OBJECTIVE: To compare the influence of cardiac-pulmonary function on clinical acute respiratory failure patients using Proportional assist ventilation (PAV), Pressure support ventilation (PSV) and intermittent positiv...OBJECTIVE: To compare the influence of cardiac-pulmonary function on clinical acute respiratory failure patients using Proportional assist ventilation (PAV), Pressure support ventilation (PSV) and intermittent positive pressure ventilation (IPPV). Here, we also describe some our experience with the clinical use of PAV. METHODS: Using the IPPV mode in ten acute respiratory failure patients, calculate Elastance (Ers) and Resistance (Rrs), then change to PSV, set inspiratory positive airway pressure (IPAP) according to IPPV, so that tidal volume (V(T)) is the same as that of IPPV. We then changed the mode into PAV and set the assist ratio according to PSV, so that V(T) and Ppeak were the same as that of PSV. Then we observed the changes of respiratory mechanics, blood gas levels and hemodynamics during ventilation. RESULTS: Compared with PSV and IPPV, peak pressure (Ppeak) of PAV was markedly lower while V(T) was similar; work of breathing of patient (WOBp), and work of breathing of ventilation (WOBv) were also lower; center vein pressure (CVP) and pulmonary capillary wedge pressure (PCWP) of PAV were markedly lower than that of IPPV while V(T) were similar. Compared with PSV, V(T), mean blood pressure (mBP) and cardiac output (CO) of PAV were higher. Mean pulmonary artery pressure (mPAP) and WOBp of PAV were lower while Ppeak was similar; the differences in WOBp were notable. CONCLUSIONS: For clinical acute respiratory failure patients, compared with PSV and IPPV, PAV has lower airway pressure, less WOBp and less influence on hemodynamics.展开更多
Objective To choose one optimal extrinsic positive end-expiratory pressure (PEEPe) for ventilated patients with chronic obstructive pulmonary disease (COPD) and to compare two methods for choosing the optimal level o...Objective To choose one optimal extrinsic positive end-expiratory pressure (PEEPe) for ventilated patients with chronic obstructive pulmonary disease (COPD) and to compare two methods for choosing the optimal level of PEEPe.Methods Ten ventilated patients with COPD were included in the study. First, static intrinsic positive end-expiratory pressure (PEEPi,st) was measured when PEEPe was zero, and the PEEPi,st was called PEEPi,stz. PEEPe at 0%, 40%, 50%, 60%, 70%, 80%, 90% and 100% of PEEPi,stz, respectively, were applied randomly. Respiratory mechanics, hemodynamics, and oxygen dynamics were recorded 30 minutes after the level of PEEPe was changed.Results When PEEPe was not higher than 80% of PEEPi,stz, no measurement changed significantly. When PEEPe was increased to 90% and 100% of PEEPi,stz, PEEPi,st, peak inspiratory pressure, plateau pressure, pulmonary capillary wedge pressure and central venous pressure increased significantly, P<0.01. Cardiac output and left ventricular work index decreased significantly, P<0.01. Oxygen delivery decreased significantly, P<0.05. When PEEPe was increased to 100% of PEEPi,stz, the right ventricular work index decreased significantly, P<0.05.Conclusion Eighty percent of PEEPi,stz was the upper limit of PEEPe. The results of the two methods used to set the level of PEEPe were identical.展开更多
文摘OBJECTIVE: To compare the influence of cardiac-pulmonary function on clinical acute respiratory failure patients using Proportional assist ventilation (PAV), Pressure support ventilation (PSV) and intermittent positive pressure ventilation (IPPV). Here, we also describe some our experience with the clinical use of PAV. METHODS: Using the IPPV mode in ten acute respiratory failure patients, calculate Elastance (Ers) and Resistance (Rrs), then change to PSV, set inspiratory positive airway pressure (IPAP) according to IPPV, so that tidal volume (V(T)) is the same as that of IPPV. We then changed the mode into PAV and set the assist ratio according to PSV, so that V(T) and Ppeak were the same as that of PSV. Then we observed the changes of respiratory mechanics, blood gas levels and hemodynamics during ventilation. RESULTS: Compared with PSV and IPPV, peak pressure (Ppeak) of PAV was markedly lower while V(T) was similar; work of breathing of patient (WOBp), and work of breathing of ventilation (WOBv) were also lower; center vein pressure (CVP) and pulmonary capillary wedge pressure (PCWP) of PAV were markedly lower than that of IPPV while V(T) were similar. Compared with PSV, V(T), mean blood pressure (mBP) and cardiac output (CO) of PAV were higher. Mean pulmonary artery pressure (mPAP) and WOBp of PAV were lower while Ppeak was similar; the differences in WOBp were notable. CONCLUSIONS: For clinical acute respiratory failure patients, compared with PSV and IPPV, PAV has lower airway pressure, less WOBp and less influence on hemodynamics.
文摘Objective To choose one optimal extrinsic positive end-expiratory pressure (PEEPe) for ventilated patients with chronic obstructive pulmonary disease (COPD) and to compare two methods for choosing the optimal level of PEEPe.Methods Ten ventilated patients with COPD were included in the study. First, static intrinsic positive end-expiratory pressure (PEEPi,st) was measured when PEEPe was zero, and the PEEPi,st was called PEEPi,stz. PEEPe at 0%, 40%, 50%, 60%, 70%, 80%, 90% and 100% of PEEPi,stz, respectively, were applied randomly. Respiratory mechanics, hemodynamics, and oxygen dynamics were recorded 30 minutes after the level of PEEPe was changed.Results When PEEPe was not higher than 80% of PEEPi,stz, no measurement changed significantly. When PEEPe was increased to 90% and 100% of PEEPi,stz, PEEPi,st, peak inspiratory pressure, plateau pressure, pulmonary capillary wedge pressure and central venous pressure increased significantly, P<0.01. Cardiac output and left ventricular work index decreased significantly, P<0.01. Oxygen delivery decreased significantly, P<0.05. When PEEPe was increased to 100% of PEEPi,stz, the right ventricular work index decreased significantly, P<0.05.Conclusion Eighty percent of PEEPi,stz was the upper limit of PEEPe. The results of the two methods used to set the level of PEEPe were identical.
