Respiratory Mechanics During One-lung Ventilation
Condition: Ventilator-Induced Lung Injury; Lung Ventilator; One-lung Ventilation
MeSH terms: Lung Injury; Ventilator-Induced Lung Injury
Study type: Observational [Patient Registry]

Summary: 
      Intraoperative lung protective ventilatory strategy has been widely recognized to reduce
      postoperative pulmonary complications in laparotomy and laparoscopic surgeries. However, the
      clinical evidence and consensus for ventilatory strategy to protect the dependent lung
      segments during thoracic surgery that requires one-lung ventilation (OLV) is currently not
      available. Since lung compliance changes significantly during OLV, the levels of respiratory
      mechanics should be optimized to avoid barotrauma and volutrauma. This study aims to
      determine the optimal levels of volume-pressure dynamics during OLV and at the phase of
      recruitment of the independent lungs by achieving optimal lung compliance, gas exchange and
      hemodynamics.
    

Detailed description: 
      Background One-lung ventilation (OLV) is the foremost used technique of ventilation during
      thoracic procedures. Intraoperative lung separation can be managed by means of double-lumen
      endotracheal tube (DLT), bronchial blocker (BB), or nonintubated method. OLV is impeded by
      significant reduction in lung volume, decline in lung compliance at lateral decubital
      position, formation of intrapulmonary shunting and exposure of the dependent lung to
      ventilator-induced lung injury (VILI). In addition, patients receiving thoracic surgeries are
      more prone to developing acute lung injuries due to direct surgery-related trauma caused by
      instrumentation or manipulation of the lung tissues, hypoperfusion induced by hypoxic
      pulmonary vasoconstriction, and dysfunction of surfactant system. The non-dependent lung is
      injured by surgical manipulation and atelectrauma. Re-expansion of the collapsed
      non-dependent lung at the end of surgery inevitably results in systemic inflammatory response
      in the local and contralateral lungs, which in turn leads to biotrauma. Therefore, a
      significantly high pulmonary complication of up to 14-28.4% was reported in patients that
      received OLV surgery.

      In the recent two decades, there is a major paradigm shift for mechanical ventilator support
      during operation by the introduction of intraoperative lung protective ventilation
      strategies. Some of these changes include a low tidal volume (Vt), moderate levels of
      positive end-expiratory pressure (PEEP), optimal driving pressure (∆P) and the appropriate
      use of lung recruitment maneuver. Intraoperative lung protective ventilation strategies have
      been shown to reduce post-operative pulmonary complications and improve overall clinical
      outcomes in intermediate and high-risk patients undergoing major abdominal surgery.
      Currently, however, there is a lack of clinical evidence in regard to appropriate
      protective-lung strategies during OLV. The optimal levels of intraoperative use of oxygen
      fraction, the ventilatory settings for volume and pressure variables during OLV and
      re-expansion phases for lung recruitment are debating. The main objective of this clinical
      study is to determine the optimal levels of volume-pressure dynamics during OLV and at the
      phase of recruitment of the independent lungs by achieving optimal lung compliance, gas
      exchange and hemodynamics.
    

Intervention name(s): Optimal lung compliance during OLV
Intervention type(s): Procedure
Intervention description(s): Stepwise increase of tidal volume from 4 ml/kg PBW to 7 ml/kg PBW during OLV to determine the optimal tidal volume at the level the the pressure-volume loop reaches upper refection point where the peak airway pressure at or just below 30 cmH2O
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Generally healthy (ASA PC I-III) patients receiving thoracic surgery that required
        intraoperative OLV
      
Keywords: Barotrauma; Volutrauma; Biotrauma; Atelectasis; Lung recruitment