[Effects of positive end expiratory pressure ventilation upon respiratory function and hydrophobic surfactants proteins in rabbit with seawater respiratory distress syndrome].
OBJECTIVE
To investigate the effects of positive end-expiratory pressure (PEEP) ventilation upon respiratory function and lung surfactant protein B (SP-B)/SP-C in seawater respiratory distress syndrome (SW-RDS) rabbit.


METHODS
Twenty-four female New Zealand rabbits were randomly equally divided into three groups:conventional mechanical ventilation (CMV) group, PEEP group, and control group. After anesthesia and tracheal intubation followed by 20 minutes of CMV, SW-RDS model was established by lung perfusion of artificial seawater through tracheal intubation. Then the CMV group ventilated for 6 hours (each parameter unchanged); PEEP group ventilated with PEEP of 8 cm H2O for 2 hours based on prior parameters and subsequently with CMV for 4 hours; control group without ventilation after modeling. Oxygenation indices and lung compliance were continuously monitored during ventilation. After ventilation, the rabbits in study groups were sacrificed while those dying a natural death in the control group selected. Bronchoalveolar lavage fluid of the left lung was collected to determine the alveolar surface tension and the right lung was harvested to measure the mRNA expression of SP-B/SP-C by real-time PCR as well as SP-B protein by Western blotting.


RESULTS
After modeling, the data of lung compliance and oxygenation indices became significantly worse in every group but without statistical difference in three groups. All rabbits in control group died within 15 minutes of ventilator withdrawal. After receiving PEEP ventilation for 30 minutes, these indices significantly improved compared with CMV group in which there was no significant change of the indices (P < 0.05). Minimal alveolar surface tension in CMV group (mN/m, 30.8 +/- 6.3) was greater than in PEEP group (21.1 +/- 4.4, P < 0.05) and control group (23.6 +/- 4.6, P < 0.05); SP-B/SP-C mRNA relative expression (0.37 +/- 0.15/0.60 +/- 0.19) and SP-B relative protein abundance (0.38 +/- 0.17) in CMV group were obviously lower than in PEEP group (0.73 +/- 0.15/0.92 +/- 0.40, 0.52 +/- 0.22, P < 0.05).


CONCLUSIONS
PEEP ventilation can improve the oxygenation indices and lung compliance in SW-RDS animals. And such an effect is correlated with both the mRNA expressions of SP-B/SP-C and mechanical distension.
Zhao
Xiao-wei
XW
Department of Respiratory Diseases, General Hospital of Armed Police Forces, Beijing 100039, China.
Zhang
Jian-peng
JP
Huang
Xian
X
Liu
You-ning
YN
D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D011175:Positive-Pressure Respiration; D037701:Pulmonary Surfactant-Associated Protein B / Q000378:metabolism; D037721:Pulmonary Surfactant-Associated Protein C / Q000378:metabolism; D011817:Rabbits; D012128:Respiratory Distress Syndrome / Q000378:metabolism* / Q000503:physiopathology*; D012623:Seawater
D037701:Pulmonary Surfactant-Associated Protein B; D037721:Pulmonary Surfactant-Associated Protein C