Effects of Different Tidal Volumes on Extravascular Lung Water Content During One-lung Ventilation for Video-assisted Thoracoscopic Surgery: Dammam University Experience

Nowadays most thoracic procedures are performed via video-assisted thoracoscopic surgery (VATS) which necessitates the use of one lung ventilation (OLV).

Acute lung injury (ALI) is the most serious pulmonary complication after lung resection which may be aggravated with the use of large tidal volume (TV) and high peak airway pressures (Paw) during one-lung ventilation (OLV). In a large multicenter trial included 861 patients at 10 university centers of the Acute Respiratory Distress Syndrome Network of the National Heart, Lung, and Blood Institute, the use of lower tidal volumes from 4 to 6 ml/kg of the predicted body weight (PBW) during ventilation in patients with acute lung injury and the acute respiratory distress syndrome may reduce injurious lung stretch, the release of inflammatory mediators, days of mechanical ventilation and mortality (P=0.007).

By the late 1990s the standard VT for managing thoracic surgical patients had already been adjusted downwards [from 10 to 12 ml/kg in the 1980s] to 8 to 10 ml/kg, although no specific guidelines existed for one-lung ventilation.

The implementation of lung protective strategy during OLV using low TV [5-6 ml/kg PBW], pressure-controlled ventilation, limiting inspiratory plateau pressures and adding end-expiratory positive pressure (PEEP) with or without recruitment maneuvers has been shown to attenuate the incidence of ALI by 76-82% and satisfactory gas exchange after lung surgery without inducing a possible inflammatory/remodeling response.

The use of lower tidal volumes for OLV with subsequently decreased peak airway pressures may be associated with less production of tumor necrosis factor (TNF)-alpha and soluble intercellular adhesion molecule (sICAM)-1.8 Recent data have highlighted the role of extra vascular lung water index (EVLWI) as a useful good parameter for early diagnosis of pulmonary complication including acute lung injury after thoracic surgery. The diagnosis of postoperative ALI is often delayed because clinical signs of pulmonary edema present only once the extra vascular lung water (EVLW) exceeds 7 ml/kg (ideal body weight).