A comparison of intratracheal pulmonary ventilation to conventional ventilation in a surfactant deficient animal model.
OBJECTIVE
To compare intratracheal pulmonary ventilation (ITPV) with conventional ventilation in a rabbit model of surfactant deficiency.


METHODS
A prospective randomized animal study.


METHODS
The Children's National Medical Center Research Animal Facility in Washington, DC.


METHODS
Adult male New Zealand white rabbits (n = 20), weighing 1.4-4.2 kg.


METHODS
After anesthesia and catheter placement, rabbits were tracheotomized, paralyzed, and placed on the conventional ventilator. We determined pulmonary functions at baseline. We washed surfactant out of the lungs by using serial bronchoalveolar lavages. Pulmonary function studies were determined after completion of the bronchoalveolar lavages and were used as an indication of severity of lung injury. Animals were randomized into two groups: We placed ten animals on ITPV, using the ITPV reverse thruster catheter designed by Kolobow and a prototype ITPV ventilator designed at Children's National Medical Center; we placed ten animals on conventional ventilation using the Sechrist iv-100 ventilator. Arterial blood gases were drawn every 15 mins, and the ventilator settings were adjusted to the minimal level that would maintain arterial blood gases in the following ranges: pH 7.35-7.45, PaCO2 30-40 torr (3.995.33 kPa), PaO2 50-70 torr (6.66-9.33 kPa). Animals were ventilated with the randomized ventilation techniques for 4 hrs.


RESULTS
Peak inspiratory pressure, mean airway pressure, and positive end-expiratory pressure were measured at the distal end of the endotracheal tube. We recorded these variables plus respiratory rate at baseline and every 30 mins for a total of 4 hrs of ventilation. Lung compliance did not differ between groups at the postlavage study period (ITPV, 0.56+/-0.13 mL/cm H2O/kg; conventional 0.49+/-0.15 mL/cm H2O/kg). At the end of the 4 hr study period, peak inspiratory pressure (ITPV, 26.2+/-4.6 cm H2O; conventional, 32.4+/-5.04 cm H2O, p = .007) and positive end-expiratory pressure (ITPV, 3.9+/-1.96 cm H2O; conventional, 6.3+/-1.42 cm H2O, p = .005) were lower in the ITPV ventilation group. Peak inspiratory pressure was significantly lower in the ITPV group by 2 hrs into the study.


CONCLUSIONS
In this model of surfactant deficiency lung injury, ventilation and oxygenation were achieved at significantly lower ventilator settings using ITPV compared with conventional ventilation. Long-term studies are needed to determine whether this reduction in ventilation is maintained, and if so, if lung injury is reduced.
Velarde
C A
CA
George Washington University School of Medicine and Health Sciences, Department of Pediatrics, Washington, DC, USA.
Short
B L
BL
Rivera
O
O
Seale
W
W
Howard
R
R
Kolobow
T
T
Rais-Bahrami
K
K
D000818:Animals; D001784:Blood Gas Analysis; D001992:Bronchoalveolar Lavage Fluid; D004195:Disease Models, Animal; D006801:Humans; D007231:Infant, Newborn; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D008168:Lung / Q000503:physiopathology; D008176:Lung Volume Measurements; D008297:Male; D011663:Pulmonary Surfactants / Q000172:deficiency*; D011817:Rabbits; D012121:Respiration, Artificial / Q000295:instrumentation*; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology*
D011663:Pulmonary Surfactants