Two-needle tunnel PICC procedure:

1. Local anesthesia at puncture and catheter exit sites;
2. Ultrasound-guided vascular puncture at puncture site, guide wire inserted via puncture needle;
3. Skin dilation at both puncture and exit sites;
4. 4cm saline tunnel created with 0.9% NaCl: 10mL syringe advanced along tunnel path while injecting solution;
5. Subcutaneous tunnel formed from exit site to puncture site with tunneling tool, catheter pulled through tunnel to puncture site;
6. Vascular sheath inserted over guide wire, catheter trimmed to length, advanced through sheath after guide wire removal;
7. Vascular sheath peeled off, catheter adjusted to proper position;
8. Catheter tip position confirmed;
9. Puncture site closed with suture-free tape, both sites covered with sterile dressings, catheter secured.

Ultrasound guidance is used for vascular puncture and assisted subcutaneous tunnel creation:

1. Local anesthesia is administered at the puncture site，the puncture needle travels 4 cm through the subcutaneous tissue before entering the blood vessel;
2. The guide wire is inserted along the puncture needle;
3. skin dilation;
4. The vascular sheath is advanced into the blood vessel via the guide wire, and the catheter is inserted through the vascular sheath;
5. The catheter tip position is confirmed, and the catheter is secured.

1. Local anesthesia is administered at the puncture site，Ultrasound guidance is used for vascular puncture and assisted subcutaneous tunnel creation，the puncture needle travels 4 cm through the subcutaneous tissue before entering the blood vessel;
2. The guide wire is inserted along the puncture needle;
3. skin dilation;
4. The vascular sheath is advanced into the blood vessel via the guide wire, and the catheter is inserted through the vascular sheath;
5. The catheter tip position is confirmed, and the catheter is secured.

these complications include catheter exit site oozing, contact dermatitis, venous thrombosis, infection, catheter displacement or dislodgement, mechanical phlebitis, catheter occlusion, and catheter fracture or damage.

Evaluated by Numerical Rating Scale , a self-report tool where individuals rate their pain intensity from 0 (no pain) to 10 (worst possible pain)，with higher scores indicating more severe pain.