The role of prothrombin time (PT) in evaluating green pit viper (Cryptelytrops sp) bitten patients

Abstract

Viper bites cause consumptive coagulopathy resulting in hypofibrinogenaemia. Whole-blood clotting time is a standard test used to assess bleeding risk. Prothrombin time (PT) and activated partial thromboplastin time (APTT) are better standardised assays that are widely available, but their diagnostic accuracy in viper bites remains unknown. Adult patients presumed bitten by green pit vipers (Cryptelytops sp.) were enrolled. Conventional venous clotting time (VCT), 20min whole-blood clotting time (20WBCT), PT with international normalized ratio (INR) and APTT were determined. A fibrinogen level below 1.0g/litre was used as the gold standard. There were 97 patients. The average age was 46.1 years and 49.5% were men. VCT >30min, INR >1.2 and fibrinogen level <1.0g/litre were found in 9.3, 10.3 and 7.2%, respectively. The sensitivities of VCT >30min, 20WBCT (N=55), INR and APTT were 57.0%, 85.7%, 85.7% and 57.1%, respectively. The respective specificities were 94.4%, 95.8%, 95.6% and 72.4%. Three hypofibrinogenaemic patients who did not receive antivenom because of VCT <30min had persistently normal VCT and went home without clinical bleeding. In conclusion, PT with INR can be an alternative test for evaluation of coagulopathy in green pit viper bitten patients with potentially improved inter-laboratory standardisation.

Delayed double reading of whole blood clotting test (WBCT) results at 20 and 30 minutes enhances diagnosis and treatment of viper envenomation

“…One study on diagnosis of green pit viper ( Cryptelytops sp.) envenomations found a sensitivity of 85.7% and specificity of 95.8% for the WBCT20 when the fibrinogen level was less than 1.0 g/L [ 4 ]. Research conducted in Papua New Guinea on reliability of the WBCT20 under different conditions reported a positive predictive value of 89.7%, negative predictive value of 93.5%, sensitivity of 92.9%, and specificity of 90.6% when fibrinogen concentrations were lower than 0.5 g/L in patients suffering from taipan ( Oxyuranus scutellatus ) snakebite [ 17 ].…”

“…Venom-induced consumption coagulopathies (VICC) are present in more than two-thirds of African snake envenomations [ 3 ]. When used correctly, the whole blood clotting test (WBCT) is a simple, effective, affordable bedside examination that provides valuable information during initial assessment and ongoing management of snakebite patients throughout the course of treatment [ 4 – 7 ]. Use of the WBCT for detecting VICC in snakebite patients was standardized by Sano-Martins et al [ 8 ].…”

“…It requires collection of a small amount of venous blood (about 2 mL) in a dry and clean glass tube to evaluate the coagulation time by simple direct observation of clot formation and stability 20 min after collection. Several field studies have confirmed that the WBCT was sufficiently sensitive and specific to be of clinical value [ 4 , 5 , 9 – 11 ]. It is a comprehensive blood test to diagnose and monitor coagulopathy in patients bitten by most viper species, which is valid throughout the world.…”

Comparison of green pit viper and Agkistrodon halys antivenom in inhibition of coagulopathy due to Trimeresurus albolabris venom: an in-vitro study using human plasma

“…1 Its bite can cause potentially life-threatening bleeding. 2 In Hong Kong, death following a T albolabris is, fortunately, rare. The last reported case occurred in 1986 when an aged woman died of cerebral haemorrhage.…”

Avaliação dos distúrbios hemostáticos induzidos por venenos de serpentes Bothrops jararaca (Squamata: Viperidae) adultas e filhotes e eficácia do tratamento com soro antibotrópico

“…6).O veneno foi diluído imediatamente antes do uso e os ratos foram inoculados s.c.no dorso com 1,6 mg/kg (3,2 mg/mL) de cada um dos pools de venenos ou com solução salina. Após 1 hora da inoculação do veneno, os animais receberam100 µL de solução salina estéril (154 mM) i.v. Para a avaliação da neutralização dos venenos sobre a hemostasia de ratos, foram delineados outros dois grupos (vBjA + SAB; vBjF + SAB), nas mesmas condições descritas no item anterior, exceto que aos animais foi administrado 100 µL de soro antibotrópico (SAB) i.v., uma hora após a inoculação dos venenos (Fig.…”