Clinical trial NCT04739904: Hypoxia Intolerance in Preterm Individuals
Official title: Mechanisms of Hypoxia (in)Tolerance in Prematurely Born Individuals
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Premature Birth
Hypoxia
Keywords: Acclimatization
Altitude
Preterm birth
Cardiorespiratory
Cerebrovascular
Exercise
Lead sponsor: Jozef Stefan Institute
Sponsor class: OTHER
Collaborators: name: University of Lausanne
First posted: 2021-02-05
Enrollment: 36
Sex: MALE
Minimum age (years): 18
Maximum age (years): 30
Standard ages: ADULT
Accepts healthy volunteers: yes
Observational model: CASE_CONTROL
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Prematurely born adults involved in this study must fulfil the following characteristics at birth: gestational age ≤ 32 weeks and gestational weight ≤ 1500g.

Conversely, full-term adults involved in this study must fulfil the following characteristics at birth: gestational age of at least 38 weeks.

Brief summary: Reduced Hypoxic Ventilatory Response (HVR) and systemic O2 saturation subsequently leading to blunted aerobic capacity as well as decreased overall physical and cognitive performance are the main physiological challenges faced by prematurely born individuals in hypobaric hypoxia (i.e. during high altitude sojourn). While these phenomena have been described previously, the underlying mechanisms are currently unresolved. Given that the reduction in altitude-performance and its underlying mechanisms are not well understood, it is currently impossible to give evidence-based recommendation for altitude sojourns in this cohort. It is also of note, that even hypobaric hypoxia exposure during long-haul flights might be detrimental to well-being of pre-term born individuals.

The present project aims to comprehensively investigate physiological responses to altitude/hypoxia during rest and exercise in prematurely born, but otherwise healthy adults. Specifically, the investigators aim to elucidate the underlying mechanisms of the altered resting and exercise cardiovascular, respiratory, cerebral and hematological responses to hypoxia in prematurely born individuals. The obtained results from this cohort will be compared to the data from a control groups consisting of healthy, age and aerobic capacity-matched individuals born at full-term. While acute hypoxic effects will be the focus of the project's first phase, the researchers will test the effect of prolonged terrestrial (real) or simulated (normobaric hypoxia) altitude exposures in the second part. This phase will, in addition to the insight into the prolonged altitude acclimatization modulation in prematurely born individuals, also enable the potential differences between the effects of normobaric (simulated) and hypobaric (terrestrial) hypoxia in this cohort to be investigated.


Eligibility criteria: Inclusion Criteria:

* prematurely born (gestational age: ≤ 32 weeks; gestational weight ≤ 1500g)
* full-term born
* healthy individuals
* male

Exclusion Criteria:

* presence of any medical risk factors to exercise and/or exposure to altitude
* presence of any medical condition that would make the protocol unreasonably hazardous for the patient
* smokers
* exposure to altitude above 1000m in the last 2 months

Primary outcomes:
measure: Cerebrovascular reactivity to carbon dioxide (CO2)
timeFrame: 48 hours after exposure to normoxia and hypobaric hypoxia, respectively.
measure: Cognitive function
timeFrame: 24 hours after exposure to normoxia, hypobaric hypoxia, and normobaric hypoxia, respectively
measure: Acute Mountain Sickness (AMS)
timeFrame: 8 hours (prior to sleep) and 16 hours (upon waking) after exposure to hypobaric and normobaric hypoxia
measure: Change in respiratory function
timeFrame: Immediately after exposure to hypobaric and normobaric hypoxia, relative to baseline.
measure: Lung comets
timeFrame: Every day before and immediately after each exercise bout.
measure: Heart rate response to exercise
timeFrame: Every day before exercise, during exercise and at the instant of volitional exhaustion.
measure: Respiratory response to exercise
timeFrame: Every day before exercise, during exercise and at the instant of volitional exhaustion.
measure: Changes in muscular oxygenation during exercise
timeFrame: Every day before exercise, during exercise and at the instant of volitional exhaustion.
measure: Changes in cerebral oxygenation during exercise
timeFrame: Every day before exercise, during exercise and at the instant of volitional exhaustion.
measure: Changes in the rate of muscular oxygen consumption (mV̇O2)
timeFrame: Before each exercise bouts.
measure: Acute change in sleep quality
timeFrame: On the first night in normoxia, normobaric hypoxia and hypobaric hypoxia.
measure: Change in sleep quality after prolonged exposure to hypobaric hypoxia
timeFrame: On the third night after exposure to terrestrial altitude.
measure: Changes in endothelial capacity to flow-mediated dilation (FMD)
timeFrame: 24 hours after exposure to normoxia and hypobaric hypoxia.
measure: Changes in orthostatic tolerance
timeFrame: At 6am on every trial day (upon waking).
measure: Changes in oxidative stress markers in the blood
timeFrame: Blood samples will be collected at 6am (upon waking).
measure: Change in salivary cortisol concentration
timeFrame: Saliva samples will be collected at 6am (upon waking).
measure: Change in hydration status
timeFrame: Urine samples will be collected at 6am (upon waking).
Secondary outcomes:
measure: Change in cerebral blood flow in the internal carotid artery
timeFrame: Cerebral blood flow will be measured at 10am.
Other outcomes:
Locations:
city: Ljubljana
country: Slovenia
facility: Jozef Stefan Institute
city: Ljubljana
country: Slovenia
facility: University of Ljubljana
city: Lausanne
country: Switzerland
facility: Institute of Sport Sciences of the University of Lausanne
state: Canton Of Vaud
Study officials:
References: