Venom-Induced Consumption Coagulopathy Following Hump-Nosed Pit Viper (Genus: Hypnale) Envenoming in Sri Lanka: Uncertain Efficacy of Fresh Frozen Plasma

• Published in: Wilderness & environmental medicine Vol. 31; no. 2; pp. 131 - 143
• Main Authors: Namal Rathnayaka, R.M.M.K., Ranathunga, P.E. Anusha Nishanthi, Kularatne, S.A.M.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA Elsevier Inc 01-06-2020; SAGE Publications
• Subjects: Hypnale nepa, WBCT20; Hypnale zara; snakebites; thrombotic microangiopathy; snakebites; thrombotic microangiopathy; Hypnale zara; Hypnale nepa, WBCT20
• ISSN: 1080-6032; 1545-1534
• DOI: 10.1016/j.wem.2019.12.006

Hump-nosed pit vipers (Hypnale spp) cause the highest number of venomous snakebites in Sri Lanka. Bites commonly cause local envenoming leading to local pain, swelling, and necrosis of the site of the bite. Acute kidney injury is the most common systemic manifestation, and some patients develop venom-induced consumption coagulopathy (VICC). Genus Hypnale comprises 3 species. Of them, H hypnale is found in Sri Lanka and the Western Ghats region of India. The other 2 (H nepa and H zara) are endemic species in Sri Lanka.
This study included 500 patients with hump-nosed viper bites studied prospectively over 4.5 y starting June 2014. All patients were assessed and the data were collected by the principal investigator (primary data). A subgroup of patients who developed VICC is described. There were 2 groups, including proven (patients with the specimen of the snake) and probable (specimen of snake not available) bites.
Thirty (n=500; 6%) patients developed VICC; of them, 17 (3%) were proven cases, and 13 (2%) were probable cases. In both groups, 24 (80%) recovered, 2 (7%) progressed to chronic kidney disease, 1 (3%) died of severe hemostatic dysfunction, and 3 (10%) were lost to follow-up. Systemic bleeding was observed in 16 patients (53%), including hematuria (microscopic and gross) in 8 (27%) and venipuncture bleeding in 5 (17%). Eleven (37%) developed local bleeding at the site of the bite. Fresh frozen plasma was administered to 20 patients (67%), among whom only 11 (55%) experienced early correction of VICC. In both groups, 15 (50%) developed acute kidney injury, and 2 (7%) progressed to chronic kidney disease. Microangiopathic hemolysis was observed in 18 patients (60%) and thrombocytopenia in 16 (53%). Thrombotic microangiopathy was detected in 13 patients (43%), of whom 10 (33%) developed hemolytic uremic syndrome and 2 (7%) had thrombotic thrombocytopenic purpura. Of patients with VICC in the proven group, 94% (n=16) was caused by H hypnale and 1 (6%) was caused by H zara. In the proven group, median international normalized ratio was 3.7 (interquartile range 1.6–5.0); in the probable group, it was 5.0 (interquartile range 2.1–5.4).
We found that 6% of patients develop hemostatic dysfunction after hump-nosed viper bites. However, which patients will develop coagulopathy or die of envenoming is unpredictable. Reliable and accessible treatments are unmet essential needs because antivenoms for these bites are currently not available in the country. Therapy with fresh frozen plasma has doubtful efficacy in early correction of VICC and needs further evaluation.