The Use of Intra-Tracheal Pulmonary Ventilation (ITPV) and Partial Liquid Ventilation (PLVSM) in Newborn Piglets with Meconium Aspiration Syndrome

Abstract

OBJECTIVE: To determine whether intratracheal pulmonary ventilation (ITPV) combined with partial liquid ventilation (PLV) improves oxygenation and ventilation at lower mean airway and peak inspiratory pressures when compared with conventional mechanical ventilation in a piglet model of meconium aspiration syndrome. DESIGN: Prospective, randomized, interventional study. SETTING: Animal Research Laboratory at the Children's National Medical Center, Washington, DC. SUBJECTS: Twenty newborn piglets, 1 to 2 wks of age, 1.8-2.8 kg in weight. INTERVENTION: The animals were anesthetized, paralyzed, and intubated with a 4.0 mm (internal diameter) endotracheal tube via a tracheostomy and were ventilated. Catheters were placed in the femoral artery and vein. Seven milliliters per kilogram of 20% human meconium was insufflated into the lungs over 30 mins. Dynamic pulmonary compliance was measured before and after instillation of meconium. Animals were ventilated to maintain arterial blood gases in a normal range, that is, pH = 7.35-7.45, Paco(2) = 40-45 torr (5.3-6.0 kPa), and Pao(2) = 70-90 torr (9.3-12.0 kPa). Ventilator settings were increased as needed to a maximum setting of Fio(2) = 1.0, peak inspiratory pressure (PIP) = 40 cm H(2)O, positive end-expiratory pressure = 5 cm H(2)O, and intermittent mandatory ventilation = 60 bpm. After a period of stabilization, 30 mL/kg of perflubron (Liquivent; Alliance Pharmaceutical Corp., San Diego, CA) was given intratracheally over 30 mins and the animals were randomized to either ITPV or control group. Measurements and RESULTS: Arterial blood gases were taken every 30 mins, and ventilatory settings were adjusted to achieve the targeted blood gas parameters. The animals' temperature, arterial blood pressure, heart rate, and oxygen saturation were monitored continuously. There was a significant decrease in the dynamic pulmonary compliance measurements in both groups immediately after meconium instillation. Compliance measurements after meconium instillation were similar in both groups (0.67 +/- 0.23 mL/cm H(2)O/kg ITPV; 0.88 +/- 0.46 mL/cm H(2)O/kg conventional, p =.17), indicating a similar degree of injury before the administration of perflubron. PIP and mean airway pressures were not significantly different at baseline; however, there was significant difference in PIP at 0, 2, and 4 hrs after administration of perflubron (p