Category Archives: skin

Does paper tape prevent blisters?

Feet get blisters, and the longer distances you move, the more likely they are to get them. While nuisances by themselves, blisters can lead to more concerning conditions such as cellulitis. Then they become a real problem, especially if you’re in an austere environment. Thus preventing these blisters can make a significant difference in your race, hike, or military operation.

Since commercial products are relatively expensive and poorly studied, these authors wanted to see if a cheaper alternative would be effective. Their choice for this cheaper alternative was paper tape. The fiscal impact is comical considering they tested this on people running 7 day, 250 km ultramarathons in such exotic locations as China, Egypt, Nepal, and Chile. Registration alone is $3600, and then there are the rest of the gear, travel, and food costs. That being said, if the tape worked in such extreme conditions, it would likely have worked for the more mundane activities the majority participate in.

Sadly, it didn’t work. Using patients as their own controls, they taped one foot and left the other native.  Even though they covered a significant portion of the foot with tape, there were more blisters on the taped foot than on the control foot. If you just examined the taped foot, there were more blisters under the tape than the surrounding exposed skin. After all of this, a large majority (84%) of their runners said they would use tape again in the future. Laughably, this same group didn’t usually use blister prevention prior to the study.

Even more interesting is that when they broke down the subgroups, they discovered that if you taped the foot ipsilateral to the dominant hand, tape suddenly became protective (statistically). Also, having a smaller pack weight to body weight ratio was similarly protective. unfortunately, use of toe socks increases blister formation. Of course, of their final study group of 90 patients, 100% had blisters. It may be that the 31 patients they lost to followup simply did not have blisters, which would completely change the results of this study. Also, while runners were asked not to tape the control foot, the study authors were not able to control for other lubricants and powders that could have affected outcomes.

In the end, not much you can take from this. The theoretical friction barrier that tape would provide does not seem to prevent blisters. However, the runners sure did like it due to ease of application and relatively low-cost. There’s nothing in this study that makes me tell runners change their routines. Throw this on in the “needs further study” bin.

A Prospective Randomized Blister Prevention Trial Assessing Paper Tape in Endurance Distances (Pre-TAPED)

Wilderness wound pitfalls

Wounds happen out there. Even with maximum preventive measures, they’re inevitable, so we should definitely know how to manage them appropriately.

This handy little report talks about a Grand Canyon boatman who injured himself at the beginning of a trip down the Colorado. It goes downhill from there, but it is a useful case to point out the things they didn’t do right, and did do wrong. The narrative is also mostly written by the river guide himself, and the style is quite humorous.

Serendipitously, or so he thought, there were two doctors on the trip, one of which whipped out his suture kit and fixed the rather large bleeding wound on his shin. I don’t have a problem with closing the wound, as it was large and likely to cause problems if left open. 

What did they do wrong? First, they didn’t irrigate the wound. It goes without saying that the raft, the pack, and the Colorado River were not sterile, and thus the wound wasn’t clean either. They also shaved his leg with a razor, because apparently JCAHO was going to make a trip to the park that day. Must have left the batteries out of the electric clippers. 

They correctly covered the wound with Tegaderm and Coban for protection on the first day, with subsequent dressing changes. 4 days later, the wound developed cellulitis, so he was started on Bactrim (TMP/SMX). It wouldn’t be my first choice for cellulitis, but it isn’t the worst drug to use as it covers Aeromonas. Levaquin (levofloxacin) would be great, or just adding Keflex (cephalexin) to the bactrim for better gram positive coverage coverage.

Two days later the cellulitis is progressing even with antibiotics, and now there is a pitting edema below the wound. Too late to evacuate that day, they elect to open the wound that evening. Anesthesia provided by gin and tonic. They irrigate using Betadine  and pack it with Betadine-soaked gauze. The tissue-toxic solution could certainly reduce wound healing, and I can’t recommend using it.  Using a squirt gun for higher pressure irrigation is a neat trick though. 

Azithromycin is added to the antibiotic regimen, likely because it’s all they had. The next morning he is flown out. The good news is that after a washout in the OR and two days of wound vac therapy, they get the skin closed and it heals nicely.

Recap of important points for austere wound therapy

  • Irrigate with clean water, but nothing toxic. You want to clean and promote healing, not kill tissue.
  • Consider prophylactic antibiotics for dirty wounds that can’t be cleaned, especially penetrating injuries in water.
  • Use occlusive dressings. They promote healing and decrease infection rates.
  • Wounds less than 1 inch do not need closure, as cosmesis and infection rates are similar open or closed. Close if in an area prone to reopening certainly. Sutures, adhesive strips, and skin glue are all similar in efficacy if used appropriately.

They Had Me in Stitches: A Grand Canyon River Guide’s Case Report and a Review of Wilderness Wound Management Literature.

Wound closure on a budget

Cyanoacrylates (CAs), around since the 40s, have been used for wounds since Vietnam. Therefore, it is odd to consider that the FDA did not approve their use for skin until 1998. Much of this came from the reports of skin injury from the short chain CAs secondary to heat generation from the polymeration reaction, as well as lack of sterile preparation.

The problem with the FDA approved items is that they are often in single use applications, sometimes have refrigeration requirements, have significant costs, and require a physician order or prescription to carry. Would using the commercially available CAs aid in austere environments? Other authors have certainly looked at their use, and this paper basically reviews a large chunk of those papers to attempt to answer that question.

Looking in MEDLINE, The Cochrane Database, Web of Science, Cinahl, CAB Abstracts,Google Scholar, and BIOSIS, the authors used multiple search terms and reviewed all pertinent abstracts and papers. They looked at use for wound closure, as well as for burns, abrasions and blisters. A total of 82 papers were eventually referenced in the final manuscript. And in the end?

Studies showed that the tensile strength of wounds closed cyanoacrylate adhesives are dependent on the length of the alkyl group. Octyl CAs approach monocryl level of strength, but methyl and ethyl CAs are significantly weaker. Since the shorter chain CAs are the non-medical products, this is important to know if you are using it for wound closure. Reports of histotoxicity had both pro and con reports for ethyl CAs, but it most reports of injuries are minor. Applying adhesive to blisters looks to be a wash, but it may have a use yet for prevention of blisters as an artificial callous.

For burns and abrasions, the octyl CAs do not have any benefit over standard bandages or Tegaderm. All CAs appear to be bacteriotoxic, but there are no patient oriented studies. All of them are performed in petri dishes, so applicability is unknown. Certainly the products can create a barrier over any wound, but outcomes have not been measured. Non-medical CAs are certainly cheaper, with one study showing a 98.5% reduction in cost.

So you have a product that doesn’t work as well, may cause inflammation, but costs significantly less. Would you use it for wound closure? The case can be made that carrying around industrial grade adhesive is useful in all aspects of wilderness medicine, even apart from medical use. Many other things may require repair, so you likely would not be carrying anything extra in your pack. And while it isn’t the best agent, it is certainly better than nothing, and there are plenty of reports of safe use for simple injuries. No, I can’t argue that you should use it to close up your chainsaw wound, but simple lacerations are amenable to repair by non-medical adhesives.

Cyanoacrylate glues for wilderness and remote travel medical care.

Denim as snake protectant?

Source: Wikimedia Commons

Denim pants, worn since 1873 by workers, and since the 50s by everyone else, have had a reduction in their use as outdoor clothing due to the emergence of performance hiking apparal. Denim jackets are markedly less popular recently. Now, what if it turns out denim protects you from envenomation? Would denim then come back as an overlander outfit?

Crotalus oreganus helleri

Source: Matthew Robinson

This article tried to ascertain whether denim has any ability to decrease the severity of snake bites, mainly be decreasing or eliminating envenomation. To study this, they used 17 different southern Pacific rattlesnakes divided into small (35-54cm) and large (66-102cm) groupings, and had them bite latex gloves that were either uncovered or covered with standard denim cloth. The paper has a very detailed methods section, including even the material in the snake cages when they were being stored!

The results were pretty surprising. There was a 60% reduction in venom for the small snakes, and 66% reduction in the large snakes. If it were simply a material thickness, a larger snake should be better at penetrating the material, but this was not borne out by the data. Since defensive strikes by nature are very fast (<0.33s), the reduction is likely from simple physics.

Thus, you can take home that denim can reduce the amount of venom you receive if a snake strikes you defensively. Sadly, the reduction is probably academic for big snakes, as the amount you receive can still be enough to kill you. Especially in the case of the snake species studied, a particularly nasty rattlesnake that has both hemorrhagic and neurotoxic venom components.

The bigger take home point from this article is that it is yet another nail in the coffin for the “small snakes are more dangerous” myth about defensive strikes. Bigger snakes will deliver more venom, regardless of what you are wearing. In this paper, they delivered 41 times the venom load of the smaller snakes, and 26 times the load when denim interfered. Please make sure and correct the next person you hear trying to propagate this myth.

And wear some denim if you’re going rattlesnake wrangling.

Denim clothing reduces venom expenditure by rattlesnakes striking defensively at model human limbs.