Lung meridian acupuncture point skin impedance in asthma and description of a mathematical relationship with FEV₁

Alteration in acupoint skin impedance is purportedly associated with health impairment. This study examined lung meridian acupoint skin impedance in healthy individuals and patients with controlled asthma and the relationship if any with Forced Expiratory Volume in 1s (FEV1).Twenty-eight subjects diagnosed with asthma and 28 age and gender-matched healthy subjects had their FEV1and skin impedance, at acupoints LU 7 (Lieque) and LU 9 (Taiyuan) on the lung meridian, measured. Skin impedance was significantly higher in subjects with asthma (p<0.05) and negatively correlated with percent predicted FEV1(r=-0.34 to -0.40, p<0.005). The Receiver Operating Characteristic (ROC) suggested the cutoff point for logarithm-transformed mean of skin impedance for asthma was ≥3.59 unit (sensitivity=82.1%, specificity=82.1%) (AUC=0.878, p<0.001). A regression prediction equation of asthma was derived. This study suggests that acupoint skin impedance on the lung meridian may reflect the asthma condition. The use of skin impedance as an adjunctive, objective assessment in asthma screening and treatment monitoring, warrants further investigation.