Patients were routinely implanted with PICC and received routine health education. The content of health education included face-to-face language explanation of the whole process of catheter knowledge, issuing catheter maintenance manual, issuing ordinary grip ball and telling how to use it, and follow-up.

Patients were routinely implanted with PICC, and the optimal duration-relaxation time of grip strength training was adopted on the basis of health education in the control group.

On the basis of control group

1. Determine the best grip strength On the basis of the control group, color Doppler ultrasound and electronic grip force were used to record the optimal grip strength of patients to achieve effective blood flow velocity before and 24 hours after PICC insertion.
2. Design precise grip strength training guidance program On the basis of the control group, the patients were instructed to perform grip strength training according to the determined best grip strength and the best duration of clenching and relaxation time.

First determine patients for holding the ball movement should reach the effective blood flow velocity and best duration - relaxation, and USES the electronic grips and color doppler ultrasonic diagnostic apparatus, for individual patients to choose the best grip the efforts and training, to form the best grip the training plan, and observe the scheme for Peripheral central venous catheter-associated thrombosis prevention effect.

Before catheterization, 24 hours after catheterization, and weekly maintenance, color Doppler ultrasound diagnostic instrument was used to diagnose venous thrombosis (including asymptomatic thrombosis) and its classification. The patients were observed for 8 weeks.

During weekly maintenance, color Doppler ultrasound was used to measure the blood velocity of the arm axillary vein on the side of the catheter, and the maximum blood velocity (Vmax, cm/s) was recorded.