Localized Pulmonary Edema in the Middle and Inferior Lobes of the Right Lung after One-lung Ventilation for Minimally Invasive Mitral Valve Surgery

Minimal volume ventilation during robotically assisted mitral valve surgery

INTRODUCTION

A minimal volume ventilation method for robotically assisted mitral valve surgery is described in this study. In an attempt to reduce postoperative pulmonary dysfunction, 40 of 174 patients undergoing robotically assisted mitral valve surgery were ventilated with a small tidal volume during cardiopulmonary bypass.

METHODS

After propensity score matching, 31 patients with minimal volume ventilation were compared with 54 patients with no ventilation. Total ventilation time, PaO₂/FiO₂ ratio, arterial lactate concentration, and the rate of unilateral pulmonary edema in the matched minimal ventilation and standard treatment groups were evaluated.

RESULTS

Patients in the minimal ventilation group had shorter ventilation times, 12.0 (interquartile range: 9.9-15.0) versus 14.0 (interquartile range: 12.0-16.3) hours (p = 0.036), and lower postoperative arterial lactate levels, 0.99 (interquartile range: 0.81-1.39) versus 1.28 (interquartile range: 0.99-1.86) mmol/L (p = 0.01), in comparison to patients in the standard treatment group. There was no difference in postoperative PaO₂/FiO₂ ratio levels or in the rate of unilateral pulmonary edema between the groups.

CONCLUSION

Minimal ventilation appeared beneficial in terms of total ventilation time and blood lactatemia, while there was no improvement in arterial blood gas measurements or in the rate of unilateral pulmonary edema. The lower postoperative arterial lactate levels may suggest improved lung perfusion among patients in the minimal volume ventilation group. The differences in the ventilation times were in fact small, and further studies are required to confirm the possible advantages of the minimal volume ventilation method in robotically assisted cardiac surgery.