Monthly Archives: April 2015

If you don’t use it, you lose it

It’s a common perception that “book knowledge” does not give on the ability to perform skills. People can answer the questions correctly on a test, but not do the right thing in a real life scenario. For the practical component to be there, you must have some degree of hands-on education and experience. Most (if not all) wilderness medicine courses have a mixture of both lecture and practical stations because of this need. But how long does that knowledge stay with the learner?

Honestly, nobody seems to know. Skills degrade when they aren’t used, but does it happen in one day, a week, a month, or a year? To see how well students retained the information they received from wilderness first aid courses, the authors of this study took participants and measured their baseline (post course) knowledge, and then randomized them to be followed up at 4, 8, or 12 months for retesting. To measure knowledge, they were given a 25 question multiple choice exam. It doesn’t mention if the followup test was identical to the original, but lets hope it isn’t. The participants were also asked to rate their own self efficacy based on an 11 point Likert scale that ranged from “cannot perform this at all” to “can perform this with high certainty”. The designers of that scale must have been fans of Spinal Tap.

At their followup testing, the study participants were again given the exam and asked to rate themselves. Then, first aid skill was measured by observing them do 8 specific skills as part of a clinical scenario. Unfortunately, this skill measurement was not performed at baseline, so absolute decline in practical application cannot be determined. However, based on their data (not shown in the article), they determined that skills declined as the time delta widened. It’s a bit confounding though, as the 8 month group did worse than the 12 month group in some skills. Their exam scores also decreased as time went on, but not to the same degree.

Thus, ability to do well on repeat written examination does not magically give one the ability to manage an actual clinical scenario (but those people probably do better than someone who did poorly on the written exam). And, as it turns out, how well you think you’re going to do doesn’t mean you’ll have the practical skills needed either. Like tying knots, the more regularly you practice them, the better you’ll get. And the knot you should use in a rescue situation is the one you can tie the best, not necessarily the ideal one taught in a class. In that regard, it’s important to note that they specifically excluded anybody who did have further training in wilderness medicine since the first course.

The problem is this: How often do you have to refresh those skills? This article doesn’t answer that question, but it certainly points out that those practical skills erode to a higher degree in between training than test scores do.  Some of this is common sense. It’s easy to do well on a multiple guess test if you’ve had some passing familiarity with the material, as the answers often refresh your memory. Doing the same in a clinical scenario is much more difficult if you haven’t practiced it since the last course. None of this is necessarily groundbreaking, as other studies have shown similar time dependent degradation. Thus, anything that you need to be facile with, needs to be done more regularly than every two years.

An examination of wilderness first aid knowledge, self-efficacy, and skill retention.
http://www.ncbi.nlm.nih.gov/pubmed/22857870

How you wash your utensils matters

When you’re out in the wild for extended periods of time, you’re always reminded of the need to eat. Some get around this by only carrying pre-prepared foods. Others decide to cook, which inevitably leads to dirty dishes. Even if you make the grave sin of using disposable dishes and silverware, you still have to clean the larger containers you prepare the food in. And when somewhere between 1/3 and 3/4 of hikers end up with diarrhea, cleaning of these dishes is clearly important. 

If you’re car camping and have running water, you can go ahead and move on to another blog post. Fresh running potable water makes this job easy. But for those times when it isn’t available, you need to clean your utensils somehow. Many of us have been taught the 3 bowl system seen above, where you wash in the first bowl, rinse in the second, and disinfect in the third. It has similarities to the 3 sink systems many restaurants use. But does this mean it’s best?

To find out, a group of authors decided to test 18(!) different 3 bowl systems to see which actually reduced bacterial loads the most. They used porridge contaminated with E. coli, a practice I can’t recommend when camping. (They describe the contamination in excruciating detail, using 232 words). The authors trimmed the systems to 10 after finding 8 of them “wholly inadequate.” Describing each of the systems is needlessly complex, so here’s Table 1 from the article. Table 1

This doesn’t entirely explain their methods though. When they wrote “established”, they meant washing until visibly clean in first bowl, then using 2 and 3 just for rinsing and sanitizing, as it were. “Alternative” meant removing all easy food residue in bowl 1, then getting them visibly clean in bowl 2, and rinsing in bowl 3.

Their results weren’t entirely surprising. First they note that grease is only removed with detergent. Second, while systems D, F, G, and J were best for bacterial loads, E through I were easiest to use because you could see what you were washing easier in the cleaner bowl 2, and D-I where the ones that didn’t leave a disinfectant smell on the dishes when done. Putting this all together, the winner was system G in using the least bleach while still reducing coliform counts below measurable levels.

Of note, systems B and C are often what is used and taught for wilderness trips. This may be due to a real or perceived need to decontaminate the rinsing water, but the authors recommend using potable water for bowl 3. Otherwise you are left with a distinct disinfectant residue on your dishes that can be tasted at your next meal. More importantly, due to reduced contact time with the disinfectant (dunking takes less time than cleaning), they had higher coliform counts as well.

So there you have it. You can use the 3 bowl system, but not the way it’s been taught historically. You should have water and detergent in the first bowl, cleaning them mostly. Then continue cleaning until visibly clean in a second bowl of water with 10mL of bleach in it (5L:10mL water:bleach). Finally, rinse in potable water. In severely water restricted circumstances,  this system gives you the added benefit of still working when you remove the 3rd bowl, except for that disinfectant taste again. The authors do note that if an outbreak of diarrhea occurs at your campsite, consider increasing the bleach content of bowl 2 to 100mL.

Laboratory evaluation of the 3-bowl system used for washing-up eating utensils in the field.
http://www.ncbi.nlm.nih.gov/pubmed/16805145