Intensive Infusion Therapy: Aims, Methods and Types of Infusion Systems

Infusion therapy has a long history, with early therapeutic use in the first half of the nineteenth century. The Royal College of Physicians of Edinburgh describes Thomas Latta’s use of intravenous saline during the 1832 cholera epidemic. In intravenous treatment, a prescribed solution enters the bloodstream directly, bypassing the gastrointestinal tract. This can be useful when oral administration is unsuitable or a controlled intravenous delivery is needed. Direct delivery does not mean that every nutrient is fully utilised or that a medicine works immediately. RCPE: early intravenous therapy.

What infusion therapy can achieve

Depending on the diagnosis and the prescribed fluid or medicine, infusion therapy may be used to pursue the following objectives:

• Provide prompt fluid replacement for dehydration when oral or enteral intake cannot meet the patient’s needs.
• Correct selected abnormalities in blood composition, where the prescribed treatment is appropriate.
• Restore circulating volume and support blood flow. Effects on the blood’s rheological properties depend on the condition and treatment; they are not a universal result of infusion.
• Provide support during poisoning. Intravenous fluids are not a general method of removing every toxin from the body.
• Correct an identified electrolyte imbalance.
• Help manage an acid–base disturbance as part of treatment of its cause.
• Influence metabolic processes through appropriately prescribed medicines or nutritional support.

These are possible treatment objectives, rather than benefits that every infusion will deliver. Assessment, fluid selection and reassessment are essential: excessive or inappropriate fluid administration can itself cause harm. Treatment for poisoning depends on the substance involved; fluids may treat dehydration, while antidotes or other measures may be needed for the poison itself. NICE: intravenous fluid therapy in adults; NHS: treatment of poisoning.

In some critical situations, timely intravenous treatment is an important part of lifesaving care. Parenteral administration allows clinicians to deliver necessary medicines and other prescribed substances when another route is unsuitable. Its role depends on the underlying emergency and the wider treatment plan.

When treatment is prescribed: areas of use

The original article identifies three broad reasons for prescribing an infusion:

• Rapid correction of a patient’s condition when intravenous treatment is clinically indicated.
• What the source calls “local administration” of a medicine. Routine intravenous infusion enters the circulation and usually has systemic effects; it should not be confused with treatment targeted only to a local area.
• Support over an extended period when the patient’s needs require it.

In adults, infusions are used in resuscitation and intensive care units, in the management of poisoning, in maternity care and in operating theatres. They may also form part of treatment for respiratory disease or infection. Certain procedures require intravenous access and prescribed infusions, but these settings and diagnoses do not automatically mean that every patient needs intravenous fluids.

Intravenous treatment may help manage shock or serious circulatory disturbances, but the cause of shock determines the appropriate intervention. Severe wasting may require nutritional support, although wasting alone is not a reason to prescribe intravenous nutrition. Where oral or enteral nutrition is inadequate, unsafe or unavailable because of gastrointestinal dysfunction, clinicians may consider parenteral nutrition; in selected cases it supplies all nutritional needs. It requires specialist prescription, monitoring and review. NICE: indications for parenteral nutrition.

Advantages of the approach

An important advantage is the ability to deliver prescribed fluids, medicines or nutrients at a controlled rate. Dose and duration matter, but calculating them is only part of safe treatment. Clinicians must also choose an appropriate preparation and route, assess the patient and monitor the response. Infusion therapy cannot be described as free from complications.

Suitable infusion systems, sterile equipment and careful handling reduce avoidable risks; they cannot eliminate every risk. Infusion pumps can control delivery, but device problems or use errors may still cause over-infusion or under-infusion. Patients in a serious condition may need additional monitoring equipment to track vital signs alongside clinical assessment. FDA: infusion pumps and their risks.

The aim is to deliver the treatment a patient needs, support physiological function and contribute to recovery. In the operating theatre, infusions may form part of support during a procedure. Neither the route nor the equipment guarantees recovery or an operation without complications.

Infusion systems should meet applicable device requirements and be used for their intended purpose, following their instructions and clinical protocols. Equipment quality is important, but the outcome also depends on the prescription and the patient’s condition. Treatment may be administered with the patient lying down or, where clinically appropriate, sitting in a purpose-designed infusion chair.

Original source: Zaplata — Intensive Infusion Therapy: Aims, Methods and Types of Infusion Systems. Russian article on MEDICTUR.