title: Oxygen supplementation and cardiac-autonomic modulation in COPD.
abstract: OBJECTIVE
  Patients with COPD have an increased sympathetic modulation and reduced baroreflex sensitivity (BRS). Therefore, we studied the effects of breathing 31% supplemental oxygen (SuppO(2)) on autonomic modulation in a group of COPD patients.
  
  
  METHODS
  We measured autonomic modulation before and during the administration of SuppO(2) on 51 patients with COPD using time-frequency analysis of R-R intervals and BP before and after intervention. This was done via a counterbalanced crossover design. The BRS index was determined using the sequence method.
  
  
  RESULTS
  Significant differences were seen in oxygen saturation levels following breathing with SuppO(2) ([mean +/- SD] 96.4+/-1.5%) when compared to those seen after breathing with compressed air (CA) (92.8+/-2.9%; p<0.0001). Significant increases were seen in the natural log-transformed high-frequency modulation (HFln) (SuppO(2), 10.8+/-1.3 natural logarithm [ln] ms(2)/Hz; CA, 10.6+/-1.3 ln ms(2)/Hz; p<0.028) and BRS (SuppO(2), 3.3+/-2.2 ms/mm Hg; CA, 2.8+/-1.8 ms/mm Hg) following the supplemental oxygen treatment (p<0.015). The low-frequency/high-frequency ratio of heart rate variability revealed significant differences between the two treatments (SuppO(2), 2.7 +/-1.2; CA, 3.1+/-1.3; p<0.008). The analysis of BP variability data revealed significant decreases in the HFln (CA, 6.9+/-1.0 mm Hg(2)/Hz; SuppO(2), 6.5+/-1.2 mm Hg(2)/Hz; p<0.0001). Hemodynamic data also revealed a decrease in mean heart rate after breathing SuppO(2) compared with that after breathing CA (CA, 87.3+/-13.3 beats/min; SuppO(2), 85.0+/-12.4 beats/min; p<0.0004). The arterial pulse pressure significantly decreased when breathing SuppO(2) compared with that when breathing CA (CA, 57.2+/-13.5 mm Hg; SuppO(2), 53.3+/-13.0 mm Hg; p<0.0023).
  
  
  CONCLUSIONS
  Oxygen supplementation in COPD patients significantly and favorably alters autonomic modulation.
authors.affiliation: Human Performance Laboratory, Presbyterian Hospital of the New-York Presbyterian Hospital, New York, NY 10032, USA. mnb4@columbia.edu
authors.forename: M N
authors.initials: MN
authors.lastname: Bartels
authors.forename: J M
authors.initials: JM
authors.lastname: Gonzalez
authors.forename: W
authors.initials: W
authors.lastname: Kim
authors.forename: R E
authors.initials: RE
authors.lastname: De Meersman
mesh_terms: D001341:Autonomic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology; D018592:Cross-Over Studies; D004562:Electrocardiography; D005080:Exercise Test; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000503:physiopathology / Q000628:therapy*; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D011379:Prognosis