The purpose of this study is to examine the blood flow and the delivery of oxygen to the brain and gut in preterm babies while they are supported with two modes of breathing machine and compare these two methods to see if one allows for better blood flow to the brain and gut.

Preterm babies under 32 weeks of gestational age usually needs to be supported with breathing machine because of different kinds of problems like lungs immaturity or infection. One type of breathing machine support is called CPAP(Continuous Positive Airway Pressure).This breathing support machine is connected to the nose to help preterm baby breathe. This machine blows air or an air/oxygen mixture through the nose and in to the baby's lung; this helps to keep baby's lungs fully open and makes it easier for the baby to breathe. There are two ways this machine can help the baby breathe - it can either blow the air/oxygen mixture at the same pressure all the time…we call that CPAP, or we can vary the pressure - we call that TrPA(Trigger Pressure Assist). Both methods have been in use in neonatal intensive care units(NICUs) for several years and both methods help with the breathing of babies.

The breathing machine (CPAP) makes the lungs better inflated. This inflation might affect the ability of the heart to push the blood to the organs through the blood vessels. Also we do not know whether there is any difference in the blood flow or oxygen delivery depending whether the baby is on CPAP or TrPA.

We will measure the heart function using Ultrasound (Echocardiography). To measure the efficiency of the flow of the blood through the vessels to the organs we will use Near Infra Red Spectroscopy (NIRS); this involves applying a sensor to the baby's skin - one on the forehead and one on the tummy and connecting the sensors to a machine which can measure the oxygen level in the organ under the skin.

While the baby is on CPAP, we will start monitoring oxygen saturation by applying NIRS sensors to the forehead and the abdomen. After 3 hours we will do echocardiography (ultrasound of the heart)to see any changes that might happen to the heart and blood vessels while the baby is on CPAP. Then, using the same machine, we will change the mode of respiratory support to TrPA. After another three hours, we will do another echocardiography (ultrasound of the heart), then we will stop NIRS monitoring and change the mode of respiratory support back to CPAP.

Inclusion Criteria:

• Preterm infants less than 34 weeks gestational age
• Requirement of CPAP or TrPA as a mode of respiratory support

Exclusion Criteria:

• Lack of parental consent
• Preterm infants more than 34 gestational weeks
• Preterm infants with congenital malformation
• Severe perinatal asphyxia
• Hemodynamically significant patent ductus arteriosus (PDA)
• Pulmonary hypertension
• Septic shock
• Any associated congenital heart diseases other than non-significant PDA or patent foramen ovale (PFO)
• Stage 2 or 3 necrotising enterocolitis (NEC)
• Intraventricular hemorrhage (IVH) grade 3 or 4

Newborn infants less than 34 weeks gestational age at birth Requiring CPAP or TrPA as a mode of respiratory support