1. After the infusion, 150 ml of normal saline was absorbed and 3 ml of heparin solution was added with heparin sodium 12500 U (2 mg). All the needles were inserted into the heparin cap with a 5ml syringe.
2. When the tube is sealed with high concentration or irritating drugs, 20ml of normal saline is first injected by intravenous drip or push. Then, 150 ml of normal saline is added with 12500 U (2 mg) heparin solution and 3 ml of slow positive pressure is used to seal the tube.