title: Respiratory biofeedback during CT-guided procedures.
abstract: OBJECTIVE
  Respiratory motion can be a complicating factor during image-guided interventions. The ability to reproduce breath-holds may facilitate safer needle-based procedures. The purpose of this study was to evaluate if respiratory biofeedback decreased variability among breath-holds and if the signals from the respiratory bellows belt can be used to measure target motion.
  
  
  METHODS
  In phase 1 of the study, a respiratory bellows belt was applied to patients before image-guided interventional procedures. Belt stretch from respiratory motion was converted into voltage readings and displayed on a monitor as biofeedback. Patients were asked to perform inspiratory, expiratory, and midcycle breath-holds with and without the biofeedback. The variability in voltage readings between breath-holds with and without biofeedback was compared. In phase 2, the respiratory bellows belt was used during computed tomography (CT)-guided procedures with the patients blinded to the biofeedback. Voltage readings and CT series numbers were recorded as patients were asked to hold their breath during scans. The variability of CT z-axis targets was compared with the variability of voltage readings.
  
  
  RESULTS
  A significant decrease in variability was found during expiratory breath-holds (P = .0083) with trends toward significance with midcycle and inspiratory breath-holds. A positive correlation (Kendall tau = 0.5; P = .024) was shown between CT z-axis and belt stretch variability in subjects who received smaller doses of moderate sedation compared with those who received larger doses or general anesthesia.
  
  
  CONCLUSIONS
  Biofeedback may help the patient to have a more consistent breath-hold. The belt could decrease the error and unpredictability from craniocaudal motion of targets during image-guided interventions.
authors.affiliation: Diagnostic Radiology Department, National Institutes of Health, Clinical Center, Bethesda , Maryland 20892, USA. locklin.linj@cc.nih.gov
authors.forename: Julia K
authors.initials: JK
authors.lastname: Locklin
authors.forename: Jeff
authors.initials: J
authors.lastname: Yanof
authors.forename: Alfred
authors.initials: A
authors.lastname: Luk
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Varro
authors.forename: Alexandru
authors.initials: A
authors.lastname: Patriciu
authors.forename: Bradford J
authors.initials: BJ
authors.lastname: Wood
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D018592:Cross-Over Studies; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology; D015641:Radiography, Interventional / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed