title: Slow and fast lung compartments in cystic fibrosis measured by nitrogen multiple-breath washout.
abstract: Imaging studies describe significant ventilation defects across a wide range of cystic fibrosis (CF) related lung disease severity. These are unfortunately poorly reflected by phase III slope analysis-derived Scond and Sacin from multiple-breath washout (MBW). Methodology extending previous two-lung compartment model-based analysis is presented describing size and function of fast- and slow-ventilating lung compartments from nitrogen (N2) MBW and correlation to obstructive lung disease severity. In 37 CF subjects (forced expiratory volume in 1 s [FEV1] mean [SD] 84.8 [19.9] % predicted; abnormal lung clearance index [LCI] in 36/37, range 7.28-18.9) and 74 matched healthy controls, volume and specific ventilation of both fast and slowly ventilated lung compartments were derived from N2-based MBW with commercial equipment. In healthy controls lung emptying was characterized by a large compartment constituting 75.6 (8.4)% of functional residual capacity (FRC) with a specific ventilation (regional alveolar tidal volume/regional lung volume) of 13.9 (3.7)% and a small compartment with high specific ventilation (48.4 [15.7]%). In CF the slowly ventilated lung compartment constituted 51.9(9.1)% of FRC, with low specific ventilation of 5.3 (2.4)%. Specific ventilation of the slowly ventilated lung compartment showed stronger correlation with LCI (r2 = 0.70, P < 0.001) vs. Sacin (r2 = 0.44, P < 0.001) or Scond (no significant correlation). Overventilation of the fast lung compartment was no longer seen in severe CF lung disease. Magnitude and function of under- and overventilated lung volumes can be derived from routine N2 MBW in CF. Reported values agree with previous modelling-derived estimates of impaired ventilation and offer improved correlation to disease severity, compared with SnIII analysis.
authors.affiliation: Department of Pediatrics, Central Hospital, Skövde, Sweden; The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; per.gustafsson@vgregion.se.
authors.forename: P M
authors.initials: PM
authors.lastname: Gustafsson
authors.affiliation: Department of Respiratory Medicine, The Children's Hospital at Westmead, Sydney, New South Wales, Australia; Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Australia;
authors.forename: P D
authors.initials: PD
authors.lastname: Robinson
authors.affiliation: The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; Department of Chest Medicine and Allergology, The Sahlgrenska University Hospital, Gothenburg, Sweden;
authors.forename: M
authors.initials: M
authors.lastname: Gilljam
authors.affiliation: The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; Queen Silvia Children's Hospital, Gothenburg, Sweden; and.
authors.forename: A
authors.initials: A
authors.lastname: Lindblad
authors.affiliation: The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; Department of Clinical Physiology, The Sahlgrenska University Hospital/East, Gothenburg, Sweden.
authors.forename: B K
authors.initials: BK
authors.lastname: Houltz
mesh_terms: D000293:Adolescent; D000328:Adult; D003550:Cystic Fibrosis / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume; D005652:Functional Residual Capacity; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D013990:Tidal Volume; D055815:Young Adult
keywords: adults; children; lung clearance index; lung function; specific ventilation; ventilation distribution