Bubble continuous positive airway pressure (B-CPAP) applies small-amplitude, high-frequency oscillations in airway pressure (⌬P aw ) that may improve gas exchange in infants with respiratory disease. We developed a device, high-amplitude B-CPAP (HAB-CPAP), which provides greater ⌬P aw than B-CPAP provides. We studied the effects of different operational parameters on ⌬P aw 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 (F i O 2 ) 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°(HAB-CPAP135). Arterial blood gases and pressure-rate product (PRP) were measured after 15 min at each bubbler angle. PaO 2 levels were higher (p Ͻ 0.007) with HAB-CPAP135 than with conventional B-CPAP. PaCO 2 levels did not differ (p ϭ 0.073) among the three bubbler configurations. PRP with HAB-CPAP135 were half of the PRP with HAB-CPAP0 or HAB-CPAP90 (p ϭ 0.001). These results indicate that HAB-CPAP135 provides greater respiratory support than conventional B-CPAP does. (Pediatr Res 67: 624-629, 2010) B ubble-nasal continuous positive airway pressure (BnCPAP) is a form of noninvasive respiratory support that is used frequently as a primary strategy for supporting spontaneously breathing preterm infants at risk of developing respiratory distress syndrome. Compared with intubation and mechanical ventilation, the use of B-CPAP has been associated with lower indicators of acute lung injury (1) and bronchopulmonary dysplasia (2).Recent studies suggest that the bubbling of gas exiting the B-nCPAP circuit at the water seal creates oscillations in airway pressure (⌬P aw ), having broadband high frequencies (3), which may promote airway patency and enhance lung volume and gas exchange in preterm lambs (4). However, a study of 261 consecutively born premature infants revealed that 24% of infants born weighing Ͻ1250 g and 50% of infants weighing Ͻ750 g failed B-nCPAP and required endotracheal intubation and mechanical ventilation (5). In an effort to diminish the potentially deleterious effects of invasive mechanical ventilation (6), we designed a novel device, highamplitude B-CPAP (HAB-CPAP), which, through alterations in angle of gas entry at the water seal, may enhance respiratory efficiency and improve oxygenation when compared with conventional B-nCPAP.In this report, we describe a device that provides ⌬P aw higher in amplitude than B-CPAP. Studies were conducted to determine the effects of bubbler angle and bias flow on ⌬P aw and the amplitude of oscillations in volume (⌬V) delivered to a mechanical model of an infant lung. In addition, studies were con...

SummaryNitrogen washout measurements and blood-gas analyses were made on 32 newborn infants with severe RDS at continuous positive airway pressures (CPAP) of 5, 10, and 15 cm H2O. Increases in airway pressure resulted in significant increases in Pa02 and functional residual capacity (FRC). It also produced significant decreases in alveolar turnover rates of the "fast" and "slow" alveolar spaces of a two-space lung model. Changes in CPAP did not significantly affect the distribution of ventilation.The changes in PaO2. due to changes in CPAP, did not correlate well with changes in &/wt nor wi& changes in'alveolar turnover rates. Thus, the effects of increasing CPAP on Pa02 were not simply due to increases in FRC. The changes in Pa02 are due to a complex relationship between changes in FRC, alveolar turnover rates, and to other alterations in cardiopulmonary function that are yet to be fully understood. SpeculationResults from this study show that large portions of the lung have alveolar turnover rates below normal. Increasing airway pressures could lead to decreases in the rate of pulmonary perfusion and to an improvement in the ventilation-perfusion ratio of these alveolar units. This could partially account for the observation that increases in CPAP generally produce increases in PaO2.CPAP (4, 12) has become a mainstay of therapy in the treatment of newborn infants with RDS. In order to optimally manage these the infants were 33.7 -+ 0.4 wk and 2013 + 93 g. Some infants were studied several times during the course of their disease so that 52 sets of data were gathered at infant postnatal ages ranging from 4 to 152 h (mean 38 h). Four of the infants required mechanical ventilation due to the inability to maintain Paon of 60 mm Hg with airway pressure greater than 15 cm HzO and FiOz of 1.0. Three of these four infants died of intraventricular hemorrhages. A fourth infant died of necrotizing enterocolitis. All four infants that died also had pneumothoraces, and were the only infants with pneumothoraces. EQUIPMENTOpen circuit nitrogen washout techniques were used to determine FRC, alveolar ventilation (VA), distribution of ventilation, and alveolar turnover rates. Respiratory nitrogen concentrations were measured by placing the Nitralyzer (model 391 nitrogen analyzer, Warren E. Collins, Inc., Braintree, MA) needle of the pickup head directly in the endotracheal tube; thus, the nitrogen signal to recording delay was only 15 msec for 90% response. Flow rates of respiration were measured by a heated Fleisch "00" pneumotachometer (Instrumentation Association, Inc., New York, NY).and integrated electronically (IC-RESP respiratory flow rate integrator, Gilson Medical Electronics, Inc., Middleton, WI) to obtain tidal volumes. The logarithmic output of the nitrogen analyzer and exhaled tidal volumes were recorded on an X-Y plotter (model 815 X-Y recorder, MFE Corp., Salem, NH). Calculations of VA and FRC and multiple space curve analyses were made directly on the recorded X-Y washout traces.infants the clinician needs to kn...

BackgroundAlmost one million prematurely born infants die annually from respiratory insufficiency, predominantly in countries with limited access to respiratory support for neonates. The primary hypothesis tested in the present study was that a modified device for bubble nasal continuous positive airway pressure (Bn-CPAP) would provide lower work of spontaneous breathing, estimated by esophageal pressure-rate products.MethodsInfants born <32 weeks gestation and stable on Bn-CPAP with FiO2 <0.30 were studied within 72 h following delivery. Esophageal pressures during spontaneous breathing were measured during 2 h on standard Bn-CPAP, then 2 h with Bn-CPAP using a modified bubble device presently termed Seattle-PAP, which produces a different pattern of pressure fluctuations and which provided greater respiratory support in preclinical studies, then 2 h on standard Bn-CPAP.ResultsAll 40 infants enrolled completed the study and follow-up through 36 wks post menstrual age or hospital discharge, whichever came first. No infants were on supplemental oxygen at completion of follow-up. No infants developed pneumothoraces or nasal trauma, and no adverse events attributed to the study were observed. Pressure-rate products on the two devices were not different, but effort of breathing, assessed by areas under esophageal pressure-time curves, was lower with Seattle-PAP than with standard Bn-CPAP.ConclusionUse of Seattle-PAP to implement Bn-CPAP lowers the effort of breathing exerted even by relatively healthy spontaneously breathing premature neonates. Whether the lower effort of breathing observed with Seattle-PAP translates to improvements in neonatal mortality or morbidity will need to be determined by studies in appropriate patient populations.

ABSTRACT:We have developed two devices: a high-amplitude bubble continuous positive airway pressure (HAB-CPAP) and an inexpensive bubble intermittent mandatory ventilator (B-IMV) to test the hypotheses that simple, inexpensive devices can provide gas exchange similar to that of bubble CPAP (B-CPAP) and conventional mechanical ventilation (CMV). Twelve paralyzed juvenile rabbits were intubated, stabilized on CMV, and then switched to CPAP. On identical mean airway pressures (MAPs), animals were unable to maintain pulse oximeter oxygen saturation (SpO 2 ) Ͼ80% on conventional B-CPAP, but all animals oxygenated well (97.3 Ϯ 2.1%) on HAB-CPAP. In fact, arterial partial pressures of O 2 (PaO 2 ) were higher during HAB-CPAP than during CMV (p ϭ 0.01). After repeated lung lavages, arterial partial pressures of CO 2 (PaCO 2 ) were lower with B-IMV than with CMV (p Ͻ 0.0001), despite identical ventilator settings. In lavaged animals, when HAB-CPAP was compared with CMV at the same MAP and 100% O 2 , no differences were observed in PaO 2 , but PaCO 2 levels were higher with HAB-CPAP (70 Ϯ 7 versus 50 Ϯ 5 mm Hg; p Ͻ 0.05). Arterial blood pressures were not impaired by HAB-CPAP or B-IMV. The results confirm that simple inexpensive devices can provide respiratory support in the face of severe lung disease and could extend the use of respiratory support for preterm infants into severely resourcelimited settings. (Pediatr Res 68: 526-530, 2010) I nfant mortality caused by respiratory distress syndrome in the United States decreased from ϳ268 in 100,000 live births in 1971 to 98 in 100,000 live births in 1985 (1) and 17 in 100,000 live births in 2007 (2). The decrease in mortality from 1971 to 1985 was, in large part, due to the development and widespread availability of mechanical ventilators and continuous positive airway pressure (CPAP) devices designed to assist lung recruitment and gas exchange in newborn infants in respiratory distress. However, Ͼ4 million infants die throughout the world each year, with 1 million dying principally from respiratory insufficiency (3,4), largely because of the lack in resource-limited countries of the respiratory support devices and technologies that are commonly used in more affluent societies.Modern ventilators are expensive to purchase, which limits availability in resource-limited countries. Even if the devices are donated, the need for highly trained personnel to operate, maintain, and repair the ventilators effectively prevent significant use of modern ventilators in most facilities. Practical methods for respiratory support of prematurely born infants could save hundreds of thousands of newborn lives each year.In an effort to bridge the gap between the need for less expensive, simpler, more practical approaches to respiratory support and the need for greater range of simple support methods, we have developed two novel devices that can be used separately or together to provide a broad range of respiratory support for infants.One device, termed high-amplitude bubble continuous positive...