Australian snakebite myotoxicity (ASP-23)

Abstract

Background

Myotoxicity is a recognised but poorly characterised effect of snake envenoming worldwide. We aimed to describe the clinical effects, complications and effectiveness of antivenom in myotoxicity from Australian snake envenoming.

Methods

Patients were recruited to the Australian Snakebite Project (ASP), a prospective, observational study of patients with suspected or proven snakebite countrywide. After informed consent data is collected and stored in a dedicated database and blood samples are taken and stored. We included patients with envenoming and biochemical evidence of myotoxicity (peak creatine kinase [CK] > 1000 U/L). Snake species was determined by expert identification or venom specific enzyme immunoassay. Analysis included patient demographics, clinical findings, pathology results, treatment and outcomes (length of hospital stay, complications).

Results

1638 patients were recruited January 2003–December 2016, 935 (57%) were envenomed, 148 developed myotoxicity (16%). Snake species most commonly associated with myotoxicity were Notechis spp. (30%), Pseudechis porphyriacus (20%) and Pseudechis australis (13%). Bite site effects occurred in 19 patients. Non-specific systemic symptoms occurred in 135 patients (91%), specific signs and symptoms in 83. In 120 patients with early serial CK results, the median peak CK was 3323 U/L (IQR;1050–785100U/L), the median time to first CK >500 U/L was 11.1 h and median time to peak CK of 34.3 h. White cell count was elevated in 136 patients (93%; median time to elevation, 4.9 h). 37 patients had elevated creatinine, six were dialysed. Two patients died from complications of severe myotoxicity. Antivenom given before the first abnormal CK (>500 U/L) was associated with less severe myotoxicity (2976 versus 7590 U/L). Non-envenomed patients with elevated CK had rapid rise to abnormal CK (median 3.5 h) and less had elevated WCC (32%).

Conclusion

Myotoxicity from Australian snakes is relatively common and has systemic effects, with significant associated morbidity and mortality. CK is not a good early biomarker of mytoxicity. Early antivenom may play a role in reducing severity.

Keywords:

• Myotoxicity
• elapid
• snakebite
• envenoming
• snake
• antivenom
• toxin
• rhabdomyolysis

Acknowledgements

We acknowledge the support of the large number of clinicians and laboratory staff that have made the Australian Snakebite Project possible. In particular, we thank all the research administrative staff for the Clinical Toxicology Research Group for collecting and recording data, organizing transport of blood samples, including Jen Robinson, Kylie Tape, Marea Herden and Renai Kearney. We thank Margaret O’Leary and Kellie Fakes for doing the venom assays.

Disclosure statement

C.I.J. is an employee of Boehringer Ingelheim Australia. This research is independent of his employment by Boehringer Ingelheim. GKI has no conflicts of interest.

Additional information

Funding

G.K.I. is funded by a National Health and Medical Research Council Senior Research Fellowship, ID 1154503. The Australian Snakebite Project is funded by a National Health and Medical Research Council Centre for Research Excellence ID 1110343.