IV fluid therapy

Overview of Treatment

Intravenous Fluid Therapy (IVFT) is a medical procedure that involves delivering fluids directly into the bloodstream via blood vessels, primarily used to replenish body fluids, electrolytes, or to transport medications throughout the body. This treatment can rapidly improve emergency conditions such as dehydration, shock, and fluid loss during surgery, serving as a fundamental measure in emergency medicine and critical care.

Compared to oral or subcutaneous injections, intravenous infusion can immediately increase blood volume and precisely control the composition and infusion rate. It is commonly used in patients with trauma, severe vomiting, diabetic ketoacidosis, and also for physiological support during surgery.

Types and Mechanisms of Treatment

Intravenous fluids are mainly divided into three categories:

Crystalloids (such as normal saline, Ringer's solution): composed of inorganic salts, capable of rapidly replenishing water and electrolytes.
Colloids (such as lactated Ringer’s, albumin solutions): contain large molecules that prolong the residence time of fluids within blood vessels.
Special additive solutions: include glucose, antibiotics, or nutrients, targeting metabolic abnormalities or infections.

Mechanistically, once the fluids enter the circulatory system, they can immediately raise blood pressure and restore extracellular fluid balance. Colloid solutions can also maintain intravascular osmotic pressure, preventing tissue edema. When transporting drugs via this route, the onset of drug effects is 3-5 times faster than oral administration.

Indications

This therapy is suitable for the following conditions:

Acute dehydration (such as severe vomiting, diarrhea)
Severe hypotension or shock
Fluid replacement during or after surgery
Patients unable to take fluids orally (such as coma, esophageal obstruction)
Emergencies requiring immediate medication (such as antibiotics, vasopressors)

Special cases include:

Burn patients requiring large amounts of fluid and protein replacement
Capacity management in patients with renal failure
High-precision dosing of chemotherapeutic agents

Usage and Dosage

The treatment is usually performed by healthcare personnel in hospitals or emergency rooms. First, an appropriate puncture site (such as the forearm vein or subclavian vein) is selected, and a catheter is inserted using sterile technique. The infusion rate is adjusted based on the patient's weight and condition, with an adult baseline rate of approximately 50-100 ml/h; in severe dehydration, it may be increased to 150 ml/kg/hr.

Dosage calculation considerations include:

Body weight: adults typically receive 0.3-0.5 ml/kg/hr as a baseline supplement
Loss volume: dehydration severity (such as decreased urine output, dry mucous membranes) determines additional water supplementation
Electrolyte concentration: for hypernatremia, low-sodium solutions are preferred

Benefits and Advantages

Main advantages include:

Immediate effect: improves hemodynamics within 20-30 minutes
Precise control: components and speed can be adjusted in real-time
Versatility: suitable for various symptoms, from rehydration to drug delivery

Clinical benefits are especially significant in shock treatment, with studies showing that moderate fluid resuscitation can reduce mortality by 40%. For patients unable to take oral fluids, this is a critical support method to maintain vital signs.

Risks and Side Effects

Potential complications include:

Infection: bacterial phlebitis at the puncture site
Fluid overload: excessive infusion may lead to pulmonary edema or cerebral edema
Electrolyte disturbances: such as hypernatremia or hypocalcemia

Serious risks include thrombophlebitis and catheter-related bloodstream infections (CR-BSI), with higher risks in elderly or immunocompromised patients. There have been cases of overload due to rapid infusion, requiring strict monitoring of blood pressure and central venous pressure.

Precautions and Contraindications

Contraindications include:

Congestive heart failure (may worsen pulmonary edema)
Specific electrolyte abnormalities (such as hypernatremia contraindicates high-sodium solutions)
History of local phlebitis or thrombosis at the puncture site

During administration, attention should be paid to:

Daily monitoring of urine output, body weight, and blood biochemical indices
Daily disinfection of the catheter site to prevent infection
Use of central venous catheters in high-risk patients to reduce local complications

Interactions with Other Treatments

Drug interactions include:

Antibiotic solubility affected by the pH of the infusion
Hypertonic solutions may influence the efficacy of vasoactive drugs
When used with diuretics, adjustments to the total infusion volume are necessary

Comparison with other fluid replacement methods:

Oral rehydration: slower but lower risk
Subcutaneous infusion: narrower scope of application

Therapeutic Outcomes and Evidence

Early appropriate fluid resuscitation in shock can increase survival rates by over 30%. The 2019 international emergency medicine guidelines recommend administering 20 ml/kg of crystalloid fluids within the first hour for hypovolemic shock patients. For hypernatremia, 3% hypertonic saline can rapidly correct electrolyte imbalances.

Long-term monitoring data shows that standardized infusion protocols can shorten hospital stays by 2-3 days. However, over-resuscitation may increase the risk of acute kidney injury, requiring dynamic adjustments based on the "resuscitation response curve".

Alternatives

Alternative methods include:

Oral electrolyte solutions (such as ORS)
Subcutaneous fluid injection (suitable for mild dehydration)
Nasal gastric feeding

However, these methods are limited in effectiveness for severe dehydration or unconscious patients. Oral therapy takes 2-4 hours to take effect, whereas intravenous treatment can improve blood pressure within 5-10 minutes. Therefore, in emergency scenarios, IV therapy remains the first choice.

Frequently Asked Questions

What preparations are needed before receiving intravenous fluid therapy?

Before treatment, patients should inform healthcare providers of any allergies, current medications, and chronic illnesses. For prolonged infusions, medical staff will assess vascular condition, select suitable puncture sites, and explain potential risks. Patients should wear loose clothing for easy access and empty their bladder before treatment.

What should I do if I experience swelling or coldness in my hand during infusion?

If swelling or cold sensation occurs locally during infusion, it may be due to rapid infusion rate or vascular irritation. Notify medical staff immediately to adjust the drip rate or re-puncture. If redness, pain, or fever develops, it could indicate inflammation, requiring prompt examination for phlebitis or infection.

Do I need to adjust my diet or water intake during treatment?

Dietary adjustments should follow medical instructions, such as limiting salt intake in hypertensive patients or appropriately supplementing water in dehydrated patients. If diuretics are used during treatment, doctors will monitor daily weight to assess fluid balance.

What are the key points for caring for the puncture site after infusion?

After removing the needle, apply pressure to the puncture site for at least 5-10 minutes and avoid removing the pressure dressing too early. Avoid heavy lifting or blood pressure measurement on the limb for 24 hours. If swelling, bleeding, or fever persists at the puncture site, return to the clinic promptly for possible thrombosis or infection management.

Does the efficacy of intravenous therapy vary between individuals? How is treatment success evaluated?

Effectiveness depends on factors such as age, underlying conditions, and infusion composition. For example, dehydrated patients often show blood pressure improvement within 6-8 hours. Healthcare providers monitor hematocrit, urine output, and vital signs to evaluate, and blood tests may be needed for complex cases to confirm efficacy.