Effects of Two Modalities of Non-invasive Ventilation After Extubation in Very Low Birth Weight Neonates

Effects of Two Modalities of Non-invasive Ventilation After Extubation in Very Low Birth Weight Neonates

Effects of Two Modalities of Non-invasive Ventilation on Breathing Pattern Variables of Preterm Neonates of Very Low Weight After Extubation

The objective of this study is to evaluate the effects of continuous positive airway pressure and nasal intermittent positive pressure ventilation on breathing pattern variables of very low birth weight neonates immediately after extubation.

The effects of non-invasive ventilation on the respiratory function of neonates have not been fully elucidated. Currently, two modalities of non invasive ventilation are commonly used in Brazilian neonatal intensive care units: continuous positive airway pressure (CPAP) and nasal intermittent positive pressure ventilation (NIPPV). In this study, it was hypothesized that NIPPV will improve tidal volume when compared to CPAP. The objective of this study is to evaluate the effects of continuous positive airway pressure and nasal intermittent positive pressure ventilation on breathing pattern variables of very low birth weight neonates immediately after extubation. Soon after extubation, the neonates will be randomized into the CPAP-NIPPV (sequence 1) or the NIPPV-CPAP (sequence 2). The sequence will be assigned at random using sealed envelopes. Respiratory inductive plethysmography will be used to evaluate the breathing pattern (tidal volume, respiratory rate, minute ventilation, mean inspiratory flow) and chest wall motion (labor breathing index, inspiratory phase relation, expiratory phase relation, total phase relation and phase angle). Student t tests for paired samples will be used and the Wilcoxon test according to the data distribution. A significance level of 5% will be adopted. The analyzes will be performed by StatisticalPackage software for the Social Sciences® (SPSS, Chicago, IL, USA), version 17.0 for Windows.

In this group, soon after extubation, the newborns will be studied initially in NIPPV for one hour. Infants will be studied in supine while in their incubator. NIPPV: Nasal Intermittent Positive Pressure Ventilation

In this group, soon after extubation, the newborns will be studied initially in CPAP for one hour. Infants will be studied in supine while in their incubator. CPAP: Continuous Positive Airway Pressure

- NIPPV The following parameters: inspiratory pressure = 15 cmH2O / final expiratory positive pressure = 6 cmH2O / inspiratory time = 0.40 / flow = 6-8 L.min-1 / respiratory rate = 24. Respiratory inductive plethysmography is used to evaluate breathing pattern (tidal volume, respiratory rate, minute ventilation, mean inspiratory flow) and chest wall motion (labor breathing index - LBI, phase relation in inspiratory breathing - PhRIB, phase relation in expiratory breathing - PhREB, total phase relation - PhRTB and phase angle).

- CPAP The following parameters: pressure of 6 cmH2O, with flow of 6-8L/min. Respiratory inductive plethysmography is used to evaluate breathing pattern (tidal volume, respiratory rate, minute ventilation, mean inspiratory flow) and chest wall motion (labor breathing index - LBI, phase relation in inspiratory breathing - PhRIB, phase relation in expiratory breathing - PhREB, total phase relation - PhRTB and phase angle).

Measure during the two non-invasive ventilation strategies. Tidal volume will be measured for 2 hours, one hour in continuous positive airway pressure and one hour in nasal intermittent positive pressure ventilation.

Measure during the two non-invasive ventilation strategies. Respiratory rate will be measured for 2 hours, one hour in continuous positive airway pressure and one hour in nasal intermittent positive pressure ventilation.

Measure during the two non-invasive ventilation strategies. Minute ventilation will be measured for 2 hours, one hour in continuous positive airway pressure and one hour in nasal intermittent positive pressure ventilation.

Is a estimation of respiratory center drive activity. The higher its value, the greater the drive and vice-versa.

Measure during the two non-invasive ventilation strategies. Mean inspiratory flow will be measured for 2 hours, one hour in continuous positive airway pressure and one hour in nasal intermittent positive pressure ventilation.

This is a measure of chest wall coordination. This is the Labored Breathing Index (LBI) of a breath that takes into account phase and amplitude of the ribcage and abdomen traces. It is computed as the ratio of the sum of the integrals of the absolut values of the derivatives of the inspiratory limbs of ribcage and abdomen excursions divided by the corresponding integral of the derivative of the inspiratory limb of the tidal volume deflection. This measure of thoracoabdominal coordination is computed on a breath by breath basis. Perfect thoracoabdominal coordination produces an LBI of 1.0. In babies or adults who are relaxed and awake or in Quiet State, LBI lies between 1.0 and 1.2 but no systematic study of the normal values of LBI as a function of sleep stage and body posture has yet been undertaken. In Active State, thoracoabdominal discoordination generally is associated with elevated LBI values.

Measure during the two non-invasive ventilation strategies. Labor breathing index (LBI) will be measured for 2 hours, one hour in continuous positive airway pressure and one hour in nasal intermittent positive pressure ventilation.

This express the percentage agreement between direction of ribcage and abdomen movements during the inspiratory phase of breath.

Measure during the two non-invasive ventilation strategies. Phase relation in inspiratory breathing will be measured for 2 hours, one hour in continuous positive airway pressure and one hour in nasal intermittent positive pressure ventilation.

This express the percentage agreement between direction of ribcage and abdomen movements during the expiratory phase of breath.

Measure during the two non-invasive ventilation strategies. Phase relation in expiratory breathing will be measured for 2 hours, one hour in continuous positive airway pressure and one hour in nasal intermittent positive pressure ventilation.

This express the percentage agreement between direction of ribcage and abdomen movements during the entire breath cycle.

Measure during the two non-invasive ventilation strategies. Phase relation in total breathing will be measured for 2 hours, one hour in continuous positive airway pressure and one hour in nasal intermittent positive pressure ventilation.

The phase angle is computed from Lissajous loops between ribcage and abdomen excursions on a breath by breath basis.

Measure during the two non-invasive ventilation strategies. Phase angle will be measured for 2 hours, one hour in continuous positive airway pressure and one hour in nasal intermittent positive pressure ventilation.

Inclusion Criteria: Presented gestational age less than or equal to 32 weeks and weight less than or equal to 1,500 g; Stability from an hemodynamic point of view (without use of amines); Have undergone invasive mechanical ventilation; Absence of congenital heart diseases and / or other congenital anomalies (myelomeningocele, gastroschisis and / or omphalocele) or chromosomal abnormalities; Absence of any condition that requires surgery in the neonatal period. Exclusion Criteria: Presented air leak syndrome (pneumothorax, pneumomediastinum); upper airway obstruction after extubation and non-scheduled extubation.