Adler M Salazar1, Christopher CJL Newth1, Robinder G Khemani1, Hammer Jürg2, Patrick A Ross1
1 Children's Hospital Las Angeles, Department of Critical Care Medicine, Los Angeles; Keck School of Medicine at University of Southern California, Los Angeles, CA, USA
2 University Children's Hospital Basel, Division of Pediatric Critical Care and Pulmonology, Basel, Switzerland
Aim: Absent pulmonary valve syndrome (APVS) is found in 3-6% of patients with Tetralogy of Fallot (TOF). Along with findings of TOF, absence of pulmonary valve tissue results in aneurysmal dilatation of the main and branch pulmonary arteries compressing the trachea, main-stem, and intrapulmonary bronchi leading to obstructive airways disease. Our objective was to review pulmonary function tests (PFT) in TOF-APVS patients.
Materials and Methods: Eight PFT were performed on five mechanically ventilated TOF-APVS patients in the intensive care unit. Tidal volume, forced vital capacity (FVC), maximal expiratory flow 25%, resistance and compliance of the respiratory system were measured.
Results: Pre-operative PFTs showed markedly elevated airways resistance (R RS ) (median 0.45 cmH 2 O/mL/sec, range 0.17-0.66) and marked variability of the static compliance of the respiratory system (C RS ) (median 0.6 mL/cmH 2 O/kg, range 0.25-2.6). Flow-volume loops measured by forced deflation showed flow limitation within the medium to small airways. Post-operative FVC was reduced in four of the five patients (median 46 mL/kg, IQR 42.9 - 48.8 mL/kg). Patients studied with various levels of positive end expiratory pressure (PEEP) showed improvement in tidal volume and reduced obstruction with PEEP greater than 10 cmH 2 O. For three patients with pre-operative data available, surgical correction resulted in near-normal post-operative C RS and improved, but still elevated R RS (median 0.14 cmH 2 O/mL/sec, interquartile range [IQR] 0.11-0.31).
Conclusion: For our patients with TOF-APVS, airway resistance was elevated. Flow limitation was seen in the medium to small airways with a mild reduction of FVC. PFTs may help guide management of mechanical ventilation for TOF-APVS patients.
Patrick A Ross
Anesthesiolog Critical Care Medicine, Children's Hospital, Los Angeles, 4650 W. Sunset Boulevard, MS # 12, Los Angeles, 90027, CA
Source of Support: None, Conflict of Interest: None
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