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.

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    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
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    ABSTRACT: The current trend for supporting neonates with respiratory distress syndrome is nasal continuous positive airway pressure (CPAP). Nearly half of all neonates who are supported with CPAP will still develop respiratory failure that requires potentially injurious endotracheal intubation and invasive ventilation. Thus, the role of any neonatal clinician is to minimize invasive ventilation whenever possible, to avoid the multitude of complications that can arise when using this form of therapy. Noninvasive ventilation (NIV) is a form of respiratory assistance that provides greater respiratory support than does CPAP and may prevent intubation in a larger fraction of neonates who would otherwise fail CPAP. With the inception of nasal airway interfaces, clinicians have ushered in many different forms of NIV in neonates, often with very little experimental data to guide management. This review will explore in detail all of the different forms of neonatal NIV that are currently focused within an area of intense clinical investigation.
    Respiratory care 09/2011; 56(9):1273-94; discussion 1295-7. DOI:10.4187/respcare.01376 · 1.84 Impact Factor
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    ABSTRACT: Respiratory distress syndrome (RDS) is a major contributor to neonatal mortality worldwide. However, little information is available regarding rates of RDS-specific mortality in low-income countries, and technologies for RDS treatment are used inconsistently in different health care settings. Our objective was to better understand the interventions that have decreased the rates of RDS-specific mortality in high-income countries over the past 60 years. We then estimated the effects on RDS-specific mortality in low-resource settings. Of the sequential introduction of technologies and therapies for RDS, widespread use of oxygen and continuous positive airway pressure were associated with the time periods that demonstrated the greatest decline in RDS-specific mortality. We argue that these 2 interventions applied widely in low-resource settings, with appropriate supportive infrastructure and general newborn care, will have the greatest impact on decreasing neonatal mortality. This historical perspective can inform policy-makers for the prioritization of scarce resources to improve survival rates for newborns worldwide.
    PEDIATRICS 06/2011; 127(6):1139-46. DOI:10.1542/peds.2010-3212 · 5.30 Impact Factor


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