Study Of Airway Pressure Release Ventilation On Respiratory And Circulatory Function Of Patients After Heart Operation

Background:Airway pressure release ventilation (APRV) is inverse ratio, pressure controlled, intermittent mandatory ventilation with unrestricted spontaneous breathing. It is based on the principle of open lung approach. It has many purported advantages over conventional ventilation, including alveolar recruitment, improved oxygenation, preservation of spontaneous breathing, improved hemodynamics, and potential lung-protective effects. It has many claimed disadvantages related to risks of volutrauma. increased work of breathing, and increased energy expenditure related to spontaneous breathing. APRV is used mainly as a rescue therapy for the difficult to oxygenate patients with acute respiratory distress syndrome (ARDS). Heart operation by general anesthesia and median sternotomy will significantly affect the pulmonary function and chest movement; Early postoperative, mismatch of (V/Q) and intrapulmonary shunt in gas exchange capacity decreased in oxygenation and the cardiopulmonary function of patients with cardiac surgery. According to a study, about20%of heart patients with operation acute respiratory distress syndrome in peri-operation period, the mortality rate as high as80%. Therefore, how to prevent ALI and ARDS on patients after cardiac surgery should we pay close attention to. The purpose of this study was to patients who undergoing cardiopulmonary bypass in the early postoperative period, through the comparison of airway pressure release ventilation (APRV) and pressure controlled ventilation (PCV) on respiratory mechanics, hemodynamics and arterial blood gas test, clinical application value of APRV in these patients. Methods:During the period from2012November to2013February in our hospital,57cases by cardiopulmonary bypass heart operation patients (exclude the chronic obstructive pulmonary disease history). Randomly divided into pressure control PCV (P group), and27cases of airway pressure release APRV (A group) and30cases in two groups. Both groups of patients with PCV mode ventilation for half an hour to confirm circulatory and respiratory index is stable. Then change ventilation mode on group A to APRV mode, ventilation settings on group P to continue, if the patients have decreased saturation of oxygen, treated by the lung recruitment maneuvers.Bedside respiratory monitor, multi-channel monitor, artery indwelling tube, Swan-Ganz catheter, central venous catheter and arterial blood gas analyzer monitoring of respiratory mechanics, hemodynamics and blood gas analysis results of Oh,1h,4h after ventilation two model:(PaO2/FiO2), partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaC02), lactic acid (LAC), arterial oxygen saturation (SaO2), Alveolar arterial oxygen pressure (PA-a DO2), mixed venous oxygen saturation (SvO2). Respiratory parameters:airway pressure (Paw), peak airway pressure (PIP), mean airway pressure (P mean), dynamic compliance of the respiratory system (CRS, dyn), airway resistance (R). Hemodynamic parameters:heart rate (HR), mean arterial pressure (MAP), pulmonary artery pressure (PAP), central venous pressure (CVP), pulmonary artery wedge pressure (PAWP), cardiac output (CO), cardiac index (CI), stroke volume (SV), cardiac index (SI), lung vascular resistance index (PVRI), systemic vascular resistance index (SVRI), left ventricular (LCW), right heart function (RCW), left ventricular stroke work (LVSW), right ventricular stroke work (RVSW); Result:Effect on respiratory mechanics:There was a significant difference between the trend test(P<0.05).C increased in ventilation, R, P plat, P high decreased in ventilation of group A.Effect on hemodynamics:there were significant differences between the trend test of APRV and PCV (P<0.05) MAP, CVP, HR, PAP, PVRI, SVRI, LCW, RCW, RVSW, PAWP group. In group A, LCW, RCW, RVSW, PAWP increased while PVRI, SVRI, LVSW decreased in ventilation. Each time after ventilation CO,, CI, SV SI differences (P<0.05),4h data>1h data, and different time points and group independent effect of the monitoring indicators. There are differences between the two groups, CO, CI, SV in group A are higher than those in the group P, the trend test showed significant differences(P<0.05). In group A, CO, CI, SV, SI increased after ventilation.Effect on blood gas results:there were significant differences trend between the APRV test and PCV (P<0.05).Lac, PCO2, PO2, BE, PO2/FiO2, PA-aO2,SVO2In group A, PO2, PO2/FiO2, SvO2increased, while PCO2, BE, PA-aO2, decreased.Conclusion:APRV mode can more effectively improve patients with postoperative oxygenation, prevent atelectasis, prevention of ALI、ARDS and avoid AILI, promote human-machine coordination. Reduce PVRI, SVRI, improve the acid poisoning. The appropriate P high enables P mean to control in circulating side effects in a small range. High LCW, RCW, RVSW explained that APRV has protection and promotion on hemodynamics, especially CO, CI, SV time point has the positive effect of APRV mode.