Now, researchers at the University of Virginia, the UVA School of Medicine and the College of William & Mary have developed a new way to measure the coupling of an infant’s heartbeat and breathing – a key indicator for whether a newborn is ready to leave a neonatal intensive care unit (NICU).
Their research was published Monday in the Journal of Applied Physiology, based on an analysis of the breathing and heartbeat patterns of 1,202 infants in the NICU at the UVA Medical Center from January 2009 to June 2011.
Apnea of prematurity: The importance of connections
Babies born extremely prematurely often forget to breathe – a condition called apnea of prematurity – due to their immature nervous systems, says UVA neonatologist John Kattwinkel, MD, a co-author of the research paper. Very premature babies must stay in the NICU for weeks or months so healthcare workers can monitor the babies’ breathing patterns and help them breathe when apnea of prematurity occurs.
The coupling of a baby’s heartbeat to its breathing patterns is an important sign that an infant’s nervous system is developing properly, says UVA cardiologist J. Randall Moorman, MD, a co-author of the research paper. “The close matching of the heartbeat to breathing shows that there is a maturation of connections within the brain,” he says. “This is a good surrogate for maturation of other connections, and is very specifically reassuring that the infant’s control of breathing is stable.”
The researchers developed an analytic tool that combines algorithms and a software program to review breathing and heartbeat data in 4-minute segments to determine how closely matched the two patterns are for each infant. The researchers found that the coupling of breathing and heartbeat in premature infants is a function of their post-menstrual age – the amount of time since the mother’s last menstrual period – not of the infant’s birth weight or how prematurely the infant was born.
The researchers plan to further refine their analytic tool with the hopes of providing a reliable guide to NICU physicians. “We want to collect and analyze data from preterm infants with the goal of giving more attention to sick babies and releasing healthy babies sooner,” says Matthew Clark, the study’s lead author and a research associate at UVA’s Department of Chemical Engineering.
Kattwinkel adds: “Our eventual goal will be to develop a measure of neurologic maturity that can reassure the clinician that it is safe to discharge the baby home, perhaps reducing the length of an infant’s hospitalization.”