Although some important progresses were made in the field of the meridian research, no breakthroughs have been achieved. Besides,there are some problems in meridian researches. The majority of the existing studies involve lots of subjective assessments for meridian phenomena. In addition, few studies have investigated the site specificity between two specific meridians.Therefore, this study is designed to detect the microcirculatory characteristics of meridian phenomena by using an objective assessment tool and investigate the site specificity for the meridian-visceral association and surface-surface association between two specific meridians.

The Lung and Heart meridians are chosen as two specific studied meridians. 120 participants will be enrolled and divided into the healthy control group, chronic obstructive pulmonary disease (COPD) group and healthy intervention group. Laser doppler flowmetry (LDF) will be used to assess the microcirculatory characteristics of meridian phenomena for the Heart and Lung meridians. The site specificity for the meridian-visceral association will be investigated by comparing the microcirculatory difference between the Heart and Lung meridians in the healthy control group and COPD group. Besides, participants in the healthy intervention group will receive two sessions of moxibustion in the Heart meridian and Lung meridian respectively to explore the site specificity for the surface-surface association.

Inclusion Criteria:

Inclusion criteria for COPD patients

• Patients should meet the COPD diagnostic criteria, and the severity of COPD is in the stage of GOLD 2 or 3 based on pulmonary function testing;
• COPD patients in the stable phase and present with mild symptoms;
• 35 ≤ age ≤75 years, male or female;
• Patients have clear consciousness and could communicate with others normally;
• Patients could understand the full study protocol and written informed consent is signed.

Inclusion criteria for healthy volunteers

• Healthy volunteers who could provide a recent medical examination report to confirm they have not any cardiovascular, respiratory, digestive, urinary, hematological, endocrine and neurological disease;
• age ≥20 years, male or female;
• Participants have clear consciousness and could communicate with others normally;
• Participants could understand the full study protocol and written informed consent is signed.

Exclusion Criteria:

Exclusion criteria for COPD patients

• Patients who fail to meet the diagnostic criteria for COPD, or COPD patients in the phase of acute exacerbation;
• Patients have the following complications, such as bronchial asthma, bronchiectasis, active tuberculosis, pneumothorax, chest trauma, tumors of the lung or thorax;
• Patients have concomitant conditions of heart diseases, such as chronic stable angina pectoris;
• Patients have serious concomitant conditions and fail to treat them effectively, such as diseases of the digestive, urinary, respiratory, hematological, and nervous system;
• Patients have mental illness, severe depression, alcohol dependence or history of drug abuse;
• Pregnant or lactating patients; Patients are participating in other trials.

Exclusion criteria of healthy volunteers

• Participants have mental illness, severe depression, alcohol dependence or history of drug abuse;
• Pregnant or lactating participants ;
• Participants are participating in other trials