title: Short-term oxygen administration restores blunted baroreflex sensitivity in patients with type 1 diabetes.
abstract: OBJECTIVE
  We hypothesised that the blunted baroreflex sensitivity (BRS) typical of type 1 diabetes is caused by a higher degree of tissue hypoxia in diabetes, and tested whether oxygen increased BRS and ventilation less, equally or more than in healthy control participants (the latter suggesting higher tissue hypoxia). In addition, we also considered the possible interference between oxygen and breathing pattern.
  
  
  METHODS
  In 96 participants with type 1 diabetes and 40 age-matched healthy controls, we measured BRS (average of six different standard methods), oxygen saturation, end-tidal carbon dioxide and ventilation changes during spontaneous and controlled breathing at 15 and six breaths/min, in normoxia and during 5 l/min oxygen administration.
  
  
  RESULTS
  BRS was blunted and blood pressure higher in diabetic participants during spontaneous breathing (p < 0.05). BRS increased with oxygen during spontaneous breathing in diabetic (p < 0.001) but not in control participants, and with oxygen the difference in BRS was no longer significant. Slow breathing in normoxia restored BRS to a similar extent to giving oxygen. Oxygen increased systolic and diastolic blood pressure, RR interval, heart rate variability, minute ventilation and tidal volume to a greater extent in diabetic patients than in controls, and decreased carbon dioxide similarly to controls.
  
  
  CONCLUSIONS
  The increased response to hyperoxia suggests a pre-existing condition of tissue hypoxia that functionally restrains parasympathetic activity in patients with type 1 diabetes. Autonomic abnormalities can be partially and temporarily reversed by functional manoeuvres such as slow breathing or oxygen administration through enhancement of parasympathetic activity and/or correction of tissue hypoxia.
authors.affiliation: Folkhälsan Institute of Genetics, Folkhälsan Research Center, University of Helsinki, Helsinki, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Bernardi
authors.forename: M
authors.initials: M
authors.lastname: Rosengård-Bärlund
authors.forename: A
authors.initials: A
authors.lastname: Sandelin
authors.forename: V P
authors.initials: VP
authors.lastname: Mäkinen
authors.forename: C
authors.initials: C
authors.lastname: Forsblom
authors.forename: P-H
authors.initials: PH
authors.lastname: Groop
mesh_terms: D000293:Adolescent; D000328:Adult; D017704:Baroreflex / Q000187:drug effects*; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy* / Q000503:physiopathology; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D010100:Oxygen / Q000494:pharmacology* / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D010100:Oxygen