Generation of Data:
1. Spirometry-Spirometry will be performed in accordance with ATS/ERS (American Thoracic Society/ European Respiratory Society) Task Force using a KoKo spirometer (KoKo system, PDS Inc., Ferraris Cardiopulmonary System Group; Louisville, CO, USA). Each maneuver will be repeated for at least three technically acceptable FEFV curves; the best results were used for analysis. \[6\]
2. Whole Body Plethysmography- FRCpleth will be measured in a commercial, whole body ZAN500 constant volume body plethysmograph (ZAN-Messgeraete GmbH, Germany); the surrounded glassed cabin of 980 L includes a chair with adjustable height, all meeting the ATS/ERS recommendations for plethysmography measurements \[7,8\]. The flow, volume, cabin pressure, and mouth pressures are automatically calibrated. BTPS conditions for lung volumes are automatically corrected. According to the manufacturer, environmental interference is automatically reduced by a numeric-drift-compensation, enabling quick stable signals for immediate testing.
3. MCT - Methacholine challenge tests will be performed in a designated room at the Pediatric Pulmonary Unit, Meyer Children's Hospital, Haifa, Israel. MCT was performed with double doses of fresh methacholine solutions in saline. Solutions were driven by KoKo-PDS dosimeter via mouthpiece. The MCT will end when FEV1 dropped by more 20% from baseline FEV1 values or when a methacholine concentration of 16 mg/ml was reached. The exact PC20 value will be then calculated by the program according to the log-transformed formula, as described in the guidelines for methacholine.\[9\] Airway hyper-reactivity was defined as PC20 \<8 mg/ml. Oxygen saturation and heart rate were monitored by pulse oximetry (Nonin Wrist Ox 3100, Nonin Medical, Inc., Plymouth, MN, USA).
4. FENO: Measurement of FENO will be performed by portable electrochemical analyzer NIOX MINO (Aerocrine AB, Smidesvägen, Sweden),\[10\] and according to ATS recommendations . The measurement procedure includes a deep inhalation to total lung capacity followed by exhalation for 10 seconds at a mouth flow rate of 50 mL/sec and a pressure of 10 cmH2O.\[11\] Analysis of Data: Subjects of study will be patients post-Fontan operation over the age of 6 years in order to fulfill the cooperation requirement necessary to obtain data. Patients should be in general good health without any ongoing acute pulmonary disease.
