Effect of Short-term Simulated Altitude Exposure on Cardiopulmonary Functional Capacity

To determine if exposure of older volunteers, age 50-70y, who are healthy, but not physically active, to 7 days of mild hypoxia (15% oxygen, equivalent 2440m) will improve cardiopulmonary functional capacity.

Study Overview

• Status: Terminated
• Conditions: Hypoxia
• Intervention / Treatment: Other: Hypoxia; Other: Normoxia

Detailed Description

Background There is an urgent need to reduce morbidity and mortality following major surgery. Bodily demands for oxygen increase after major surgery, and postoperative outcomes can be predicted by quantifying the body's ability to meet increased mitochondrial demand for oxygen using cardiopulmonary exercise testing (CPET).

Design This is a preliminary, physiological study to establish the baseline relationship between mild hypoxia exposure and cardiopulmonary function. This study will begin to examine the feasibility and potential for achieving risk modification through low-oxygen (hypoxic) conditioning, in which a safe and convenient "dose" of mild hypoxia is used to improve CPET derived variables that predict mortality following surgery.

The study will use a randomised, double blind, sham-controlled, crossover design. After a baseline CPET test, participants will be exposed to 7 days of either mildly hypoxic or normoxic air. A follow up CPET test will then be used to determine if cardiopulmonary functional capacity increased after exposure. After a two week washout period, participants will return for a second 7-day session where the alternate exposure will be given. A final follow-up CPET test will then be performed.

• Study Type: Interventional
• Enrollment (Actual): 8
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Healthy male and female individuals aged 50-70 years with sedentary lifestyles.

Exclusion Criteria:

• Known intolerance to altitude identified by the participant's clinical examination, history and pre-altitude screening completed by the research clinician.
• Non-availability and/or suitability to complete the required residential period within the altitude centre.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Hypoxia; Mild hypoxia of 15% oxygen, equivalent altitude of 2440m over a period of 7 days	Other: Hypoxia; Participants live within an altitude residence facility. Hypoxic acclimatisation will be achieved by venting the rooms with air containing a reduced oxygen content. The degree of hypoxia is ramped over a 2-day period as participants experience 14 hours of overnight hypoxic exposure (simulating altitude of : 1830m on Day 1; 2130m on Day 2). The final 5 days will be spent entirely in the altitude residence facility at a consistent hypoxia level (simulating approximately 2440m).
Sham Comparator: Normoxia; Exposure to normal, sea-level air	Other: Normoxia; Participants will live in the altitude residence facility. As a sham-control, normal sea level air will be circulated throughout the house.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Cardio pulmonary functional variables	Assess cardio pulmonary functional variables using cardio pulmonary exercise testing (CPET) prior and following participants completing each arm of the study	Change in Cardio pulmonary functional variables between day 0 and day 7 in each arm of the study.

Collaborators and Investigators

• Sponsor: University of Limerick
• Collaborators: University of Oxford
• Investigators: Principal Investigator: Thomas Smith (Chief Investigator), MBBS, DPhil, FRCA, FAsMA, University of Oxford; Principal Investigator: Phillip Jakeman, BSc, MSc, PhD, University of Limerick

Study record dates

Study Major Dates

• Study Start: May 1, 2015
• Primary Completion (Actual): September 30, 2015
• Study Completion (Actual): December 30, 2015

Study Registration Dates

• First Submitted: June 2, 2015
• First Submitted That Met QC Criteria: August 13, 2015
• First Posted (Estimated): August 14, 2015

Study Record Updates

• Last Update Posted (Actual): December 6, 2023
• Last Update Submitted That Met QC Criteria: December 5, 2023
• Last Verified: April 1, 2021

More Information

Terms related to this study

• Keywords: Hypoxic conditioning; Cardio pulmonary exercise testing
• Additional Relevant MeSH Terms: Signs and Symptoms, Respiratory; Hypoxia
• Other Study ID Numbers: 2014_02_33