IV fluid therapy

Overview of Treatment

Intravenous Fluid Therapy (IVFT) is a medical procedure that delivers fluids directly into the bloodstream via blood vessels, primarily used to replenish body fluids, electrolytes, or transport medications throughout the body. This treatment can rapidly improve conditions such as dehydration, shock, and fluid loss during surgery, making it 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 (e.g., normal saline, Ringer's lactate): Composed of inorganic salts, capable of rapidly replenishing water and electrolytes.
Colloids (e.g., lactated Ringer’s, albumin solutions): Contain large molecules that prolong the retention time of fluids within blood vessels.
Special additive solutions: Include glucose, antibiotics, or nutrients, tailored for metabolic abnormalities or infections.

Mechanistically, once the fluid enters the circulatory system, it can immediately elevate blood pressure and restore extracellular fluid balance. Colloid solutions help maintain intravascular osmotic pressure, preventing tissue edema. When transporting drugs via this route, the onset of action is 3-5 times faster than oral administration.

Indications

This treatment is suitable for the following conditions:

Acute dehydration (e.g., severe vomiting, diarrhea)
Severe hypotension or shock
Fluid replacement during or after surgery
Patients unable to take fluids orally (e.g., coma, esophageal obstruction)
Emergency conditions requiring immediate drug therapy (e.g., antibiotics, vasopressors)

Special cases include:

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

Usage and Dosage

The procedure is usually performed in hospitals or emergency rooms by nursing staff. First, an appropriate puncture site (such as the antecubital 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 a typical adult rate of about 50-100 ml/h; in severe dehydration, it may be increased to 150 ml/kg/hr.

Dosage calculation considerations include:

Body weight: Adults generally receive 0.3-0.5 ml/kg/hr as a baseline
Loss volume: Degree of dehydration (e.g., decreased urine output, mucous membrane dryness) determines additional water supplementation
Electrolyte concentration: For hypernatremia, low-sodium solutions are preferred

Benefits and Advantages

Main benefits include:

Immediate effect: Hemodynamic improvements within 20-30 minutes
Precise control: Real-time adjustment of composition and rate
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 method is critical for maintaining vital signs.

Risks and Side Effects

Possible complications include:

Infection: Bacterial phlebitis at the puncture site
Fluid overload: Excessive infusion may cause 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 cardiac 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 (e.g., 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 biochemistry
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 infusion pH
Hypertonic solutions may influence the efficacy of vasoactive drugs
When used with diuretics, adjustments to total infusion volume are necessary

Comparison with other fluid replacement methods:

Oral rehydration: Slower but lower risk
Subcutaneous infusion: More limited scope

Therapeutic Effectiveness 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 of hospital arrival for hypovolemic shock. Hypernatremic patients may be rapidly corrected with 3% hypertonic saline.

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

Alternatives

Alternative methods include:

Oral electrolyte solutions (e.g., ORS)
Subcutaneous fluid injections (suitable for mild dehydration)
Nasal gastric tube feeding

However, these methods are less effective in severe dehydration or unconscious patients. Oral therapy takes 2-4 hours to take effect, while 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 diseases. For long-term infusion, medical staff will assess vascular condition, select appropriate puncture sites, and explain potential risks. Patients should wear loose clothing for easier 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 or vascular irritation. Notify medical staff immediately to adjust the drip rate or re-puncture. If redness, pain, or fever develops, it may indicate inflammation, and prompt examination for phlebitis or infection is necessary.

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

Diet and water intake should be adjusted according to medical instructions. For example, hypertensive patients may need to limit salt intake, while dehydrated patients should follow medical advice for appropriate hydration. If diuretics are used during treatment, daily weight monitoring will be instructed 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. The limb should be kept free of heavy lifting or blood pressure measurement 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 effectiveness of intravenous therapy vary between individuals? How is treatment success evaluated?

The efficacy depends on factors such as age, underlying diseases, and infusion composition. For example, dehydration patients typically show blood pressure improvement within 6-8 hours. Healthcare providers monitor changes in hematocrit, urine output, and vital signs to evaluate effectiveness. Complex cases may require blood biochemical tests for confirmation.