Effects of Continuous Positive Airway Pressure on Peripheral Oxygen Saturation, Work of Breathing, and Exercise Tolerance at Altitude

Dyspnea and exercise intolerance are well known to travelers who have experienced time at high elevations, greater than 2500 meters (8200 feet). As individuals ascend to higher elevations, oxygen saturations significantly decrease as the partial pressure of oxygen decreases. Additionally, many individuals develop subclinical cases of high altitude pulmonary edema (HAPE), which may worsen hypoxemia and decrease exercise performance. While dyspnea and exercise intolerance are usually self-limiting and improve with rest, some individuals experience severe symptoms that prevent safe evacuation to lower elevation.

Individuals experiencing high altitude dyspnea, subclinical HAPE, or clinical HAPE will see improvements in symptoms and SpO2 when receiving supplemental oxygen, however this requires heavy and unwieldy tanks that make it difficult to carry across irregular terrain. Additionally, given the often-remote conditions where supplemental oxygen is needed, it is often difficult to replenish supplies. Other devices, such as the portable hyperbaric chamber (often referred to as Gamow bag), can temporarily improve dyspnea and oxygen saturation at high and extreme altitudes without the use of oxygen tanks. This device also carries some of the same disadvantages as supplemental oxygen, however, as the bag is also heavy and patients are not ambulatory while using the device.

Similar to supplemental oxygen and the portable hyperbaric chamber, there is some evidence that CPAP may improve SpO2 and dyspnea at high and extreme altitudes. CPAP has already demonstrated significant efficacy in reducing symptoms of acute mountain sickness (AMS) when used in the field. At the time these small studies were conducted, CPAP therapy carried similar disadvantages in weight and portability. In recent years, however, CPAP devices have become increasingly lightweight and portable, with recent models weighing less than 1 kilogram (2.2 pounds). These devices are often powered by batteries, which themselves are light and easy to carry, and can be charged in the field using either a generator or foldable solar panels. These newer features of CPAP devices overcome some of the previous disadvantages that have limited its potential uses. CPAP devices can easily be carried across difficult terrain directly to individuals suffering from altitude-related symptoms, to be used as a rescue device until definitive care is available. Its portability not only allows for easy delivery to a patient, but also may allow for a patient to experience enough symptom relief to walk themselves down to lower elevation, greatly improving speed and resource utilization involved in high altitude rescues.

In previous studies, CPAP devices have been found to be effective and safe to use in high and extreme altitude locations. While a few pilot studies have assessed CPAP's utility in treating dyspnea and SpO2 at altitude, these studies were done at rest. While one study showed improved symptoms and SpO2 in normobaric and hypobaric hypoxia, the study was limited by its lack of real-world condition, and its authors suggested further study in field and extreme environmental conditions. Additional investigation is needed to determine whether or not CPAP is an effective tool in the field to improve SpO2, dyspnea, and exercise tolerance in individuals traveling at high elevations.

Study Overview

• Status: Enrolling by invitation
• Conditions: Hypoxemia; Altitude Hypoxia
• Intervention / Treatment: Device: Continuous positive airway pressure; Device: Ambient air

• Study Type: Interventional
• Enrollment (Estimated): 25
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Colorado
    • Denver, Colorado, United States, 80211
      • University of Colorado Denver

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Healthy adults (age 18-70)
• Living at lower elevation (<2500m or 8200ft)

Exclusion Criteria:

• Age > 70 or age < 18.
• History of chronic respiratory conditions (asthma, COPD, ILD)
• Obstructive sleep apnea (if currently using nighttime CPAP)
• Congestive heart failure, coronary artery disease
• History of myocardial infarction
• History of HAPE
• Neurologic disorder
• Cognitive disorder
• Altered mental status
• Pregnancy
• Current use of supplemental oxygen
• Impaired mobility
• Excessive facial hair
• Claustrophobia.
• Current use of altitude-related illness prophylaxis medications
• Current use of anticoagulant medications
• Current use of calcium channel blockers medications

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Continuous Positive Airway Pressure use	Device: Continuous positive airway pressure; Continuous positive airway pressure administered by face mask
Sham Comparator: Ambient air	Device: Ambient air; Air (fraction of inspired oxygen) at 14000 feet in elevation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peripheral oxygen saturation	SpO2 measurement in percentage	1 day
Respiratory rate	Breaths/minute	1 day
Heart rate	Heartbeats/minute	1 day

Collaborators and Investigators

• Sponsor: University of Colorado, Denver
• Investigators: Principal Investigator: Brian M Strickland, MD, UC Denver

Study record dates

Study Major Dates

• Study Start (Estimated): July 22, 2023
• Primary Completion (Estimated): October 1, 2023
• Study Completion (Estimated): October 1, 2023

Study Registration Dates

• First Submitted: July 6, 2023
• First Submitted That Met QC Criteria: July 24, 2023
• First Posted (Actual): August 2, 2023

Study Record Updates

• Last Update Posted (Actual): August 2, 2023
• Last Update Submitted That Met QC Criteria: July 24, 2023
• Last Verified: July 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Respiration Disorders; Signs and Symptoms, Respiratory; Altitude Sickness; Hypoxia
• Other Study ID Numbers: 23-0468

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No