Respiratory Support and Brain Health in Preterm Infants

Study Overview
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Brief Summary
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Premature babies often require breathing support during their neonatal intensive care unit stay. This is because their lungs are not fully developed to perform the work of breathing on their own. Although breathing support can be provided via a breathing tube, it is preferable to provide breathing support non-invasively from a breathing machine which is then connected to a mask or prongs placed on the baby's nose. In premature babies born under 32 weeks gestation, a commonly used mode of non-invasive breathing support is called Non-Invasive Positive Pressure Ventilation (NIPPV). In this mode, the breathing machine provides 2 levels of support: one is the constant distending pressure to keep the lungs open and the other provides additional 'breaths' on top of that distending pressure. This is to mimic regular breathing. These breaths are set at a fixed rate and pressure. Although NIPPV protects the lungs from injury caused by a breathing tube, the breaths are not in sync with the baby's own breathing effort. Another mode of non-invasive breathing support recently being used in premature infants called Neurally Adjusted Ventilatory Assist (NAVA). When NAVA is provided non-invasively using a mask or prongs similar to NIPPV, it is called Non-invasive NAVA (NIV-NAVA). During NIV-NAVA a special feeding tube is used that detects the baby's own breathing movement from the electrical signal of the baby's diaphragm and feeds back to the machine which then provides a 'top-up' to the baby's own breath. This top-up breath also provides only as much pressure as the baby needs on top on their own breathing effort. Therefore, this is thought to be in sync with the baby's own breathing effort. However, it is not known if this mode of ventilation leads to improved sleep, improved brain oxygen levels, reduced discomfort and improved functioning of the diaphragm. The investigators aim to examine these indices in this research project.

Detailed Description
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Rationale: It is imperative to find the optimal method of supporting not only lung development, but also brain development during this critical period of brain growth and development. NIV-NAVA is a more physiologically compatible method of supporting respiration. The investigators hypothesize that this compatibility may increase comfort and restful periods compared to standard NIPPV, and thus, may be more neuroprotective. Objective and outcomes assessed: The objective is to compare sleep-wake cycling, cerebral oxygenation, heart rate variability and diaphragm function during standard NIPPV and NIV-NAVA modes in preterm neonates born at <32 weeks' gestation who are stable on NIPPV or NIV-NAVA for at least 24 hours and are a minimum of 3 days old.

Official Title
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Respiratory Support and Brain Health in Preterm Infants: A Prospective Crossover Study

Conditions
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Sleep, Cerebral Oxygenation

Intervention / Treatment
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* Device: Non-invasive Neurally Adjusted Ventilatory Assist


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Preterm infants born between 23+0 and 31+6 weeks' GA Weight > 500 g at birth A minimum of 3 days of age Clinically stable for > 24 days while receiving NIPPV or NIV-NAVA Clinical stability will be defined as meeting all the following criteria for a 24 hour period prior to recruitment: differences in maximum and minimum fractions of inspired oxygen (FiO2) of <20%, differences in maximum and minimum MAP <4 cm H2O, no active infection, no hypotension, no use of cardioactive medications or medical therapy for patent ductus arteriosus. Exclusion Criteria: Infants with IVH of grade 3 or 4 Birth weight < 3rd percentile Genetic or congenital abnormalities

Ages Eligible for Study
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Minimum Age: 3 Days

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Device: Non-invasive Neurally Adjusted Ventilatory Assist|Neurally Adjusted Ventilatory Assist (NAVA) is a new non-invasive ventilation mode that uses the electrical activity of the diaphragm (EAdi) to offer ventilatory assistance in synchrony with patient effort, thus potentially reducing stress and discomfort. It uses electrodes placed on a modified nasogastric feeding tube to detect the electrical activity of the diaphragm (EAdi), such that both the initiation and termination of a breath during each respiratory cycle is in synchrony with the infant's effort|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of uninterrupted sleep-wake cycling (SWC) | An uninterrupted SWC will be defined as a smooth and gradual decrease in the minimum amplitude on aEEG to quiet sleep (QS), followed by a gradual increase to active sleep or awake state (AS). An interrupted SWC will be defined as a sudden or sharp increase in the minimum amplitude during QS with change to AS state that may or may not be followed by a further drop in QS. | For 24 hours after intervention initiation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Total duration of quiet sleep (QS) | First, high base voltage (HBV) will be defined as the voltage of the lower margin of aEEG during AS. Total QS duration will be calculated as the combined duration of time spent below the HBV in uninterrupted SWC during 24 h. | For 24 hours after intervention initiation | 
| Cerebral oxygen saturation (CrSO2) | Cerebral fractional tissue oxygen extraction (CFTOE), calculated as (oxygen saturation [SpO2] - CrSO2) / SpO2, will be calculated offline | For 24 hours after intervention initiation | 
| Newborn Infant Parasympathetic Evaluation (NIPE) index | Measurement of heart rate variability | For 24 hours after intervention initiation | 
| Diaphragmatic thickness | Measurement of Diaphragmatic thickness (DT) using lung ultrasound | 1 day during Nasal Intermittent Positive-Pressure Ventilation (NIPPV) period and 1 day during the Non-Invasive Neurally Adjusted Ventilatory Assist (NIV-NAVA) period | 
| Diaphragm thickness fraction | Diaphragmatic thickness fraction (DTF), calculated as ([(inspiratory thickness-expiratory thickness)]) / (expiratory thickness) x 100, will be calculated using diaphragmatic thicknesses obtained from lung ultrasound | 1 day during Nasal Intermittent Positive-Pressure Ventilation (NIPPV) period and 1 day during the Non-Invasive Neurally Adjusted Ventilatory Assist (NIV-NAVA) period | 
| Diaphragmatic excursion (DE) | Measurement of Diaphragmatic excursion (DE) using lung ultrasound | 1 day during Nasal Intermittent Positive-Pressure Ventilation (NIPPV) period and 1 day during the Non-Invasive Neurally Adjusted Ventilatory Assist (NIV-NAVA) period | 
| Lung Ultrasound Severity Score (LUSS) | Point score based on qualitative analysis using lung ultrasound. For each lung area, a 0- to 3-point score is given. Where 0 score refer to normal aeration and 3 score refer to severe loss of lung aeration. Total score ranging from 0-18 based on 3 areas on each lung, with low score means good lung aeration and higher means poor lung aeration. | 1 day during Nasal Intermittent Positive-Pressure Ventilation (NIPPV) period and 1 day during the Non-Invasive Neurally Adjusted Ventilatory Assist (NIV-NAVA) period | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Neurally Adjusted Ventilatory Assist, Non-Invasive Positive Pressure Ventilation, Preterm Neonates, Amplitude integrated electroencephalography