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Does Altitude Affect Blood Pressure

Can You Trek At High Altitude With High Blood Pressure

High Altitude and 2,3 BGP

At Indiahikes we pride ourselves to be the safest trekking organisation in India. It is natural that our conversations often revolve around how to make high altitude trekking a safer experience.

Today, we discuss whether trekkers with high blood pressure levels can trek at high altitudes.

Very often, we are asked about why we take BP readings before trekkers start their treks. A lot of trekkers end up frustrated when we turn them around because of a severe rise in blood pressure.

Its an often misunderstood concept, yet something extremely prevalent among trekkers.

Lakshmi Selvakumaran, our Head of Learning and Development team, estimates that there is at least one person with high blood pressure when we take BP readings at the start of the trek .

To understand this topic better, I spoke to a few experts at Indiahikes and outside. I interviewed Dr. Sreelakshmi Thirumoorthy at length. Dr Sree is our go-to medical practitioner. She is a high altitude trekker and a keen researcher on the effects of high altitude on human physiology.

I also spoke to Sandhya UC, the co-founder of Indiahikes, Vijeet Shaw, a senior Trek Leader at Indiahikes and Reena Shah, an experienced high altitude trekker and physiotherapist.

Lets start with the basics.

Effects Of Altitude On Pulmonary Pressures

Pulmonary arterial pressure is inversely dependent on a persons age and on the environment. At sea level, pulmonary arterial pressure rapidly decreases from the systemic level of the fetus to near-adult levels in the first hours or days after birth. In infants born at high altitude, however, the decrease is both slower and smaller than the decline just described.

In one study, right-heart catheterizations were performed in 32 healthy children aged 1-14 years and living permanently above 4,240 m . For children aged 1-5 years, the mean pulmonary arterial pressure was 45 mm Hg . It was lower, a mean of 28 mm Hg among children aged 6-14 years.

In anatomic terms, the delayed decrease in the pulmonary arterial pressure is associated with persistence of the fetal elastic fibril pattern and with medial hypertrophy in the pulmonary arterioles. Electrocardiography demonstrates persistence of fetal/neonatal right ventricular dominance.

In Leadville, Colorado , mean pulmonary arterial pressure was 25 mm Hg in healthy high school students and increased to 54 mm Hg after exercise. values surprisingly similar to those in adults during Operation Everest II at a simulated altitude of 8,840 m in a hypobaric chamber. Pulmonary arterial pressures at lower altitudes, such as Denver, Colorado , are near sea-level values. Thus, a critical alveolar oxygen tension appears to mark the level of hypoxia necessary to induce pulmonary vasoconstriction.

Changes In Sensory Motor And Mental Function

Because the retina of the eye has a great requirement for oxygen, vision is the first sense altered with the lack of oxygen. This phenomenon is demonstrated by diminished night vision even at altitudes below 3,000 m . At 3,048 m , people require more time to learn a new task than they do at low elevations. At 6,100 m , impairments in sensory, perceptual, and motor performance have been demonstrated.

In acute hypoxia, reduction of arterial oxygen saturation to 85% decreases a persons capacity for mental concentration and abolishes fine motor coordination. Reduction of saturation to 75% leads to faulty judgment and impaired muscular function.

One year after the American Medical Research Expedition to Everest, reductions in finger-tapping speed persisted. Also observed were declines in visual long-term memory and verbal learning, along with increased aphasic errors during neuropsychological testing after climbs to high altitude. This finding prompted some to surmise whether climbs to extreme altitude cause brain damage.

On initial exposure to altitude, cerebral blood flow decreases because of vasoconstriction associated with hypocarbia. However, when PaO2 decreases to 50-60 mm Hg, CBF increases. Blood flow appears to be regionally uneven, increasing at the brainstem level at the expense of cortical flow. This mechanism may possibly explain the increased vulnerability of the cortex to hypoxia.

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Does Altitude Increase Blood Pressure

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If Im Planning A Hike To A Very High Elevation How Can I Hike Safely Without Getting Altitude Sickness

How does altitude affect the body and why does it affect ...

These steps can help your body acclimate:

  • Walk up: Start below 10,000 feet and walk to a high altitude instead of driving or flying. If you drive or fly to an elevation higher than 10,000 feet, stay at your first stop for at least 24 hours before going higher.
  • Go slow: Once above 10,000 feet, dont increase your altitude more than 1,000 feet a day.
  • Rest: Build a rest day into your schedule for every 3,000 feet you climb.
  • Climb high and sleep low: If you climb more than 1,000 feet in a day, come down to sleep at a lower altitude.
  • Know your body: Recognize the signs and symptoms of altitude sickness. Move to a lower altitude if you notice any symptoms.
  • Stay hydrated: Drink 3-4 quarts of water per day.
  • Avoid alcohol: Alcohol can dehydrate your body. It also has stronger effects at higher elevations, which can impair judgment.
  • Eat carbs: Eat a diet thats more than 70% carbohydrates.
  • Know the donts: Avoid tobacco and depressant drugs, such as sleeping pills and tranquilizers.

What should I ask my doctor?

If youre planning to travel to high altitudes, ask your healthcare provider:

  • Should I take a preventive medication to avoid altitude sickness?
  • Do I have any risk factors that would prevent me from visiting high elevations?
  • What other steps can I take to prevent altitude sickness?
  • What steps should I take if I start to feel symptoms during my climb?

A note from Cleveland Clinic

Last reviewed by a Cleveland Clinic medical professional on 09/23/2020.

References

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The Effect Of High Altitudes On Blood Pressure

Q: About 2 years ago I moved to a high altitude location in the west. My blood pressure was always high normal and after a year it went sky high, 200+/110 and I had to be put on Clonidine .1mg to lower it. Within about 6 months of relocating back to sea level I was off medication and my blood pressure is now normal. Does high altitude have this much effect on blood pressure?

A: At high altitudes the body has to work harder to get oxygen. This can cause an increase in blood pressure even in people with normal blood pressure. With time, the body usually is able to adjust and blood pressure returns to its usual level. It sounds like you had prehypertension prior to moving to a high altitude. With prehypertension, blood vessels are less able to adjust to change. I assume your body was not able to accommodate for the extra work of getting oxygen to your body and your prehypertension became hypertension needing treatment. When you returned to sea level, the extra work was removed and your blood pressure reverted. Prehypertension is a risk factor for developing high blood pressure later on so you need to continue to monitor your pressure.

Who Is At Risk For Altitude Sickness

Anyone can get altitude sickness. Your age, sex and general health dont seem to affect your risk. You may be at higher risk if you:

  • Have a lung or heart condition: Your healthcare provider may recommend avoiding high altitudes if possible.
  • Are pregnant: Talk to you provider before traveling to a high-altitude location.
  • Live at low elevation: Since your body isnt used to higher altitudes, you have a greater risk for symptoms. If youre planning a trip to a high-altitude location, be aware of the symptoms of altitude sickness and how to treat it.
  • Previously had altitude sickness: Talk to your provider about prevention and treatment before your next trip.

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Ask The Doctor: Is It Okay To Travel To A High Altitude With High Blood Pressure

Q. Some friends invited me to accompany them to Rocky Mountain National Park. I would love to go, but I have high blood pressure and worry that high altitudes are dangerous for people with high blood pressure. Is that the case?

A. If you have high blood pressure but are otherwise healthy, your blood pressure is under control, and you take some precautions, a trip to the Rocky Mountains should be fine.

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Increased Pulmonary Blood Flow

Altitude sickness high blood pressure 10125 ft [colorado]

The reactivity of the pulmonary vascular bed is known to vary widely from one person to another. In healthy people, pulmonary arterial pressure does not substantially increase until alveolar oxygen tension falls below 65 mm Hg. However, in people with reactive pulmonary vasculature and a chronic stimulus to maintain reactivity , even the minimal hypoxia due to a moderate increase in elevation may be enough to stimulate a substantial increase in pulmonary vascular resistance.

In Denver, 34 infants with a ventricular septal defect and pulmonary hypertension were compared with 54 infants at sea level at Texas Childrens Hospital. Despite similar pulmonary arterial pressures, the infants at sea level had half the vascular resistance that the infants from Denver had.

The hypoxic banding of the pulmonary artery is responsible for the relative infrequency with which infants with refractory congestive failure from left-to-right shunts at moderate altitude are encountered. However, this situation is a double-edged sword. A thriving infant may have a clinically significant defect with severe pulmonary arterial hypertension.

Consequently, examination of the right ventricular precordial impulse, assessment of the second heart sound, electrocardiography , and echocardiography are extremely important. The author has heard a loud murmur in a patient at a relatively low altitude that could not be heard during an examination at a higher elevation.

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Effects Of High Altitude On Humans

The effects of high altitude on humans are considerable. The oxygen saturation of hemoglobin determines the content of oxygen in blood. After the human body reaches around 2,100 metres above sea level, the saturation of oxyhemoglobin begins to decrease rapidly. However, the human body has both short-term and long-term adaptations to altitude that allow it to partially compensate for the lack of oxygen. There is a limit to the level of adaptation mountaineers refer to the altitudes above 8,000 metres as the death zone, where it is generally believed that no human body can acclimatize.

What Does Indiahikes Do To Support Trekkers With A History Of High Bp

Before your Trek As soon as you sign up for your trek, your Experience Coordinator gets in touch with you to get to know you better. If you have any health-related issues, let your Experience Coordinator know. Our ECs are all trekkers themselves and have the expertise to guide you towards the right kind of preparation.

At the Base Camp A blood pressure reading is taken on the first morning of the trek before breakfast. Our Trek Leaders take note of any medical conditions you may have and medications that you are currently on.

During the Trek If your BP falls between 140/90 and 160/100, you automatically go on our watch list, and our Trek Leaders will keep track of your readings once or twice a day during the trek. If necessary, our Trek Leader may prescribe a low or no salt diet to get blood pressure levels stable and within permissible limits.

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What Precautions Should I Take During A Trek If I Have A History Of High Blood Pressure

1. Communicate with your Trek Leader During your Safety Check-In at the basecamp, discuss any health conditions that might need attention with your Trek Leader. Provide a list of all medications you are taking. Remember, the more information we have on your health conditions, the more we will be in a position to help you.

2. Reach your base camp a day earlier This is so that you give your body enough time to get acclimatized. Make sure you get adequate sleep in the days leading to your trek. Another hack is to take a journey break during your drive to the base camp. Try to stay overnight at a beautiful scenic place that is roughly half-way on your journey.

3. Pace yourself As you start your trek, remember that this is not a race. Maintain a steady pace and take breaks for water and energy-boosting snacks. Of course, dont forget to enjoy the breathtaking views.

4. Go easy on salty foods Skip the pickle, papad, and ORS and load up on dals and veggies.

5. Hydrate and rest well Make sure you drink enough water and get enough shut-eye.

6. Carry an adequate supply of your medications We advise our trekkers to carry sufficient quantities of their medication. And most importantly, dont forget to take your medicines as prescribed by your doctor.

Recommendations For Pregnant Tourists Visiting High Altitude:

What Happens To Your Body At High Altitude

Have a check-up with your doctor to assure your pregnancy is low-risk this might include an ultrasoundAvoid trauma if skiing, cycling, climbing, etc.Avoid over-exertion exercise a bit less than at you do at homeStay well hydratedAvoid altitude illness see aboveSeek medical care early if any problems

Peter Hackett, MD and Linda Keyes, MDINSTITUTE FOR ALTITUDE MEDICINE

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Why Heart Function Is Reduced At High Altitude

Date:
The Physiological Society
Summary:
For over a century, we have known that high altitude reduces the amount of blood the heart pumps around the body with each beat. New research has unearthed why this is the case and the findings will be important for people who live, travel and exercise at high altitudes.

For over a century, we have known that high altitude reduces the amount of blood the heart pumps around the body with each beat. New research published in The Journal of Physiology has unearthed why this is the case and the findings will be important for people who live, travel and exercise at high altitudes.

Over the years, several theories have been proposed to explain the reduction in the amount of blood the heart can pump this was even of interest to the scientists involved in the first summit of Mt Everest in the 1950’s. It has now been shown that this is because at high altitudes , the lower amount of oxygen in the air leads to a decrease in the volume of blood circulating around the body, and an increase in blood pressure in the lungs. The researchers found that both of these factors play a role in the reduction in the volume of blood the heart can pump with each beat, but importantly neither of these factors affects our ability to perform maximal exercise.

Story Source:

High Altitude Exposure Among People With Cardiovascular Conditions

Parati G, Agostoni P, Basnyat B, et al.
Citation:
Clinical Recommendations for High Altitude Exposure of Individuals With Pre-Existing Cardiovascular Conditions: A Joint Statement by the European Society of Cardiology, the Council on Hypertension of the European Society of Cardiology, the European Society of Hypertension, the International Society of Mountain Medicine, the Italian Society of Hypertension and the Italian Society of Mountain Medicine. Eur Heart J 2017 Jan 11:.

Physiological acclimatization to altitude can impose an increased workload on the cardiovascular system. At high altitudes, considered those higher than 2500 m above sea level, physiologic responses may start to represent challenges for the human body. This article reviews available evidence on the effects of high altitude among patients with cardiovascular conditions, and the risks of developing clinical cardiovascular events. The following are points to remember:

  • Physics and cardiovascular physiology at high altitude:
  • High altitude is associated with progressive reduction in barometric pressure, air temperature, and humidity. A reduction in barometric pressure results in hypobaric hypoxia.Acclimatization consists of physiological responses to help maintain adequate tissue oxygen, and includes increase in ventilation, cardiac output, red cell mass and blood oxygen-carrying capacity, and other metabolic modifications at the microvascular and cellular levels.
  • Systemic arterial hypertension:
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    How Is Altitude Sickness Diagnosed

    If you get a headache and at least one other symptom with 24 to 48 hours of moving to a higher elevation, its most likely altitude sickness. If youre climbing, a more experienced climber may recognize symptoms of altitude sickness and guide you to get help.

    If you have severe altitude sickness, a healthcare provider will ask about your symptoms, activities and location. The provider may perform a physical exam, including listening to your chest.

    What Is Considered A High Elevation In Terms Of Getting Altitude Sickness

    What Does Altitude Sickness Do to the Human Brain?

    Climbing to these elevations can bring on symptoms of altitude sickness:

    • High altitude: 8,000 to 12,000 feet above sea level.
    • Very high altitude: 12,000 to 18,000 feet.
    • Extremely high altitude: 18,000+ feet.

    For context, New York City is at an elevation of 33 feet above sea level. Denver sits at 5,000 feet, and many Rocky Mountain ski slopes are at 11,000 feet or higher. The Grand Canyon is 6,600 feet above sea level. The summit of Mount Everest is over 29,000 feet.

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    Low Altitude Resident Mothers Visiting High Altitude

    Many women in all stages of pregnancy safely visit moderate altitude every year. In fact, elevated hormone levels increase the breathing rate, raise blood oxygen and may protect against AMS.

    The safety of travel to altitude during pregnancy has not been thoroughly studied. However, many pregnant tourists visit high altitude destinations such as Colorado every year and report no complications. One study found no difference in fetal heart changes and circulating stress hormones between mothers exercising at sea level and at 6000ft. This suggests that the exposure to this altitude does not produce additional stress on pregnant women. Women with complications of pregnancy, such as hypertension, preeclampsia, placental insufficiency, or any other complication, should avoid unnecessary exposure to high altitude. The pregnant woman can take Diamox, but only if truly necessary slow ascent is preferred to medications.

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