Gauze is taped to the bare side of a man's torso with a cord protruding from it. The body is horizontal on a hospital bed. A hand is visible holding a hospital gown open exposing the torso. An IV is taped to the hand.

HAST: the High Altitude Simulation Test

Maybe you are planning to ski or hike a 14er. Taking a leap of faith and moving out of the city and into the mountains. Or maybe it’s just taking a flight in a pressurized airplane cabin. Maybe you just spent 10 days in the hospital with rib fractures and are now anxious to return home to 9000 feet in elevation. You could be an individual that is worried you will miss out on that incredible work retreat to a beautiful mountain sanctuary due to your apprehension about your Chronic Obstructive Pulmonary Disease COPD.

Wouldn’t it be nice to know how you would respond to altitude prior to reaching your destination, so you could be better prepared?   

There is such a test. It is called HAST: High Altitude Simulation Testing. This test can simulate 8000 feet in elevation, in the safety of a doctor’s office at lower elevations.  HAST is a diagnostic test that can effectively calculate an individual’s supplemental oxygen needs prior to traveling to high altitude. The California Thoracic Society recommends that individuals diagnosed with severe airway disease, cystic fibrosis, neuromuscular disease, kyphoscoliosis, individuals who have been hospitalized for acute respiratory illness within the last 6 weeks, individuals with previous air travel intolerance, COPD, or cerebral vascular disease would benefit from a HAST prior to traveling to altitude (Corby-DeMaagd, 2020).

This test is performed by obtaining a patient’s blood pressure, heart rate/rhythm, and oxygen saturation at baseline. Once baseline vitals are complete the patient is monitored while breathing in a mixture of gases containing approximately 15.1% oxygen, simulating the FiO2 at an elevation of 8,000 feet. A patient;s oxygen saturation levels can be recorded by an arterial line (large IV in the wrist) monitoring the patient’s arterial blood gasses, or by an oxygen monitor attached to the patient’s finger or on a nasal cannula. This allows the physician to screen for hypoxia, arrhythmias, or other significant symptoms. If the patient becomes symptomatic, the oxygen levels are reassessed while providing the patient with supplemental oxygen to identify exactly how much oxygen would be needed to keep the patient comfortable at a higher altitude.  This test on average takes 2 hours to complete (Corby-DeMaagd, 2020).  

According to Mark Fleming, the supervisor of the Pulmonary Physiology Services at National Jewish Health in Denver, Colorado, for an individual to receive a HAST they would need a referral from a provider.  National Jewish Health is one of the few facilities in the nation that provides this service. Most patients that request this test in the state of Colorado are pilots that have had a recent ailment and need a work clearance prior to being exposed to the airplane cabin pressure, those that are interested in relocating to the mountains, planning on a high-altitude vacation and currently on supplemental oxygen, or those with a history of pulmonary embolism or lung resections.  Fleming states that they are anticipating an increase in High Altitude Simulation Testing being needed for patients that have recovered from COVID-19.  

However, there may be a vulnerable population that is not receiving the benefit of this test. Newborn babies that are delivered at 5000 feet but must return home to 8500 feet. Those that have experienced a chest trauma and must return home to altitude. Or maybe even those that have experienced an invasive surgery that involved the lungs, chest, spine, or abdomen.  These are all individuals that would benefit from knowing if they would need oxygen once they return back to elevation. Hopefully as people continue to heal from COVID the word will spread that this test is available to the public for those that are concerned about journeying to altitude.

Amanda Bergin is currently in her second year of her Family Nurse Practitioner Program for the Rural and Underserved at Regis University. She is a member of the class of 2021 and will be graduating in August. She started her medical career as a corpsman in the United States Navy and after the completion of her service, she returned to school to complete her bachelor’s degree of Science in Nursing at the Denver School of Nursing.  Amanda currently lives in a rural mountain community with very limited healthcare, and dreams to help her community start a family practice clinic. In her free time, she loves spending time with her family, fishing, camping and raising dairy goats.

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