Detection of CardioRespiratory Events Using Acoustic Monitoring in Preterm Infants on CPAP

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.

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.

Inclusion criteria

for all infants:

• Gestational age < 32+0 weeks
• Postmenstrual age between 28+0 and 36+6 weeks.

Additional inclusion criteria for Groups 1 and 2:

• Off any respiratory support and breathing in-room air
• Less than 3 clinically significant cardiorespiratory events per calendar day

Additional inclusion criteria for Group 3:

• On the bubble CPAP device with the binasal prongs interface
• Receiving CPAP levels of 5 to 7 cm H2O with gas flows not exceeding 10L/min
• At least 3 clinically significant cardiorespiratory events per calendar day

Exclusion criteria

• Major known congenital abnormalities
• Known congenital heart disorders
• Known neuromuscular disease
• Known diaphragmatic paralysis or a diagnosed phrenic nerve injury
• History of esophageal perforation in the 7 days preceding the study
• History of pneumothorax requiring chest tube insertion in the 7 days preceding the study
• Receiving inotropes, narcotics, or sedative agents at the time of study recording

Additional exclusions at the time of the study recording:

• Infants receiving ventilator-derived CPAP
• Infants receiving CPAP via a nasal mask interface.
• Infants receiving inotropes, narcotics or sedative agents
• Infants deemed clinically unstable for the study by the attending neonatologist.