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Projects / Programmes source: ARRS

Cardio-respiratory responses during hypoxic exercise in individuals born prematurely

Research activity

Code Science Field Subfield
3.05.00  Medical sciences  Human reproduction   

Code Science Field
B007  Biomedical sciences  Medicine (human and vertebrates) 

Code Science Field
3.02  Medical and Health Sciences  Clinical medicine 
Keywords
Hypoxia, pre-term birth, exercise tolerance, oxygenation, ventilation control, cardiorespiratory responses
Evaluation (rules)
source: COBISS
Researchers (10)
no. Code Name and surname Research area Role Period No. of publications
1.  28474  PhD Tadej Debevec  Sport  Researcher  2016 - 2018  337 
2.  37386  Uroš Krivec  Human reproduction  Researcher  2016 - 2018  311 
3.  33333  PhD Adam Charles McDonnell  Neurobiology  Researcher  2016 - 2018  134 
4.  14676  PhD Igor Mekjavić  Cardiovascular system  Researcher  2016 - 2018  1,250 
5.  25792  PhD Minca Mramor  Human reproduction  Researcher  2016 - 2017  58 
6.  09180  PhD David Neubauer  Oncology  Researcher  2016 - 2018  721 
7.  21413  PhD Damjan Osredkar  Human reproduction  Principal Researcher  2016 - 2018  407 
8.  19104  PhD Blaž Stres  Animal production  Researcher  2016 - 2018  348 
9.  07002  PhD Dušan Šuput  Neurobiology  Researcher  2016 - 2018  423 
10.  03264  Bogomir Vrhovec  Systems and cybernetics  Technician  2016 - 2018  60 
Organisations (3)
no. Code Research organisation City Registration number No. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  85,011 
2.  0312  University Medical Centre Ljubljana  Ljubljana  5057272000  73,076 
3.  0381  University of Ljubljana, Faculty of Medicine  Ljubljana  1627066  44,169 
Abstract
Hypoxia associated with high altitude exposure triggers numerous cardiovascular adjustments and decreases overall physical performance. Exaggerated physiological responses to hypoxia can lead to life-threatening conditions such as pulmonary and/or cerebral edema. As a result of transportation modernization an increasing number of individuals visit high-altitude destinations for work, leisure and recreational purposes. Consequently, there is also a greater number of high-altitude visitors that are potentially more susceptible to detrimental effects of hypobaric hypoxia. In particular, individuals born prematurely might be especially vulnerable due to alternations in cardiorespiratory control. Hypoxic ventilatory response (HVR) is an acute increase in ventilation as a consequence of decreased arterial O2 pressure. Blunted HVR might delay or compromise acclimatization and can intensify hypoxia-induced medical issues. Preterm infants have been shown to demonstrate lower ventilatory responses to both hypoxia and hyperoxia. This blunted HVR in preterm infants has been ascribed to immature respiratory control, secondary to prolonged post-birth hyperoxia treatment. While it was initially thought that these impairments diminish with age, recent evidence suggests that HVR remains blunted in preterm individuals even in adult age. The main aim of the present project is to investigate the cardio-respiratory responses during rest and exercise in three groups of prematurely born, but otherwise healthy children, adolescents and adults. The project aims to elucidate the underlying mechanisms as well as the changes over maturation-time of the resting and exercise cardio-respiratory responses in prematurely born individuals. The project comprises three separate studies, each investigating resting and exercise cardiorespiratory responses during exposure to hypoxia in individuals of three different age groups: Children (10-13 yrs), Adolescents (14- 18 yrs) and Young adults (18-22 yrs). For each age group we will recruit 15 prematurely born, but otherwise healthy individuals (PRETERM group; gestational age: ≤ 32 weeks; gestational weight ≤ 1500 g) and 15 healthy, age-matched individuals born at full term (CONTROL group). The experimental protocol in each age group will comprise of two testing sessions. On both occasions, separated by no more than seven days, the participants will perform a graded exercise test to voluntary exhaustion. During the exercise tests the participants will breathe either the ambient normoxic air (NORM; fraction of inspired oxygen (FiO2)=0.209) or a humidified hypoxic air mixture (HYPO; FiO2=0.130 corresponding to terrestrial altitude of approx. 3800 m) in a randomized, placebo-controlled manner. Indirect calorimetry, near infrared spectroscopy and ECG measurements will be performed throughout all tests. During both testing session, the participants will also perform a hypoxia sensitivity test to assess the resting and exercise HVR. In addition, select hematological and oxidative stress markers will be determined from the blood samples obtained before and after each hypoxia sensitivity test. This research will be unique since no similar studies to date have been performed in these cohorts. These data will enable evidence-based recommendations for high altitude sojourns in different age groups of individuals born prematurely, which to date is poorly understood. The obtained results will also provide extensive basic physiological data on the development of cardiorespiratory control in individuals born prematurely during maturation. In order to expand on the obtained data we also initiated a collaboration with our international colleagues from University of Lausanne and University Lyon, with whom an additional study will be performed to test the potential differences in the effects of hypobaric & normobaric hypoxia in this vulnerable cohort.
Significance for science
More than 5% of world population was born prematurely. The population of individuals born prematurely has a higher risk for various health problems such as breathing, heart, temperature control, gastrointestinal, blood, metabolism, immune system problems and long term complications such as cerebral palsy, impaired cognitive skills, visual, hearing, dental, behavioral and psychological problems and other chronic health issues. However, many of the underlying mechanisms are not yet fully understood. The proposed research project is aimed at better understanding certain aspects of how well and in what ways this population can adapt to certain nonphysiological conditions to which they are exposed in daily life, ie. while travelling at high altitudes or air travel. Data obtained and published in this study could help guide health workers and industry in better accommodating the needs prematurely born individuals.
Significance for the country
According to International Civil Aviation Organization (ICAO), three billion passengers travel by air each year. While traveling, these passengers are exposed to lower cabin pressures and lower humidity of air. Although many passengers don’t experience any problems under such conditions, certain groups of passengers adapt to these changes with more difficulty. One such population are individuals born prematurely. According to WHO, 5% - 18% of babies are born preterm in various countries around the world. Therefore, each year at least 150 million individuals born prematurely travel by air, but little is known about  how well they can tolerate the in-flight conditions. Insight into the physiological responses of individuals at risk in such conditions, could help form safety measures for the airline industry.
Most important scientific results Interim report, final report
Most important socioeconomically and culturally relevant results Interim report, final report
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