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...
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...
Poster Presentation Abstracts 173neonatal resuscitation, to determine the surface activity and to compare the results with clinical data. Methods:Suction aspirates and clinical data of 74 individuals were collected with parental consent, weighed and mucus, cell detritus plus large particles were removed. Subsequently the samples were ultracentrifugated. The pellet was resuspended at a ratio of 60µL/1g of original sample size. Then surface tension of 1-5µL of the samples was determined after 5 min adsorption to a ~20µL bubble in the CBS using sucrose as a surfactant hypophase.Results: Surface tension of aspirates of neonates with a bw < 1500g was 48.6±5.4mN/m (Mean±SD) and significantly increased compared to individuals >2000g (35.8±9.9; p< 0.01). Absorption surface tension in non-ventilated neonates was significantly lower (34.1±9.8mN/m) compared to CPAP treated neonates (47.8±7.4 mN/m; p< 0.05) or mechanically ventilated individuals (48.4±5.6 mN/m; p< 0.01) Conclusions: Small volume airway samples from neonatal aspirates may be used to determine biophysical activity of the surfactant system quantitatively using the CBS. The obtained data correlate with the clinical course, birth weight and the mode of ventilatory support.
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