| Objective : To determine the efficacy of does response relationships to inhaled aerosolized prostacyclin(IAP)in canines with oleic acid-induced acute respiratory distress syndrome(ARDS).Method : The models of ARDS were reproduced by intravenous injection of oleic acid in 13 canines. The model was regarded successful when Pa02/FiO2 is no more than 200mmHg.The ARDS canines were randomly assigned to control group(n=5)and IAP group(n=8)with the same ventilator parameters between the two groups (FiO2=50%, Vt=15ml · kg-1, PEEP=5mmHg). Animals in the control group were only mechanically ventilated, while animals in the IAP group received IAP 0, 5, 10, 20, 30, 50, 100ng · kg-1 · min-1 with each dosage for 15 minutes and each interval for 15 minutes. The arterial and mixed venous blood gas, homodynamic parameters, pulmonary dynamic compliance(Cdyn)were measured or calculated just before and after the different IAP dosage. The pulmonary pathology, lung water were assessed at the end at the experiment.Result : The arterial blood gas analysis showed that PaO2 increased markedly from 50 to 100ng · kg-1 · min-1 (p<0.05) while there was no significant difference of PaO2 (p>0. 05) among these doses. There was also no significant difference of improvement in PaO2 at other dosages(P>0.05). The Qs/Qt decreased markedly during IAP from 20 to 100 ng · kg-1 · min-1 with the increase of IAP dosage(p<0.05), while there was no significant difference (p>0. 05)among above doses except that the improvement of Qs/Qt at IAP100 ng· kg-1, min-1 was better than that of 20 and 30 100ng · kg-1 · min-1 . Homodynamic monitoring did not indicate any significant difference of systemic parameters at any IAP dose including MAP, HR, CVP, PCWP, CO, CI and SVR.However, the PAP decreased markedly during IAP from 10 to 100ng · kg-1 · nun-1. And the PVR decreased significantly during IAP from 20 to 100ng · kg-1· min-1 (p<0. 05) with no difference(p>0. 05) among above doses. |
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