Novel Use of Negative Pressure Assist in Neonates With Respiratory Distress: a Feasibility Study Using Neovest

Respiratory distress is a common reason why newborn infants require intensive care soon after birth. Premature infants are at risk of having immature lungs and/or weak respiratory muscles requiring the provision of respiratory support with a mechanical ventilator. Full term infants can also require respiratory support for lung disease or lung immaturity. The most commonly used form of non-invasive respiratory support is positive pressure delivered via nasal prongs or a nasal mask, also known as nasal continuous positive airway pressure (nCPAP). Nasal CPAP is thought to be effective in a variety of newborn lung disorders including respiratory distress syndrome, transient tachypnea of the newborn, etc. Although many forms of nCPAP exist, they are not typically synchronized to a baby's breathing efforts (1,2).

Furthermore, due to the infants' sensitive skin and underdeveloped nasal bridges, continued use of nasal devices can lead to skin breakdown and permanent damage to the nose (3). In order to provide optimal ventilation, these devices must be tight-fitting nasal interfaces to provide a leak-free environment (3). There is also variability in the success of nasal interfaces in providing uniform ventilation. This is because the positive pressure provided at the level of the infants' nostrils is dissipated (through the open mouth, etc.) as it travels down the infants' airways to the alveoli of their lungs (3). Additionally, prolonged use of nasal ventilation methods may impede infant bonding with their mothers via decreased skin-to-skin time, etc. Nasal CPAP is often cited as a reason why feeding (including breastfeeding) is delayed in babies requiring neonatal intensive care stay.

Negative pressure ventilation (NPV) involves the application of sub-atmospheric pressures around the abdomen to displace the diaphragm. It is a unique alternative for administering NIV to infants and would avoid complications associated with nasal interfaces. NPV has previously been used in treating infants with respiratory distress using old-fashioned, large and bulky "iron-lung" devices (4-12). One of the earliest studies using NPV for infants with respiratory failure showed that in a series of 26 patients, NPV provided a sustained increase in PaO2 (5). The infants were a mean gestational age of 32 to 33 weeks and met the criteria for respiratory failure defined by PaO2 < 40mmHg on 100% inspired oxygen and/or PCO2 > 70mmHg during bag-mask ventilation (5). Further studies on NPV, continued to show effectiveness in the ventilation of infants with lung disease with improved oxygenation (6-12).

In this study, the investigators propose a novel negative pressure interface and device that is synchronized to the infant's respiratory drive and provides intermittent application of negative pressure. The device utilizes Neurally Adjusted Ventilator Assist (NAVA) technology to achieve synchronization to the infant's underlying respiratory drive and control.

The electrical activity of the diaphragm (Edi) is measured using a specialized feeding tube catheter with miniaturized sensors at the end. There is a small balloon at the tip of the catheter that measures the gastric pressure which provides evidence that the diaphragm is being displaced. The Edi catheter has been shown in previous work to be effective in delivering both invasive and non-invasive positive pressure ventilation with the FDA-approved NAVA and a variety of interfaces (13-15). The Edi catheter is used routinely in many NICUs worldwide as a conventional nasal or oral catheter.