CARDIOVASCULAR-RESPONSES TO TESTS FOR AUTONOMIC DYSFUNCTION IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE WITH AND WITHOUT CONTINUOUS LONG-TERM OXYGEN-THERAPY

The aim of this study was to investigate autonomic neuropathy, with an d without oxygen therapy, in patients with chronic obstructive pulmona ry disease (COPD). Four cardiovascular tests for autonomic function we re used, and in addition, basal pancreatic polypeptide (PP) was measur ed. The following COPD patients were studied: 10 normoxemic (mean PaO2 10.9 +/- SD 1.1 kPa), 10 hypoxemic (PaO2 7.6 +/- 0.7 kPa before, and 10.6 +/- 1.4 kPa after 24 h oxygen therapy), and 6 hypoxemic on long-t erm oxygen therapy (LTOT) (PaO2 10.3 +/- 1.3 kPa before, and 7.0 +/- 0 .8 kPa after 4 h of low dose or oxygen free interval). Twenty healthy age-matched subjects served as controls. In the individual tests the h ypoxemic and the LTOT groups had a significantly decreased heart rate response to the Valsalva manoeuvre (ratio 1.23 +/- 0.17 and 1.12 +/- 0 .07 versus control's 1.45 +/- 0.26 (p < 0.01 and 0.005, respectively) and versus the normoxemic group 1.46 +/- 0.30 (p < 0.05)) and the hypo xemic as well as the LTOT group had a significantly decreased heart ra te response to standing up (ratio 0.97 +/- 0.04 and 0.97 +/- 0.07, res pectively, versus the controls 1.06 +/- 0.09 (p < 0.005 and 0.05)). Th e blood pressure response to standing up and to sustained handgrip did not differ significantly between the groups. In spite of apparent aut onomic dysfunction, PP levels in the LTOT group were significantly hig her than in the controls (p < 0.01-0.001) and the normoxemic group (p < 0.05-0.01). Twenty-four hours of oxygen treatment in the hypoxemic g roup or four hours of oxygen withdrawal in the LTOT group did not chan ge the results significantly. In conclusion, our findings are consiste nt with the previous notion of neurological dysfunction from hypoxemia , but this may not be corrected by the use of short term oxygen treatm ent. This contrasts to previous findings in which longer term oxygen d id correct some of these problems.