Page 64 - Journal of Special Operations Medicine - Winter 2014

Strength of Recommendations Taxonomy (SORT) grade was equally effective as budesonide, a glucocorticoid
8
based on its individual study quality. On review, the similar to dexamethasone. 19
studies were divided into four categories and given an
overall SORT category grade.
Pharmacological Acclimatization Techniques:
Acclimatization With Dexamethasone
The primary purpose of this literature review was to
determine the medical efficacy of dexamethasone as an Dexamethasone is a potent glucocorticoid. It has a long
intervention for the prevention and treatment of high- history of treating cerebral edema derived from multiple
altitude illness. The secondary purpose of this literature etiologies. It is also used as a potent antiemetic for cancer
review was to determine the state of knowledge on the chemotherapy patients. Several studies (Table 1) show
effects of dexamethasone on improving physical/cogni- that dexamethasone is an effective and reliable form of
tive performance at high altitude. treatment for AMS, HACE, and HAPE. Although the
specific mechanism of action is not fully known and
under investigation, there is strong evidence that dexa-
Physical Performance Decrements methasone may prevent the onset of HAPE. 2,19–21 Com-
in SOs at High Altitude
mon dexamethasone dosages to prevent AMS for adults
Special Operators are an elite group, physically and men- ascending to altitude are either 2mg every 6 hours or
tally trained to overcome the worst possible conditions 4mg every 12 hours. For SOs who routinely deploy to al-
and battlefield scenarios, continuously pushing the hu- titudes exceeding 11,000 feet, a “very high” dose of 4mg
man body to its limits. The physical prowess of SOs has taken every 6 hours may be appropriate. Nonetheless,
been compared to elite athletes. Nonetheless, this elite this particular dosage should not exceed 10 consecutive
2,5
group of Warfighters will begin to experience decrements days of use. A group of researchers, using AMS as an
in physical performance at altitudes above 5000 feet. end point, tested dexamethasone in eight trials with ex-
Typically, SOs do not have adequate time to preacclimate posure above 13,000 feet. The researchers reported that
to altitude prior to a mission. a dosage range of 8 to 16mg/day was a more efficacious
prophylactic treatment for AMS than placebo and was
The increases in physical activity, altitude, and recruited especially worthwhile when ascent rate was high. 4
muscle mass lead to an inversely proportional reduction
in physical performance. Additionally, physiological re- Regarding the potential for side-effects, we must re-
9
sponses to acute high-altitude exposure adversely affect member that the duration of the majority of ground op-
submaximal aerobic endurance performance, potentially erations where dexamethasone might be considered for
compromising mission success. This phenomenon is il- prophylaxis will be a few days or less. There are two pos-
lustrated by increases in blood lactate levels and ratings sible side-effects that are those most often touched on in
of perceived exertion and decreases in stored muscle gly- such discussions. First, the possible side-effect of aseptic
cogen. 3,10,11 Furthermore, environmental conditions such bone necrosis has usually been associated with the long-
as low barometric pressure, low air density, and dry term use of dexamethasone over a period of 3 months or
ambient air cause significant tissue hypoxia and loss of longer. The second is the possible side-effect of insomnia
moisture in ventilator passageways and negatively affect and daytime “energetic hyperness” with eventual per-
normal breathing mechanics. 12,13 Combined, these envi- formance decrement due to lack of sleep. Currently, that
ronmental variables lead to an increase in the amount of seems to occur to the point of making dexamethasone
effort required to achieve effective pulmonary respira- unusable in about one of every five to 10 individuals.
14
tion. Without preacclimatization, the capacity of the To prevent this possible side-effect from affecting a real-
operator to perform heavy work on varying terrain can world mission, unit members can have a trial of dexa-
significantly diminish physical work. 10,14 methasone prior to using it on an actual Operation. Last,
like all medications, there is a possibility in a minority of
There are a number of prophylactic drugs that have been individuals of an allergic reaction, interactions with other
found to prevent or reduce HAPE and AMS. Currently, medications (in this population, none are usually being
the most widely used and accepted of these drugs is ac- taken), as well as gastrointestinal upset and others—the
etazolamide, which can cause unwanted side-effects. 15,16 usual list associated with all drugs. Again, a trial of dexa-
Dexamethasone has been found to be equally effective methasone will reveal whether most of these side-effects
as acetazolamide in reducing AMS symptoms up to 70% are an issue in an individual Operator.
versus a placebo following 9 hours of hypoxia. Dexa-
17
methasone also proved superior to tadalafil, a phosphodi- Cognitive deficits can be observed during the first few
esterase-5 inhibitor that is another commonly used drug hours at high altitude for otherwise asymptomatic sub-
to treat AMS, in preventing AMS by 50% and in reduc- jects. This is possibly a result of cerebral edema second-
ing the incidence of HAPE by 78%. Dexamethasone ary to an increase in the permeability of cerebral vessels.
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54 Journal of Special Operations Medicine Volume 14, Edition 4/Winter 2014