Tent Poles and High Altitude

What should you pack for a casual trek up Mt. Everest (29,029ft) or Aconcagua (22,000ft)? Of course, your essentials including food, climbing tools, hand warmers, lots of warm clothing and….Viagra (so in other words, avoid packing your sweat pants). Why Viagra? Well, it can help minimize the chances of high altitude pulmonary edema (HAPE). HAPE is a very dangerous condition that involves an accumulation of fluid in the lungs that can occur at a high altitude (greater than 2500-3000m) by promoting leaky capillaries and vasoconstriction (Paralikar, S, 2012). This exaggeration of vasoconstriction in pulmonary vessels can subsequently cause hypoxic conditions (in an already hypoxic environment) that may encompass cyanosis, slow heart rate, difficult/labored breathing and an elevation in body temp (Paralikar, S, 2012). Solution? Dilate those vessels! How? You got it, take a vasodilator such as Viagra or Cialis. Don’t worry, taking Viagra at very high altitudes will not likely cause an erection but rather bring your body back to a homeostatic level.

Studies have shown that taking vasodilators such as Viagra at high altitudes decreases pulmonary hypertension by minimizing vasoconstriction and further reducing the chances of developing HAPE (Maggiorini, M et al., 2006). Viagra is a phosphodiesterase type 5 (PDE-5) inhibitor that increases nitric oxide-mediated vasodilation. Vasoconstriction can occur through contraction of arterial smooth muscle that is largely mediated by a reduced amount of nitric oxide in the pulmonary system (Paralikar, S, 2012; Busch, T et al, 2001). If there is vasoconstriction, vascular resistance increases, thus blood pressure increases. If blood pressure is increased in the pulmonary circuit, it results in an increased blood flow through capillary beds because there is no mechanism of compensation (such as dilation) present in capillaries, causing them to become leaky by breaking the junctions that hold together the walls of the vessels due to an excessive amount of distension (Paralikar, S, 2012). This increased blood pressure in capillary beds is further exacerbated in low oxygen environments through constriction of pulmonary veins which increases the pressure in capillary beds even more (Paralikar, 2012).

This all being said, the same studies pointed out that altitude accommodation reduces the chances of developing HAPE just as effectively as taking Viagra because quick ascent and quick descent is a key contributor in developing HAPE (Paralikar, S, 2012). This is why people will climb to a certain level, then trek back down the mountain to camp up for the night – seems like a waste of energy to hike up then back down, right? This technique is what allows people to overcome altitude sickness and eventually be able to sumit. Sleeping at lower altitudes gives the body hours to adjust to the decrease in oxygen, reducing the chances of developing HAPE (Paralikar, S, 2012). It is recommended to not increase elevation more than 300 meters per day…one reason why it takes 6-9 weeks to summit Everest (Paralikar, S, 2012).

Busch T, Bärtsch P, Pappert D, Grünig E, Hildebrandt W, Elser H, Falke KJ, Swenson ER. (2001). Hypoxia decreases exhaled nitric oxide in mountaineers susceptible to high-altitude pulmonary edema. Am J Respir Crit Care Med, 163(2), 368–373. https://doi.org/10.1164/ajrccm.163.2.2001134

Maggiorini M, Brunner-La Rocca HP, Peth S, Fischler M, Böhm T, Bernheim A, Kiencke S, Bloch KE, Dehnert C, Naeije R, Lehmann T, Bärtsch P, Mairbäurl H. (2006). Both tadalafil and dexamethasone may reduce the incidence of high-altitude pulmonary edema: A randomized trial. Annals of Internal Medicine, 145(7), 497–506. https://doi.org/10.7326/0003-4819-145-7-200610030-00007

Paralikar, S. (2012). High altitude pulmonary edema-clinical features, pathophysiology, prevention and treatment. Indian Journal of Occupational and Environmental Medicine, 16(2), 59–62. https://doi.org/10.4103/0019-5278.107066