This project will consist of two studies, each investigating resting and exercise cardio-respiratory responses during exposure to hypoxia in individuals born prematurely and individuals born at full term of two different age groups: Kids (10-14 yrs) and Adults (18-22 yrs).Additional study will be performed on a preterm adult cohort (15 participants) that will investigate potential differences between hypobaric and normobaric hypoxia as outlined in the following section.
The study protocol in each age group will comprise two visits to the laboratory testing sessions in a randomized order. On one occasion the participants will perform a resting hypoxia test and a graded exercise test to voluntary exhaustion in normoxic condition ((NORM; fraction of inspired oxygen (FiO2)=0.209, placebo). On a second visit the participants will perform a hypoxia sensitivity test and a graded exercise test to voluntary exhaustion in hypoxic condition (HYPO; FiO2=0.120 corresponding to terrestrial altitude of approx. 4000 m). Indirect calorimetry, near infrared spectroscopy and ECG measurements will be performed throughout all tests. During both testing sessions the participants will also undergo anthropometry measurements and pulmonary function testing. The outline of the research visits is presented in the bellow figure:
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
SINGLE
Enrollment
37
All graded exercise tests will be performed on electromagnetically controlled cycle-ergometer Ergo Bike Premium. The testing protocol will commence with a 10-min resting period, to obtain the resting cardio-respiratory values, followed by a 5-min warm up at a work rate of 60 W. Thereafter the workload will increase every fourth minute by 40 W. The participants will be required to maintain a cadence of 60·min-1 throughout the whole test. The test is terminated when the participant is unable to maintain the assigned cadence.
The resting test will be performed in supine position with participants breathing normoxic air (FiO2=0.21) for 30 min and hypoxic gas for the subsequent 30-min (FiO2=0.120). During the whole protocol duration the respiration, local blood flow, ECG and EEG will be measured non-invasively.
Jozef Stefan Institute
Ljubljana, Ljubljana, Slovenia
RECRUITINGUniversity Children's Hospital Ljubljana Department of Pediatric Neurology
Ljubljana, Ljubljana, Slovenia
RECRUITINGTolerance to hypoxia during rest and exercise in preterm and full term individuals
All graded exercise tests will be performed on electromagnetically controlled cycle-ergometer Ergo Bike Premium.The participants will be required to maintain a cadence of 60·min-1 throughout the whole test. The test is terminated when the participant is unable to maintain the assigned cadence. The resting test will be performed in supine position with participants breathing normoxic air (FiO2=0.21) for 30 min and hypoxic gas for the subsequent 30-min (FiO2=0.120). During the whole protocol duration the respiration, local blood flow, ECG and EEG will be measured non-invasively. The resting test will be performed in supine position with participants breathing normoxic air (FiO2=0.21) for 30 min and hypoxic gas for the subsequent 30-min (FiO2=0.120). During the whole protocol duration the respiration, local blood flow, ECG and EEG will be measured non-invasively.
Time frame: Two year
Cardio-respiratory control at rest in normoxia and hypoxia in preterm and full term individuals
The resting test will be performed in supine position with participants breathing normoxic air (FiO2=0.21) for 30 min and hypoxic gas for the subsequent 30-min (FiO2=0.120). During the whole protocol duration the respiration, local blood flow, ECG and EEG will be measured non-invasively. The resting test will be performed in supine position with participants breathing normoxic air (FiO2=0.21) for 30 min and hypoxic gas for the subsequent 30-min (FiO2=0.120). During the whole protocol duration the respiration, local blood flow, ECG and EEG will be measured non-invasively.
Time frame: One year
Oxidative stress responses to hypoxic exercise in preterm and full term
Blood sampling will be performed during each visit at four time points (before and after each test, as detailed on the bellow figure. Besides general hematological markers (CBC, ferritin, transferrin etc.) oxidative stress (advanced oxidation protein products, malondialdehyde and nitrotyrosine) and antioxidant system markers (superoxide dismutase, catalase, ferric-reducing antioxidant power, glutathione peroxidase and uric acid) will be determined as described previously (3). Select gene polymorphisms and their association with the above mentioned oxidative stress markers will also be assessed from the collected blood samples in collaboration with the laboratory for Pharmacogenetics, Medical Faculty, UL
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Time frame: One year
Sensitivity to hypoxia during rest and exercise - Richalet test
This test will assess individuals tolerance to hypoxia and HVR. As noted in the above figure the test consist of a 4-min periods of normoxic (FiO2=0.210) and hypoxic (FiO2=0.120) rest and hypoxic and normoxic low-intensity exercise. Respiration, gas exchange and capillary oxygen saturation will be measured during the course of the test.
Time frame: One year
Changes in intestinal metabolites as a result of hypoxic exposure
The aim of this protocol is to assess whether there are significant differences in physiological status of intestinal metabolites (reducing sugars, short chain fatty acids, amino-acids, index of molecular weight, polyphenols, sterols) between the two populations in response to normoxic and hypoxic testing procedures. As sampling needs to be conducted during the period preceding the actual days of experiments and after the completion of testing, i.e. during the daily routines of participants, auto-sampling protocol was selected as the only option through which samples of feces and urine are going to be collected by participants three days before and after physical testing.
Time frame: One year
Differences between normobaric and hypobaric hypoxia in preterm individuals
This part of the study will investigate potential differences between normobaric and hypobaric exposure to hypoxia in preterm born individuals. For this purpose the participants will perform another laboratory visit in Ljubljana and will also be exposed to hypobaric hypoxia in a physiology lab at Aiguille du Midi, which is run by our collaborators. As noted in the bellow schematic each exposure will last 8-hours and measures of respiration, gas exchange and blood sampling will be performed at 2-4 hour periods during the exposure. The participants will be transferred to Chamonix using a van with our research team in groups of four. The transfer from Chamonix to Aiguille du Midi laboratory will be performed via cable car
Time frame: Two years