Physiologic Biomarkers Predicting Ventilatory Instability and Hypoxemia in Pre Mature Infants

The investigator will look at results of breathing tests, non-invasive sound wave (ultrasound) test of the heart and blood vessel (Echocardiography), and a sample of blood to see if it is possible for early detection of breathing control and lung blood vessel dysfunction (pulmonary vascular disease) in infants that are at risk for exposure to long term low oxygen levels. A subset of infants will have a magnetic resonance Imaging study (MRI) between 37- 40 weeks gestational age (GA) or at the time of discharge, whichever comes first.

Respiratory tests include:

• Bedside Physiology Study completed at 28, 32, 36, 40, and 52 weeks GA in conjunction with the respiratory tests. A 90-minute recording will be made using standard recording equipment that includes a conventional pulse oximeter, an EEG, an airflow sampling catheter near the nose, and respiratory inductance plethysmography (RIP) bands. Standard bedside monitoring will continue during the physiologic studies
• Carotid Body Function Test completed at 32, 36, 40 and 52 weeks GA. This test is to unmask respiratory instability in response to hyperoxia.
• Challenge Test completed at 36 weeks GA.

1. Infants receiving nasal cannula flow with or without supplemental oxygen will undergo a Room Air Challenge Test.
2. Infants on RA alone will undergo a Hypoxia Challenge test.

• Effects of Nasal Cannula Flow completed at 28, 32, 36, 40 and 52 week's GA. The flow will be increased through a nasal cannula. This test is to see how flow effects the breathing pattern.

A subset of infants will have an MRI between 37-40 weeks GA or before discharge, whichever comes first. The MRI will allow the doctors to look and see if there is any injury present in the brain that can be linked to an abnormal breathing pattern called periodic breathing.