Effects Of Fluid Restriction On Intraoperative Extravascular Lung Water And Short-term Outcomes In Patients Undergoing Lobectomy

Background: The current practice of perioperative fluid administration remains controversial with regard to how much to infuse. Practice guidelines span a wide range, and this issue becomes more critical in patient with pulmonary disease. In lung surgeries, especially lobectomy, intraoperative fluid restriction is a routine approach to reduce the occurrence of postoperative pulmonary edema (PPPE), a rare but severe complication which increases respiratory dysfunction and mortality. But previous studies have demonstrated that fluid balance alone is not responsible for PPPE. Some researchers argued that severe fluid restriction may lead to hypovolumeia and insuffcient tissue perfusion, thus other complications increase.Fluid therapies tend to be so nebulous in lung surgeries that fluid administration guided by invasive hemodynamic monitoring would be much more satisfactory. extravascular lung water (EVLW), as a specific marker of pulmonary edema and lung injury, may help us to determine how much fluid is appropriate to maintain stable hemodynamics without evoking PPPE during lobectomy. Objective: To evaluate the effects of fluid restriction on extravascular lung water and short-term outcomes in patients undergoing lobectomy.Methods: In this prospective study, thirty patients,ASA I -III,aged 41-68 years, scheduled for lobectomy, were enrolled in and randomized to 5ml/kg/h (Restrictive group, n=11), 10ml/kg/h (Control group 1, n=10) or 15ml/kg/h (Control group 2, n=9) intraoperative administration of fluid (lactated Ringer's solution: 6%HES=1:2 in each group). All other aspects of perioperative management as well as preoperative fluid status were standardized. Primary parameters, including EVLW, extravascular lung water index (EVLWI), pulmonary vascular permeability index (PVPI), intrathoracic blood volume index (ITBVI), global end-diastolic volume index (GEDVI), central venous pressure (CVP), systemic vascular resistence index(SVRI), cardiac output index (CI), general ejection fraction (GEF), et al, were assessed at pre-anesthesia (T₁), lateral position (T₂), 15 min after one lung ventilation (T₃), suturing (T₄), returning to decubitus (T₅) and 2 hours after surgery (T₆), with a pulse-induced contour cardiac output (PiCCO) system. Outcomes, including thoracic drainage volume, breathholding time, dyspnea, postoperative nausea and vomiting (PONV), visual analog scale (VAS) pain score, thoracic X-ray score and ICU stay, were evaluated for the first 6 postoperative days. Length of postoperative hospital stay was recorded as well. Statistic analysis was managed with SPSS 13.0 edition software, outcome variables were analysed by ANOVA, while EVLW and other PiCCO parameters by repeated measurement.Results: Compared with 10ml/kg/h or 15ml/kg/h intraoperative fluid administration, 5ml/kg/h fluid had no significant improvements in EVLW and other PiCCO parameters. Scores of Chest X-ray on the 3rd postoperation day were similar in three groups. In the first 24 postoperative hours, thoracic drainage volume was significantly lower in Restrictive group than in Control group 2. Restrictive group had an earlier postoperative revival, compared with Control group 1. Respiratory support time, extubation time and length of postoperative hospital stay may be shortened in Restrictive group than other two groups, but there were no statistic significance.Conclusions: Infusion of 5-15ml/kg/h intraoperative fluid do not alter EVLW nor EVLWI during lobectomy, but administration of 5ml/kg/h fluid maintains stable intraoperative hemodynamics and it helps to reduce thoracic drainage volume. Fluid restriction may be beneficial to patients by promoting postoperative revival and early extubation as well as shortening average postoperative hospital stay.