Infusion devices or infusion sets
Infusion sets convey fluids from a bottle or bag into the patient’s bloodstream. Generally, four different types of fluids are administered intravenously through the use of infusion devices. These are:
- Water. Dehydrated patients who lost much of their bodily water need fluid replacement. Hence, preserving the patient’s blood pressure requires water infusion in the form of saline or dextrose.
- Medications and electrolytes. Patients who are in dire need of drugs and electrolytes require intravenous administration. These curative substances reach the patient’s bloodstream in a short time without going through digestion and absorption. Thus, their healing benefits take effect immediately, possibly saving the lives of patients. Some of these drugs belong to the treatment of heart ailments and cancer.
- Nutrition. Patients who cannot afford to ingest, absorb, or tolerate their foods may need to have the so-called parenteral feeding. Necessary foods in fluid forms reach the bloodstream of patients through the use of the intravenous route.
Types of an infusion set in terms of the source of the driving force
Gravity infusion set
The gravity infusion set allows the flow of the fluid through the action of the gravitational force. Therefore, the source of fluid is always higher than the location of the patient receiving the infusion. The higher the height of the infusion bottle is, the stronger the force of gravity that will act on the flow of fluid. Expectedly, the flow of fluid will be faster and more robust.
Pump-driven infusion set
The pump-driven infusion set pushes the flow of fluid using the force coming from the pump. This offers several advantages, but it will turn out to be more expensive.
Parts
Gravity infusion set
The gravity infusion set is composed of the following parts: (1) the bottle containing the infusion fluid, (2) the drip chamber, (3) the flow regulator, (4) the injection site, (5) the hypodermic needle or catheter or Luer connector, (6) flexible tubing.
- The infusion bottle contains the fluid for intravenous administration. The gravitational force acting on this fluid causes it to flow from the bottle to the receiving vein of the patient.
- The drip chamber serves as the venue for counting the flow rate.
- The flow regulator is used to control the flow of fluid. In between the drip chamber and the needle or Luer lock connector, a flow rate controller, known as the control device or flow regulator, is attached to the flexible line.
- The injection site is used for injection medicines or drugs.
- The flexible tubing connects the drip chamber to the needle or Luer lock connector.
Pump-driven infusion set
The parts in the gravity infusion set are also present in the pump-driven infusion set. However, the infusion pump will be situated along the flexible tube. After placing in a segment of the flexible tube inside the infusion pump, the operation of the pump can start after setting the flow rate, infusion volume, occlusive pressure alarm, fluid depletion alarm, and other parameters in the infusion pump. Specifically, this describes the peristaltic type of volumetric pumps.
Advantages
Gravity infusion set
- The operational cost is lower and cheaper because no need to use electrical energy.
Pump-driven infusion set
- This infusion set delivers a more precise dose of medicines per infusion duration and higher flow rate accuracy.
Disadvantages
Gravity infusion set
- It is relatively imprecise for administering medicines and has lower flow rate accuracy.
- The hospital staff must adjust the flow rate several times a day to comply with the prescribed dose of medicine and the amount of fluid to be infused.
Pump-driven infusion set
- The total costs of operation are relatively expensive.
Major drawbacks
Gravity infusion set
The main drawback of gravity flow infusion is the low flow rate accuracy. This problem stems from the fact that compression of the PVC tubing controls the flow. As the infusion goes on without any intervention, the flow rate gradually decreases. The imperfect elastic nature of the infusion line causes this slowing down and gradual reduction in the flow rate.
In addition, the amount of fluid remaining in the infusion bottle or bag also plays a significant role in slowing down of flow rate. Experiments showed that it drops by 40% after two hours after the start of the infusion. Thus, a healthcare worker, such as a nurse, needs to check it now and then after the initial set-up and re-establish the desired flow rate.
Pump-driven infusion set
The major drawback of the pump-driven infusion set is the high operational costs of energy, cleaning, and maintenance.
Summary of differences between the gravity and the pump-driven infusion sets
| Points of differences | Gravity infusion set | Pump-driven infusion set |
| Source of the driving force | Gravitational force | Pump |
| Major advantage | Low operational costs | High flow rate accuracy |
| Major drawback | Low flow rate accuracy | High operational costs |
| Frequency of adjustments and monitoring | More frequent | Less frequent |
| Capitalization costs | Very much less | Higher and not always affordable |
| Cleaning and maintenance | Generally none | Needed, thus increasing operational costs |
| Place of usage | Everywhere | Sites with available electricity |
Usage and terminology
Some infusion pumps use a particular infusion set without specifications. However, some infusion pumps require specifications for the infusion set, or the infusion set must come with the infusion pump. In some infusion pumps, you cannot use infusion sets that are not specified.
A flexible segment of the tube occupies a groove inside the pump, and subsequently, the operation starts. Hence, any infusion set works for as long as the flexible tubing fits in the pump. An infusion set becomes a gravity infusion set if the infusion bottle hangs up and gravity pushes the fluid down. An infusion set wherein a segment of its flexible tubing lies in the groove of a pump becomes a pump-driven infusion set. Thus, a particular infusion set works either as gravity or pump-driven, depending on its use.
