EpiPen Basics

An epiPen is a lifesaver. Anaphylactic shock is often a quick and severe allergic reaction to things like insect bites and stings, foods ingredients, penicillin or other allergens. In those affected, the skin shows the most common symptoms: hives, flushing and itchiness. anaphylaxisThe lips, tongue and throat often swell. Swallowing and breathing can become extremely difficult. But the epiPen quickly offsets the body’s potentially fatal IgE-overreaction by delivering an epinephrine dose to the outer side of the thigh. From there the compound reaches two types of receptors in the body, alpha and beta. epinephrineThe alpha receptors are found on cells of blood vessel walls. When in contact with epinephrine, the vessels constrict, raising blood pressure, redirecting blood to vital organs such as the heart and brain. When epinephrine reaches the beta receptors, the heart rate increases and airways relax, preventing potential suffocation.

The epiPen has been made straight-forward to use. All one has to do is:

1) Hold it firmly with the orange tip pointing downward and pull out the blue safety cap.

2) Swing and push the orange tip firmly into mid-outer thigh until one hears a “click.”
3) Hold the epiPen on the thigh for ten seconds.
4) Massage the thigh for an equal amount of time.
A child who weighs up to 20 kg receives a dose of only 0.01 milligrams of epinephrine per kg of body mass, which amounts to 0.20 mg. Older toddlers, teens and adults need a 0.30 mg dose. In Canada, an epiPen costs about $100. The plastic injection system is surely more expensive than the injected fluid’s compounds. The solvent and stabilizing ingredients are simple and also present in small quantities: water(2 ml), salt(6 mg), 1.67 mg of sodium metabisulfite, Na2S2O5 and a very minute amount of HCl to lower the pH to about 4. Interestingly, if one calculates the cost of epinephrine alone, it is equivalent to ($100/0.30 mg)*(1000mg/g)*(28.3 g/ounce)* 16 oz* 1 lb = over $150 million per pound! Double that if you’re paying for the 0.15 mg dose!
Returning to medical issues, how long is it before an epiPen reaches its expiry date? The manufacturers aim for a minimum of 12 months. They don’t recommend using expired products. The findings of a University of Manitoba study confirmed the manufacturers’ recommendations. In 28 pens that were between 1 and 90 months (7.5 years) old, they did see evidence of product-breakdown. Moreover, the spike in epinephrine-levels in the blood provided by fresh pens was much higher than what’s obtained from expired ones. See the contrast between dark circles and the squares in the graph of their data. EpiPens

If we compare the squares to the white circles, which represent the control saline solution and the body’s natural levels of hormone, the other conclusion drawn by the investigators becomes apparent. As long as no discoloration or precipitates are seen through the pen’s clear window,  if nothing else is available, an old pen is still better than nothing at all. 

A persistent medical mystery is why allergic reactions and anaphylaxis are becoming more common in children. Skin allergies specifically the United states have almost doubled between 1998 and 2010.  In Canada, in this century’s first decade, type 1 diabetes, another example of immunological responses gone awry and leading to self-destruction of insulin-producing cells, has increased by 40%.  Are immune systems  being compromised by a common stress-factor in our environment?
Other Sources:

http://www.netdoctor.co.uk/allergy-and-asthma/medicines/epipen.html

http://www.epipen.ca/en/about-epipen/how-to-use-epipen

Click to access WAO_Anaphylaxis_Guidelines_2011.pdf

Click to access 1710-1492-7-S1-S6.pdf

Thanks to our nurse Claude Davilmar whose excellent presentation sparked the creation of this essay.

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At the Mercy of Diffusion

Both the mechanism and appearance of hoarfrost are sublime. Hoarfrost results when water vapor encounters a very cold surface and undergoes reverse sublimation. Such ice crystals normally grow on the ground, but it can also form on twigs or on a poorly insulated pane of glass.The latter is usually called  “window frost” because of its flatter appearance. But it’s no less interesting.

103hoarfrostEnergy considerations maximize hydrogen bonding and determine the hexagonal nature of snow crystals, yet it will not predict the pattern of window frost. In this picture above, there are parts that resemble radial spider webs; other sections look like the chaotic streets of downtown Boston. And there are artsy stickmen and elongated patterns resembling those of airport runways.

In order to grow, ice crystals need a “seed”, and each imperfection along the surface of the glass provides the nucleation site. The distribution of dust or soap residue is rarely uniform. Scratches are random. And who’s to say that every point on the surface is exactly at the same temperature? All of these differences are make each hoarfrost event unique.

If we go back in time, we can ask: why was the water vapor that crystallized evenly distributed in the air when it evaporated from concentrated sources? As water molecules evaporate from a living body or from a body of water, they are initially concentrated among themselves. As a result, they are more likely to collide with molecules of their own type. But the collisions send them in random directions. Slowly, air molecules which are themselves bouncing all over the place find themselves mixed in that thinning concentration of water molecules. As long as temperature is high enough, there’s not much of a force discriminating among water vapor and other air molecules. Everything eventually becomes evenly mixed, similar to but faster than the way a dye can spread evenly in water without any human stirring.

Of course, a cold surface slows all molecules that collide with it, but now the fact that attractions between water molecules can be much stronger than those between air molecules becomes significant and leads to the loss of that freedom of random motion that they previously “enjoyed”.

It’s similar to the blogosphere. So much of what is typed, even though it may be advertised through a hashtag or by word of mouth, comes across billions of other thoughts and messages, and the ideas of a specific blog spread thinly among the vast volume of what’s in real or virtual libraries. The content must find the right surface under the right conditions to crystallize in some other mind. And even then, like the frost itself, there’s usually no permanence. Most often, it does not even get to that stage. Our words are like molecules at the mercy of diffusion.

Adding Scientific Insight to a Sensual World

In college, a trick to surviving the rigors of the pure and applied science program was to choose mandatory humanities courses that were not too demanding in terms of work. Ironically, many of the courses turned out to be at least as stimulating as any science subject, and their content stayed with me for life.

In one humanities course, a teacher with an Afro-hairdo taught us how to sense-juggle. afroI especially liked practicing the technique in a safe park. We had to close our eyes and feel our clothes, the tingling breeze and temperature gradients between skin and surrounding. Then we shifted to sounds, listening to rustling leaves and to the background murmur of conversations and distant traffic. A minute later, it was back to the tactile world, followed by a shift to auditory stimuli. Next we tuned into  smells such as hexenals from freshly-cut grass or geosmin from soil bacteria. The fourth sense to juggle was taste. Even if we weren’t eating we could use the pleasant aftertaste of a recent meal. Finally, we opened our eyes and looked straight ahead but included all peripheral movement of passerbys, noticed the fluid rubbery movement of their legs (which somehow became more obvious if you let your head hang from the edge of a park bench and view them upside down) and the different hues and glimmers on the surface of leaves.

103_8696But why not extend the exercise and add scientific insight to the sensual world? If one is by the seaside and juggling the sound of rolling waves; the smell of algal compounds from minute droplets in the air; the taste of salt on one’s lips; the sight of the unbroken boundary between water and sky and the sensation of the sea breeze on exposed skin, why not wonder about the mechanism of wind direction? Due to water’s high specific heat, the sea warms up more slowly than the sand crystals in the sun. Air molecules colliding with the latter reach a higher temperature than those above the water. The warm air rises and spreads due to its lower density, lowering pressure above the land. Meanwhile colder air sinks above the sea and exerts more pressure. This allows the greater force of the cool air to push towards the warmer shore, so that we feel air’s accentuated movement as we continue to juggle between five senses and the concepts that were generated from within our brains.