomized to receive normal saline solution (placebo) or antivenom after receiving standardized analgesia. The primary outcome was a clinically significant reduction in pain 2 hours after trial medication compared with baseline. A second primary outcome for the subgroup with systemic features of envenomation was resolution of systemic features at 2 hours. Secondary outcomes were improved pain at 4 and 24 hours, resolution of systemic features at 4 hours, administration of opioid analgesics or unblinded antivenom after 2 hours, and adverse reactions. RESULTS: Two hours after treatment, 26 of 112 patients (23%) from the placebo arm had a clinically significant improvement in pain versus 38 of 112 (34%) from the antivenom arm (difference in favor of antivenom 10.7%; 95% confidence interval -1.1% to 22.6%; P=.10). Systemic effects resolved after 2 hours in 9 of 41 patients (22%) in the placebo arm and 9 of 35 (26%) in the antivenom arm (difference 3.8%; 95% confidence interval -15% to 23%; P=.79). There was no significant difference in any secondary outcome between antivenom and placebo. Acute systemic hypersensitivity reactions occurred in 4 of 112 patients (3.6%) receiving antivenom. CONCLUSION: The addition of antivenom to standardized analgesia in patients with latrodectism did not significantly improve pain or systemic effects.

Abdominal compression effectively increases the size of the common femoral vein, as measured by ultrasonography.

STUDY OBJECTIVE: We determine the effect of abdominal compression on common femoral vein cross-sectional area. The effects of Valsalva maneuver and reverse Trendelenburg's position are also studied. METHODS: Prospective, observational, comparative evaluation performed on sequential patients presenting to an adult emergency department. Using ultrasonography, common femoral vein area was measured with patients in supine and reverse Trendelenburg's positions. In each position measurements were taken at baseline while abdominal compression was performed and while the patient performed the Valsalva maneuver. Abdominal compression involved pressing with an examining hand over the patient's right upper abdomen. RESULTS: Fifty patients were enrolled in the study. The average common femoral vein area measured 0.89 cm2 at baseline in the supine position. It increased 0.47 cm2 (95% confidence interval [CI] 0.38 to 0.57 cm2) to 1.36 cm2 with abdominal compression and by 0.90 cm2 (95% CI 0.74 to 1.07 cm2) to 1.79 cm2 with the Valsalva maneuver. In the reverse Trendelenburg's position, the common femoral vein area averaged 1.10 cm2, 0.22 cm2 bigger than the supine baseline area (95% CI 0.13 to 0.30 cm2). With additional abdominal compression, the vein area increased by 0.71 cm2 to 1.59 cm2 (95% CI 0.59 to 0.83 cm2). With the patient performing the Valsalva maneuver in the reverse Trendelenburg's position, the vein increased in area 1.07 cm2 (95% CI 0.91 to 1.24 cm2) to 1.96 cm2. CONCLUSION: Abdominal compression increases the cross-sectional area of the common femoral vein, and the reverse Trendelenburg's position has a further additive effect. Abdominal compression may be useful when femoral venous cannulation is attempted. In patients who can comply, the Valsalva maneuver may be even more effective.