Abstract
BackgroundSnakebite is a global health issue and treatment with antivenom continues to be problematic. Brown snakes (genus Pseudonaja) are the most medically important group of Australian snakes and there is controversy over the dose of brown snake antivenom. We aimed to investigate the clinical and laboratory features of definite brown snake (Pseudonaja spp.) envenoming, and determine the dose of antivenom required.Methods and FindingThis was a prospective observational study of definite brown snake envenoming from the Australian Snakebite Project (ASP) based on snake identification or specific enzyme immunoassay for Pseudonaja venom. From January 2004 to January 2012 there were 149 definite brown snake bites [median age 42y (2–81y); 100 males]. Systemic envenoming occurred in 136 (88%) cases. All envenomed patients developed venom induced consumption coagulopathy (VICC), with complete VICC in 109 (80%) and partial VICC in 27 (20%). Systemic symptoms occurred in 61 (45%) and mild neurotoxicity in 2 (1%). Myotoxicity did not occur. Severe envenoming occurred in 51 patients (38%) and was characterised by collapse or hypotension (37), thrombotic microangiopathy (15), major haemorrhage (5), cardiac arrest (7) and death (6). The median peak venom concentration in 118 envenomed patients was 1.6 ng/mL (Range: 0.15–210 ng/mL). The median initial antivenom dose was 2 vials (Range: 1–40) in 128 patients receiving antivenom. There was no difference in INR recovery or clinical outcome between patients receiving one or more than one vial of antivenom. Free venom was not detected in 112/115 patients post-antivenom with only low concentrations (0.4 to 0.9 ng/ml) in three patients.ConclusionsEnvenoming by brown snakes causes VICC and over a third of patients had serious complications including major haemorrhage, collapse and microangiopathy. The results of this study support accumulating evidence that giving more than one vial of antivenom is unnecessary in brown snake envenoming.
Highlights
[2] antivenom is the major treatment for snake bite there are ongoing issues with the effectiveness and dose of antivenom, and deaths continue to occur despite antivenom and good supportive care, even in developed countries. [3]
All cases recruited to Australian Snakebite Project (ASP) between January 2004 and January 2012 were reviewed if they were identified as possible brown snake bites or envenoming cases based on expert snake identification, positive snake venom detection kit for brown snake venom, or clinical suspicion
Cases of venom induced consumption coagulopathy (VICC) positive for tiger snake or taipan venom on snake venom detection kit (sVDK) on bite site or urine, but found to be negative in the serum for either venom were tested with formal venomspecific enzyme immunoassay (EIA) for brown snake, and included if positive
Summary
Snake envenoming is a major problem in many parts of the world. [1] It has been estimated that there are over 440,000 snake envenomings and 20,000 deaths every year. [2] antivenom is the major treatment for snake bite there are ongoing issues with the effectiveness and dose of antivenom, and deaths continue to occur despite antivenom and good supportive care, even in developed countries. [3].The widely distributed elapid genus of brown snakes (Pseudonaja spp.) (Figure 1) accounts for the majority of cases of severe envenoming and deaths from snakebite in Australia. [4] The correct dose of brown snake antivenom has been the subject of considerable debate and change over time. Brown Snake Antivenom has been available from CSL Ltd. since 1956 and one vial (1000 Units) is aimed at neutralising the average yield of venom from one milking of an eastern brown snake (Pseudonaja textilis); one unit (1 U) of antivenom is defined as the amount required to neutralise 0.01 mg of dried venom [7,8] This dose is expected to cover the most extreme theoretical possibility that the venom yield on milking is completely injected by the snake bite (i.e. the venom glands are almost completely emptied and no venom is left on the skin) and this amount is completely absorbed (i.e. none is inactivated locally in the tissues mast cell and macrophage responses). We aimed to investigate the clinical and laboratory features of definite brown snake (Pseudonaja spp.) envenoming, and determine the dose of antivenom required
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