Babies who are born very prematurely are often born with murmurs in the heart. In preterm babies, one of the most common causes of murmur is the presence of a PDA. This is the persistence of a connection that normally exists in the baby before it is born, connecting between the major blood vessels that leave the heart. In term babies, this channel closes shortly after birth when normal adult circulation is achieved. However, in preterm babies, the PDA can remain open, which can lead to multiple problems in the baby.

Our current standard of treatment in the Neonatal Intensive Care Unit (NICU) is to perform cardiac ultrasound (echocardiogram) in all babies less than 29 weeks gestation to diagnose the presence of hsPDA. We also use an echocardiogram to follow the PDA until complete closure. If present, the standard treatment in the NICU is to give medication, usually Ibuprofen, a non-steroidal anti-inflammatory drugs (NSAID), to close the PDA.

Near-infrared spectroscopy (NIRS) is a new type of device to detect oxygenated blood supply to the brain, kidney, and abdominal regions. This device is used to assess the effects of Ibuprofen on oxygen supply to these three regions.

Inclusion Criteria:

• Preterm infants less than (< )29 weeks gestation at birth
• Echocardiographic evidence of hsPDA (as outlined in the NICU PDA treatment guidelines) at 7-21 days of life requiring pharmacologic treatment as determined by the managing physician.

Exclusion Criteria:

• Not able to consent for any reason
• Preterm infants with congenital heart disease except for PDA, PFO (patent foramen ovale), small and restrictive ASD (atrial septal defect), or small VSD (ventricular septal defect).
• Preterm infants with lethal genetic malformations.
• Preterm infants with congenital abdominal wall defects (omphalocele, gastroschisis).
• Preterm infants with congenital or acquired brain anomaly.
• Infants who receive ibuprofen for PDA treatment during the first week of life will be excluded. We will recruit infants between day 7 and 21 only because high-dose ibuprofen is not indicated during the first week of life
• Preterm infants with contraindications to Ibuprofen therapy, including severe intraventricular hemorrhage (IVH), low platelet count < 50,000 platelets per microliter, renal impairment with creatinine >160 mmol/L or necrotizing enterocolitis (NEC) > Stage 2 (using modified bell's Criteria).
• Preterm infants with spontaneous intestinal perforation (SIP).
• Acute kidney injury (defined as an increase in serum creatinine of 50% or more from the previous lowest value or a urinary output of less than 1 mL/kg per hr.).