title: 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.
authors.affiliation: Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Rama IV Road, Patumwan, Bangkok 10330, Thailand.
authors.forename: Jamrus
authors.initials: J
authors.lastname: Pongpit
authors.forename: Paweenrat
authors.initials: P
authors.lastname: Limpawittayakul
authors.forename: Jumlong
authors.initials: J
authors.lastname: Juntiang
authors.forename: Benjaporn
authors.initials: B
authors.lastname: Akkawat
authors.forename: Ponlapat
authors.initials: P
authors.lastname: Rojnuckarin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000997:Antivenins / Q000008:administration & dosage*; D001778:Blood Coagulation Disorders / Q000097:blood / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy; D023381:Endpoint Determination; D005260:Female; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D011446:Prospective Studies; D011517:Prothrombin Time; D012016:Reference Values; D012909:Snake Bites / Q000097:blood* / Q000175:diagnosis*; D013785:Thailand; D013997:Time Factors; D017819:Viperidae; D055815:Young Adult
chemical_list: D000997:Antivenins; D005340:Fibrinogen