Acoustics as a Metric of Airway Pressure in Premature Infants Using Bubble Continuous Positive Airway Pressure (Bubble CPAP)

McGill University

Status: Enrolling

Conditions: Preterm Infant

Treatments: Device: Internal pressure transducer; Device: Standard microphone; Device: External pressure transducer; Device: Wireless acoustic sensor

Study type: Observational

Funder types: Other

Identifiers

NCT07060833

2025-10708

Details and patient eligibility

About

This is an observational, proof-of-concept, feasibility study where 30 preterm infants on bubble CPAP 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 main goals are:

1. To determine the relationship between ambient bubbling sounds and delivered pressures in preterm infants on bCPAP.
2. To determine the relationship between transmitted bubbling sounds and airway pressures transmitted to the lungs of preterm infants on bCPAP.
3. To develop models to predict delivered and transmitted bCPAP pressures from the acoustic properties of bubbling sounds.

Full description

Continuous positive airway pressure (CPAP) is an essential, non-invasive therapy for treating various respiratory conditions in the Neonatal Intensive Care Units (NICU). CPAP is an effective treatment for respiratory distress syndrome, apneas, or after extubation, exerting its physiological benefits by maintaining upper airway patency and functional residual capacity. Bubble CPAP (bCPAP) is the most widely used CPAP due to its low cost and ease of use. It consists of an inspiratory tube carrying heated and humidified air, a nasal interface, and an expiratory tube immersed in a water chamber. The generation of bubbles in the water chamber by exhaled gas creates low amplitude and high-frequency pressure oscillations that are transmitted back to the chest. Successful CPAP requires constant transmission of the pressure via an unobstructed circuit. However, this is difficult to achieve in practice due to inadequate interface, leaks from an open mouth, and obstructed airway. As a result, bCPAP requires frequent manual checks by nurses and respiratory therapists to ensure that the circuit is secure and unobstructed.

As a proposed solution, bCPAP sounds heard in the patient room or upon auscultation are routinely used to assess the effectiveness of CPAP therapy. This sound can be heard both from the water tank creating the vibrations and during auscultation with a stethoscope, as the sound vibration is transmitted to the neonatal lungs. In the current era of digital technology, acoustic sounds can be converted to electronic signals for further processing and analysis.

We hypothesize that continuous recording and analysis of bCPAP sounds could be used as a proxy for real-time objective monitoring of the pressure transmitted to infants' lungs.

Enrollment: 30 estimated patients

Sex: All

Ages: 28 to 32 weeks old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Infants on bCPAP with gestational age < 32+0 weeks
• Postmenstrual age between 28+0 and 36+6 weeks at the time of the study
• Postnatal age greater than 168 hours (7 days) at the time of the study
• On the bubble CPAP device with binasal prongs at the time of the study
• Receiving bubble CPAP levels of 5 to 7 cm H2O with gas flows between 6L/min and 10L/min at the time of the study

Exclusion criteria

• Infants with known major congenital anomalies
• Infants with known congenital heart disorders
• Infants with known neuromuscular disease
• Infants receiving ventilator-derived CPAP at the time of the study
• Infants receiving CPAP via a nasal mask interface at the time of the study
• Infants receiving inotropes, narcotics or sedative agents at the time of the study
• Infants deemed clinically unstable for the study by the attending neonatologist

Trial design

30 participants in 2 patient groups

Phase I: 15 preterm infants on Bubble Continuous Positive Airway Pressure (bCPAP)

Description:

Group 1 will consist of 15 preterm infants on bCPAP in whom the external bubble CPAP sounds and the pressures from the CPAP system itself will be recorded for 3 hours. To do so, we will use a standard microphone placed on the water tank and an external pressure transducer inserted into the expiratory limb of the bubble CPAP circuit.

Treatment:

Device: External pressure transducer

Device: Standard microphone

Phase II: 15 preterm infants on Bubble Continuous Positive Airway Pressure (bCPAP)

Description:

Group 2 will consist of 15 preterm infants on bCPAP in whom the external bubble CPAP sounds and the pressures from the CPAP system itself will be recorded. To do so, we will use a standard microphone placed on the water tank and a pressure transducer inserted into the expiratory limb of the bubble CPAP circuit. In addition, the internal bubble CPAP sound and pressure transmitted to the infant's lungs will be measured. For these, a wireless acoustic sensor will be secured on the infant's suprasternal notch to capture transmitted CPAP sounds, and an internal pressure transducer will be inserted from the infant's mouth into the nasopharynx to record the pressure delivered in the airway. Data will be recorded for 3 hours.

Treatment:

Device: Wireless acoustic sensor

Device: External pressure transducer

Device: Standard microphone

Device: Internal pressure transducer