Moser, Jason S.

Slow, deep breathing (SDB) is thought to lead to reductions in blood pressure by decreasing vascular‐sympathetic coupling. Venous Occlusion Plethysmography (VOP) is used to assess forearm blood flow (FBF) (ml/min/100 dl tissue). We used this technique to determine the vasodilatory effect of device‐guided (DG) vs self‐paced (SP) slow, deep breathing. We hypothesized that SP would lead to a larger vasodilation response than DG due to a more profound reduction in vascular‐sympathetic coupling, and that this would be correlated with psychological evaluations. Young, healthy male subjects (Mean age: 20 yr; DG: n=10; SP: n=11) rested supine for 20 minutes (baseline), followed by 20 minutes of SP or DG slow, deep breathing, then completed 20 minutes of endogenous breathing (recovery). At baseline, there was no difference in breathing rate between SP and DG (14.36±1.03 vs 15.39±1.29 breaths per minute, p=0.27) and respiratory rate was reduced to 8.36±0.74 breaths per minute (BPM) in the SP group (p<0.01 compared to baseline) and to 6.37±0.10 BPM in the DG group (p<0.01 compared to baseline). Respiratory rates between the two groups differed significantly during SDB (p<0.01 between groups). There was a significant increase in SP FBF compared to baseline at the end of the 20 minute intervention (p<0.05),while the DG group saw no significant increases. In DG, there was a strong negative correlation with the cognitive interference scores to VOP responsiveness (−0.77; R2=0.591), as well as between the cognitive failure score and VOP responsiveness (−0.61; R2=0.3693). In contrast, the SP groups had positive correlations when comparing VOP responsiveness to cognitive interference (0.1; R2=0.093) or cognitive failure (0.30; R2=0.011). For subjects in either breathing group, those who had an increase in FBF in response to SDB also had reductions in STAI anxiety score after the intervention whereas those with a decrease in FBF to SDB had an increase in anxiety score during the slow breathing (p=0.04). Overall, male subjects have a variable vasodilator responses to two types of SDB practices related to underlying psychological metrics. Our data underscores the importance of psychological metrics in physiological outcomes related to SDB practices.