[A comparison of the effects of PAV, PSV and IPPV on cardiopulmonary function in patients with acute respiratory failure].
OBJECTIVE
Comparing the effects of proportional assist ventilation (PAV), pressure support ventilation (PSV), and intermittent positive pressure ventilation (IPPV) on cardiopulmonary function in patients with acute respiratory failure, in particular, evaluating the clinical significance of PAV.


METHODS
Ten patients with acute respiratory failure were firstly ventilated with IPPV. Elaslance (Ers) and Resistance (Rrs) were measured and calculated. Then PSV mode was adapted. Based on the parameters of IPPV, inspiratory positive airway pressure was adjusted to maintain the same tidal volume (V(T)) as that in IPPV. Finally PAV mode was used. According to the parameters of PSV, the assist ratio was adjusted to maintain the same V(T) and peak pressure peak, as those in PSV. Respiratory mechanics, arterial blood gas and hemodynamics were recorded during above three modes of ventilation.


RESULTS
Comparing with PSV and IPPV mode, PAV created a significantly lower peak, less work of breathing of patients (WoBp) and work of breathing of ventilation (WoBv) under the similar V(T); Central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP) were significantly lower in PAV mode as compared with those in IPPV; While comparing with PSV, V(T), mean blood pressure (mBP) and cardiac output (CO) were higher and mean pulmonary arterial pressure (mPAP), WoBp were lower in patients with PAV under similar peak. Among them the fall of WoBp was statistically significant.


CONCLUSIONS
In patients receiving three modes of ventilation, PAV presents with lower airway pressure, less WoBp and less effect on hemodynamics as compared with those with PSV or IPPV.
Fang
Z
Z
Department of Chest, Zhongshan Hospital, Medical College, Fudan University, Shanghai 200032, China.
Niu
S
S
Zhu
L
L
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006439:Hemodynamics; D006801:Humans; D007385:Intermittent Positive-Pressure Ventilation / Q000379:methods*; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008451:Maximal Voluntary Ventilation; D008875:Middle Aged; D012121:Respiration, Artificial / Q000379:methods*; D012131:Respiratory Insufficiency / Q000503:physiopathology / Q000534:rehabilitation*