What is an Infusion Set?

An infusion set is a sterile medical consumable made of medical-grade polymer materials, primarily used for intravenous infusion of medications into patients. Its design follows ergonomic principles and allows control of infusion flow rate through standardized tubing.

The main infusion sites (i.e., puncture locations) include the following:

Back of the hand: The most commonly used site, with superficial veins that are easy to locate.

Forearm: Includes the median antebrachial vein and cephalic vein, suitable for longer-term infusions.

Antecubital fossa: Larger veins, often used for emergency or large-volume infusions.

External jugular: Mainly for patients with no suitable limb veins, requiring professional operation.

Pediatric scalp: Infants and young children often receive scalp vein punctures due to small limb veins.

In other special cases, lower limb veins (e.g., dorsal foot vein) or central venous catheterization may be used, but standard infusion typically utilizes the aforementioned sites.

Key Parts of an IV Set

IV tubing: A transparent, flexible tube that serves as a channel for fluid flow. The material must be flexible and biocompatible.

Puncture device: Includes the puncture needle used to pierce the infusion bag or bottle outlet to draw the liquid.

Drip chamber: A transparent container for observing drip rate and remaining fluid. Also serves to expel air to prevent it from entering the bloodstream.

IV tubing filter: Usually located at the top of the drip chamber or in the tubing, it blocks airborne particles and removes excess gas to prevent air entry into the infusion line.

Dial flow tubing: A manual roller clamp that compresses the tube to control the liquid flow rate, enabling precise drip rate adjustment.

Infusion set needle: Includes a connector needle (sharp interface component matching the medication bag) and an intravenous needle (inserted into the patient's vein), some with protective sheaths to prevent contamination.

Some advanced infusion sets may also include medication filters, check valves, iv extension tube, or pressure monitoring devices, but the above six are the basic and essential components.

What Are the Uses of an Infusion Set?

Medication Infusion

Delivers liquid medications (e.g., antibiotics, analgesics) intravenously. Some chemotherapy drugs require precise infusion rate control via infusion sets.

Fluid and Electrolyte Replenishment

For patients with dehydration, hemorrhage, or shock, infusion of saline, glucose solutions, etc., helps maintain circulatory stability and electrolyte balance.

Blood or Blood Product Transfusion

Connects blood bags to the venous route for infusing whole blood, red blood cells, plasma, etc., often with specialized filters to reduce transfusion risk.

Nutritional Support

Provides parenteral nutrition to patients unable to eat orally, such as amino acids, fat emulsions, etc. Requires strict aseptic operation to avoid infection.

Infusion Rate Regulation

Flow regulator manually controls drip rate to meet various therapeutic needs (e.g., rapid infusion in emergencies or slow delivery for chronic conditions).

Special Medical Procedures

Used in emergency care (e.g., vasopressor infusion), anesthesia (intraoperative medication delivery), dialysis support, and more.

Additionally, they can be used for catheter flushing, connecting medical devices (e.g., analgesic pumps), and are a fundamental tool in clinical treatment.

Types of IV Sets and Their Applications

Gravity IV Tubing

Relies on gravity to slowly infuse fluids into the vein. Mainly used for basic fluids like saline or glucose, or component blood products. Common in general wards, with flow rate controlled by adjusting the height of the medical IV stand.

Pressure Infusion Set

Uses external pressure devices like manual squeeze bulbs or medical infusion pumps for rapid infusion. Suitable for quick fluid resuscitation in critical patients and for infusing high-viscosity liquids such as hydroxyethyl starch or albumin. Pressure must be controlled to prevent vascular injury.

Air-eliminating Infusion Set

Equipped with one-way air valves or automatic air-release structures to autonomously expel air during infusion. Reduces the need for frequent manual venting and is commonly used in rapid fluid replacement or continuous infusion scenarios.

Precision Filter Infusion Set

Built-in filter membranes with pore size ≤5μm to intercept crystalline drug precipitates or residual particulates. Often used for parenteral nutrition, traditional Chinese medicine injections, or chemotherapy drugs, lowering the risk of phlebitis.

Light-resistant Infusion Set

Features brown tubing and light-resistant drip chambers, specifically for photosensitive drugs such as sodium nitroprusside, cisplatin, and quinolones. Prevents drug degradation or toxicity increase due to light exposure.

Precautions When Using Intravenous Infusion Sets

Proper Setup

Ensure all components are intact and undamaged. Connect tubing under sterile conditions. Confirm appropriate needle angle and perform priming before use.

Flow Rate Calculation

Calculate drip rate strictly according to medical orders, adjusted based on patient age, cardiopulmonary function, and drug properties. For example, patients with heart failure require slower rates, while vasoactive drugs should use infusion pumps for precision.

Regular Monitoring

Observe drip rate and puncture site condition every 30-60 minutes. If swelling, leakage, or pain occurs, stop immediately and assess the need for re-puncture.

Air Bubble Prevention

Inspect all tubing for seal integrity before infusion. Replace fluids when the liquid level drops below 1/3 of the drip chamber. Double-check for bubbles before transfusing blood or colloids.

Maintenance and Calibration

Replace infusion sets daily during continuous use. Devices with infusion pumps require monthly flow rate calibration. Deformed or aged tubing can significantly affect infusion accuracy.

Frequently Asked Questions

Can an infusion set be reused?

No, it cannot be reused. Infusion sets are single-use consumables and must follow the principle of "one patient, one use, one disposal". Reuse risks microbial contamination, endotoxin buildup, and air embolism. If used for over 24 hours continuously, degradation products from plastic materials may increase adverse drug reaction risks.

What is the allowable IV dial flow rate?

For routine fluid replacement, adult drip rates are generally 40-60 drops/minute; for children, 20-40 drops/minute. Patients with impaired cardiopulmonary function or elderly individuals should be limited to below 20 drops/minute. For rapid volume expansion, some infusion sets allow up to 150 drops/minute temporarily, but central venous pressure must be monitored simultaneously.

How does the height of the infusion bag affect flow rate?

For every 10 cm increase in vertical height from the puncture site, hydrostatic pressure increases by approximately 7.4 mmHg, thus speeding up the drip rate. The recommended hanging height is 80-100 cm. Too high may cause uncontrolled drip rate; too low may require manual squeezing of the drip chamber to maintain flow. If the fluid level is more than 30 minutes below heart level, blood may reflux and block the needle.

What is the difference between microdrip and macrodrip?

Microdrip infusion sets deliver about 20 drops per milliliter, while macrodrip sets deliver about 15 drops per milliliter (based on the specific dropper label). Microdrip is suited for pediatrics, precise dosage control, or drip rates below 30 drops/minute. Macrodrip is used for rapid fluid replacement or for infusing non-sensitive solutions like saline. Their flow rate calculations are not interchangeable, and dropper type must be verified before use to avoid 20%-30% dosing errors.