The open lung concept: pressure-controlled ventilation is as effective as high-frequency oscillatory ventilation in improving gas exchange and lung mechanics in surfactant-deficient animals.
OBJECTIVE
To demonstrate in experimental animals with respiratory insufficiency that under well-defined conditions, commercially available ventilators allow settings which are as effective as high-frequency oscillatory ventilators (HFOV), with respect to the levels of gas exchange, protein infiltration, and lung stability.


METHODS
Prospective, randomized, animal study.


METHODS
Experimental laboratory of a university.


METHODS
18 adult male Sprague-Dawley rats.


METHODS
Lung injury was induced by repeated whole-lung lavage. Thereafter, the animals were assigned to pressure-controlled ventilation (PCV) plus The Open Lung Concept (OLC) or HFOV plus OLC (HFO(OLC)). In both groups, an opening maneuver was performed by increasing airway pressures to improve the arterial oxygen tension/fractional inspired oxygen (PaO(2)/FIO(2)) ratio to L 500 mm Hg; thereafter, airway pressures were reduced to minimal values, which kept PaO(2)/FIO(2) L 500 mm Hg. Pressure amplitude was adjusted to keep CO(2) as close as possible in the normal range.


RESULTS
Airway pressure, blood gas tension, and arterial blood pressure were recorded every 30 min. At the end of the 3-h study period, a pressure-volume curve was recorded and bronchoalveolar lavage was performed to determine protein content. After the recruitment maneuver, the resulting mean airway pressure to keep a PaO(2)/FIO(2) L 500 mm Hg was 25 +/- 1.3 cm H(2)O during PCV(OLC) and 25 +/- 0.5 cm H(2)O during HFOV(OLC). Arterial oxygenation in both groups was above L 500 mm Hg and arterial carbon dioxide tension was kept close to the normal range. No differences in mean arterial pressure, lung mechanics and protein influx were found between the two groups.


CONCLUSIONS
This study shows that in surfactant-deficient animals, PCV, in combination with a recruitment maneuver, opens atelectatic lung areas and keeps them open as effectively as HFOV.
Vázquez de Anda
G F
GF
Department of Anaesthesiology (Room Ee 2393), Erasmus University Rotterdam, P. O. Box 1738, 3000 DR Rotterdam, The Netherlands.
Hartog
A
A
Verbrugge
S J
SJ
Gommers
D
D
Lachmann
B
B
D000818:Animals; D006612:High-Frequency Ventilation / Q000295:instrumentation / Q000379:methods; D008168:Lung / Q000503:physiopathology*; D008297:Male; D011175:Positive-Pressure Respiration / Q000295:instrumentation / Q000379:methods; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D011663:Pulmonary Surfactants / Q000172:deficiency*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012131:Respiratory Insufficiency / Q000503:physiopathology / Q000628:therapy; D015656:Respiratory Mechanics / Q000502:physiology*; D013997:Time Factors; D012122:Ventilators, Mechanical
D011663:Pulmonary Surfactants