Effects of small tidal volume combined with PEEP on extravascular lung water during one-lung ventilation in patients undergoing thoracic surgery

Abstract

Objective To investigate the effects of small tidal volume combined with PEEP on extravascular lung water during one-lung ventilation （OLV） in patients undergoing thoracic surgery. Methods Forty ASA I or II patients of both sexes aged 45-80 yr undergoing esophagectomy for esophageal cancer were randomly assigned into 2 groups （ n = 20 each） ： group I IPPV （VT 9 ml/kg ,RR 12 bpm） and group IT IPPV ＋ PEEP （VT 6 ml/kg, RR 15 bpm, PEEP 5 cm H2O）. FiO2 was 100% and I：E 1：2 in both groups. Anesthesia was induced with fentanyl 3-5 ug/kg, propofol 1.0-1.5 mg/kg and vecuronium 0.10-0.15 mg/kg and maintained with continuous infusion of propofol 4-7 mg·kg- 1 · h- 1 and vecuronium 0.07-0.08 mg· kg- 1 · h-1 and intermittent iv boluses of fentanyl. Double lumen endobronchial tube was inserted. Correct position was confirmed by bronchoscopy. Right internal jugular vein was cannulated. A 4F thermodilution catheter was inserted into right femoral artery and connected to PICCO monitor. Extravascular lung water （EVLW）, EVLW index （EVLWI）, pulmonary vascular permeability index （PVPI）, cardiac output （CO） and oxygenation index （OI） were recorded before anesthesia （To, baseline）, at 30 min of two lung ventilation （T1）, 30 min and 1 h of OLV （T2, T3 ）, before extubation （ T4 ） and 18 h after operation （ T5 ）. Airway peak pressure （Ppeak） was recorded at T1-4 , Results EVLWI and PVPI were significantly higher in group IPPV ＋ PEEP than in group IPPV. There was no significant difference in Ppcak, CO and OI at any time point between the 2 groups. In group IPPV there was no significant change in EVLW and EVLWI during and after mechanical ventilation, while PVPI was significantly increased at TI as compared with the baseline before anesthesia. In group IPPV ＋ PEEP EVLW was significantly increased at T2 and PVPI was significantly increased at T1 and T2 compared with the baseline at T0 . Conclusion OLV with IPPV ＋ PEEP results in more EVLW and it exerts no significant effect on lung function. Key words: Tidal volume ; Positive- pressure respiration; Extravascular lung water; Respiration,artificial