The Clinical Contrast Research On Choosing Ideal Tidal Volume Based On Pressure-Volume Curve

Objective To study the influence of the different tidal volume on hemodynamics, pulmonary mechanics and lung injury during mechanical ventilation in patients。 According the P-V curve, to find out the ideal tidal volume which can decrease the harm of ventilator-associated lung injury.Methods To adopting contrast method, making use of P-V curve to decide PEEP, then according to the VUIP of P-V curve, obtaining the three different data of humidity VUIP/kg( A ), 85% Vuip/kg (B) and 70 VUIP/kg (C) respectively. At the same time, monitoring the changing of static compliance, peak airway pressure(PIP), plateau pressure(Pplat) and mean pressure(Pm) ,the changing of hemodynamics, blood-gas, heart rat, arterial blood pressure and P-V curve. Results 1. The index change of hemodynamics Comparing with the data of A group, the heart rates of B group and C group are low, and the changes of heart rate are notable(P<0.05); while there is no remarkable difference between the heart rate of B group and C group (P > 0.05 ) .In the aspect of blood pressure, the data of three groups shows no notable change, along with the increase of the volume of humidity, CVP trends to be high, when tidal volume is A , CVP increased to (13.6 ± 2.2 ) cmH2O.2. There is no remarkable change in PH (P > 0.05 ). While there is a notable rise in PaC>2 in groups of A and B. It differs from the Cgroup (P<0.05) . Among the three groups of PaCO2, decreases when tidal volume increases, the difference is remarkable (P<0.05 ) ; regarding to PetCO2, the difference is also prominent; ADco2 in three groups is normal and the peak is 6mmHg maximum. Concerning PaO2/FiO2, the change in B group, is biggest, the difference is clearly (P<0.05 ) .3. The change of static compliance(Cst) , the peak airway pressure(PIP), plateau pressure(Pplat) and mean pressure(Pm) rise along with the increase of tidal volume (P<0.05) . Compared with the group of A group, PIP,Pm in B group and C group decrease sharply, so is the difference (P<0.05). There is no more difference in PIP, Pm between B group and C group (P > 0.05 ) . The Cst of C group of tidal volume...