|
 
 |
| REVIEW ARTICLE |
|
| Year : 2022 | Volume
: 3
| Issue : 1 | Page : 42-48 |
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Pilgrim health: Short sojourns to high altitude with pre-existing medical problems
Latika Mohan1, Surinderpal P Singh2, Jayanti Pant1
1 Department of Physiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
2 Department of Physiology, Army College of Medical Sciences, New Delhi, India
| Date of Submission | 21-Jul-2021 |
| Date of Decision | 13-Nov-2021 |
| Date of Acceptance | 13-Nov-2021 |
| Date of Web Publication | 28-Apr-2022 |
Correspondence Address:
Dr. Jayanti Pant
Department of Physiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand
India
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/JME.JME_71_21
Mountains have attracted travelers for short sojourns for pilgrimage, recreation or adventure which exposes them to the environmental stressors such as hypoxia, cold, low humidity and increased UV radiation. Such places are also often located in wilderness with poor access to medical aid and other resources. The present article aims to provide an overview for understanding the pathophysiology of common medical conditions in such extreme environments and the principles of their management.
Keywords: Acclimatisation, altitude, ascent
How to cite this article:
Mohan L, Singh SP, Pant J. Pilgrim health: Short sojourns to high altitude with pre-existing medical problems. J Med Evid 2022;3:42-8 |
| Introduction | |  |
Mountains and various high-altitude (HA) locations have lured travellers on short sojourns for adventure or holidays since time immemorial. In India and Nepal, sacred locations in HA (Kedarnath, Badrinath, Hemkund, Amarnath, Kailash) attract a large number of pilgrims every year. Pilgrims constitute a unique population, older and sedentary; as compared to the usual more physically fit mountaineer or trekker who may venture to these locales. There is the added factor of faster means of travel to the places of religious importance, with better roads, ropeways and air travel allowing pilgrims to rapidly ascend to altitude locations, not allowing adequate time for physiological adjustments and acclimatisation. The scope of this article is to present brief guidelines for medical professionals to deal with common medical problems in sedentary to moderately active persons traveling to HA for short stay tourism/pilgrimage.
It is well documented that there is a significant increase in morbidity due to certain specific HA illnesses at altitudes >2500 m.[1] These include acute mountain sickness (AMS), HA cerebral oedema (HACE) and HA pulmonary oedema (HAPE)[2] which are collectively referred to as acute HA illnesses and result from exposure to hypobaric hypoxia.[3] Several excellent reviews are available for the prophylaxis and management of these conditions.[3],[4],[5] Hypoxia, cold, the wilderness and sudden increase in physical activity also increase the risk of deterioration of premorbid cardiorespiratory illnesses such as hypertension, coronary artery disease, COPD, pulmonary hypertension and asthma.[6] In addition, there are special considerations for travellers with diabetes, hypothyroidism and other medical conditions which medical professionals need to be aware of for appropriate prophylaxis or adjustments prior to travel.[7],[8]
This review presents an overview of current evidence for prophylaxis and management in brief of various common medical or surgical problems which may decompensate in HA. Detailed guidelines and recommendations for the ailments have been documented elsewhere.[2] The two fundamental questions a physician advising a person travelling to altitude must answer is, how will the pre-existing disease respond to hypoxic stress and does the condition increase the chances of developing an acute HAI?
| Defining High Altitude | | |
The most universally accepted definition of HA is any altitude >2500 m, heralded by compensatory cardiorespiratory responses coming into play and a distinct increase in the incidence of altitude illnesses such as AMS, HACE and HAPE. It may however be noted that physiological compensations to ambient hypobaric hypoxia and cold start at much lower altitudes and may be influenced by local climatic conditions as well.[9] Another definition was given by Bärtsch and Saltin 2008.[10]
Persons with low physiological reserves and poorly controlled disease may start to deteriorate at altitudes as low as 1800 m, in low-to-moderate range.[11] Prolonged stay produces acclimatisation and improvement of performance over days to weeks and often continuing for months, in healthy individuals at HA. There are no permanent human settlements at altitudes >5500 m. However, in soldiers sojourning for weeks to months at such altitudes, acclimatory responses may be exaggerated causing ailments such as chronic mountain sickness and HA pulmonary hypertension, which at lower altitudes occur over a course of years.
| General Stressors in High Altitude an Overview | | |
A decrease in barometric pressure with gain in altitude leads to a decrease in partial pressure of oxygen with consequent hypoxemia.[12] The main stressor at altitude is hypoxia, with its consequent cardiorespiratory, haematological, endocrine and renal responses. In addition to hypoxia, other stressors include hypobaria, change in ambient air quality, increase in ultraviolet (UV) radiation, snow, cold, reduced activity and remote locations with poor access to medical care. Hypobaria with its effects on closed air pockets in the body may lead to presentations such as aerodontalgia in persons with pre-existing dental caries, aggravation of middle ear infections, ear pain.[13],[14] A common related problem observed by many sojourners is increase in flatulence in the first few days after ascent to altitude.[15]
Altitude and cold interact to decrease absolute humidity at altitude. A frequent consequence is dehydration due to increased insensible water loss. There is hyperventilation due to the hypoxia at altitude producing respiratory alkalosis and attendant alkaline diuresis. While these factors greatly increase the risk of dehydration universally, the short-term sojourner/pilgrim may also indulge in greater than usual activity, enhancing risk of dehydration. Cold dampens the sensation of thirst. Hence, the dwellers of extreme altitude have increased risk of chronic volume depletion. It is reported that hypoxia alters ADH regulation due to increased osmotic threshold causing increase in ADH responsiveness.[16] Therefore, water consumption of 3–5 L/day is advisable to prevent dehydration in sojourners.[17] Lack of humidity may also give rise to dry eye, which is compounded by prolonged screen time in the cell-phone-dependent sojourner. Xerostomia and dental caries are other problems which may arise with a prolonged stay at altitude.
Air quality may also be affected by a fuel burned for heating and light in remote locations. Most common are kerosene and wood or coal. Carbon monoxide poisoning is a constant threat and stray incidents are reported every season. Detailed reviews on the topic are available elsewhere.[18] Other effects of cold air/pollution due to combustion of fuels may be aggravation of asthma in the susceptible. On the other hand, the rarefied clean air at HA locations is beneficial for those in-home asthma is triggered by airborne dust/pollutants/dander. Decreased airway resistance and better lung mechanics are other benefits of rarefied air at HA, for asthmatics. The intensity of solar and ionising radiation increases substantially with increase in altitude. This is partly due to the rarefied atmosphere and may be aggravated by reflection of the sun rays from snow.[17] Sojourners are advised to wear protective sunscreens to prevent sunburn. Snow blindness may occur if protective goggles are not worn.
Cold and snow bring in a range of cold injuries such as chilblains, trench foot and frostbite. Outdoor accidents may lead to hypothermia. The interested reader shall benefit from detailed reviews available on the subject.[19]
Travel to HA locations may have various individual and group psychological consequences. Persons who have not travelled to such locations before as may be common in pilgrims may find the lack of facilities and remoteness of location overwhelming, inducing severe anxiety. Anxiety and depression in one member of the team may affect team dynamics and morale of the whole group. Fear and anxiety may compound the effects of the cold and hypoxia thereby additionally stressing the cardiorespiratory system.
When advising any individual planning travel to remote locations, the scope of availability of emergency health care and urgent evacuation must always be kept in mind, as also the unpredictable weather conditions which may hamper swift evacuation. Sojourners of older age and greater morbidities are becoming more common with improved access and better services. Deeply religious pilgrims are often highly motivated to such travel despite contra-indicating medical conditions.
| Cardiovascular Responses to High Altitude Hypoxia | | |
Kedarnath, Badrinath, Amarnath and Leh, sites of importance for tourism/pilgrimage are located at altitudes between 3000 and 3800 m. In a study, at Leh (3300 m/mean barometric pressure 510 mmHg) blood haemoglobin-oxygen saturations were reported to be 91% ± 2% in healthy acclimatised male sojourners. Women had insignificantly higher values.[20] Hypoxic stress initiates various cardiorespiratory responses which aid acclimatisation and are well tolerated by healthy individuals but may lead to decompensation in the presence of pre-existing cardiovascular or respiratory disease. Carotid body-mediated increase in sympathetic activity causes an increase in heart rate and cardiac output, with little change in stroke volume, over the first 48–72 h. There is peripheral vasodilation due to hypoxic functional sympatholysis.[21] These changes therefore lead to a variable response in blood pressure, systolic pressure may rise and there may be increase in pulse pressure. Epicardial coronary vessels dilate with an increase in resting blood flow, and oxygen extraction increases, compensating for hypoxemia.[22] The pulmonary circulation responds to hypoxia with regional hypoxic vasoconstriction to match ventilation with perfusion and there is increase in pulmonary arterial pressure (PAP). With a continued stay in altitude and acclimatisation, the blood pressure may settle, cardiac output decreasing to lower than sea-level values. However, the increase in heart rate and raised PAP may persist, albeit being lower than early in the stay at altitude. There is a decrease in maximal oxygen consumption on exercise at altitude with roughly a 10% decrease for every 1000 m above 1500 m altitude.[23] Exercising in an altitude location in the first few days has not been found to be a risk for the healthy heart, dyspnoea being a limiting factor, but hypoxemia, tachycardia and peripheral vasodilatation may overstress an already compromised coronary circulation.
| Cardiovascular Disease and Travel to Altitude | | |
Coronary artery disease
Individuals with well-compensated asymptomatic coronary artery disease who have a good exercise capacity at sea level may safely travel to HA. The myocardium is stressed by tachycardia, so caution needs to be exercised to reduce workload, especially in the initial 2–3 days. Low-dose aspirin is to be used with caution as retinal bleeds are known to occur. Patients who have undergone angioplasty or coronary bypass and have good exercise capacity at sea level have no additional risk for HA travel.[24] Patients with symptomatic heart conditions, such as angina or heart failure, with poor effort tolerance may avoid travel to regions with altitude >2500 m.
Hypertension
The interplay of increased sympathetic discharge, hypoxia-induced peripheral vasodilation and changes in fluid balance results in a notoriously variable response in blood pressure.[24] Most people experience an increase in systolic and diastolic blood pressure in the first few days at altitude, which settles over weeks. In some, the blood pressure remains unchanged on entry into HA but may increase over the next few weeks as acclimatisation proceeds and peripheral resistance increases along with reduction of hypovolemia and electrolyte alterations. From a clinical standpoint, travellers with pre-existing hypertension would be advised to continue their medication as before, but monitor blood pressure in altitude more vigilantly. Some adjustments of drug dosage may be required. It may be borne in mind that that all electronic equipment is liable to malfunction and batteries lose charge faster in cold and HA.[25] Headache, a common symptom of increase in blood pressure is also the cardinal symptom of AMS, which is seen in over 30% of sojourners in the first few days at HA. Persons with poorly controlled hypertension should avoid travel to altitudes more than 2500 m.
Pulmonary hypertension
The pulmonary circulation consistently responds to environmental hypoxia by pulmonary arterial vasoconstriction (hypoxic pulmonary vasoconstriction [HPV]). HPV is well conserved in nature, only variable in the extent to which it occurs. Acclimatised lowlanders are seen to develop mild pulmonary hypertension (as defined at near sea level) on prolonged stay at altitude, with one study showing an increase of mean PAP from a sea-level value of 12–18 mmHg after 1 year at 4540 m.[25] Although reversible on descent, pulmonary arterial remodelling and persistence of pulmonary hypertension[26] after a prolonged stay at altitude is reported. In addition, HPV is aggravated by exercise, which is likely to increase in any travel to an altitude location. Individuals who have an exaggerated HPV response are liable to have an increased susceptibility to develop HAPE. Patients with pre-existing pulmonary hypertension (mean PAP >25 mmHg at rest or >30 mmHg with exercise) are at higher risk of developing HAPE and clinical decompensation on travel to even moderate altitudes. Deterioration of the right ventricular function leading to worsening of hypoxemia may occur with subsequent RV dilatation. This could compromise coronary blood flow and increase risk of myocardial ischemia. Careful assessment is essential with echocardiography and a hypoxia challenge test to assess PAPs. Persons with mean PAPs >35 mmHg or systolic PAP >50 mmHg should avoid travel to even altitudes as low as 2000 m (Mussoorie/Nainital/Shimla and Manali, common tourist destinations in India all come in this range of altitude). Persons with milder disease may travel to such altitudes, but with supplemental oxygen and on pulmonary vasodilators.[27]
Arrythmias
Increase in sympathetic discharge and fluid and electrolyte imbalances known to occur in the initial few days on travel to altitude, provide an environment for the development of arrythmias. Although field studies have not shown any serious risk, it is advisable for persons with pre-existing serious arrhythmias not to travel to altitudes more than 2500 m.[6]
| Respiratory Illness and Travel to High Altitude | | |
Increasing hypobaric hypoxia with increased elevation at HA induces a carotid body-mediated hypoxic ventilatory response, leading to hyperventilation. This causes partial correction of hypoxemia but also induces hypocapnia. Decrease in air density, humidity and ambient temperature also affect ventilation. The effect of hypoxia on the pulmonary circulation (HPV) has been discussed above.
HAPE, a non-cardiogenic oedema is the most common respiratory illness of significance that occurs within the first 2–4 days of entry into HA. It is usually seen in altitudes over 2500 m, although cases at moderate altitude have been reported. Exposure to hypoxia in susceptible individuals leads to an exaggerated HPV and rise in PAP. The distribution of vasoconstriction is uneven and leads to regional overloading of the capillary beds and stress failure. Pulmonary oedema results from the breakdown of the alveolocapillary barrier. The oedema is non-cardiogenic and non-inflammatory. It is consistently and rapidly reversed by evacuation to lower altitudes and by oxygen therapy. A gradual and graded ascent to altitude is the best way to prevent HAPE. Pharmacological prophylaxis with nifedipine or phosphodiesterase-5 inhibitors such as sildenafil/tadalafil has been found to be effective.[3],[28],[29]
Although there has been significant interest in the epidemiology of COPD at HA in recent times, very few studies are available which clearly define the pathophysiology or progression of the disease in altitude. Notable in recent years is a study conducted by Lichtblau et al. from the university college at Zurich.[30] COPD patients have antecedent problems of bronchial obstruction, poor gas exchange and increased work of breathing[30] at HA or during air travel (reaching altitudes of 2438 m) have shown significant desaturation, with hypoxemia worsening on mild exertion. Most studies show a fall in arterial oxygen tension (PaO2) to 50 mmHg or below, equivalent to sudden exposure to 2440 m, a defined by the ATS and BTS as the minimum PaO2 to be maintained for air travel.[31] It is advisable that persons with forced expiratory volume in 1 s <1 L or CO2 retention or pulmonary hypertension or history of active or recent exacerbation of disease avoid travel to ≥2000 m altitude. If necessary they may travel with supplemental oxygen only if emergency medical facilities are available at the HA location. Patients with mild disease who may travel are advised to monitor pulse oximetry and have supplemental oxygen on hand. Unless otherwise contraindicated, prophylaxis with dexamethasone rather than acetazolamide is advisable. As medical care and evacuation facilities may be tenuous in remote locations, travel may be advised with an adequate supply of medicines to deal with acute events such as inhalers and steroids.
Asthma
There is reduced air density at altitude, hence decreased work of breathing and decrease in dust mites and vehicular pollution. Mild-to-moderate asthmatics may show some improvement with travel to altitude locations. As with any travel, it is not advisable to travel during an acute asthma exacerbation/until recovery to baseline. Fuel for indoor heating such as kerosene, wood, coal and cow dung may be a source of indoor pollution and triggering an exacerbation. In those reactive to cold exacerbations may be triggered by ambient cold at HA (the temperature decreases approximately 1°C for every 150 m gain in altitude). Cold and altitude may reduce the number of doses available in inhalers. If an acute exacerbation does occur special attention is to be paid to ensure hydration of the patient.[3]
Sleep apnoea
Studies in patients of obstructive sleep apnoea (OSA) have indicated that altitude hypoxia switches OSA to central sleep apnoea. The resolution of OSA is attributed to an increase in respiratory rate and upper airway tone at altitude.[32],[33],[34] Nishida et al. have indicated in their study on ten participants of OSA on PAP, a worsening of hypoxemia in sleep, with decreased sleep time and increase in frequency of hypopneas with moderate altitude when patients used baseline PAP settings.[35]
It is recommended that patients of OSA travel to altitude locations with their continuous positive airway pressure (CPAP) machine wherever electrical supply is assured, and continue taking treatment. Acetazolamide improves sleep apnoea by decreasing apnoea hypopnoea index, periodic breathing and hypoxemia. A daily dose of 250 mg is recommended.[36],[37] Older generation CPAP machines need to have pressure adjustment to altitude.[3]
| Endocrine Disorders and Travel to High Altitude | | |
Diabetes mellitus
There are no contraindications for patients of type 1 or type 2 diabetes to travel to HA or to participate in trekking/mountaineering activities. For diabetics, hypoxia per se does not present any problems, but the increase in exercise, change in food availability, food timings and remote location may create problems of hypoglycaemia or hyperglycaemia. Seasoned mountaineers who are diabetic have a good understanding of their condition and are able to effectively titrate their insulin requirements against their carbohydrate intake and exercise output. Pilgrims who are lowlanders traveling to altitude for the first time, may not on the other hand have such a good understanding of diabetic self-care. A strict monitoring of blood glucose levels (BG) is required. Glucometers usually have an operating temperature of 10°C–40°C and may malfunction at low temperatures, giving falsely low results. Efforts must be made to keep both insulin and glucometers warm (near body temperature) when travelling in cold/remote areas. A simple solution may be to carry them next to the body in an inside pocket. It may also be advisable to shift to a short-acting insulin for the duration of the sojourn.
Team leaders and travel companions must be informed of the diabetic condition and should be aware of symptoms[36],[37] of hypoglycaemia. Hypothermia, alcohol intake and exhaustion may precipitate hypoglycaemia when travelling to remote locations. Patients may be advised to carry a fast acting easily absorbed form of sugar and spare food and a glucose monitoring system along. Type 1 diabetics may in addition carry spare equipment as needed for their insulin, injectable glucagon kit and reagent blood and urine kits for ketones.
Acetazolamide due to its multiple metabolic effects is not advisable as prophylaxis for AMS in diabetics and dexamethasone is also avoidable in diabetics. The best option is slow ascent to allow for adequate acclimatisation. Both these medications however can be used in acute life-threatening conditions such as HAPE and HACE, with stringent monitoring of BG. It was believed that symptoms of AMS like headache, giddiness and nausea could be mistaken for hypoglycaemia in diabetics, which prevented many diabetics from travelling to altitude locations. This has not been found to be so common and AMS is usually self-limiting.[7]
Patients with diabetic retinopathy should undergo a baseline screening retinal examination before undertaking travel, as there is an increased risk of retinal bleed. Travel to steeping elevations >4000 m should be avoided in persons with ischemic or proliferative retinopathy. Such patients should also avoid using aspirin for headache/AMS.[3]
Thyroid function
Limited studies are available on thyroid function at HA but a recent study by von Wolff et al. has demonstrated an overall activation of the thyroid axis.[38] Hypothyroid patients who are on oral replacement may not be able to launch an increase in thyroid hormones. For brief sojourns, this may not present a problem, but a longer stay in cold and altitude may be associated with a poor cold tolerance, anaemia and aggravation of hypothyroid symptoms.
| Haematological Disorders and Travel to High Altitude | | |
Anaemia
There is no evidence to suggest that persons with anaemia are at a higher risk for HA illness nor is there any risk of aggravation of the clinical condition. There are no studies that define cut off haematocrit for safe travel to HA. Anaemic persons planning a longer stay in HA should be advised to take iron folate and B12 supplementation. Patients on erythropoietin (EPO) supplementation should have a careful monitoring of their EPO dosing and haematocrit levels.
Hypoxia precipitates sickling and vaso-occlusive crisis in sickle cell anaemia, and care must be taken in patients even in air travel and while traveling through HA passes. Patients with sickle cell disease may be advised to travel to even moderate elevations such as 2000 m with supplemental oxygen and to maintain adequate hydration. They must report for medical care immediately on developing symptoms of the left upper quadrant pain.
Thromboembolic disease
Although there have been a large number of recent studies on thromboembolic phenomenon at HA, there is no convincing evidence that hypoxia/altitude acts an independent stressor, and that the incidence is higher than seen in the plains.[3] The fluid and electrolyte adjustments that occur initially on entry to altitude, along with the relative dehydration, may precipitate thrombotic episodes in those who are already prone, such as on oral contraceptive or a hypercoagulable state. The clinical threshold for a symptomatic disease may be lower at altitude due to the prevalent tissue hypoxia, with patients who may be asymptomatic at sea level presenting with clinical features of ischaemia.
There is no evidence that additional screening is required for coagulopathy or that patients of pre-existing coagulopathy to add or increase their pre-existing treatment on travel to HA.[3] Patients who are on anticoagulants should continue their treatment in altitude but are advised to exercise care not to travel to very remote locations or to where there is increase in risk of trauma.
In general, all individuals travelling to altitude may be advised to maintain good hydration and mobility, as is advised in long-haul air travel.
| Gastrointestinal Disease and Travel to High Altitude | | |
There may be a general increase in gastrointestinal (GI) complaints on travel to HA locations for various reasons. AMS and travel on mountain roads are very often accompanied with nausea and loss of appetite. Both are self-limiting and can be managed with symptomatic treatment. Water in the mountains has a high mineral content and is generally hard water and hygiene/potability is a source of concern. Bloating, flatulence and traveler's diarrhoea are common.
Wu et al. have reported an increase in the incidence of GI bleed at altitude.[39] The risk factors may be antecedent use of aspirin or dexamethasone. It is not clear from this study or other subsequent reports whether there is any direct correlation with hypoxia and upper GI bleeding. Patients with prior history of upper GI bleeds may be careful not to take aspirin or dexamethasone which is often prescribed for AMS prophylaxis/treatment.
Food and water hygiene in many remote locations is suboptimal and there are anecdotal reports of increase in giardiasis, amoebiasis and Helicobacter pylori infections after such travels. If symptoms persist after return from a sojourn, this may be kept in mind during further evaluation.
| The Eye at High Altitude | | |
Besides the problems posed by hypoxia and decreased humidity at HA, other risk factors include strong winds and flying debris which may increase the risk of injury, high UV radiation and cold.[40]
Snow blindness
The quantity of UV light exposure increases at the rate of 4% for each 300 m ascent in altitude and is further increased by lower latitude and reflective surfaces such as snow and reflection from a body of water. Acute exposure to UV light damages the conjunctiva and cornea and causes snow blindness. Symptoms are blepharospasm, pain, photophobia and watering. Mild cases may present with foreign body sensation and photophobia. Symptoms start in 4–10 h after exposure and may last from 48 h to several days. The eye may be vulnerable to opportunistic infections during this time. Supportive treatment and rest to the eye help in the resolution of the condition. Long-term exposure to UV rays may pre-dispose to degenerative changes in the conjunctiva (Pterygium) and incidence of cataract is higher in HA residents.[41]
Dry eye
Low humidity at altitude, wind and use of supplementary oxygen increase evaporation of tears and tear breakup time is reduced.[42] Regular use of lubricating eye drops should be encouraged in travelers. Persons wearing contact lenses may be more susceptible may suffer foreign body sensation, lid spasm and photophobia. Extended and overnight use of contact lenses should be discouraged as hypoxia and dry eye may pre-dispose to infections. Persons who have undergone corneal refractive surgery may have corneal oedema and visual disturbances, although this is now less common with advanced surgical techniques.
Retinal haemorrhage
Retinal haemorrhage has been reported to occur in altitude, but is mostly asymptomatic, unless there is macular involvement. Descent is not indicated if asymptomatic haemorrhages are discovered and the individual is in good health. Hypoxia-induced transient monocular blindness (amaurosis fugax) and bilateral cortical blindness have been described. All these conditions mentioned are self-resolving and recover on descent to lower altitudes.
In general, all sojourners should be advised to wear sunglasses with good UV protection, hats and use lubricating eyedrops. Extended wear contact lenses should be avoided.
| Pre-Existing Renal Disease and High Altitude | | |
Patients with renal disease are at increased risk for volume depletion or overload since their concentrating and diluting capacity of the kidneys are impaired. Patients with chronic renal disease may have metabolic acidosis which might increase the risk for HAPE. Hence their choice and dose of medication is dependent on glomerular filtration rate.[43]
| Pregnancy | | |
Pregnancy presents a special physiological condition, and risk to the foetus, the future child and to the pregnant women cannot be ascertained with confidence. There is no epidemiological data on travel of pregnant women for short sojourns into HA. Such journeys are attempted unknowingly by women who may not yet be aware that they are pregnant or they may have already planned the trip and come to know they are pregnant and may come for travel advice. Data from lowlanders indicates that pregnant women have higher ventilation leading to a lightly higher PaO2 than non-pregnant women, with greater carbon dioxide washout. Ensuing respiratory alkalosis is not completely compensated by the kidneys. There is a higher metabolic demand from the mother and foetus and the maternal oxygen consumption increases by 20% in pregnancy. There is peripheral vasodilatation. These are the same systems where physiological reserves are already compromised in HA. How pregnant physiology readjusts in the presence of hypoxia, in an unacclimatised lowlander, especially so in the presence of exercise is incompletely understood. In women living for prolonged periods at HA IUGR has been documented, roughly at the rate of 100 g birth weightless for every 1000 m increase in altitude. There is a three-fold increase in the incidence of gestational hypertension and pre-eclampsia.. Other data indicate a higher incidence of spontaneous abortion, premature labour.
To err on the side of being conservative, as there is insufficient data on safety, it is advised that pregnant women who have past history of spontaneous abortion or ectopic pregnancy not to travel to locations over 2500 min. As Acetazolamide is contraindicated in first trimester due to possible teratogenic effects, as the option of natural acclimatisation should be allowed, slow ascent is advised and all exercise should be avoided first 2–3 days on entry to altitude location. Women who travel in second trimester are at higher risk of gestational hypertension/pre-eclampsia and remote locations may not allow for adequate monitoring of mother and foetal health. Travel in third trimester carries a risk of IUGR, preterm labour. These risks need to be explained to pregnant women planning to undertake a sojourn to HA.[44],[45]
| Paediatric Population | | |
The risk of developing AMS, HAPE, HACE are similar to the adults, however, they may not be able to express the symptoms. Therefore, both over or underestimation of the symptoms make the diagnosis quite challenging. Children are smaller with less efficient thermal balance as compared to adults and hence are at risk to hypothermia.[46]
| Conclusions | | |
Despite the risks of the travel and rigors of cold and hypoxia, the sacred sites in HA locations draw millions of pilgrims each year. Many come ill-prepared physically, carried forward in the name of faith. Fundamentally, avoid HA journeys in the presence of any active or poorly compensated illness. If cardiorespiratory physiology is well compensated and there is good exercise tolerance, there is no contraindication to HA travel even in the presence of past disease. Prior planning, strict monitoring is required for diabetics to have an uneventful sojourn. As insufficient data is available, the safety of pregnant women cannot be ensured in HA.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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