Mechanical ventilation with high positive end-expiratory pressure and small driving pressure amplitude is as effective as high-frequency oscillatory ventilation to preserve the function of exogenous surfactant in lung-lavaged rats.
OBJECTIVE
To demonstrate that under well-defined conditions, pressure-controlled ventilators (PCV) allow settings that are as good as high-frequency oscillatory ventilators (HFOV) at preserving the function of exogenous surfactant in lung-lavaged rats.


METHODS
Experimental, comparative study.


METHODS
Research laboratory of a large university.


METHODS
Sixteen adult male Sprague-Dawley rats (280-310 g).


METHODS
Lung injury was induced by repeated lavage. After last lavage, all animals received exogenous surfactant and were then randomly assigned to two groups (n = 8 per group). The first group received PCV with small pressure amplitudes and high positive end-expiratory pressure. The second group received HFOV. In both groups, an opening maneuver was performed by increasing airway pressure to improve PaO2/F(IO2) to > or =500 torr.


RESULTS
Blood gases were measured every 30 mins for 3 hrs. Airway pressures were measured with a tip catheter pressure transducer. At the end of the study period, a pressure-volume curve was recorded and a broncho-alveolar lavage was performed to determine protein content and surfactant composition. The results showed that arterial oxygenation in both groups could be kept >500 torr during the 3-hr study period by using a mean airway pressure of 13+/-3 cm H2O in PCV and 13+/-2 cm H2O in HFOV. Further, there were no differences in the Gruenwald index, protein influx, or ratio of small to large aggregates between the study groups.


CONCLUSIONS
PCV with sufficient level of positive end-expiratory pressure and small driving pressure amplitudes is as effective as HFOV to maintain optimal gas exchange, to improve lung mechanics, and to prevent protein influx and conversion of large into small aggregates after exogenous surfactant therapy in lung-lavaged rats.
Vazquez de Anda
G F
GF
Department of Anesthesiology, Erasmus University Rotterdam, The Netherlands.
Gommers
D
D
Verbrugge
S J
SJ
De Jaegere
A
A
Lachmann
B
B
D000818:Animals; D001784:Blood Gas Analysis; D018893:Bronchoalveolar Lavage; D006612:High-Frequency Ventilation; D008171:Lung Diseases / Q000097:blood / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D008297:Male; D011175:Positive-Pressure Respiration; D011663:Pulmonary Surfactants / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D011663:Pulmonary Surfactants