title: The impact of tidal volume on pulmonary complications following minimally invasive esophagectomy: a randomized and controlled study.
abstract: BACKGROUND
  Minimally invasive esophagectomy (MIE) has been advantageous for lowering pulmonary complications compared with open approaches.(1) However, pulmonary complications remain the most common morbidity after surgical resection of esophageal cancer.(2,3) The aim of this prospective, randomized, controlled, clinical trial was designed to see whether low tidal volume (VT) could further minimize pulmonary complications after MIE.
  
  
  METHODS
  Between June 2011 and July 2012, a total of 101 patients who underwent MIE received left-lung ventilation during thoracoscopic esophagectomy. All patients received left-lung ventilation during thoracoscopic esophagectomy. Patients were randomly assigned to a low VT (5 mL/kg + 5 cm H2O positive end-expiratory pressure) preserved ventilation (PV) group (n = 53) and a conventional VT (8 mL/kg) controlled ventilation (CV) group (n = 48) in the thoracic stage. Alveolar lavage fluid was harvested from the ventilated lung at intubation and at 18 hours after surgery for analysis of interleukin (IL)-1ß, IL-6, and IL-8 levels. Clinical characteristics, including patient demographics, operation features, and changes in oxygenation index, were recorded and analyzed. Pulmonary complications were identified and statistically compared between the 2 groups.
  
  
  RESULTS
  The clinical characteristics and operation features were comparable between the 2 groups. IL-1ß, IL-6, and IL-8 expressions in preoperative alveolar lavage fluid were similar between the 2 groups. Significantly lower IL expressions were observed in the PV group than those in the CV group at 18 hours after MIE (IL-1ß, 25.42 ± 31.01 vs 94.96 ± 118.24 pg/mL; IL-6, 30.86 ± 75.78 vs 92.99 ± 72.90 pg/mL; IL-8, 258.75 ± 188.24 vs 403.95 ± 151.44 pg/mL; all P < .05). The 18-hour postoperative oxygenation index was lower in the CV group than that in the PV group (292.85 ± 28.74 vs 326.35 ± 34.43; P = .046). Pulmonary complications were observed in 18 cases of our series, occurring more frequently on the ventilation side (right, 6 cases; and left, 12 cases). All patients were cured by conservative therapy without severe sequelae. The occurrence of pulmonary complications in the PV group was lower than that in the CV group (9.43% vs 27.08%; P = .021).
  
  
  CONCLUSIONS
  Lung injury due to intraoperative single-lung ventilation may contribute to pulmonary complications after MIE. Low VT ventilation could decrease ventilation-associated lung inflammation, thus minimizing pulmonary complications after MIE. Further studies, based on a larger volume of populations, are required to confirm these findings.
authors.affiliation: Division of Thoracic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China.
authors.forename: Yaxing
authors.initials: Y
authors.lastname: Shen
authors.forename: Ming
authors.initials: M
authors.lastname: Zhong
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Mingxiang
authors.initials: M
authors.lastname: Feng
authors.forename: Lijie
authors.initials: L
authors.lastname: Tan
authors.forename: Qun
authors.initials: Q
authors.lastname: Wang
mesh_terms: D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D016009:Chi-Square Distribution; D002681:China; D004938:Esophageal Neoplasms / Q000601:surgery*; D016629:Esophagectomy / Q000009:adverse effects*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D008168:Lung / Q000276:immunology / Q000503:physiopathology*; D011175:Positive-Pressure Respiration / Q000009:adverse effects* / Q000379:methods; D011446:Prospective Studies; D013906:Thoracoscopy / Q000009:adverse effects*; D013990:Tidal Volume; D013997:Time Factors; D016896:Treatment Outcome; D055397:Ventilator-Induced Lung Injury / Q000209:etiology / Q000276:immunology / Q000503:physiopathology / Q000517:prevention & control*
chemical_list: C508606:CXCL8 protein, human; C508600:IL6 protein, human; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8
keywords: 28; 41.2; 7; CV; EtCO(2); ICS; IL; MIE; OI; PC; PEEP; PV; SLV; VT; controlled ventilation; end-tidal carbon dioxide concentration; intercostal space; interleukin; minimally invasive esophagectomy; oxygenation index; positive end-expiratory pressure; preserved ventilation; pulmonary complication; single-lung ventilation; tidal volume