Infusion — Intravenous Delivery of Medication

An infusion is the controlled instillation of fluid solutions, biological agents, or pharmacotherapeutic drugs into a vein, arterial vessel, or subcutaneous space. In oncology, it primarily denotes intravenous administration using gravity systems, electronic pumps, or ambulatory infusion devices to maintain steady physiological drug concentrations.

Infusions range in duration from brief thirty-minute administrations to continuous ambulatory infusions lasting several days. Delivery occurs via peripheral intravenous cannulas or central venous access devices (CVADs), such as peripherally inserted central catheters (PICCs) or implanted ports, reducing the risk of vascular irritation from caustic substances.

Many cancer drugs cannot be taken orally as stomach acids would neutralise them, or they would cause intolerable gastrointestinal upset. Infusions bypass the digestive tract entirely, ensuring the complete intended dose reaches the target tissues reliably.

Understanding your infusion process helps you prepare for treatment sessions, manage your clinic schedule, recognise possible infusion-related reactions promptly, and care appropriately for your intravenous access site.

Before an infusion, blood tests (full blood count, renal and liver function) confirm it is safe to proceed. During the infusion, physiological parameters such as blood pressure, heart rate, and oxygen levels are monitored. Diagnostic tests do not measure the infusion itself, but evaluate patient tolerance and therapeutic drug levels.

Infusions are central to the management of almost all cancers. They are routinely utilised in haematological diseases like leukaemia and lymphoma, as well as solid tumours such as lung, colorectal, ovarian, pancreatic, and breast malignancies requiring systemic intravenous chemotherapy, immunotherapy, or targeted monoclonal antibodies.

Infusion protocols determine drug scheduling and supportive care. Clinicians frequently administer pre-medications—such as antihistamines, paracetamol, or antiemetics—to prevent infusion reactions. If a patient experiences an acute physiological reaction, the infusion rate is slowed or discontinued, and therapeutic alternatives may be evaluated.