Effects Of Posture And Positive End Expiratory Pressure On Central Venous Pressure And Mean Arterial Pressure In Patients After Cardiopulmonary Bypass

Objective: Cardiopulmonary bypass is a classical operation mode on the treatment of congenital heart disease,valvular heart disease and large vascular disease at present. Although open heart operation under cardiopulmonary bypass in heart disease has been very skilled, but the postoperative ventilator assisted breathing process often leads to the abnormal hemodynamics, especially the patients with positive pressure ventilation, all have a significant effect on the venous pressure and artery pressure. Change the posture have no effect on arterial pressure and venous pressure in normal persons, but the effect on the patients after cardiopulmonary bypass is inconclusive. The influence between positive end expiratory pressure and central venous pressure(CVP), mean arterial pressure(MAP) have many differences in patients with different diseases. The study is to investigate the effect of posture, different positive end expiratory pressure on central venous pressure and mean arterial pressure in patients after cardiopulmonary bypass. In order to find the relationship between PEEP and CVP, MAP.Method: In a prospective self-controled research, the patients after cardiopulmonary bypass operation were enrolled.At first,central venous pressure(CVP), mean arterial pressure(MAP), heart rate(HR), oxygen saturation of pulse(Sp O2), mean airway pressure(Pm) and peak airway pressure(PIP) were measured with a supine flat position, each parameters were measured of 3 times. And then, the same method was used to measuring the above-mentioned parameters of 30°. Every 10 minute measuring parameters in both postures. The PEEP increased 3cm H20 each time from 0 cm H20 to 15 cm H20. Changes in various parameters measured values under different conditions were compared. Data were analyzed by spss13.0 statistical software, P < 0.05 was considered has statistically significant.Result: The experiment results showed that:after cardiopulmonary bypass, with the same level of PEEP, there were no statistically significance in the measurements between the different postures, it included CVP, MAP, HR, RR, Sp O2, PIP and Pm(P>0.05). With the same posture, CVP totally had statistically significant(P<0.05), CVP increased gradually by the increment of PEEP. They have positive relationship(r=0.374). There were no significant differences in the measurements between 0cm H2 O PEEP and 3cm H2 O PEEP(P>0.05). With the same posture, MAP totally has statistically significant(P<0.05), MAP decreased gradually by the increment of PEEP. They have negative correlation(r=-0.66). There were big significant differences in the measurements between 0cm H2 O PEEP and 12 cm H2O PEEP, 15 cm H2O PEEP(P<0.05). With the increase of PEEP, PIP and Pm were increased, the difference was statistically significant(P<0.05). There were no differences in HR,RR and Sp O2( P>0.05).Conclusion: With the same PEEP level,there were no significant effect of posture on CVP and MAP, it also have no significant effect on HR, RR, Sp O2, PIP, Pm. CVP increased gradually by the increment of PEEP. They have positive relationship(r=0.374). There were no significant differences in the measurement between 0cm H2 O PEEP and 3cm H2 O PEEP(P>0.05). MAP decreased gradually by the increment of PEEP after cardiopulmonary bypass operation. They have negative correlation(r=-0.66). When PEEP≥12cm H2 O, MAP decreased more significantly(P<0.05). With the increase of PEEP, PIP and Pm were increased gradually after cardiopulmonary bypass. PEEP have no influence on RR, HR, Sp O2 after cardiopulmonary bypass operation.