Increased Alveolar Damage After Mechanical Ventilation in a Porcine Model of Thoracic Surgery

Abstract

Mechanical stress during one-lung ventilation (OLV) results in lung injury. This study compared the effects of mechanical ventilation, OLV, and surgical manipulation on diffuse alveolar damage (DAD) after application of different anesthetic regimens. Prospective, randomized, controlled, blinded animal experiment. University hospital. Twenty-one piglets. Animals (27.5 kg) were randomized into 4 groups: spontaneous breathing (SB, n = 3), two-lung ventilation (TLV, n = 6), OLV during desflurane (n = 6), and propofol anesthesia (n = 6). SB pigs were killed after the induction of anesthesia. Lung tissue samples were analyzed to obtain reference values for alveolar damage. TLV pigs underwent standard TLV (tidal volumes [V(T)] = 10 mL/kg, F(I)O(2) = 0.40, positive end-expiratory pressure = 5 cmH(2)O). In OLV pigs, after lung separation by a bronchial blocker, OLV (V(T) = 10 mL/kg) and thoracic surgery were performed. After the procedure, the pigs were killed. Lung tissue samples were harvested for histologic examination. Lung injury was quantified by DAD score; sequestration of leukocytes was assessed by the recruitment of CD45(+) cells into the lungs. TLV resulted in increased DAD scores in both lungs (TLV v SB: 6.9 v 2.7, p < 0.05); the number of CD45(+) cells was not increased (TLV v SB: 8.7 v 5.0 cells per view). OLV and surgical manipulation increased DAD and leukocyte sequestration without differences between the ventilated and manipulated lungs. Leukocyte recruitment was not differently affected by the anesthetic regimen (propofol v desflurane: CD45(+) cells per view: 13.5 v 11.3). TLV resulted in increased DAD scores in the lungs as compared with SB. OLV and thoracic surgery further increased lung injury and leukocyte recruitment independently of the administration of propofol or desflurane anesthesia.