Visualizing and Quantifying Ventilation-Perfusion Mismatch by Electrical Impedance Tomography in Patients Undergoing Lung Transplantation: A Pilot Physiological Study

INTRODUCTION: Ventilation-perfusion (V/Q) mismatch is common in lung transplant recipients, particularly during the early postoperative period. It may lead to impaired gas exchange and prolong the duration of mechanical ventilation. Electrical impedance tomography (EIT) is a novel bedside imaging modality, facilitating the real-time regional assessment of V/Q mismatch. This pilot study aimed to visualize and quantify V/Q mismatch using EIT in lung transplant recipients during the early postoperative period. METHODS: This pilot single-center retrospective study included ten recipients following lung transplantation (5 single lung transplantation (SLT) and 5 bilateral lung transplantation (BLT)). During mechanical ventilation, the regional ventilation and perfusion were evaluated using EIT in the first 5 postoperative days. V/Q mismatch was quantified by calculating the percentages of only ventilated units, only perfused units, and unmatched units as well as the fractions of wasted ventilation and wasted perfusion. RESULTS: The SLT recipients exhibited a significantly higher percentage of only ventilated units than the BLT recipients (2.9% [2.8, 3.2] vs. 0.8% [0.0, 1.0], p = .012). In contrast, the BLT recipients showed a numerically higher percentage of only perfused units (28.8% [28.8, 34.1] vs. 19.4% [19.3, 19.4], p = .095). Moreover, the percentages of unmatched units, fractions of wasted ventilation, and fractions of wasted perfusion were comparable between the 2 groups. CONCLUSION: Distinct V/Q patterns for the SLT and BLT recipients were observed. This highlights the need for individualized ventilatory strategies to optimize postoperative respiratory management in lung transplant recipients.