The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

WHAT ARE THE EFFECTS OF DIFFERENT BUBBLE CONTINUOUS POSITIVE AIRWAY PRESSURE (B-CPAP) SYSTEMS ON THE MAGNITUDE OF OCSILLATIONS IN LUNG VOLUME WHILE USING A REALISTIC AIRWAY/LUNG MODEL OF PRETERM INFANTS?

Rob DiBlasi1, Jay Zignego1, Jonathan Poli1, Buket Barutcu2, Peter Richardson1; 1Developmental Therapeutics, Seattle Children’s Research Institute, Seattle, WA; 2Institute of Pulmonary Disease and Tuberculosis, Istanbul University, Istanbul, Turkey

BACKGROUND: High-frequency oscillations in pressure are created by gas bubbling through an underwater-seal during B-CPAP. These pressure oscillations may enhance ventilation and aid in lung recruitment in premature infants (Pillow JJ; Am J Respir Crit Care Med,2007). We designed a study to test the hypothesis that the magnitude of oscillations in lung volume (delta-volume) and frequency range, created by B-CPAP systems, are not different using: 1) a homemade B-CPAP system; 2) F&P B-CPAP; and 3) Babi.Plus B-CPAP in an passive nasal airway/ lung model affixed with “leaky” nasal prongs. METHODS: An anatomically accurate infant nasal airway model, fabricated using a 3D printer and dimensions obtained from a CT-scan of a preemie, was attached to a silastic test lung (C:0.47 mL/cmH20 and R:150 cmH20/L/s) sealed within a calibrated plethysomograph. The nasal airway model was affixed with nasal prongs and attached to B-CPAP systems set at 6 cmH2O CPAP. Hudson prongs (size 0) were used with systems 1 and 3 and F&P prongs (size extra small) were used with system 2. Adjustments were made to maintain the same CPAP level across all testing conditions. Bias flow was varied between 4-10 L/min and delta-volume and frequency were calculated using pressure data obtained from the plethysomograph. Data were compared using ANOVA and Student-Newman Kuels for post-hoc analyses. RESULTS: The F&P B-CPAP system provided greater delta-volume than the other devices at all bias flows (P< 0.05; Figure). The F&P system generally provided lower frequencies than the other B-CPAP systems. The magnitude of delta-volume and frequencies increased at bias flows > 6 L/min in the F&P and Homemade systems but showed relatively small changes during bubbling with the Babi.Plus (see Figure). DISCUSSION/CONCLUSIONS: The major finding of this study was that B-CPAP can provide measureable, and potentially clinically beneficial, oscillations in lung volume. In the F&P system, the delta-volume approximated nearly 10% of a 1 kg preterm infants’ spontaneous tidal volume. Increasing bias flow, in systems 1 and 2, may provide additional support during B-CPAP. We speculate that the higher delta-volume provided by the F&P system is a combination of the circuit/nasal prong configuration and the lower frequencies applied to the nasal airway interface. Additional testing is needed in spontaneously breathing infants to determine whether a physiologic benefit exists when using the different B-CPAP systems. Sponsored Research - None