An evidence based analysis of bee stings, and why the best tool to remove a stinger is your fingers.

[wilderness911]

I originally put this post together because one thing I have encountered in my work is a plethora of bad information regarding the best practices for management of various bites and stings, both in the field and in the clinic. So on to the subject of this post; an evidence-based debunking of the common misconceptions surrounding initial actions following a bee sting and a simple recommendation for the best strategies in removal of the stinger. As a wilderness medicine guy, I am often asked what to do in the event of a bee sting. To be clear, I am not addressing the clinical management of patients suffering from massive envenomations by dozens to hundreds of bees, which can result in coagulopathies and all sorts of other systemic effects. This post details the best practices for responding to a single bee sting (or a couple of stings) in the first minute or two following the event.
I originally wrote this up to answer a question from a woman who asked whether the sawyer venom extractor (an ineffective and potentially dangerous mechanical suction device marketed as the "only medically proven field treatment for snakebites and other envenomations") could provide any benefit for treating bee stings, which is of course one of the other things the sawyer company claims it does well. Without further adieu, the meat and potatoes of this argument.

Since I am not a bee guy by training, I did a pretty extensive search of the literature to make sure I wouldn't be misinforming anyone. The information I dug up in a few old journals was very interesting. Surprisingly few studies have been done on this subject, but I found a fantastically designed, peer-reviewed study looking at the kinetics of bee stings and venom injection "Rate and quantity of delivery of venom from honeybee stings." I will post the abstract and a link to the full text PDF at the bottom of this post so you all can come to your own conclusions, but here are the important pieces with respect to your question. This applies to honeybee species that leave the venom sac and stinger in the victim; wasps retain their stingers and can sting repeatedly. The study doesn't tell us much of anything about wasp stings, but the venom should be injected and distributed into the tissue much faster than a honeybee sting and there is no stinger left behind, so the sawyer would definitely not make sense to use on a wasp sting either.

Back to the honeybees...
What they consistently found in honeybees that leave the stinger and venom sac in the victim can be distilled down to a few key points.
1. When a bee sting occurs, the smooth muscle surrounding the venom sac immediately begins to contract. This causes the stinger to embed deeper into the victim's skin (about 2/3 of the way into the skin in the first 30 seconds). At the same time the venom sac is being squeezed like a turkey baster and injecting its contents deeper into the tissue due to the burrowing of the stinger.

2. All of this happens really fast. In the first 20 seconds after the stinger hits skin, 90% of the venom is injected into the victim and the stinger has burrowed deeper to facilitate injection into deeper tissues simultaneously. Even the slowest stingers in the group were done burrowing and injecting the vast majority of their venom by 30 seconds after the sting occurred.

3. Part of the study involved removal of the stingers at various times (5 seconds, 10 seconds, 15 s, etc) after the sting occurred and then quantifying the differences in amount of venom injected over time. Not surprisingly, they found that the earlier a stinger was removed, the less venom was injected into the recipient...however, after 20 or 30 seconds the process of envenomation is basically over with so to make any real difference you need to get the stinger out in the first couple of seconds.

CONTINUES BELOW IN PART II

 

[wilderness911]

PART II

Okay, so the take-away's here are that you need to get the stinger out fast. How many people would be able to stop whatever they were doing, throw down their pack, locate, open, and assemble the sawyer extractor with the appropriately sized suction head for the affected body part in 5 or 10 seconds? I know I certainly couldn't. Even if I could do it in under thirty seconds, it would still be the worst option available to me - sorry again, sawyer.
The fastest way I can think of for removing a stinger would be to use my fingers, pinch it, and pluck it out as fast as possible. The sawyer might seem to make more sense here, because even though it would take longer to put on you wouldn't be squeezing the rest of the venom in by pinching the sac. The big question becomes, what is the fastest way to get the stinger out with the least amount of venom injected? So I did a little more research, and found this in the excellent wilderness medicine tome (Wilderness Medicine, 6th Edition) by Paul Auerbach:
"Although recommendations were that stingers should be scraped or brushed off with a sharp edge and not removed with forceps, which might squeeze the attached venom sac and worsen the injury, this has been refuted (304,364). Advice to victims on the immediate treatment of bee stings now emphasizes rapid removal of the stinger by any method (364). Wheal size and degree of envenomation increased as the time from stinging to stinger removal increased, even for a few seconds. The response was the same whether stings were scraped or pinched off after 2 seconds."
So there you have it, folks - the sawyer will likely (almost certainly) prove less effective than your fingers, as will fishing around for a credit card or similar flat object to scrape the stinger off. Don't waste time trying to get the stinger out without crushing/squeezing the venom sack, just get that thing out the patient as quickly as possible. (Kind of reminds me of the song from monsters inc, if anyone else gets that reference). To recap: the biggest determinant in how much venom will be injected is the length of time that it remains in the victim prior to removal; crushing or pinching the venom sac during removal does not significantly alter the amount of venom injected. Like I said, pretty useful tidbit of obscure information to come across.
But what about home remedies like baking soda? I'll let the good Dr. Auerbach answer that one as well.
"Home remedies, such as baking soda paste or meat tenderizer applied locally to stings, are of dubious value, although the latter is often regarded as effective. Topical anesthetics in commercial "sting sticks" are also of little value. Topical aspirin paste is not effective in reducing the duration of swelling or pain in bee and wasp stings and may actually increase the duration of redness (18). Local application of antihistamine lotions or creams, such as tripelennamine, may be helpful. An oral antihistamine, such as diphenhydramine, 25 to 50 mg for adults and 1 mg/kg for children, every 6 hours is often effective."
If you want me to provide citation links for the papers Auerbach cites as (18, 304, 364) I will dust off my copy of his book and pull them for you. The study I draw my earlier conclusions from is titled "Rate and quantity of delivery of venom from honeybee stings" and a direct link to the abstract, as well as a full text PDF, can be found here: http://www.jacionline.org/article/0091-6749(94)90373-5/abstract
Ironically, it seems that the study was sponsored in part by Sawyer. Oops. I wrote out the abstract below, for anyone who wants to get the abbreviated version. I also included some of the findings from the full text version to provide additional information.
Abstract To determine the rate and completeness of delivery of venom from honeybee stings, European bees were collected at the entrance of a hive and studied with the use of two laboratory models. In one model bees were induced to sting the shaved skin of anesthetized rabbits. The stings were removed from the skin at various time intervals after autotomization, and residual venom was assayed with a hemolytic method. In the other model the bees were induced to sting preweighed filter paper disks, which were weighed again after removal of the sting at various intervals. Results of both experiments were in agreement, showing that at least 90% of the venom sac contents were delivered within 20 seconds and that venom delivery was complete within 1 minute. The data suggest that a bee sting must be removed within a few seconds after autotomization to prevent anaphylaxis in an allergic person. The extensive variation found in the amount of venom delivered at each time point may explain inconsistencies in relationships among reactions to field stings, sting challenge testing, venom skin tests and RAST.
Pertinent data drawn from the full text article: "In both rabbit skin and various artificial media, the autotomized sting was noted to embed itself progressively deeper over a period of approximately 30 seconds. By the end of this period, it was noted that at least two thirds of the length of the sting was embedded. In the rabbit skin model venom in 63 sacs was depleted by 90% over a period of 20 seconds. There was a statistically significant negative relationship between residual venom and time (p <0.05). No residual melittin could be detected at 40 seconds, indicating that the venom sac was empty (Fig.

2). In the paper stinging model the rate of increase in dry weight of venom delivered into the paper medium was similar to the rate of depletion of venom from the stings implanted in rabbit skin (Fig. 3). The relationship between venom delivery to the disk and time, analyzed by linear regression, was significant (p < 0.05). Although venom delivery varied considerably, the average weight gain of the disks at 20 seconds after autotomization was 140 pg, similar to the average venom sac contents of domestic honeybees. There was no tendency for further weight gain after this time, indicating that venom delivery was rapid and complete in less than 30 seconds."

Thank you all for taking the time to read this. I hope it proves informative. Since I am new to EMTlife I don't know if this is the correct place to post this, mods are welcome to move if it should be elsewhere.

Regards,

Jordan