Effects Of Two Ventilatory Modes On Oxygenation For Pulmonary Resection

Objective: To investigate the effects of two different ventilation mode using low tidal volumes with PEEP: volume controlled ventilation(vcv)vs.pressure controlled ventilation(pcv)on oxygenation during one lung ventilation and prognosis of operation.Methods: Forty patients with good preoperative pulmonary function scheduled for lung resection were prospectively randomized into 2 groups.After endobroncheal intubation,two lung ventilation(TLV)with vcv was performed in all patients using the following variables: tidal volume(VT)8ml/kg,respiratory rate 12 breaths/min,inspired oxygen fraction(Fi O2)of 0.8.No external positive end expiratory pressure(PEEP)was applied during this period.Prior initiation of OLV,patients were randomly assigned to one of two groups.Group A: one lung ventilation(OLV)with vcv was performed using a VT of 6ml/kg,PEEP of 5 cm H2 O,respiratory rate 12 breaths/min.,Fi O2 of 0.8.Group B: one lung ventilation(OLV)with pcv was performed using a peak airway pressure that provided VT of 6ml/kg,PEEP of 5 cm H2 O,respiratory rate 12 breaths/min.,Fi O2 of 0.8,and the respiratory rate adjusted to maintain arterial carbon dioxide tension(Pa CO2)of 35 to 45 mm Hg.Heart rate(HR),mean arterial pressure(MAP),peak inspiratory pressure(Ppeak),plateau inspiratory pressure(Pplat),mean inspiratory pressure(Pmean),dynamic lung compliance(Cdyn),blood gas analysis were measured and recorded at the end of the following study periods: 30 min after TLV using vcv prior the beginning of OLV(T0),30 min after OLV(T2),60 min afte OLV(T3),20 min after reestablishing TLV after pulmonary resection(T4).Postoperative hospitalization days,the incidence of postoperative complications such as pulmonary inflammation and atelectasis were recorded after the surgery.Results: There were no differences during OLV in arterial oxygenation between VCV and PCV.Peak airway pressure was significantly lower in PCV compared VCV(P<0.05).Mean and plateau airway pressures,PH,Pa CO2,dynamic lung compliance,alveolar-arterial oxygen difference did not differ between PCV and VCV.There were no significant differences in postoperative hospitalization days and the incidence of postoperative pulmonary complications.Conclusion : In patients with good preoperative pulmonary function undergoing lung resection,the use of a protective lung ventilation strategy with VCV or PCV does not affect the oxygenation and prognosis of operation.Further study is needed for patients with severe obstructive or restrictive pulmonary disease.