Noninvasive respiratory support of juvenile rabbits by high-amplitude bubble continuous positive airway pressure.

Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA.
Pediatric Research (Impact Factor: 2.84). 03/2010; 67(6):624-9. DOI: 10.1203/PDR.0b013e3181dcd580
Source: PubMed

ABSTRACT Bubble continuous positive airway pressure (B-CPAP) applies small-amplitude, high-frequency oscillations in airway pressure (DeltaPaw) that may improve gas exchange in infants with respiratory disease. We developed a device, high-amplitude B-CPAP (HAB-CPAP), which provides greater DeltaPaw than B-CPAP provides. We studied the effects of different operational parameters on DeltaPaw and volumes of gas delivered to a mechanical infant lung model. In vivo studies tested the hypothesis that HAB-CPAP provides noninvasive respiratory support greater than that provided by B-CPAP. Lavaged juvenile rabbits were stabilized on ventilator nasal CPAP. The animals were then supported at the same mean airway pressure, bias flow, and fraction of inspired oxygen (FiO2) required for stabilization, whereas the bubbler angle was varied in a randomized crossover design at exit angles, relative to vertical, of 0 (HAB-CPAP0; equivalent to conventional B-CPAP), 90 (HAB-CPAP90), and 135 degrees (HAB-CPAP135). Arterial blood gases and pressure-rate product (PRP) were measured after 15 min at each bubbler angle. Pao2 levels were higher (p<0.007) with HAB-CPAP135 than with conventional B-CPAP. PaCO2 levels did not differ (p=0.073) among the three bubbler configurations. PRP with HAB-CPAP135 were half of the PRP with HAB-CPAP0 or HAB-CPAP90 (p=0.001). These results indicate that HAB-CPAP135 provides greater respiratory support than conventional B-CPAP does.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The introduction of assisted ventilation for neonatal pulmonary insufficiency has resulted in the successful treatment of many previously fatal diseases. During the past three decades, refinement of invasive mechanical ventilation techniques has dramatically improved survival of many high-risk neonates. However, as with many advances in medicine, while mortality has been reduced, morbidity has increased in the surviving high-risk neonate. In this regard, introduction of assisted ventilation has been associated with chronic lung injury, also known as bronchopulmonary dysplasia. This disease, unknown prior to the appearance of mechanical ventilation, has produced a population of patients characterized by ventilator or oxygen dependence with serious accompanying pulmonary and neurodevelopmental morbidity. The purpose of this article is to review non-invasive respiratory support methodologies to address the physiologic mechanisms by which these methods may prevent the pathophysiologic effects of invasive mechanical ventilation.
    Pediatric Pulmonology 07/2012; 47(9):837-47. DOI:10.1002/ppul.22610 · 2.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background Bubble continuous positive airway pressure (B-CPAP) is frequently used in spontaneously breathing infants with lung disease. Often, the B-CPAP systems lack pressure alarms and pressure release valves. We observed a large volume of condensate in the exhalation limb of a patient circuit and conducted a series of experiments to test the hypothesis that accumulated condensate could affect delivered pressures.Methods An anatomically accurate nasal airway model of a preterm infant was attached to a spontaneously breathing lung model. A Fisher & Paykel B-CPAP system was attached to the nasal airway with bi-nasal short prongs and the rate of fluid condensation was measured. Next, tracheal pressures were monitored digitally to detect changes in airway pressure related to condensate accumulation. Measurements were obtained with volumes of 0, 5, 10, 15, and 20 mL of water in the exhalation limb at flow rates of 4, 6, 8, and 10 L/min. Measurements with 20 mL in the exhalation limb were recorded with and without an F&P pop-off valve in the circuit.ResultsThe rate of condensate accumulation was 3.8 mL/hour. At volumes of ≥10 mL, noticeable alterations in the airway pressure waveforms and significant increases in mean tracheal pressure were observed. The pop-off valve effectively attenuated peak tracheal pressures but only decreased mean pressures by 0.5-1.5 cmH2O.Discussion/Conclusion Condensate in the exhalation limb of the patient circuit during B-CPAP can significantly increase pressure delivered to the patient. The back and forth movement of this fluid causes oscillations in airway pressure that are much greater than the oscillations created by gas bubbling out the exhalation tube into the water bath. We recommend continuously monitoring pressure at the nasal airway interface, placing an adjustable pop-off valve in the circuit set to 5 cmH2O above desired mean pressure, and emptying fluid from the exhalation limb every 2-3 hours.
    Respiratory care 03/2013; 58(11). DOI:10.4187/respcare.02322 · 1.84 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background:Short-term high-frequency nasal ventilation (HFNV) of preterm neonates provides acceptable gas exchange compared to endotracheal intubation and intermittent mandatory ventilation (IMV). Whether long-term HFNV will provide acceptable gas exchange is unknown. We hypothesized that HFNV for up to 21d would lead to acceptable gas exchange at lower inspired oxygen (O2) levels and airway pressures compared to intubation and IMV.Methods:Preterm lambs were exposed to antenatal steroids, and treated with perinatal surfactant and postnatal caffeine. Lambs were intubated and resuscitated by IMV. At ~3h of age, half of the lambs were switched to non-invasive HFNV. Support was for 3d or 21d. By design, PaO2 and PaCO2 were not different between groups.Results:At 3d (n=5) and 21d (n=4) of HFNV, fractional inspired O2 (FiO2), peak inspiratory pressure, mean airway, intra-tracheal, and positive end-expiratory pressures, oxygenation index, and Alveolar-arterial gradient were significantly lower than matched periods of intubation and IMV. PaO2/FiO2 ratio was significantly higher at 3d and 21d of HFNV compared to matched intubation and IMV. HFNV led to better alveolarization at 3d and 21d.Conclusion:Long-term HFNV provides acceptable gas exchange at lower inspired O2 levels and respiratory pressures compared to intubation and IMV.Pediatric Research (2013); doi:10.1038/pr.2013.254.
    Pediatric Research 12/2013; DOI:10.1038/pr.2013.254 · 2.84 Impact Factor


Available from