Real‐time ventilation and perfusion distributions by electrical impedance tomography during one‐lung ventilation with capnothorax

Background Carbon dioxide insufflation into the pleural cavity, capnothorax , with one‐lung ventilation ( OLV ) may entail respiratory and hemodynamic impairments. We investigated the online physiological effects of OLV /capnothorax by electrical impedance tomography ( EIT ) in a porcine model mimicking the clinical setting. Methods Five anesthetized, muscle‐relaxed piglets were subjected to first right and then left capnothorax with an intra‐pleural pressure of 19 cm H 2 O . The contra‐lateral lung was mechanically ventilated with a double‐lumen tube at positive end‐expiratory pressure 5 and subsequently 10 cm H 2 O . Regional lung perfusion and ventilation were assessed by EIT . Hemodynamics, cerebral tissue oxygenation and lung gas exchange were also measured. Results During right‐sided capnothorax, mixed venous oxygen saturation ( P  = 0.018), as well as a tissue oxygenation index ( P  = 0.038) decreased. There was also an increase in central venous pressure ( P  = 0.006), and a decrease in mean arterial pressure ( P  = 0.045) and cardiac output ( P  = 0.017). During the left‐sided capnothorax, the hemodynamic impairment was less than during the right side. EIT revealed that during the first period of OLV /capnothorax, no or very minor ventilation on the right side could be seen (3 ± 3% vs. 97 ± 3%, right vs. left, P  = 0.007), perfusion decreased in the non‐ventilated and increased in the ventilated lung (18 ± 2% vs. 82 ± 2%, right vs. left, P  = 0.03). During the second OLV /capnothorax period, a similar distribution of perfusion was seen in the animals with successful separation (84 ± 4% vs. 16 ± 4%, right vs. left). Conclusion EIT detected in real‐time dynamic changes in pulmonary ventilation and perfusion distributions. OLV to the left lung with right‐sided capnothorax caused a decrease in cardiac output, arterial oxygenation and mixed venous saturation.