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A new ventilator improves CO2 removal in newborn lambs with congenital diaphragmatic hernia
J J Schnitzer1, J E Thompson, H L Hedrick
1Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston 02114-2696, USA.
Objectives:
To demonstrate improved ventilation with intratracheal pulmonary ventilation (ITPV) in new-born lambs with congenital diaphragmatic hernia, using a new microprocessor controlled ITPV-specific ventilator.
Design:
Prospective study, with each animal serving as its own control (paired data).
Setting:
Large animal research laboratory.
Subjects:
Diaphragmatic hernias were created surgically in seven fetal sheep on gestational day 100 (term = 145 days).
Interventions:
Lambs (2.7 to 5.0 kg) were delivered by cesarean section anywhere between gestational days 136 and 140. Arterial and venous catheterizations, bilateral chest tube thoracostomies, and tracheostomies were performed while the lambs received placental bypass. Initially, congenital diaphragmatic hernia lambs were supported on conventional pressure control mechanical 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) on 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+/-1.35 L/min (p = .0016). Peak carinal pressures and postductal Pao2 were unchanged.
Conclusions:
ITPV significantly improved CO2 removal in newborn lambs with diaphragmatic hernias without increasing airway pressures or changing oxygenation. Based on these results, we are conducting human clinical trials.