It is known that 0,1Hz paced breathing reduces blood pressure, but the mechanisms involved in this phenomenon are not completely clear. The aim of our study was to evaluate the changes of finger artery compliance associated with this breathing pattern.

We measured ECG, arterial pressure and finger artery compliance in 21 young adults at rest and during slow breathing. Values obtained were compared by paired t-test. The finger artery compliance measurements based on the comparison of two oscilometric signals, one from Finapres and another from the cuff attached to the middle finger of the same hand, measuring the finger volume changes. A spectral analysis of R-R intervals was done by autoregression method to determine the changes of autonomic tone during slow breathing. We determined the area under the power spectrum curves over high frequency (HF) band (0.15–0.4 Hz), low frequency (LF) band (0.04–0.15 Hz) and very low frequency (VLF) band (<0.04 Hz).

Our results show that finger artery compliance decreased (from 1.04±0.12 to 0.50±0.06), HF component of HRV decreased (from 58.62±5.31 to 26.59±3.81) and percent of LF component increased (from 38.15±4.23 to 69.58±3.43) during slow breathing. All differences were statistically significant (p<0.001).

Our results unexpectedly showed that sympathetic tone increased during slow breathing. This could be the reason for diminished finger artery compliance in our experimental settings. We suspect that paced breathing acted as stressor agent on persons not familiar with such breathing. Further investigation should be done to clarify this question.