The present study will use a new type of respirator in premature babies who need help with their breathing. This new respirator uses signals from the baby's diaphragm - the most important breathing muscle - to control the timing and the amount of air that the baby needs. The goal of the study is to demonstrate that this new respirator can synchronize delivery of air to the baby's efforts, and that synchrony is maintained regardless of whether the baby is breathing with a tube or a mask.