Non-Invasive Ventilation of the Neonate

Abstract

Nasal Intermittent Positive Pressure Ventilation (NIPPV) or Nasal Intermittent Mandatory Ventilation (NIMV) are non-invasive modes of ventilation generated by ventilators that provide NCPAP plus superimposed ventilator mandatory breaths and are identified as SNIPPV/SNIMV when the ventilator pressure waves are synchronized with the spontaneous efforts of the patient. These techniques are being increasingly used in preterm infants with respiratory failure and several trials seems to demonstrate that NIPPV and SNIPPV are more effective than NCPAP in reducing extubation failure (1-3) and also as primary mode of ventilation (4). Their effects include a higher mean airway pressure (MAP), a washout of the anatomical dead space in the upper airways and a stimulatory effect on the respiratory drive. With SNIPPV the benefits are more consistent due to the positive effects of synchronized mechanical breaths in reducing thoraco-abdominal asynchrony, inspiratory effort (5), breathing frequency and work of breathing (WOB) and at the same time in increasing tidal volume (Vt) and minute volume (Ve) (6), gas exchange (7) and respiratory drive (8). Different modes of synchronization have been reported. SNIPPV was initially performed by a capsule (Graseby capsule) placed on the baby's abdomen which detects the increase of the pressure due to the contraction of the diaphragm, but this device has several disadvantages. Although it is a relatively simple device, accuracy is limited by position and fixation, movement is often misinterpreted as breathing and at higher spontaneous breath rates its response is less consistent. Neurally adjusted ventilatory assist (NAVA), which uses electrical activity of the diaphragm (Edi) to trigger the ventilator, has been developed more recently. However, it has the disadvantage of being invasive and costly, as a dedicated electrode-equipped catheter to detect Edi is required and to date there are few data on clinical outcomes. To overcome all these disadvantages our team decided to create a ventilator expressly developed to perform flow-SNIPPV (Giulia®; GINEVRI srl, Albano Laziale, Rome, Italy). The flow-sensor, a simpler differential pressure transducer, is interposed between the nasal prongs and the Y piece (1, 2). Using this device we were able to demonstrate that flow-SNIPPV is more effective than conventional NCPAP in improving ventilation and in decreasing extubation failure in preterm infants who had been ventilated for respiratory distress syndrome (RDS) (6, 9). Later we used flow-SNIPPV as the primary mode of ventilation, after surfactant replacement, reducing the need for mechanical ventilation and favorably affecting short-term morbidities of treated premature infants (10). More recently we have also successfully applied flow-SNIPPV in the treatment of apnea of prematurity (AOP) (8). This technique has also been successfully used as rescue therapy for infants failing on NCPAP (11). Moreover, the modern concept of precision medicine aims for the improvement of efficacy of flow-SNIPPV also with continual enhancements in comfort and another main goal to further improve this technique was the development of very light and comfortable nasal prongs that have similar characteristics to the HHFNC and with the flow-sensor placed far away from the infant's head, at the level of the Y-piece. Preliminary bench and clinical studies to test this new interface confirmed the efficacy of this new lighter and more comfortable device (12).