Monthly Archives: November 2013

What to do for bug bites?

Face it. Except for the very lucky, few of us are able to escape biting insects. After getting bit, the range of reactions is immense; from no reaction to anaphylaxis. Thankfully, most simply have mild pruritis and urticaria. But how are we supposed to treat these?

This review article from the UK lays out the evidence behind all the common treatments for bug bites. Here is a summary:

  • Oral antihistamines are recommended, but data is lacking. A review consisting mostly of multiple studies from one group in Finland showed them to be effective.
  • Use non-sedating antihistamines during the daytime, and sedating ones as night.
  • Topical antihistamines don’t work well, can cause sensitization, and aren’t recommended for longer than 3 days.
  • Topical corticosteroids are poorly studied but may be effective.
  • Topical corticosteroids shouldn’t be used on broken skin or on the face.
  • Oral corticosteroids are used for severe urticaria, but no studies have been found to support this.
  • Use the lowest dose for the shortest time possible for oral corticosteroids.
  • OTC analgesics can be used for pain, but topical anesthetics can cause sensitization.
  • Calamine isn’t the slightest bit effective, so don’t use it.
  • Counter-irritants (such as dilute ammonium) may be effective based on one double blind RCT.
  • Topical antiseptics after bites are probably overkill.
  • Generalized symptoms or redness/swelling over 10cm should be referred to an allergist.
  • Secondary infections should be treated with antibiotics.
  • Treat anaphylaxis appropriately.

Nothing earth shattering here, but maybe this will prevent unnecessary topical treatments which are often ineffective and possibly harmful. I do wish more people would recommend loratidine or cetirizine for this instead of diphenhydramine. The sedating effects as well as the duration of effect would tend to recommend the newer, now OTC agents, but I still see most everyone giving patients prescriptions for Benadryl®.

Management of simple insect bites: Where’s the evidence?
http://dtb.bmj.com/content/50/4/45.full

Do air pockets help avalanche survival?

The theoretical is obvious. If you have an air pocket you can breathe into after an avalanche, you should survive longer than if you don’t. This study intended to ascertain if this was true, as their hypothesis was that air pocket subjects would develop hypoxia, hypercarbia, and hypothermia, while those breathing outside air would simply develop hypothermia. Now, they did their study on piglets, as it is hard to get IRB approval for studies where the endpoint is asystole.

While the premise is good, unfortunately conditions outside the control of the researchers severely limited their study.

Eight piglets per group plus five pilot animals were planned; because of massive sensational media coverage, protests by animal activists and threats of violence and death towards the study team the study had to be terminated prematurely and only eight animal experiments were conducted

So they went ahead and used the 8, with 3 breathing from a 1L air pocket, 2 breathing from a 2L air pocket, and 3 breathing ambient air. All of them were anesthetized, intubated, and packed in snow during the measurement phase of the study.

A bigger problem with the study is what they did with their data. After collecting core temperature, cardiac output, paO2, paCO2, pH, and potassium (?), they then combined the 1L and 2L air pocket groups into one due to small sample size. They do include their data tables if you want to look at it yourself. It is full of interesting findings, such as measurable cardiac output on 6 of the 8 pigs during “asystole”. You’ll probably need to look at the raw data anyway, as the results figure online and in the pdf is impossible to read. You cannot tell which line is supposed to be which by looking at them.

The results were along the lines of what they were expecting. Yes, piglets with air pockets do worse than piglets with ambient air. And perhaps surprisingly, piglets with an air pocket develop hypoxia and loss of cardiac output relatively quickly (~10 min). The authors thankfully describe all the limitations of the study, and the difficulty in generalizing this to humans (surface ratio differences, general anesthetics present, higher metabolic rates, etc). While good proof of concept and need for further study, I’m not exactly sure what got this published in Resuscitation.

Factors affecting survival from avalanche burial–a randomised prospective porcine pilot study
http://www.ncbi.nlm.nih.gov/pubmed/22771873

Mediterranean recluse bite necroses cartilage

Short case report from the Netherlands today. It involves a 22 year old woman who went to Italy on vacation, and one night woke up with left ear pain. This progressed to a small vesicle, then to swelling of the entire left side of her face. She was given antihistamines, but 2 days later had continued edema, worsening ear pain and a rash of her entire body. She also developed the characteristic red, white, and blue discoloration of her ear at that time. She was given higher doses of antihistamines, but no other treatment per the report. She developed necrosis by day 12.

Once she returned home, she went to a plastic surgery clinic where she received a partial ear reconstruction using costal cartilage and a full thickness graft. The authors wrote the case up as the first documented instance of cartilage necrosis due to (presumed) recluse bite.

The report then does a good job of describing proper recognition and treatment of recluse bites, as has been discussed here before. Pretty decent write-up and excellent figures by the Journal of Plastic, Reconstructive & Aesthetic Surgery.

Partial ear necrosis due to recluse spider bite
http://www.ncbi.nlm.nih.gov/pubmed/24183057

Big powder, bigger injuries

Go to almost any mountain resort and you’ll see that skiers and snowboarders are not alike. Even though snowboarding has been popular for nearly 30 years, there is still very little overlap between the two cultures.

This extends to injuries the participants receive as well. If you’ve ever done either, it’s easy to see that the mechanics of each are completely different. Sure, the end result is the same, in that you go from a higher elevation to a lower elevation while gliding over snow, but facing sideways with both feet strapped securely to a board is distinctly unlike facing forwards with each foot strapped less securely to skis that can go in different directions.

Fresh off the internet press from WEMJ comes this brief report on the injury patterns skiers and snowboarders receive at Big Sky. They examined the patient population of the medical clinic at the base of the mountain between 1995-2000, and again from 2009-2010 to see if there were any differences. They did this by way of prospective surveys given to patients when the arrived at the clinic. They received 1662 total, of which they used 1593 after excluding those with incomplete data. Right at 25% were snowboarders. The data they obtained is intriguing.

  • Skiers were 48% male, while snowboarders were 73% male
  • Skiers were 35.4 ±15.2 years old, while the average snowboarder was 23.6 ±9.5 (you kids get off my powder!)
  • The most common injury location for skiers was the knee (43%), followed by leg, then shoulder
  • Snowboarders injure their wrists (19%)  most, then their shoulder

They went further into the injuries to pull out the ICD-9 codes for each participant. What is shocking is that the most common specific diagnosis for skiers was torn cruciate ligament at 10.6%, and knee ligament sprain/strain was 25%. Conversely, for snowboarders, 10.1% of ICD-9 codes were for fractures of the radius or ulna.

If you separate injuries by self-reported skill levels, you find that snowboarders are more likely to be injured at the beginner skill level (31%), whereas skiers are more likely to be injured in the “advanced intermediate”  skill level at 37%. “Extreme” skiers and snowboarders are over-represented on ESPN, but both only represent single digit percentages of the injured in this series. The authors attribute this to the difficulty in staying upright while learning to snowboard causing upper extremity injuries, while skiers get more adventurous as they advance in skill level, leading to injuries at speed when they overestimate their abilities. As snowboarders advance in skill level, they are less likely to injure their wrists and more likely to injure their lower bodies. Skiers keep the same injury patterns as they advance in skill.

Sadly, they have no data for the severe injuries that were transported to higher levels of care than their mountainside clinic. Also not commented on in the paper, but apparent on looking at the data is that head injuries in snowboarders went down significantly from 7.8% to 0.0%. Since there is no discussion, it is left up to the reader to wonder if perhaps the use of helmets is the cause of this decline, or if there is some other factor in play.

Bonus ski joke: There are 206 bones in the human body, but don’t worry. There are two bones in the middle ear that haven’t been broken while skiing.

Injury patterns in recreational alpine skiing and snowboarding at a mountainside clinic
http://www.ncbi.nlm.nih.gov/pubmed/24138836