A dose scaling antivenin protocol in treatment of Daboia palaestinae envenomation may reduce morbidity and costs

TL;DR

A new protocol for treating snakebites from Daboia palaestinae uses smaller antivenin doses, reducing side effects and costs without increasing risk.

Contribution

A dose-scaling antivenin protocol is proposed and validated for Daboia palaestinae envenomation.

Findings

A median antivenin dose of 15 ml was effective, with half of patients needing only 10 ml.

Two patients had antivenin-related allergic reactions, but no deaths occurred.

The protocol reduced antivenin use and associated costs without increasing mortality.

Abstract

Daboia palaestinae is a leading cause of snakebite envenomation in the eastern Mediterranean, with substantial mortality in the absence of antivenin. Current recommended antivenin dose is 50 ml; however, antivenin is costly, may be difficult to obtain and is associated with substantial side effects. Thus, this study was designed to define the minimal effective antivenin dose and identify patients who can be safely managed without antivenin.

This retrospective single-center study was conducted in adults with suspected or confirmed D. palaestinae envenomation. Patients were treated via our previously developed envenomation protocol: no antivenin use for local symptoms and dose scaling for mild or severe systemic symptoms – initially 10 ml antivenin, with repeat dosing for ongoing systemic symptoms. The main outcomes measured were morbidity and mortality associated with this protocol. Secondary outcomes included assessing the demographics and clinical effects of snake envenomation and comparing between those who received antivenin and those who did not.

In total, 101 patients were included. A median of 45 minutes [interquartile range: 30–61 minutes] elapsed between snakebite and hospital admission, with no differences between groups. Among 52 patients receiving antivenin, 119 [60–237] minutes elapsed between snakebite and initial antivenin administration, with a maximum of 1073 minutes to initial antivenin administration. Maximum until last antivenin was 3860 minutes.

Median antivenin dose was 15 [10–22.5] ml, with 26/52 (50.0%) requiring only 10 ml. Two (2) patients developed an early antivenin immune reaction, with one developing anaphylaxis requiring invasive ventilation. Both received a single 10 ml dose of antivenin prior to allergic reaction. Neither patient had a known history of exposure to serum or relevant allergic reaction. No patients died during hospitalization.

This cohort demonstrates that a dose-scaling antivenin protocol can be safely employed, reducing morbidity and costs. We recommend a randomized control trial comparing fixed dose regimen to an escalation protocol and development of similar protocols for envenomations due to other snake species.

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