• Change in amount of phasic EAdi before and after an intermittent bolus feed [ Time Frame: Day of study ] [ Designated as safety issue: No ]
• Change in the number of apnea episodes on the EAdi waveform before and after an intermittent bolus feed [ Time Frame: Day of study ] [ Designated as safety issue: No ]
• Changes in tonic and phasic EAdi, and apnea between intermittent bolus and intermittent slow-bolus feed [ Time Frame: Day of study ] [ Designated as safety issue: No ]
• Diaphragmatic fatigue [ Time Frame: Day of study ] [ Designated as safety issue: No ]
• Episodes of clinically significant apnea between intermittent bolus and intermittent slow bolus feed [ Time Frame: Day of study ] [ Designated as safety issue: No ]
• Episodes of regurgitation or vomiting between intermittent bolus and intermittent slow bolus feed [ Time Frame: Day of study ] [ Designated as safety issue: No ]

In this study, we want to see how feeding affects breathing in small premature babies. Using a special feeding tube in the stomach, we can measure how the diaphragm (a large breathing muscle) might be affected by feeding. We also want to see if slowing down the feeding may lessen this effect.

Premature babies may have pauses in breathing known as apnea, which may require invasive treatment. The exact cause of apnea is unknown, and may be related to a combination of brain, gut, and lung immaturity.

Research in premature babies suggests that feeding may affect lung functions, but such effects may be lessened if feeds are given at a slower rate. Further research showed that the diaphragm, an important breathing muscle, may be fatigued by a full stomach. We speculate that, in premature babies, feeding might tire the diaphragm, thus impairing lung function and possibly causing apnea.

We plan to study 10 stable premature babies less than 23 weeks and 1.25 kilograms at birth. By inserting a special feeding tube with sensors into the stomach, we can measure the electrical activity of the diaphragm (EAdi). By analysing EAdi before and after feeding, we want to directly measure how feeding might affect lung functions. We also want to compare feeding at the usual rate (5-15 minutes) versus a slower rate (90 minutes) to see how their effects on lung functions might differ.

This important study will help us determine the most appropriate treatment for premature babies with apnea related to feeding.

• Infant, Premature
• Apnea

Inclusion Criteria:

• Preterm infants >23 weeks gestation
• Birth weight <1250 grams
• Not requiring full mechanical ventilation
• Tolerating full regular bolus feeding for at least 48 hours

Exclusion Criteria:

• Congenital and acquired problem of the gastrointestinal tract
• Phrenic nerve injury and/or diaphragm paralysis
• Esophageal perforation/tracheoesophageal fistula
• Congenital/acquired neurological deficit and/or seizures
• Hemodynamic instability
• Congenital heart disease (including symptomatic patent ductus arteriosus)
• Undergoing treatment for sepsis or pneumonia
• Use of muscle relaxants, narcotic analgesics, or gastric motility agents