Pulmonary Function Using Non-invasive Forced Oscillometry

TremoFlo™ C-100 Airwave Oscillometry System™ (THORASYS Thoracic Medical Systems Inc.
Montreal, Quebec, Canada) is a technology for measuring lung mechanics without patient
effort. Pulmonary function testing using flow-volume and lung volumes is one of the most
widely used tests to objectively measure lung function in adults. Such measurements are
dependent on effort and coordination by the patient which is not possible for newborn
infants. The minimum age for spirometry is typically 6 years to master the technique.
Therefore, newborn infants usually require forced exhalation, flow interruption, and often
sedation/anesthesia in order to obtain accurate pulmonary function measurements. Infant
pulmonary function testing can be time-consuming and expensive to perform in newborn infants.
This has limited the utilization of this potentially informative method of studying lung
function. Measurements of lung function will be particularly informative during transition
from having lungs filled with fluid during intra-uterine life to having lungs filled with air
in extra-uterine life in preterm and term babies without lung disease, as well as in newborn
infants with lung diseases including respiratory distress syndrome, bronchopulmonary
dysplasia, transient tachypnea of the newborn, meconium aspiration syndrome, and after the
effects of treatments given to newborn infants with lung diseases.

The TremoFlo device uses the forced oscillation technique during spontaneous infant breathing
and notably does not require any sedation to perform. The forced oscillation technique
measures lung function by superimposing a gentle multi-frequency airwave onto the infant's
respiratory airflow while the infant breathes spontaneously. Only a short period of breathing
is required to obtain a reliable measurement of airway resistance and reactance. Oscillometry
has been successfully utilized to quantify lung function in asthmatic children and adults
with chronic obstructive pulmonary disease, but never previously in infants. This proposal
brings this non-invasive technique of measuring lung function to the neonatal population to
identify changes in respiratory mechanics between term and pre-term gestations and quantify
fluctuations in infant lung function in response to disease progression and therapeutic
intervention. The ease of oscillometry that only requires tidal breathing eliminates the need
for patient cooperation and maneuvers that previously excluded lung function testing in the
neonatal intensive care unit. This proposal will evaluate the feasibility and clinical value
of oscillometry in newborns, both to detect changes in premature compared to full-term
gestations as well as disease cohorts by introducing functional measures of lung function to
bedside care.

Inclusion Criteria:

- Infants with gestational age at least 22 weeks at birth

- Infants off ventilator/continuous positive airway pressure ≥ 12 hours

- Infants whose parents/legal guardians have provided consent

Exclusion Criteria:

- Infants with major malformation

- Infants with a neuromuscular condition that affects respiration

- Infants with terminal illness

- Infants with a decision made to withhold or limit support