Pulmonary Function Using Non-invasive Forced Oscillometry

TremoFlo™ N-100 (For Investigational Use Only) 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.