Donor-Recipient Size Mismatch, Donor Age and Interstitial Lung Disease Are Associated with Abnormal Reactance, Resistance and Airway Closure After Bilateral Lung Transplantation

Abstract

<h3>Purpose</h3> The effect of donor-recipient demographics and features on recipient lung mechanics after transplantation (LTx) is unknown. The Forced Oscillation Technique (FOT) measures the mechanical properties of the respiratory system. We have recently developed novel analyses of FOT parameters that assess airway closure. This study aims to assess the effect of donor and recipient clinical history on recipient respiratory system mechanics post LTx using FOT. <h3>Methods</h3> Bilateral LTx recipients were recruited into a multi-centre (Alfred Hospital, Melbourne and St Vincent's Hospital, Sydney) prospective study. Subjects underwent spirometry, plethysmography and FOT (Tremoflo 2000, Thorasys, Canada) on one occasion at 3-6 months after LTx. Donor lung size was estimated from predicted total lung capacity equations. General linear models were used to assess the effect of donor-recipient demographics and features on respiratory mechanics from FOT. <h3>Results</h3> A total of 63 patients (52% male, age 52 ±15yrs) were included. Oversized donor lungs (donor predicted TLC > recipient TLC pre-Tx) were associated with increased respiratory reactance (Xrs5, p=0.041) and increased peripheral airway resistance (R5-19, p=0.002). Undersized donor lungs (donor predicted TLC < recipient TLC pre-Tx) were associated with increased total and peripheral airway resistance (R5 and R5-19, p=0.043 and p=0.003) and markers of early airway closure from FOT (Xrs5 and DR1, p=0.047 and p=0.038). Recipients transplanted for interstitial lung disease (ILD) were more likely to have increased total and peripheral airway resistance (R5 and R5-19, p=0.035 and p=0.038). Increasing donor age was more associated with airflow limitation (FER, p=0.009) and peripheral airway resistance (R5-19, p=0.042). <h3>Conclusion</h3> LTx recipients who receive over or under-sized donor lungs, older donor lungs, or had ILD as their native lung disease were more likely to have abnormal respiratory system mechanics. Longitudinal assessment is required to understand the trajectory of novel oscillometry parameters, including FOT, in relation to lung allograft dysfunction.