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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Comparison of normobaric hypoxia and hypoxic hypoxia protocol on human performance and physiology
Scientific title
In young male population, is there difference in physiology, performance and hypoxia symptoms between normobaric hypoxia and hypobaric hypoxia?
Secondary ID [1] 282810 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
symptoms and physiological changes under hypoxia in healthy young male 289585 0
Condition category
Condition code
Respiratory 289921 289921 0 0
Other respiratory disorders / diseases

Study type
Description of intervention(s) / exposure
normobaric hypoxia: subjects in sitting position, exposed to hypoxia by inhaling 7% oxygen through face mask at sea level
hypoxia duration < 5 min (depend on invidual tolerance and SpO2)
Each participant undergo the two sessions on one occasion only. Each sessions are separated by at least 48 hours.
Intervention code [1] 287494 0
Other interventions
Comparator / control treatment
hypobaric hypoxia: subjects sitting in altitude chamber, exposed to hypoxia by ascending to simulated 25,000 feet environment; total duration of hypoxia exposure in altitude chamber varies in each individual but around 3-5 min (depend on invidivual tolerance and SpO2). All participants undergo this intervention on one occasion only.
Control group

Primary outcome [1] 289974 0
PaO2 drop below 60% (evaluated by pulse oximeter with sensor attached to subjects' middle finger)
Timepoint [1] 289974 0
between 3-4 minutes of hypoxia exposure
Primary outcome [2] 289975 0
unable to hold on to hypoxia exposure (subjective feeling of participants, also judged by inside observer [aerospace physiologist])
Timepoint [2] 289975 0
3-4 minutes of hypoxia exposure
Primary outcome [3] 289976 0
heart rate drop > 20 bpm (monitored by polysomograph, with three EKG sensors over chest region)
Timepoint [3] 289976 0
3-4 minutes after hypoxia exposure
Secondary outcome [1] 303691 0
severe hypoxia symptoms (observed by aviation physiologist, combined with subjective check list with 17 hypoxia symptom items filled out by participants)
Timepoint [1] 303691 0
3-4 minutes after hypoxia exposure

Key inclusion criteria
healthy volunteer
able to detect middle cerebral artery blood flow by doppler at temporal region.
Minimum age
20 Years
Maximum age
40 Years
Can healthy volunteers participate?
Key exclusion criteria
1. pulmonary disease (asthma, COPD, pneumothorax, pulmonary tuberculosis)
2. claustrophobia
3. heart disease
4. severe anemia

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Healthy volunteers were recruited from staff and trainees taking aviation physiology course in Aviation Physiology Research Laboratory of Kaoshiung Armed Forces Hospital Gangshan Branch. Inclusion criteria include: male between 20 to 40 years old and successful sonographic detection of blood flow signals in the middle cerebral artery using transcranial Doppler sonography. No female subjects were enrolled in order to minimize gender-related variability.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Each subject was asked to complete the NH and HH sessions in a randomized order. A list of random numbers was determined using a computer program (Research Randomizer). Numbers were placed in sealed opaque envelopes before the beginning of the study so that randomization was concealed from the recruiter.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
within group study
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Data were presented as mean+/-standard deviation. Statistical analysis wereperformed using generalized linear model (GzLM) and generalized equation estimation (GEE). Coreelation analysis was performed with Pearson analysis.
Data analysis was performed using the Statistical Package for the Social Sciences (SPSS; version 19.0, SPSS,USA). Results were considered significant when p<0.05.The sample size was calculated using G*power. With an a of 0.05, power of 0.80, and effect size of 0.5, required number of valid samples was at least 16.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 5182 0
Taiwan, Province Of China
State/province [1] 5182 0

Funding & Sponsors
Funding source category [1] 287589 0
Name [1] 287589 0
National Defense Medical Center
Address [1] 287589 0
161 Minchuan East Road, Sec. 6, Taipei 11490, Taiwan, R.O.C.
Country [1] 287589 0
Taiwan, Province Of China
Primary sponsor type
National Defense Medical Center
161 Minchuan East Road, Sec. 6, Taipei 11490, Taiwan, R.O.C.
Taiwan, Province Of China
Secondary sponsor category [1] 286336 0
Name [1] 286336 0
Address [1] 286336 0
Country [1] 286336 0

Ethics approval
Ethics application status
Ethics committee name [1] 289563 0
Institutional Review Board, Tri-Service General Hospital
Ethics committee address [1] 289563 0
No.325,Sec.2,Chenggong Rd.,Neihu District,Taipei City 114,Taiwan(R.O.C)
Ethics committee country [1] 289563 0
Taiwan, Province Of China
Date submitted for ethics approval [1] 289563 0
Approval date [1] 289563 0
Ethics approval number [1] 289563 0

Brief summary
When unexpected situations such as oxygen system failure or loss of cabin pressure occur, a pilot may suffer hypoxia. Without early recognition of hypoxia symptoms and prompt corrective measures, in-flight hypoxia could affect cognition and judgment, even jeopardize flight safety. Hypoxia symptoms are determined by inherent tolerance, among other factors.It is believed that “hypoxia signature”, aconstellation of hypoxia symptoms, is unique for each individual. To familiarize with hypoxia symptoms, all military pilots in Taiwan have to undergo hypoxia awareness training by exposing themselves to simulated hypoxia environment in altitude chamber. This hypobaric hypoxia (HH) training protocol has the potential danger of decompression sickness and barotrauma. Alternatively, normobaric hypoxia (NH) training has been developed involving breath low concentration of oxygen at sea level. NH is safer, more economical andtime saving. However, there’s no conclusion as to whether NH protocol can faithfully imitate altitude hypoxia, as represented by HH protocol currently implemented in many countries as the mainstay of hypoxia awareness training. The purpose of this study is to compare the physiological responses, performances and hypoxia symptoms between HH and NH hypoxia awareness training protocol.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 41334 0
Dr Hsin Chu
Address 41334 0
Institute of Aerospace and Undersea Medicine, School of Medicine, National Defense Medical Center.

No. 161, Section 6, Min-Chuan East Road. Taipei, 114 Taiwan, R.O.C.
Country 41334 0
Taiwan, Province Of China
Phone 41334 0
Fax 41334 0
Email 41334 0
Contact person for public queries
Name 41335 0
Dr Hsin Chu
Address 41335 0
Institute of Aerospace and Undersea Medicine, School of Medicine, National Defense Medical Center.

No. 161, Section 6, Min-Chuan East Road. Taipei, 114 Taiwan, R.O.C.
Country 41335 0
Taiwan, Province Of China
Phone 41335 0
Fax 41335 0
Email 41335 0
Contact person for scientific queries
Name 41336 0
Dr Hsin Chu
Address 41336 0
Institute of Aerospace and Undersea Medicine, School of Medicine, National Defense Medical Center.

No. 161, Section 6, Min-Chuan East Road. Taipei, 114 Taiwan, R.O.C.
Country 41336 0
Taiwan, Province Of China
Phone 41336 0
Fax 41336 0
Email 41336 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary