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<< Altitude Illness: Strategies In Prevention, Identification, And Treatment

Special Conditions And Considerations

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Special Conditions And Considerations

Special Conditions And Considerations

High Altitude Pharyngitis And Bronchitis (HAP/B)

This may be the most common condition seen at altitude.177 HAP/B was seen in 12% of Himalayan trekkers; this is 1.5 times the 8% incidence of AMS seen in the same group. In a series of climbers on Mount Aconcagua, 13 of 19 (68%) developed HAP/B.178 This condition has little literature written on it but is felt to be extremely common in those who spend over two weeks above 18,000 feet; it is felt to be a result of the hyperventilation of altitude and the very dry, cold air of altitude.179 This same review recommends that patients wear a face mask, suck on hard candy, and drink plenty of fluids to treat this condition. This condition can also cause severe coughing which may require symptomatic treatment. HAP/B can be confused with HAPE and vice versa; when treating HAP/B, one must ensure HAPE is not present.

High Altitude Retinopathy (HAR)

This is a common condition at high elevations; 22 of 36 climbers who ascended to 5360 m developed HAR as manifested by retinal hemorrhages or "cotton wool" spots on exam.180 The incidence appears to also be related to height, as 19 of 21 climbers who ascended above 25,000 ft developed high altitude retinal hemorrhages.181 There is no specific treatment for HAR, other than descent if vision problems develop.

Eye Surgery And Altitude

The effects of altitude on the eye are multifold; of greatest recent concern is the finding that those who had undergone Radial Keratotomy (RK), which involved making incisions in the cornea with a diamond blade, developed vision changes on exposure to altitude; fortunately those who had Photorefractive Keratectomy (PRK), which involves using a laser to create refractive changes in the cornea, did not develop vision changes.182 A 1998 study by Winkle found that all tested subjects who had undergone RK developed a significant hyperoptic shift and corneal flattening when exposed to ocular hypoxia. This study shows that patients who  underwent RK are subject to vision changes at altitude and that hypoxia, rather than hypobaria, is the etiology. 183 The vision changes in those with RK takes 24 hours at altitude to occur and cannot be readily reversed while at altitude.184,185 The changes with LASIK, (which is now one of the most common refractive procedures utilized and involves utilizing a lazer to reshape the cornea under a cornel flap), even at extremely high altitude, are minimal. This was confirmed in a field study on Everest where six climbers who had undergone LASIK ascended Everest. Five were asymptomatic below 26,400 ft, one developed mild blurring at 16,000 ft. Two others developed mild blurring at 27,000 and 28,500 ft. All improved with descent.186
 
Altitude also adversely effects color vision. Healthy teenagers brought to moderate altitude (3000m) developed a significant number of color vision errors, most significant in the blue-yellow range.

Coronary Artery Disease (CAD) And Altitude

Patients with stable coronary artery disease appear to do well at altitude. A review by Alleman et al in 1998 showed stable coronary patients with good exercise tolerance, no exertional ischemic symptoms, and an ejection fraction of greater than 50% to be at low risk at altitudes of 2500 to 3000 m. The greatest risk is during the first few days of altitude exposure when the patient is subject to the initial sympathetic surge that accompanies altitude exposure.188 It is recommended in this review that those with CAD going to much higher elevations acclimatize for several days first. A review of individuals with stable coronary artery disease and an ejection fraction of 39 6% were also found to have a good tolerance to altitude exposure.189

Hypertension And Altitude

Those with borderline hypertension have been shown to have an increased incidence of AMS.190 While this small study by Ledderhos showed that those with hypertension have an increased incidence of AMS, altitude does not appear to increase the risk of medical consequences to those with controlled hypertension. Thirty-three subjects with hypertension attending a conference at 2500 m developed no symptoms related to their hypertension while at attitude. 191 In an epidemiological case series of 935 hypertensive patients, there was no increase in strokes or cardiac failure due to altitude exposure.5

Diabetes And Altitude

In a comparison study of six type I diabetics with 10 normal controls climbing to 8200 m, no difference was found in AMS scores, heart rate, blood pressure, or blood lactate. Diabetics did require increased use of insulin at altitude.192 One of the confusing problems to consider is that the symptoms of AMS (headache, lightheadedness, nausea) can make recog nition of hypoglycemia more difficult.193 The literature on diabetic ketoacidosis (DKA) at altitude is limited, but, in the Moore Study, two of 15 climbers developed DKA; both were taking acetazolamide. This was felt to be a possible co-factor in its onset. The risk benefit of acetazolamide use in diabetics must therefore be considered. The greatest concern for diabetics at altitude and medical providers caring for them is that all types of glucometers are inaccurate at altitude, both over and under estimating the glucose level; this has been proven in a multitude of studies. It is therefore recommended that two types of glucometers be carried at altitude as well as three times the number of test strips and supplies one would typically utilize. Insulin pumps have been shown to have no problems with function at altitude, provided they are protected from cold.194

Sleep Disturbance At Altitude

Sleep disturbance is ubiquitous at altitude, with most new arrivals experiencing increased fragmented poor quality sleep, with frequent arousals due to periodic "cheyne-stokes" breathing, as well as a shift to lighter sleep levels.195 Several sleep agents have been studied for improving sleep at altitude. Zolpidem improved sleep at altitude, including time of onset of sleep, duration of sleep, and a decrease in arousal from sleep. There was no adverse affect on respiratory function.196 Zalephon was also effective, though not as effective as zolpidem.197 Low dose temazepam was also shown to stabilize breathing, improve sleep, and not lead to any oxygen desaturation during sleep.198 Acetazolamide has been shown to improve oxygenation and decrease periodic breathing at altitude.199

Age And Altitude

Sextagenarians can safely climb 8000 m peaks provided they are in good health, moderate fitness, and experienced. This was shown by a case series of seven men and one woman from 54 to 63 years old that ascended to 8035 m on Gasherbrum II. Three of the eight had borderline hypertension and eccentric hypertrophy of the left cardiac ventricle.200
 
A study of tenth mountain division veterans with an average age of 68 found that the elderly acclimatized well to 2500 m elevation with a return to sea level performance after five days. Those with coronary artery disease that is well compensated at sealevel  do well at altitude, although ischemia may be provoked at modestly lower myocardial work rates.201
Publication Information
Authors

Ian Wedmore; Brooks T. Laselle

Publication Date

March 1, 2007

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