Vascular Responses to Manual PC6 Acupuncture in Nonsmokers and Smokers Assessed by the Second Derivative of the Finger Photoplethysmogram Waveform

Background: Smoking is reported to increase arterial stiffness. Indices obtained from the second derivative of digital volume pulse (SDDVP) waveform have been proposed to characterize vascular aging and arterial rigidity. PC6 (Neiguan) is a traditional acupoint in each forearm that has been shown to modify cardiovascular functioning. Objective: To investigate the acute effects of manual needling with PC6 on SDDVP indices in healthy chronic smoker and nonsmoker subjects. Subjects and Methods: Aging index (AI) was defined as (b − c − d − e)/a, B:A was calculated as the ratio of the absolute value for the height of the b wave (B) to that of the a wave (A), and D:A was calculated as the ratio of the absolute value for the height of the d wave (D) to that of the a wave (A). These indices derived of the wave components of SDDVP of healthy nonsmokers (n= 40; 28.3 ± 3.0 years old) vs. chronic smokers (n= 30; 29.9 ± 2.9 years old) were compared. The digital volume pulse (DVP) was obtained by measuring infrared light transmission through the finger. Of each subject, a DVP registration 20 minutes long was obtained. PC6 was stimulated unilaterally by manual needling for 5 minutes (1−6 minutes). SDDVP indices were compared in each subject in pre- vs. post-acupuncture periods (30 seconds vs. 18 minutes, respectively). Results: At baseline, we found significant difference in B:A between nonsmokers and smokers. Comparing pre- vs. post-acupuncture periods, B:A and D:A did not show significant differences among nonsmokers, but B:A improved significantly in smokers and AI improved significantly in both nonsmokers and smokers. Conclusion: These findings suggest that manual needling with PC6 could revert some of the deleterious effects on vascular functioning produced by chronic cigarette smoking.