Observation of Pain During the Treatment of Great Saphenous Vein Using Microwave Ablation， and Analysis of Related Factors

Objective: This study is a single-center prospective observational research that recorded patients' pain scores at four time points during surgery (puncture and catheter insertion, swelling fluid injection, microwave generator operation, and end of surgery). It analyzed the correlation between pain during microwave ablation treatment for great saphenous vein varicosities and factors such as age, gender, body mass index, volume of swelling fluid used, and others, in order to summarize and improve surgical details to reduce patients' intraoperative pain.

Despite the significant progress made by global experts in vascular surgery in studying endovenous microwave ablation (EMA) for the treatment of varicose veins (VVs), there are still many unknown areas to be explored. Current research primarily focuses on the surgical outcomes and associated complications of EMA, while studies on intraoperative pain are relatively scarce. Firstly, the American College of Radiology has not provided a clear definition of intraoperative pain when treating lower extremity varicose veins, thus it has not received sufficient attention in clinical practice. Many physicians consider the success of the surgery as the endpoint of treatment, overlooking the impact of intraoperative pain on the patient's surgical experience. Ni Zhao et al. found in a prospective randomized controlled trial that EMA is associated with more pain within 48 hours post-operation. When our department introduced the use of EMA for VVs, we discovered that its working form and power differ from other thermal ablations, and there are also differences in terms of intraoperative pain, the volume of tumescent fluid used, and the requirements for vein depth. With the continuous advancement in lower limb varicose vein surgeries, anesthesia methods have evolved from general anesthesia to combined spinal-epidural anesthesia, and now to local anesthesia. Tumescent anesthetic solution is the main anesthetic agent for EMA surgery, and the infiltration of tumescent anesthetic fluid around the great saphenous vein is crucial for the success of EMA; however, paradoxically, this is also the area where patients experience the most severe pain. The commonly used tumescent solution is a crystalline solution containing local anesthetics and adrenaline, which is acidic in nature and is the main reason for the 'sting' sensation during skin infiltration. A Cochrane review indicated that adjusting the pH of lidocaine solution by adding sodium bicarbonate significantly reduced pain during the skin infiltration process, as measured by the 10-centimeter Visual Analog Scale (VAS). Moreover, the temperature of the tumescent anesthetic solution also affects pain during the skin infiltration process, as noted by Bell et al. Alonso et al. found in a prospective randomized controlled trial that heating local anesthetic solutions to 37°C and 42°C can reduce pain, and heating adrenaline-containing local anesthetic solutions to near body temperature is also an effective method to alleviate local anesthetic pain. We hope to achieve better preoperative prevention and intraoperative management through an analysis of pain-related factors, thereby improving the patient's surgical experience.

Eligibility Criteria:
Inclusion Criteria:

1. Age≥ 18 years old, ≤ 90 years old;
2. the patient's life expectancy is greater than 12 months;
3. The clinical diagnosis is primary VVs, CEAP classification C2-C6, and the GSV segment needs to be treated, including pain, burning sensation, heaviness, fatigue, itchy skin, night cramps and other clinical symptoms;
4. Doppler ultrasound confirmed that the diameter of GSV was greater than 3mm and less than 12mm when standing;
5. Doppler ultrasound confirms that GSV is located in the saphenofascia or the distance between GSV and the skin surface is \>1cm;
6. endovenous microwave ablation treatment only for unilateral GSV walking area;
7. The patient is willing to cooperate with the completion of the examination specified in the protocol.

Exclusion Criteria:

1. GSV thrombosis, or combined with deep vein thrombosis, or previous history of deep vein thrombosis and pulmonary embolism;
2. patients with recurrence after prior VVs-related surgery (C2r);
3. the GSV trunk is severely distorted, and it is expected that the catheter will not be able to pass;
4. Severe ischemia of the lower limbs, Ankle brachial pressure index (ABPI) \< 0.8;
5. Known allergy to the drugs and device materials involved in the study;
6. Previously implanted with a pacemaker or defibrillator, and currently receiving regular anticoagulation therapy (such as warfarin, heparin);
7. Pregnant or lactating females;
8. Patients who are unable or unwilling to participate in the study;
9. Participating in the research of other drugs or devices;
10. Skin malignancies other than non-melanoma that are being treated;
11. daily use of narcotic drugs or non-steroidal anti-inflammatory drugs to control pain caused by venous disease;
12. The investigator judged that endovenous treatment was not suitable;