Accuracy of the Lee–White Clotting Time Performed in the Hospital Routine to Detect Coagulopathy in Bothrops atrox Envenomation

Abstract

Snake envenomation is a major public health problem in Brazil. Systemic complications that may arise from snakebites are mainly related to coagulopathy. The Lee-White clotting time (LWCT) is a simple and inexpensive test and available even in remote health facilities. However, the diagnostic value of such test needs to be evaluated to accurately diagnose coagulopathy in the clinical practice. This study aimed to assess the reliability of the LWCT performed in hospital routine to diagnose venom-induced coagulopathy. We studied 186 patients admitted at the Tropical Medicine Foundation Dr. Heitor Vieira Dourado in Manaus, Amazonas, Brazil, with envenomation diagnosis. At admission, blood samples were collected for performing LWCT and the concentration of fibrinogen. Sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratios, diagnostic odds ratio, and accuracy were calculated with 95% confidence intervals. From the total, 85.5% had hypofibrinogenemia. The sensitivity of the LWCT to the diagnosis of hypofibrinogenemia was 78.0% and the specificity 40.7%. The accuracy of the test was 72.6%, and patients with a prolonged LWCT had 2.4 higher odds of developing hypofibrinogenemia. In addition, the LWCT was also compared with venom antigen levels and systemic hemorrhage. The LWCT showed moderate sensitivity to detect consumption coagulopathy and constitutes a valuable tool for the diagnosis of snake envenomation and indication of antivenom therapy.

Clinical Features and Management of Snakebite Envenoming in French Guiana

“…Those results suggest at least a partial efficacy of AV Antivipmyn Tri ® to reverse coagulation disorders after SB without a strong difference between the two dosage regimens used. A recent study on the use of the same antivenom in snake-bitten patients attended to in the Guianese western hospital did not reveal differences in the time needed to restore coagulation parameters between patients receiving three vials of antivenom and patients that did not receive antivenom [ 20 ]. The reasons for this discrepancy remain to be determined.…”

“…In the case of lethal activity, Antivipmyn Tri ® did not neutralize the effect at the highest antivenom level tested (1 mg venom/mL antivenom). A previous study indicated that the dose of three vials is insufficient, especially in grade 2 or 3 cases, since no improvement in the correction of coagulation parameters was observed [ 20 ].…”

The relationship between clinics and the venom of the causative Amazon pit viper (Bothrops atrox)

“…Compartment syndrome was diagnosed by an experienced physician by serial physical examinations and intramuscular pressure measurement. Coagulopathy was defined as an unclottable blood from the Lee-White clotting time method [6]. Patients were treated according the Brazilian Ministry of Health protocols.…”

“…Three applied tourniquets at the bitten limb. All patients presented edema (14), followed by pain (13) and local bleeding (6). One patient developed blistering, and 4 evolved to secondary infection after 48 hours of follow-up (3 with abscess and 1 with cellulitis) and 2 had necrosis.…”

“…However, the occurrence of each sign/symptom is variable among the patients. In a recent study, 54% of patients of Manaus, in the Brazilian Amazon, presented unclottable blood at admission [5], while systemic bleeding are reported in around 15% of the cases [6]. Several factors have been associated with the envenomations' characteristics and severity, such as the patient's condition, pre-hospital treatments and the time before antivenom therapy [7].…”