Objective:To investigate the relationship between PaCO 2 and PetCO 2 while the respiration pattern changed from spontaneous to mechanical ventilation during artificial valve replacement. Methods:The changes of PaCO 2,PetCO 2,CO,MAP,PAP,CVP,PAWP,SVR,PVR and V D/V T,alv from spontaneous respiration to mechanical ventilation were observed pre and post general anesthesia in 22 patients undergoing artificial valve replacement. Results:Compared with spontaneous respiration before general anesthesia induction, the differences between PaCO 2 and PetCO 2,CVP,V D/V T,alv ratio were significantly increased( P

Objective: To evaluate the hemodynamic and prognostic effects of milrinone in patients undergoing valve replacement throughout the process of operation. Methods: Twenty patients undergoing valve replacement were radomized into group A ( n =10) and group B ( n =10).Before induction of general anesthesia, milrinon was administered at a 30 ?g/kg bolus dose intravenously in 10 min, followed by a continuous infusion of 0.5 ?g/(kg?min) in group A, and the same volume of normal saline in group B. The parameters of hemodynamics were obtained at the following points: before and after loading dose of milrinone, after induction of general anesthesia, after opening the chest, after weaning of CPB, before and after shutting of the sternum. The time of ICU stay and quantity of fluid in and out were calculated. Results: (1) After loading dose of milrinon, CI, LVSWI in group A were significantly higher, while PAP, CVP, SVR and PVRI were significantly lower than the same point of group B. CI, LVSWI and SVR in two groups remained significant different at the other points. (2) Patients in group A had more colloed and norepinephrine infusion than group B. Conclusion: Administration of milrinone at loading dose can effectively increase cardiac output and left ventricular stroke work, and decrease pulmonary artery pressure, pulmonary and system vascular resistance. [