title: [Monitoring of functional residual capacity by bedside real-time concentration via helium dilution technique].
abstract: OBJECTIVE
  To explore the accuracy, precision and repeatability of bedside real-time concentration monitoring via helium dilution (RHe) in ventilated dogs with and without acute respiratory distress syndrome (ARDS).
  
  
  METHODS
  Functional residual capacity (FRC) measurements were performed with computer tomography (FRCCT) and RHe (FRCRHe) in 18 adult male beagle dogs. Blood gas analysis was conducted for baseline, post-lung injury and end-of-experiment. Vital signs were monitored continuously. And the differences were compared between two techniques and repeated FRCRHes.
  
  
  RESULTS
  For healthy lungs, FRCCT and FRCRHe were linearly correlated (R² = 0.89, P < 0.0001). Bias between FRCRHe and FRCCT was 6.3 ± 27.6 ml (1.5% ± 7.1%) with 95% confidence interval limits of -47.7 and 60.3 ml respectively. For ARDS lung, FRCRHe = 0.693 × FRCCT + 66.4 (R² = 0.507, P < 0.00 1). Bias between FRCRHe and FRCCT was 7.9 ± 271 ml (4.5% ± 13.6%) with 95% confidence interval limits of -45.3 and 61.1 ml respectively. And the differences of repeated FRCRHes were -0.1% ± 5.8% and 0.2% ± 9% in normal and ARDS lungs respectively.
  
  
  CONCLUSIONS
  The technique of bedside RHe may be used for measuring FRC with excellent accuracy, precision and repeatability.
authors.affiliation: Department of Respiratory & Critical Medicine, First Affiliated Hospital, Zhengzhou University, Zhengzhou 450052, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Liu
authors.forename: Rongchang
authors.initials: R
authors.lastname: Chen
authors.forename: Liuqun
authors.initials: L
authors.lastname: Jia
authors.forename: Huan
authors.initials: H
authors.lastname: Wang
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.forename: Qingsi
authors.initials: Q
authors.lastname: Zheng
authors.affiliation: Email: chengzhehi@126.com.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Cheng
mesh_terms: D000818:Animals; D004285:Dogs; D005652:Functional Residual Capacity; D006371:Helium; D008168:Lung; D055370:Lung Injury; D008297:Male; D012128:Respiratory Distress Syndrome; D014057:Tomography, X-Ray Computed
chemical_list: D006371:Helium