A Study on the Application of Technology Based on the Principle of Auxiliary Negative Pressure in Blood Collection for Patients After Chemotherapy

INTERVENTION: Observation group:Peripheral venous blood collection using a technique based on the auxiliary negative pressure principle;Control group:Single tourniquet peripheral venous blood collection method; CONDITION: Malignant tumor PRIMARY OUTCOME: Primary Outcome Indicator; SECONDARY OUTCOME: Incidence of impaired blood flow during venipuncture;Accuracy of collected blood volume;Coagulation rate of anticoagulated blood samples;Blood collection time;Patient comfort level; INCLUSION CRITERIA: 1. All patients were >=20 years old; 2. All patients were diagnosed with malignant tumors by imaging and pathological examination and had completed chemotherapy; 3. Patients and their families were informed and agreed to participate in the study and signed the informed consent form.