A new ventilator improves CO2 removal in newborn lambs with congenital diaphragmatic hernia

Objectives: To demonstrate improved ventilation with intratracheal pulmonar y ventilation (ITPV) in newborn lambs with congenital diaphragmatic hernia, using a new microprocessor controlled ITPV specific ventilator. Design: Prospective study, with each animal serving as its own control (pai red data). Setting: Large animal research laboratory. Subjects: Diaphragmatic hernias were created surgically in seven fetal shee p on gestational day 100 (term = 145 days). Interventions: Lambs (2.7 to 5.0 kg) were delivered by cesarean section any where between gestational days 136 and 140, Arterial and venous catheteriza tions, bilateral chest tube thoracostomies, and tracheostomies were perform ed while the lambs received placental bypass. Initially, congenital diaphra gmatic hernia lambs were supported on conventional pressure control mechani cal ventilation to achieve steady state with measurements of baseline vital signs, arterial blood gases, and ventilatory settings. ITPV was instituted while maintaining constant peak carinal pressures and oxygen saturations. Statistical comparisons were made using the paired t-test, Measurements and Main Results: Postductal PaCO2 decreased from 110 +/- 21 ( SD) torr (14.7 +/- 2.8 kPa) to 52 +/- 24 torr (6.93 +/- 3.2 kPa; p=.0014) o n ITPV, Simultaneously, pH improved from 7.04 +/- 0.07 to 7.31 +/- 0.15 (p =.0012) and minute ventilation increased from 0.66 +/- 0.40 to 4.00 +/- 1.3 5 L/min (p =.0016), Peak carinal pressures and postductal PaCO2 were unchan ged. Conclusions: ITPV significantly improved CO2 removal in newborn lambs with diaphragmatic hernias without increasing airway pressures or changing oxyge nation. Based on these results, we are conducting human clinical trials.