Background: While sympathetic drive in pathophysiology and pharmacological therapy shapes our understanding of systolic heart failure, it is still unclear if COPD is also associated with such an increase and which determinants lead to such an increase of sympathethic drive. In particular, obstructive sleep apnea has been discussed as a major determinant outside of COPD. The gold standard of sympathetic tone determination is invasive microneurographic measurement of muscular sympathetic nerve activity (MSNA). Burst rate (/min) or incidence (adjusted for heart rate) then express sympathetic activity as the spontaneous discharge rate of sympathetic nerve fascicles measured microneurographically as the gold standard.

Methods: In 7 COPD patients without any secondary cardiovascular disease, external and intraneural stimulation was used to locate the peroneal nerve at the leg, and then invasive microneurographic quantification of MSNA was performed via this nerve, and the influence of simulated obstructive apneas on sympathetic tone was determined (5-min simulation of 10-second apneas alternating with 30 seconds of normal breathing).

Results: In 7 COPD patients (age 63±9 years, 2 male, Gold III-IV) heart rate did not show a significant change in response to simulation of obstructive apnea (HR 74±9 vs. 82±8 bpm, p=0.16). However, burst rate was increased in COPD patients under obstructive apnea (31±7 vs. 46±12 bursts/minute, p=0.027). Burst incidence was also increased in COPD patients by obstructive apnea (42±7 vs. 57±17 bursts/100bpm, p=0.05).

Conclusion: Obstructive apnea increases sympathetic activity in COPD patients, so that the therapy for obstructive sleep apnea may have prognostic value.