Management of a Piglet Model of the Meconium Aspiration Syndrome With High-Frequency or Conventional Ventilation
1992; American Medical Association; Volume: 146; Issue: 11 Linguagem: Inglês
10.1001/archpedi.1992.02160230045013
ISSN1538-3628
Autores Tópico(s)Neuroscience of respiration and sleep
Resumo• Objective. —To assess the usefulness of three methods of high-frequency ventilation in the early management of a piglet model of the meconium aspiration syndrome. Design. —Randomized, block design. Setting. —Animal research facility. Subjects. —Fifty-six mixed-breed newborn piglets aged 1 to 4 days and weighing 1.8 to 2.7 kg. Interventions. —After instillation of a 2.2-mL/kg solution of 25% meconium, 56 piglets were randomized to receive treatment with (1) a conventional positive-pressure infant ventilator, (2) the Bunnell Life Pulse high-frequency jet ventilator, (3) the Bird model VDR high-frequency flow interruptor, or (4) the Infant Star high-frequency flow interruptor. We adjusted ventilator settings to maintain partial pressures of arterial oxygen (Pao 2 ) of 80 to 120 cm H 2 O and partial pressures of arterial carbon dioxide (Paco 2 ) of 30 to 50 cm H 2 O during the 6 hours of ventilation. Measurements and Main Results. —We compared pulmonary histologic alterations and four physiologic parameters: (1) mean airway pressure, (2) Paco 2 , (3) ratio of Pao 2 to partial alveolar oxygen pressure (PAo 2 ), and (4) oxygenation index ([(fraction of inspired oxygen)(mean airway pressure)(100)]/Pao 2 ). The two measures of oxygenation were similar for all four devices except at 4 hours, when the Pao 2 /PAo 2 ratio on positive-pressure ventilation was significantly higher than that on high-frequency jet ventilation ( P =.008). The histologic changes on positive-pressure ventilation (atelectasis, inflammation, presence of meconium, and exudative debris) were significantly worse than those on high-frequency jet ventilation or flow interruption ( P <.0001). Conclusions. —The finding of less severe pathologic alterations with various types of high-frequency ventilators justifies further investigations into the management of the meconium aspiration syndrome with these devices. ( AJDC . 1992;146:1287-1293)
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