Cardiorespiratory events, defined by the occurrence of apneas, bradycardias, and desaturations, are almost ubiquitous in very preterm infants and are associated with numerous complications. Unfortunately, the current standard for monitoring cardiorespiratory events in the NICU, transthoracic impedance (TTI), does not permit for accurate differentiation of the different types of cardiorespiratory events; TTI cannot detect airflow and has low accuracy for detecting respiratory efforts. As a result, TTI does not detect obstructive apneas and may not reliably capture all central apneas.~Respiratory sounds are an attractive surrogate measure of airflow, and can be captured using respiratory acoustic technology (akin to a miniaturized electronic stethoscope). We hypothesize that respiratory acoustic monitoring can provide a continuous, non-invasive, and accurate representation of airflow and breathing sounds in preterm infants.~Moreover, the electrical activity of the diaphragm (EAdi) represents a promising alternative surrogate to TTI for the measurement of breathing efforts. We hypothesize that non-invasive measurements of the diaphragm's electrical activity may be more accurate than current monitoring standards in detecting respiratory efforts in preterm infants.~Altogether, we conjecture that the combination of respiratory acoustic monitoring with measurements of respiratory effort will improve the ability to differentiate and describe the nature of cardiorespiratory events in preterm infants.
This is an observational, proof-of-concept, feasibility study where 25 preterm infants with gestational age < 32+0 weeks will be recruited from the neonatal intensive care unit (NICU) at the Montreal Children's Hospital.~The study's primary objective is to describe the relationship between respiratory acoustics and airflow and determine the reliability of respiratory acoustic monitoring at detecting breathing sounds in preterm infants.~The study's secondary objective is to compare transthoracic impedance, respiratory inductive plethysmography and electrical activity of the diaphragm for the detection of respiratory efforts in preterm infants.