title: [Preoperative lung function tests by impulse oscillation system].
abstract: BACKGROUND
  Preoperative respiratory function tests are important for evaluating the preoperative condition. However, maximum expiratory efforts are necessary for the patients to obtain respiratory function using the spirometry and flow-volume curve measurements. On the other hand, the impulse oscillation system (IOS) can evaluate the total airway resistance (R5), the large airway resistance (R20), the small airway resistance (R5-R20), and the reactance (X5) under normal breathing in a few minutes.
  
  
  METHODS
  Subjects are 300 adult patients scheduled for an elective surgery. Respiratory function studies including IOS, spirometry, maximum expiratory flow-volume curve and single N2 wash out were done preoperatively. Subjects were divided into 3 groups; normal (%VC > or = 80%, %FEV1.0 > or = 70%), obstructive (%VC > or = 80%, %FEV1.0 > or = 70%), and restrictive (%VC > or = 80%, %FEV1.0 > or = 70%) each comprising of 100 patients.
  
  
  RESULTS
  In both obstructive and restrictive groups, R5, R20 and R5-R20 were significantly higher than those in the normal group. In both obstructive and restrictive groups X5 was significantly lower than that in the normal group.
  
  
  CONCLUSIONS
  IOS was measured without any respiratory efforts in preoperative patients. Also, measurements can be done during spontaneous breathing with a high temporal resolution, and do not require a special lung function laboratory. The technique would seem useful for the study of physiological changes of the respiratory functions. IOS is useful to evaluate the peripheral airway conditions.
authors.affiliation: Department of Anesthesiology, Showa University School of Medicine, Tokyo 142-8666.
authors.forename: Yasura
authors.initials: Y
authors.lastname: Suzuki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000403:Airway Resistance / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D012129:Respiratory Function Tests / Q000379:methods