What are the stages of fluid therapy?

October 12, 2025 •

6 min read

Fluid overload is a common issue in critical care, affecting more than 25% of intensive care unit (ICU) patients [1.2.5]. To prevent this, clinicians ask 'What are the stages of fluid therapy?' and often use a four-phase model to guide treatment [1.2.1].

Quick Summary

Intravenous (IV) fluid therapy is a structured, four-phase process used to correct fluid deficits and maintain organ perfusion. This dynamic approach ensures patients receive the right amount of fluid at the right time.

Key Points

ROSE Model: Fluid therapy is guided by the four-stage ROSE model: Resuscitation, Optimization, Stabilization, and Evacuation [1.2.2, 1.2.4].
Resuscitation Goal: The first stage aims to rapidly reverse shock and restore organ perfusion using fluid boluses [1.2.3, 1.4.1].
Stabilization Goal: The third stage focuses on providing maintenance fluids to meet baseline needs while aiming for a neutral fluid balance [1.2.4].
De-escalation is Key: The final Evacuation stage is critical for removing accumulated fluid to prevent complications of fluid overload [1.5.2, 1.2.4].
Fluid Assessment: Continuous assessment of a patient's fluid status using clinical signs, labs, and monitoring is essential throughout all stages [1.6.3].
Crystalloids vs. Colloids: Crystalloids are generally the first-line choice for fluid resuscitation due to their safety profile and lower cost compared to colloids [1.7.2, 1.3.1].
Fluid Overload is a Risk: A major complication of IV therapy is fluid overload, which is associated with adverse outcomes and affects a significant number of ICU patients [1.2.5, 1.8.2].

Introduction to Fluid Therapy

Intravenous (IV) fluid therapy is a cornerstone of modern medical care, essential for managing patients with conditions ranging from severe dehydration and sepsis to trauma and major surgery [1.3.2, 1.3.1]. However, both insufficient and excessive fluid administration can lead to significant harm, including organ dysfunction and increased mortality [1.2.1, 1.5.2]. To optimize patient outcomes and minimize risks, clinicians have adopted a dynamic, phased approach to fluid management. The most widely recognized conceptual framework is the ROSE model, which stands for Resuscitation, Optimization, Stabilization, and Evacuation (or De-escalation) [1.2.2, 1.2.4]. This model provides a structured path for clinicians to follow, ensuring that fluid administration is timely, targeted, and tailored to the patient's evolving clinical condition [1.2.1].

Assessing a Patient's Fluid Status

Before initiating or adjusting fluid therapy, a thorough assessment of the patient's fluid status is critical. This evaluation determines whether a patient is hypovolemic (fluid deficient), euvolemic (normal fluid balance), or hypervolemic (fluid overloaded) [1.6.3]. The assessment involves a combination of methods:

Clinical Examination: This includes checking for signs like thirst, dizziness, dry mucous membranes, and poor skin turgor in dehydrated patients [1.6.1, 1.6.3]. Conversely, fluid overload may present with shortness of breath, lung crackles on auscultation, and peripheral or sacral edema [1.6.3, 1.8.2]. Vital signs such as heart rate, blood pressure (including lying and standing measurements), and respiratory rate are also key indicators [1.6.3].
Laboratory Tests: Blood tests measuring serum electrolytes, blood urea nitrogen (BUN), and creatinine provide insight into hydration and kidney function [1.6.1]. Urine specific gravity and osmolality can also indicate the body's hydration level [1.6.4].
Monitoring Intake and Output: In a hospital setting, tracking a patient's total fluid intake (oral and IV) against their total output (urine, drains, vomiting, diarrhea) is a fundamental practice [1.6.5]. Daily weight measurements are also a very helpful tool, as acute changes often reflect fluid shifts [1.6.3, 1.6.4].
Advanced Hemodynamic Monitoring: In critically ill patients, more invasive techniques may be used. These can include central venous pressure (CVP) monitoring, though its utility is debated, and dynamic assessments like the passive leg raise test or pulse pressure variation to predict fluid responsiveness [1.6.1, 1.3.2]. Point-of-care ultrasound (POCUS) of the inferior vena cava and lungs is increasingly used as a noninvasive tool to estimate fluid status and detect pulmonary congestion [1.6.2].

The Four Stages of Fluid Therapy (The ROSE Model)

The ROSE model divides fluid therapy into four distinct, sequential phases, each with specific goals and strategies [1.2.4].

1. Resuscitation (or Rescue) Phase

This initial phase occurs within minutes of a life-threatening event like septic shock, severe trauma, or burns, where the primary goal is patient rescue [1.2.3, 1.3.4]. The objective is to rapidly reverse hypotension and restore tissue perfusion to prevent organ failure [1.4.1, 1.3.1].

Goal: Correct shock and achieve adequate perfusion pressure [1.2.4].
Intervention: Rapid administration of large volumes of IV fluids, often as a fluid bolus (e.g., 500 mL over 15 minutes) [1.11.1, 1.2.3]. Isotonic crystalloids are typically the first choice [1.3.1].
Endpoints: The aim is to reach specific hemodynamic targets, such as a mean arterial pressure (MAP) greater than 65 mmHg, and to continue fluid administration only as long as the patient shows a positive response (e.g., an increase in blood pressure or cardiac output) [1.2.3]. The fluid balance will be strongly positive during this phase [1.2.4].

2. Optimization Phase

Occurring over hours, this phase begins once the patient is no longer in immediate, life-threatening shock but remains hemodynamically unstable [1.2.4]. The focus shifts from rapid rescue to fine-tuning organ perfusion.

Goal: Optimize cardiac output and ensure adequate oxygen delivery to tissues to prevent or limit organ damage [1.2.4, 1.4.3].
Intervention: Fluids are administered more cautiously, often using a "fluid challenge"—a small volume (e.g., 100–200 mL) given over 5–10 minutes to test for fluid responsiveness [1.11.1, 1.2.4]. This helps avoid unnecessary fluid administration in patients who will not benefit [1.4.4].
Endpoints: Careful monitoring of hemodynamic variables (like pulse pressure variation) and markers of tissue perfusion (like lactate levels) guides therapy [1.2.4].

3. Stabilization Phase

This phase evolves over days as the patient's condition stabilizes and the initial insult resolves [1.2.4]. The goal is no longer active resuscitation but providing for the body's baseline needs.

Goal: Maintain homeostasis, ensure adequate water and electrolytes for organ support, and prevent fluid accumulation [1.4.3, 1.2.4].
Intervention: Fluid administration is reduced to maintenance levels, meant only to replace ongoing losses from urine, sweat, and respiration [1.2.3, 1.10.1]. The focus shifts towards oral or enteral hydration whenever possible [1.5.5].
Endpoints: The target is a zero or slightly negative fluid balance [1.2.4]. Daily weights and strict fluid balance monitoring are crucial [1.2.3].

4. Evacuation (or De-escalation) Phase

This is the final phase, focused on actively removing the excess fluid accumulated during the acute phases of resuscitation and optimization [1.2.4].

Goal: Achieve a negative fluid balance to liberate the patient from IV fluids and resolve tissue edema [1.5.2]. This process is sometimes called "de-resuscitation" [1.2.3].
Intervention: IV fluid administration is stopped or significantly reduced [1.5.5]. Fluid removal is achieved through spontaneous diuresis as the patient recovers or actively with diuretics or even renal replacement therapy (ultrafiltration) in patients with kidney dysfunction [1.5.2, 1.2.3].
Endpoints: The goal is to return the patient to their baseline weight and euvolemic state. Caution is required to avoid over-enthusiastic fluid removal that could lead to hypovolemia [1.2.3].

Types of IV Fluids: A Comparison

The choice between crystalloids and colloids has been a long-standing debate in fluid therapy [1.7.3].


Feature	Crystalloids	Colloids
Composition	Solutions of small molecules and ions (e.g., sodium, chloride) dissolved in water [1.7.1, 1.7.4]. Examples: Normal Saline, Lactated Ringer's.	Solutions containing large molecules (e.g., albumin, starches) that do not easily cross capillary membranes [1.7.2, 1.7.4].
Mechanism	Briefly expand intravascular volume before quickly redistributing into the interstitial space [1.3.3, 1.7.2].	Remain in the intravascular space for a longer period, providing more sustained plasma volume expansion [1.7.2, 1.7.3].
Cost	Inexpensive and readily available [1.7.3, 1.3.2].	Significantly more expensive than crystalloids [1.7.3, 1.7.2].
Primary Use	Generally preferred for initial resuscitation and maintenance therapy due to safety, efficacy, and cost [1.7.2, 1.3.1].	Reserved for specific situations, such as when patients cannot tolerate large fluid volumes, though their superiority is not proven in most cases [1.3.2, 1.7.2].
Risks	Can lead to edema due to fluid shifting into the interstitial space [1.7.1]. Large volumes of normal saline can cause hyperchloremic acidosis [1.3.2].	Associated with risks of allergic reactions, blood clotting disorders, and kidney injury, particularly with synthetic colloids like starches (HES) [1.7.1, 1.7.2].

Conclusion

Understanding what are the stages of fluid therapy is crucial for modern medical practice. The ROSE model (Resuscitation, Optimization, Stabilization, Evacuation) provides a vital, dynamic framework that guides clinicians from initial life-saving interventions to the final phase of fluid removal. By carefully assessing fluid status and tailoring the type and volume of fluid to each specific phase, healthcare providers can maximize the benefits of IV therapy while minimizing the significant risks of fluid imbalance, ultimately improving patient safety and outcomes. The transition between these stages requires continuous reassessment and a proactive approach to prevent the harms of both under- and over-resuscitation. For further reading, the International Fluid Academy provides resources on fluid stewardship. [https://www.fluidacademy.org]

Complications of Fluid Therapy

While life-saving, IV fluid therapy is not without risks. Complications can be local to the IV site or systemic.

Local Complications

Infiltration: IV fluid leaks into the surrounding tissue, causing coolness, swelling, and taut skin [1.8.2, 1.8.4].
Phlebitis: Inflammation of the vein, characterized by pain, redness, warmth, and a palpable cord along the vein [1.8.2, 1.8.3].
Extravasation: The leakage of a vesicant (irritating) drug into the tissue, which can cause blistering and tissue necrosis [1.8.2, 1.8.3].
Hematoma: A collection of blood in the tissue surrounding the venipuncture site [1.8.4].
Infection: Local infection at the insertion site, presenting as redness, swelling, warmth, and possibly purulent drainage [1.8.2].

Systemic Complications

Fluid Overload (Hypervolemia): The most significant risk, where excessive fluid administration leads to respiratory distress, elevated blood pressure, edema, and engorged neck veins [1.8.2]. It is particularly dangerous in patients with heart or kidney failure [1.8.2].
Electrolyte Imbalances: Administering fluids with incorrect electrolyte concentrations can lead to dangerously high or low levels of sodium, potassium, and other minerals [1.8.2].
Air Embolism: Air entering the bloodstream through the IV line, which can block vessels and cause chest pain, shortness of breath, and other severe symptoms [1.8.2, 1.8.4].
Catheter-Related Bloodstream Infection (CRBSI): A serious infection that enters the bloodstream via the catheter, leading to systemic symptoms and potentially sepsis [1.8.2].

Frequently Asked Questions

The ROSE concept is a model that divides IV fluid therapy into four dynamic phases: Resuscitation, Optimization, Stabilization, and Evacuation (or De-escalation). It helps guide clinicians to apply the right amount of fluid at the right time based on the patient's condition [1.2.2, 1.2.4].

The primary goal of the resuscitation or 'rescue' phase is to save the patient's life by rapidly correcting shock and hypoperfusion. This is done by administering large volumes of fluid to restore adequate blood pressure and organ blood flow [1.2.4, 1.3.1].

A fluid bolus is a large volume of fluid (e.g., 500 mL) given rapidly over about 15 minutes to correct hypotensive shock. A fluid challenge is a smaller volume (e.g., 100-200 mL) given more slowly to test if a patient's cardiac output will improve with more fluid, helping to avoid fluid overload [1.11.1].

Maintenance fluid therapy is used during the stabilization phase for patients who cannot meet their daily fluid and electrolyte needs orally. The goal is to replace ongoing physiological losses (from urine, sweat, etc.) and maintain normal hydration, not to actively resuscitate [1.10.1, 1.10.4].

De-resuscitation, also known as the evacuation or de-escalation phase, is the final stage of fluid therapy. Its purpose is to actively remove the excess fluid that accumulated during the resuscitation and optimization phases, often using diuretics or other methods to achieve a negative fluid balance [1.5.2, 1.2.3].

Crystalloids, such as normal saline and Lactated Ringer's, are generally the preferred first-choice fluids for resuscitation. While colloids expand plasma volume more efficiently, studies have not shown a consistent survival benefit, and they are associated with higher costs and greater risks, including kidney injury and allergic reactions [1.7.1, 1.7.2, 1.3.1].

The main systemic complications are fluid overload (hypervolemia), which can cause respiratory distress, and electrolyte imbalances. Local complications at the IV site include infiltration (fluid leaking into tissue), phlebitis (vein inflammation), and infection [1.8.2, 1.8.3].