Strategic ventilation reduces non-ventilated contralateral lung injury induced by one-lung ventilation in rabbits

[Ventilação estratégica reduz lesão pulmonar contralateral não ventilada induzido pela ventilação pulmonar unilateral em coelhos]

ABSTRACT

One lung ventilation (OLV) often results in trauma to the unventilated contralateral lung. This study aims to evaluate the effects of different OLV regimens on the injury of the unventilated contralateral lung to identify the best conditions for OLV. Forty rabbits were divided into five groups: a sham group, OLV group I (fraction of inspired oxygen (F_IO₂) 1.0, tidal volume (VT) 8mL/kg, respiratory rate (R) 40 breaths/min and inspiratory/expiratory ratio (I:E) 1:2), OLV group II (F_IO₂=1.0, VT 8mL/kg, R 40 breaths/min, I:E 1:2, and positive end-expiratory pressure (PEEP) 5 cm H₂O), OLV group III (F_IO₂ 1.0, VT 6mL/kg, R 40 breaths/min, I:E 1:2 and PEEP 5 cm H₂O) and OLV group IV (F_IO₂ 0.8, VT 6mL/kg, R 40 breaths/min, I:E 1:2 and PEEP 5 cm H₂O). Animals from all OLV groups received two-lung ventilation (TLV) to establish a baseline, followed by one of the indicated OLV regimens. The rabbits in the sham group were intubated through trachea and ventilated with fresh air. Arterial blood gas samples were collected, lung injury parameters were evaluated, and the concentrations of TNF-α and IL-8 in bronchoalveolar lavage fluid (BALF) and pulmonary surfactant protein A (SPA) in the unventilated lung were also measured. In OLV group I, the unventilated left lung had higher TNF-α, IL-8 and lung injury score but lower SPA than the ventilated right lung. In OLV groups I to III, the concentrations of TNF-α, IL-8 and lung injury score in the left lung decreased but SPA increased. No differences in these parameters between OLV groups III and IV were observed. Strategic ventilation designed for OLV groups III and IV reduced OLV-induced injury of the non-ventilated contralateral lung in rabbits.

Keywords:
one-lung ventilation; acute lung injury; strategic ventilation