蛇に噛まれた時、ちょっと文献を調べて見た。最新のレビューはこれ。
Bryan G. Fry Snakebite: When the Human Touch Becomes a Bad Touch.Toxins (Basel). 2018 Apr 21;10(4). pii: E170. doi: 10.3390/toxins10040170. E170. doi: 10.3390/toxins10040170.
これらは効果がないか逆効果。
1．傷をナイフで切る --- 血を流せば、毒も血液とともに流れ出すという間違った希望に基づく。
2．圧迫帯を使う --- 酸素供給が滞るので組織が死んでしまう。
3．ポイズン・レムーバーなどによる抽出 --- 毒が傷口の傍に留まり、吸い出せるという間違った仮定に基づく。実際は毒は急速に拡散する。人で偽毒を使って行った実験ではレムーバーでは2%しか除去できなかった。豚に毒を注入し、リムーバーを使う条件と使わない条件を比較した研究では差がなかった。
---ここはイントロ、論文は長い。毒蛇に噛まれても80%は毒を出さないので、あまりじたばたしない。それと、唯一の確実な方法は解毒剤(血清)を使うこと。
その他、
冷却 ---組織にダメージを与え、血管を拡張して悪い結果になる。
アルコールの注入、植物からの抽出物、ビタミンCは悪化させるか、エビデンスがない。
// 議論中の問題//
圧迫帯と安静 ---理想的に圧迫帯が施されることは少ない。北アメリカでは組織に損傷を与えると否定的。現在のエビデンスでは圧迫帯と安静は推奨されない。
Alberts MB et al. Suction for venomous snakebite: a study of "mock venom" extraction in a human model. Ann Emerg Med. 2004 Feb;43(2):181-6.
放射線同位元素で印を付けた偽毒を被検者８名の左足に1cmの深さに注入し、３分後にソーヤーのポイズンリムーバーで吸い出す実験を行った。その結果は、2%の偽毒が抽出された。そこで、ポイズンリムーバーの有効性はないと考えられた。
Bush SP et al. Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model. Wilderness Environ Med. 2000 Fall;11(3):180-8.
豚10匹を麻酔し、25mgの毒を7mmの深さに注入、ポイズンリムーバーを3分後に適用した条件と放置した条件を、14日間、豚、脚を変更して研究した比較研究。最大の腫れが見られた6時間後では、ポイズンリムーバー適用条件と放置条件に差はなかった。96時間後に腫れが最小になったが、両条件の差はなかった。
Avau, B. et al. The treatment of snake bites in a first aid setting: A systematic review. PLOS, DOI:10.137, October 17, 2016.
毒蛇に噛まれた時のファーストエイドについてのシステマティック・レビュー。データベースから14研究を抽出、圧迫・安静法がファースト・エイドで唯一のエビデンスのある方法とされているが、収集されたデータの質が悪く、ランダム化された質の高い研究が必要である。
Toxins (Basel). 2018 Apr 21;10(4). pii: E170. doi: 10.3390/toxins10040170.
Fry BG1.
Abstract
Many issues and complications in treating snakebite are a result of poor human social, economic and clinical intervention and management. As such, there is scope for significant improvements for reducing incidence and increasing patient outcomes. Snakes do not target humans as prey, but as our dwellings and farms expand ever farther and climate change increases snake activity periods, accidental encounters with snakes seeking water and prey increase drastically. Despite its long history, the snakebite crisis is neglected, ignored, underestimated and fundamentally misunderstood. Tens of thousands of lives are lost to snakebites each year and hundreds of thousands of people will survive with some form of permanent damage and reduced work capacity. These numbers are well recognized as being gross underestimations due to poor to non-existent record keeping in some of the most affected areas. These underestimations complicate achieving the proper recognition of snakebite’s socioeconomic impact and thus securing foreign aid to help alleviate this global crisis. Antivenoms are expensive and hospitals are few and far between, leaving people to seek help from traditional healers or use other forms of ineffective treatment. In some cases, cheaper, inappropriately manufactured antivenom from other regions is used despite no evidence for their efficacy, with often robust data demonstrating they are woefully ineffective in neutralizing many venoms for which they are marketed for. Inappropriate first-aid and treatments include cutting the wound, tourniquets, electrical shock, immersion in ice water, and use of ineffective herbal remedies by traditional healers. Even in the developed world, there are fundamental controversies including fasciotomy, pressure bandages, antivenom dosage, premedication such as adrenalin, and lack of antivenom for exotic snakebites in the pet trade. This review explores the myriad of human-origin factors that influence the trajectory of global snakebite causes and treatment failures and illustrate that snakebite is as much a sociological and economic problem as it is a medical one. Reducing the incidence and frequency of such controllable factors are therefore realistic targets to help alleviate the global snakebite burden as incremental improvements across several areas will have a strong cumulative effect.
ポイズン・リムーバーは無効。
放射線同位元素で印を付けた偽毒を被検者８名のの左足に1cmの深さに注入し、３分後にソーヤーのポイズンリムーバーで吸い出す実験を行った。その結果は、2%の偽毒が抽出されたと推定される。そこで、ポイズンリムーバーの有効性はないと考えられる。
噛まれた部分が酷く腫れるので、装身具を外すこと。(血液が止まり壊死する)
https://www.ncbi.nlm.nih.gov/pubmed/27843867
止血帯などで毒の回りを止めると、かえって悪化する。
Fry BG1.
放射線同位元素で印を付けた偽毒を被検者８名のの左足に1cmの深さに注入し、３分後にソーヤーのポイズンリムーバーで吸い出す実験を行った。その結果は、2%の偽毒が抽出されたと推定される。そこで、ポイズンリムーバーの有効性はないと考えられる。
Ann Emerg Med. 2004 Feb;43(2):181-6.
Alberts MB1, Shalit M, LoGalbo F.
Abstract
We determine the percentage of mock venom recovered by a suction device (Sawyer Extractor pump) in a simulated snakebite in human volunteers.
A mock venom (1 mL normal saline solution, 5.0 mg albumin, 2.5 mg aggregated albumin) radioactively labeled with 1 mCi of technetium was injected with a curved 16-gauge hypodermic needle 1 cm into the right lateral lower leg of 8 supine male volunteers aged 28 to 51 years. The Sawyer Extractor pump was applied after a 3-minute delay, and the blood removed by suction was collected after an additional 15 minutes. A 1991 Siemens Diacam was used to take measurements of the radioactive counts extracted and those remaining in the leg and body.
The "envenomation load," as measured by mean radioactivity in the leg after injection, was 89,895 counts/min. The mean radioactivity found in the blood extracted in the 15 minutes of suction was 38.5 counts/min (95% confidence interval [CI] -33 to 110 counts/min), representing 0.04% of the envenomation load. The postextraction leg count was less than the envenomation load by 1,832 counts/min (95% CI -3,863 to 200 counts/min), representing a 2.0% decrease in the total body venom load.
The Sawyer Extractor pump removed bloody fluid from our simulated snakebite wounds but removed virtually no mock venom, which suggests that suction is unlikely to be an effective treatment for reducing the total body venom burden after a venomous snakebite.
Wilderness Environ Med. 2000 Fall;11(3):180-8.
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Bush SP1, Hegewald KG, Green SM, Cardwell MD, Hayes WK.
Abstract
To determine if a commercially available negative-pressure venom extraction device (Extractor) reduces local tissue injury after artificial rattlesnake envenomation in a porcine model.
We prospectively studied 10 pigs using a crossover design. After the pigs were anesthetized, 25 mg Crotalus atrox venom was injected obliquely with a 22-gauge needle 7 mm deep into subcutaneous tissues proximal to the ventral hind hoof. Pigs were randomized to receive either the Extractor (applied 3 minutes following envenomation and left in place for 30 minutes) or no Extractor. The protocol was repeated 14 days later by using the alternate treatment group and opposite hind leg for each animal. We measured leg circumference at standardized locations on the hoof, foreleg, and thigh at baseline and then 1, 2, 3, 4, 5, 6, 24, 48, 72, and 96 hours following venom injection. Maximal changes in circumference at 6 hours were compared using the paired t test. Minimum residual swelling at up to 96 hours was similarly compared.
Maximal 6-hour swelling was similar with and without the Extractor: the hoof difference with the Extractor was -0.1% (95% CI = -3.4% to 3.2%, P = .95), foreleg difference was 0.3% (95% CI = -4.1% to 4.7%, P = .88), and thigh difference was -2.8% (95% CI = -10.0% to 4.4%, P = .40). Minimum residual swelling at up to 96 hours was also similar with and without the Extractor: hoof difference with the Extractor was 1.2% (95% CI = -5.6% to 8.0%, P = .70), foreleg difference was 0.6% (95% CI = -3.7% to 4.9%, P = .76), and thigh difference was 0.3% (95% CI = -2.4% to 3.0%, P = .81). A circular lesion identical in size and shape to the Extractor suction cup, which later necrosed and resulted in tissue loss, developed where the device had been applied in 2 animals. No such lesions occurred in legs not treated with the Extractor.
No benefit was demonstrated from Extractor use for artificial rattlesnake envenomation in our animal study. The skin necrosis noted in 2 Extractor-treated extremities suggests that an injury pattern may be associated with the device.
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