title: Detecting central-venous oxygen desaturation without a central-venous catheter: Utility of the difference between invasively and noninvasively measured blood pressure.
abstract: The objective was to determine whether central-venous oxygen saturation (ScvO2<70%) can be detected from the difference between invasively and noninvasively measured systolic blood pressure (BP) (ie, ΔBP defined as arterial BP minus noninvasive BP).
  
  
  
  This is a cross-sectional study at a single medical and surgical intensive care unit in Japan. All hypotensive patients admitted to intensive care unit were eligible. Arterial BP was measured via a radial-artery catheter, and noninvasive BP on the same side was measured via a brachial cuff. ScvO2 was measured by gas analysis of blood sampled from a central-venous chatheter (CVC). We calculate the area under the curve for ΔBP as an indicator of ScvO2<70%.
  
  
  
  Usable data were obtained from the records of 111 patients. The median and interquartile range of ΔBP and ScvO2 were -4mm Hg (-11, 6) and 67% (60.9, 73.9), respectively. The area under the curve of ΔBP as an indicator of ScvO2<70% was 0.81 (95% confidence interval [CI], 0.73-0.89). With a cutoff ΔBP of 0, sensitivity was 65.7% (95% CI, 53.1-76.8), specificity was 97.7% (95% CI, 88.0-99.8), and positive predictive value was 97.8 (95% CI, 88.2-99.9).
  
  
  
  ΔBP can indicate whether ScvO2 is lower than 70%. When that difference is greater than 0, ScvO2 is very likely to be lower than 70%.
authors.affiliation: Department of Healthcare Epidemiology, School of Public Health, Kyoto University Faculty of Medicine, Yoshidakonoe-cho, Sakyo-ku, Kyoto City, Japan 606-8315; Department of Critical Care Medicine, Sakai City Medical Center, Ebaraji-cho 1-1-1, Nishi-ku, Sakai City, Japan 593-8304. Electronic address: jkumakumakuma@hotmail.com.
authors.forename: Junji
authors.initials: J
authors.lastname: Kumasawa
authors.affiliation: Department of Critical Care Medicine, Sakai City Medical Center, Ebaraji-cho 1-1-1, Nishi-ku, Sakai City, Japan 593-8304.
authors.forename: Akitoshi
authors.initials: A
authors.lastname: Ohara
authors.affiliation: Department of Critical Care Medicine, Sakai City Medical Center, Ebaraji-cho 1-1-1, Nishi-ku, Sakai City, Japan 593-8304.
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Kohata
authors.affiliation: Department of Critical Care Medicine, Sakai City Medical Center, Ebaraji-cho 1-1-1, Nishi-ku, Sakai City, Japan 593-8304.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Aoyagi
authors.affiliation: Department of Healthcare Epidemiology, School of Public Health, Kyoto University Faculty of Medicine, Yoshidakonoe-cho, Sakyo-ku, Kyoto City, Japan 606-8315.
authors.forename: Shingo
authors.initials: S
authors.lastname: Fukuma
authors.affiliation: Department of Healthcare Epidemiology, School of Public Health, Kyoto University Faculty of Medicine, Yoshidakonoe-cho, Sakyo-ku, Kyoto City, Japan 606-8315; Center for Innovative Research for Communities and Clinical Excellence, Fukushima Medical University, Hikarigaoka, Fukushima City, Japan 960-1295.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Fukuhara
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001795:Blood Pressure Determination / Q000379:methods*; D062905:Central Venous Catheters; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D007362:Intensive Care Units; D007564:Japan; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen
keywords: Blood pressure monitors; Central-venous catheterization; Oximetry; ROC curve; Sensitivity and specificity; Shock