Snakebite suction devices don't remove venom: they just suck.

It was only a few decades ago that incision and suction were recommended snakebite first aid. However, concerns arose about injuries and infections caused when laypersons made incisions across fang marks and applied mouth suction. Meanwhile, several snakebite suction devices (eg, Cutter’s Snakebite Kit, Venom Ex) were evaluated, and it was determined that they were neither safe nor effective.1 So, recommendations changed, and mechanical suction without incision was advocated instead.2-5 It seemed intuitive that suction alone would probably remove venom and should not cause harm. However, when the techniques were studied rigorously, quite the opposite was discovered. One of the most popular suction devices, the Sawyer Extractor pump (Sawyer Products, Safety Harbor, FL), operates by applying approximately 1 atm of negative pressure directly over a fang puncture wound (or wounds) without making incisions. The manufacturer instructs that the device be applied within 3 minutes of the snakebite and left in place for 30 to 60 minutes. For many years, most agreed (including the Wilderness Medical Society and the American Medical Association) that the Extractor might be beneficial and would probably cause no harm.2-5 Others suggested that it could exacerbate tissue damage, adding insult to injury after viper envenomation.6-9 In this issue of Annals, the Extractor’s inefficacy has been further confirmed with a well-designed study and fully detailed manuscript.10 In their prospective experimental trial, a human model was used to test the amount of radioactively labeled mock venom that could be removed by an Extractor after subcutaneous injection with a 16-gauge hypodermic needle. The investigators measured radioactive count as an approximation of the amount of venom removed. The bottom line: the Extractor removed 0.04% to 2.0% of the envenomation load. The authors conclude that this is a clinically insignificant amount and that the Extractor is essentially useless. The main limitation of their study is that they could not use real venom. The study by Alberts et al10 corroborates other studies that have tested the efficacy and safety of the Extractor. Using a porcine model and real rattlesnake venom in a randomized, controlled trial, Bush et al11 measured swelling and local effects as outcome variables after application of an Extractor to artificially envenomated extremities. The conclusion of the study was that the Extractor did not reduce swelling, but resulted in further injury in some subjects. Specifically, circular lesions identical in size and shape to the Extractor suction cups developed where the devices had been applied. These lesions subsequently necrosed, sloughed, and resulted in tissue loss that prolonged healing by weeks. Similar injuries after Extractor use have been noted in human patients.1,12 In another study, Extractors were applied to 2 human patients immediately after rattlesnake envenomations, and the device was left in place until its cup filled with serosanguinous fluid 5 times, although the authors do not specify the volume(s) of fluid obtained. The concentration of venom was measured in the fluid removed using an enzyme-linked immunosorbent assay.13 There were no control subjects, and this study has only been published in abstract form. Ironically, this abstract is cited amongst the main supporting evidence for the Extractor.4,14 However, a closer review of the results reveals that the concentration of venom in the serosanguinous fluid removed was only about 1/10,000th the concentration of rattlesnake venom. Alberts et al10 similarly noted that although a relatively large volume of bloody fluid was pulled from the puncture site, it contained virtually no venom. Most interestingly, Alberts et al found that the amount of venom T O X I C O L O G Y / B R I E F C O M M E N T A R Y