The optimal pressure of sustained inflation for alveolar recruitment
© Biomed central limited 2001
Published: 1 March 2002
To determine the optimal recruitment pressure of sustained inflation (SI) in treatment of rabbits with acute respiratory distress syndrome (ARDS).
Materials and methods
SI was applied at pressures of 1 ~ 6 times of mean airway pressure (Pm) for 20 s to saline-lavaged adult New Zealand rabbits. Hemodynamics, pulmonary mechanics and gas exchange were observed before SI, during, and 2 min, 5 min after applying SI. Lung histology was observed after experiment.
When the pressure of SI was higher than 3 Pm, arterial oxygen tension (PaO2) and arterial oxygen saturation were improved. The difference of PaO2 before and during SI were (75 ± 39)mmHg and (52 ± 25)mmHg respectively in the 5 Pm and 6 Pm group, which were higher than 1 Pm group significantly ([-5 ± 4]mmHg, P < 0.05). The difference of dynamic pulmonary compliance before and during SI in 5 Pm group was increased markedly ([1.90 ± 0.20]ml/cmH2O in 5 Pm group, [-0.02 ± 0.04]ml/cmH2O in 1 Pm group, P < 0.05). 5 Pm resulted in immediate increased significantly in lung volume ([3.1 ± 2.1]ml/kg in the group, 5 Pm [8.3 ± 0.7]ml/kg in the 1 Pm group). Histologically, Smith lung injury score was 4.03 ± 1.79 in the 5 Pm group, which was less than the score in the group of ARDS model (6.10 ± 0.77). SI with 6 Pm led to alveolar overdistention. With the increasing of SI pressure, mean arterial pressure decreased markedly.
5 Pm (25 ~ 35 cmH2O) may be the optimal recruitment pressure of SI in rabbits with ARDS.