Continuing Education Activity

Fluid management is a critical aspect of patient care, as each patient has unique needs based on their medical condition, fluid losses, and ability to maintain fluid intake. Although no universal guidelines exist, the primary goals are to replace fluid deficits when identified and maintain normal physiological balance. Clinicians must differentiate between the maintenance therapy, which replenishes daily fluid losses through urine, respiration, sweat, and stool; replacement therapy, which corrects fluid deficits caused by illness, injury, or third-space shifts; and resuscitative fluids, which are required in cases of hypovolemia or shock. Common intravenous fluids include crystalloids, such as normal saline and lactated Ringer solution, and colloids such as albumin. The choice of fluid depends on patient-specific factors, including electrolyte levels, acid-base status, and clinical response. Assessment of fluid status involves evaluating physical signs, such as weight, blood pressure, capillary refill, jugular venous pressure, and urine output, as well as laboratory values. Fluids may be administered orally, intravenously, or through alternative routes when necessary, based on the patient's condition and ability to tolerate intake.

This activity enhances understanding of fluid management principles, including assessing volume status, distinguishing between maintenance, replacement, and resuscitative therapies, and selecting appropriate intravenous fluids. This activity also promotes safe and effective fluid use while reducing the risk of complications such as electrolyte imbalances and pulmonary edema. Additionally, this activity underscores the importance of interprofessional collaboration among healthcare providers and the necessity of ongoing reassessment in achieving optimal patient outcomes and minimizing morbidity and mortality.

Objectives:

• Identify patient-specific fluid requirements based on clinical conditions, underlying medical issues, and fluid losses to guide appropriate therapy.
• Implement evidence-based strategies for fluid management, including the proper selection, dosing, and ongoing reassessment of fluids to prevent complications.
• Select the appropriate intravenous fluids (crystalloids or colloids) based on patient-specific factors, including electrolyte levels, acid-base status, and response to therapy.
• Communicate and collaborate effectively with the interprofessional healthcare team to optimize fluid management strategies and improve overall patient outcomes.

Introduction

Effective fluid management is crucial in inpatient care, as each patient has unique fluid and electrolyte needs. Although no universal formula or rigid guideline exists, one core principle, "clinicians should replenish identified fluid losses," remains.[1] These losses vary in volume and composition depending on the patient's underlying condition. For example, a patient with extensive burns will experience significantly greater fluid loss than someone who is kept nothing by mouth (NPO) before a procedure. Similarly, fluid therapy for a patient with dehydration due to diarrhea differs from that required for a patient in hypovolemic shock from a gastrointestinal bleed.

Under normal physiological conditions, the kidneys regulate circulating volume, osmolality, and electrolyte balance by adjusting the excretion of water and solutes. The normal minimum daily water intake is derived from fluid consumption, food sources, and carbohydrate metabolism, totaling approximately 1600 mL in healthy adults, with an equivalent output through urine, sweat, respiration, and stool. Patients may require maintenance, replacement, or resuscitative fluid therapy depending on their clinical situation.

Maintenance therapy addresses routine daily fluid and electrolyte needs, whereas replacement therapy corrects existing deficits due to gastrointestinal losses, bleeding, third-spacing, or other causes. Maintenance fluids come into play when oral intake is not feasible for an extended period of time. In contrast, replacement therapy corrects fluid and electrolyte deficits resulting from losses through the gastrointestinal tract, urinary system, skin, bleeding, or third-space fluid shifts. Physical examination findings and laboratory results—such as edema, skin turgor, capillary refill, weight changes, blood pressure, jugular venous pressure, urine sodium, and urine output—help guide the assessment of fluid status and determine replacement needs.[2] 

The type and rate of fluid replacement depend on the degree of depletion and patient-specific factors. Each fluid contains varying solutes, which can lead to metabolic changes.[2] Crystalloid solutions, such as normal saline (NS), half-normal saline (½ NS), and lactated Ringer (LR) solution, are the most commonly used fluids, with the final choice guided by serum sodium or potassium levels and the presence of metabolic acidosis.[3] Colloid solutions, such as albumin, may be reserved for refractory cases or when hypoalbuminemia contributes to volume instability. However, caution is warranted with hyperoncotic starches due to the risk of acute kidney injury. Clinicians must apply the "Four Rights" of fluid stewardship—right drug, right dosage, right duration, and right patient—to minimize risks such as volume overload, cerebral edema, hyponatremia, or hypernatremia. Thoughtful fluid selection and ongoing reassessment are critical to ensuring safe and effective fluid management.[4][5]

Indications

The primary indications for fluid administration include resuscitation, rehydration, and maintenance. Additionally, when determining total daily fluid intake, clinicians must consider fluids used for drug administration and maintaining catheter patency, a consideration referred to as "fluid creep."[6] Patients in need of resuscitation are hemodynamically unstable, and fluids are used to address acute volume loss or intravascular depletion. Rehydration corrects an ongoing or preexisting deficit that the patient cannot resolve with oral fluids alone. Maintenance fluids are given to hemodynamically stable patients who are unable to meet their daily fluid and electrolyte needs through oral intake.

Oral intake remains the most natural and preferred method for fluid administration. However, many patients are unable to tolerate oral intake due to acute illness or are restricted from it because of an upcoming procedure. In such cases, alternative routes—such as intravenous (IV) access—provide a direct means of delivering fluids into the vascular system. Various methods are available to assess a patient’s volume status. Clinical evaluation based on physical examination and vital signs is often sufficient, with laboratory markers offering useful supplementary information. The National Early Warning Score (NEWS) integrates clinical findings and vital signs to help assess a patient's condition and detect early signs of deterioration, aiding in the identification of patients who are at risk of developing sepsis or requiring fluid administration.

The NEWS score incorporates the following parameters:

• Respiration rate
• Oxygen saturation
• Systolic blood pressure
• Pulse rate
• Level of consciousness or new confusion 
• Temperature [7][8]

A NEWS score of 5 or higher suggests potential hypovolemia and may indicate the need for fluid administration. However, healthcare professionals should evaluate the complete clinical context before initiating fluid replacement.

No formula can precisely calculate a patient's volume deficit. However, clinicians can estimate the approximate deficit if the patient's pre-deficit body weight is known. In the absence of this information, other laboratory and clinical parameters can offer valuable insights into the patient's volume status.[9]

Patient Symptoms Due to Volume Depletion

The earliest symptoms of volume depletion may include fatigue, thirst, decreased urine output, and dizziness. As the condition progresses, patients may report abdominal pain, chest pain, or confusion due to ischemia. Muscle weakness may also occur due to hypo- or hyperkalemia, while tachypnea may result from acidosis. Confusion, seizures, and lethargy can be caused by metabolic alkalosis or hypo- or hypernatremia.

Physical Parameters to Assess Volume Status

Body weight: A patient's body weight is a highly sensitive indicator of changes in volume status. Regular monitoring of weight fluctuations is valuable for assessing fluid balance. However, variability in hospital scales presents a challenge. Patients should be weighed daily on a standardized scale to track patterns in weight changes. Weight gain may suggest fluid excess, while weight loss could indicate fluid deficits. Reviewing the patient’s records from recent outpatient visits before hospitalization can offer additional insight into their typical baseline weight.[10] 

Heart rate: Tachycardia may indicate a compensatory response to preserve perfusion in patients with hypovolemia and can serve as an early sign of compensated hypovolemic shock. Healthcare professionals should consider fluid administration when the heart rate exceeds 90 beats per minute (bpm). However, tachycardia can also result from other factors, such as pain, fever, or anxiety, and clinicians must assess for additional underlying causes.

Blood pressure: A decline in blood pressure is a concerning finding, often accompanied by tachycardia, and signals an increased risk of inadequate perfusion to vital organs. The presence of both hypotension and tachycardia suggests that the cardiovascular system can no longer effectively compensate for hypovolemia. In contrast, elevated blood pressure is more commonly associated with hypervolemia. Healthcare professionals should consider fluid administration when the systolic blood pressure drops below 100 mm Hg.

Orthostatic vital signs: A drop of at least 20 mm Hg in systolic pressure or 10 mm Hg in diastolic pressure within 2 to 5 minutes of standing after resting supine for 5 minutes indicates orthostatic hypotension.[11] This condition is often observed in individuals who are dehydrated or older adults with reduced baroreceptor sensitivity.

Respiratory rate: A respiratory rate exceeding 20 breaths per minute may indicate a compensatory response to metabolic acidosis, often caused by lactic acidosis resulting from inadequate tissue perfusion. 

Urine output: In clinical practice, healthcare professionals should expect a minimum urine output of 2 mL/kg/h in neonates after the first day of life, 1.5 mL/kg/h in children, and more than 1 mL/kg/h in adults. In infants, approximately six wet diapers per day are expected after the first week of life, although the number may decrease as bladder capacity increases with age. Certain clinical situations may require higher urine output targets, particularly to reduce the risk of renal toxicity when administering nephrotoxic medications such as acyclovir.

Capillary refill: Under normal conditions, capillary refill occurs within 2 seconds or less. Clinicians typically assess capillary refill on the fingertips or toes. Please see StatPearls' companion resource, "Capillary Refill Time," for more information.

Fontanelle: The presence of a sunken fontanelle in an infant's skull is indicative of hypovolemia.[12]

Edema: Peripheral edema may indicate either volume overload or the third spacing of intravascular fluid.

Tear production: Decreased tear production is especially relevant in infants and children, making parental observations a critical component of the clinical assessment.[13]

Peripheral pulses: Evaluation of peripheral pulses should include the brachial and femoral arteries in infants, as well as the radial or dorsalis pedis arteries in older patients. In dehydration, pulses are often fast and thready.[14]

Skin turgor and eye appearance: In severe cases of dehydration, patients may exhibit flaccid or tented skin, and the eyes may appear sunken into the orbital cavities.

Tactile skin temperature: Cool and clammy skin, especially on the hands and feet, traditionally indicates hypovolemic shock, which is attributed to peripheral vasoconstriction.

Mucous membranes: Mucous membranes in the mouth may exhibit a dry, sticky texture in cases of dehydration.[15]

Jugular vein appearance: Jugular vein distention may indicate volume overload, but it can also be present in euvolemic patients with congestive heart failure due to impaired cardiac pumping efficiency.[16]

Laboratory Findings

Blood urea nitrogen to creatinine ratio: Reduced renal blood flow, resulting from decreased intravascular volume, can cause acute kidney injury and an elevated blood urea nitrogen (BUN) to creatinine (Cr) ratio. 

Transaminases: An elevation in aspartate aminotransferase or alanine aminotransferase may result from hepatic tissue hypoperfusion and subsequent tissue hypoxia, leading to a condition known as hepatocyte injury or shock liver.

Hemoconcentration: Elevated hematocrit results from a relative excess of red blood cells compared to intravascular fluid volume.

Additional parameters: They include elevated serum urea, osmolality, sodium, urine osmolality, and specific gravity, which can indicate dehydration. 

Contraindications

Few absolute contraindications exist for fluid administration; however, fluid management requires careful consideration of several precautions.[17] Clinicians should generally avoid hypotonic solutions in patients with hyponatremia due to the risk of cerebral edema. Emerging research highlights the dangers of aggressive fluid resuscitation in patients who experience trauma, supporting the concept of "controlled hypotension" or "permissive hypotension." In this approach, fluid administration is limited to maintain a systolic blood pressure just above 70 mm Hg, thereby helping to avoid dilution of clotting factors, disruption of thrombus formation, and worsening of hemorrhage.[18][19][20] 

Clinicians should avoid controlled hypotension in patients with trauma and brain injury, as reduced cerebral perfusion can worsen outcomes. Fluid administration is often avoided or requires careful balance in conditions such as cardiogenic shock, congestive heart failure, renal failure, and increased intracranial pressure. Please see StatPearls' companion resource, "Crystalloid Fluids," for an in-depth list of contraindications to IV fluids.

Equipment

Fluid administration via the IV route is a common practice when oral intake is insufficient to address fluid deficits and ongoing losses, or in cases where a patient presents with hypovolemic shock following trauma. Alternative available options include subcutaneous, intraosseous, central venous, and enteral tube routes. Fluids are typically administered in healthcare facilities; however, community-based administration may be appropriate in specific situations. The equipment generally required to administer fluids effectively is listed below.

Primary Intravenous Fluid Equipment

Sterile spike: This connects the tubing to the IV bag.

Drip chamber: This prevents air from entering the IV tubing and allows for the regulation of the solution's flow rate.

Backcheck valve: This prevents the reverse flow of fluid or medication within the IV line.

Access ports: These enable the administration of secondary and IV push medications.

Extension set: This connects the IV tubing to the cannula, reducing micromovements at the IV insertion site and minimizing exposure to blood and body fluids during tubing changes.

Slide clamps: They are used to initiate ot stop the flow of IV fluids. 

IV poles: They provide stable and adjustable support for IV bags and tubing.

Additional supplies: These typically include non-sterile gloves, a tourniquet, an antiseptic solution (such as 2% chlorhexidine in 70% isopropyl alcohol or antiseptic wipes), an IV needle, 2x2-inch gauze, an adapter, a saline or heparin lock, saline or heparin solution, a transparent dressing, and paper tape. Please see StatPearls' companion resources, "Intraosseous Access" and "Central Venous Catheter Insertion," for a discussion on the necessary equipment for administering fluids through an intraosseous or central venous route. 

Intravenous Fluid Solutions

The selection of IV fluid should be guided by the nature of fluid loss and the presence of any associated electrolyte or acid-base imbalances. The most commonly used IV fluids in clinical practice include:

• 0.9% Sodium chloride or normal saline (NS), with or without potassium 
• 0.45% Sodium chloride or 1/2 normal saline (1/2NS), with or without potassium 
• Lactated Ringer solution
• 5% Dextrose in normal saline (D5NS), with or without potassium 
• 5% Dextrose in 1/2 normal saline (D5 1/2NS), with or without potassium 

Enteral Tubes

Enteral tubes are available in various types, each designed to meet specific clinical needs and patient conditions. These include nasogastric, orogastric, gastric, nasoduodenal, and gastrojejunal tubes. Enteral fluid solutions also vary to address different medical requirements, from clinical rehydration to providing nutritional support for infants and supplementing electrolytes in athletes. These solutions include commercial rehydration fluids, rehydration solutions recommended by the World Health Organization (WHO), breast milk or formula, and commercially available sports drinks.

Technique or Treatment

Intravenous fluid administration varies based on each patient's unique clinical condition. Whenever possible, oral intake remains the preferred method. However, in some cases, patients may need alternative enteral methods, such as feeding tubes. Combination regimens that incorporate both IV and oral approaches have proven effective for patients who cannot meet their total daily fluid requirements enterally. 

Clinicians can adjust the proportions of IV and oral fluids based on the patient's ability to tolerate oral intake. The selection of the appropriate IV fluid solution and infusion rate depends on the patient's clinical presentation and the need for resuscitation, rehydration, or maintenance fluids. Regular assessment of vital signs, physical examination findings, and supplementary laboratory data is crucial for determining the most suitable fluid management strategy. Reevaluation, including an assessment of pulmonary edema, is crucial before and after administering a fluid bolus. 

Adults

Maintenance fluid: Serum sodium and body weight are the 2 key parameters for assessing a patient's water balance and volume status. Normal serum sodium levels indicate that the patient is in water balance relative to their sodium level, while body weight serves as a reliable indicator of fluid loss or gain. A normal adult requires a minimum intake or production of 1600 mL of free water per day.

A typical starting point for most adult patients with normal kidney function who require maintenance IV fluids is 2 liters of D5 1/2NS daily, supplemented with 20 mEq of potassium chloride. This allows for 9 grams of sodium chloride, or 3.4 grams of sodium, and 400 kilocalories, enough to suppress catabolism. Clinicians can make adjustments accordingly. If the serum sodium level begins to fall, isotonic saline should be administered. If the serum sodium level increases, D5 1/4NS should be administered. Similarly, if the serum potassium level decreases, additional potassium should be added. If the serum potassium increases, potassium should be eliminated. 

Replacement fluid: In cases of severe volume depletion or hypovolemic shock, patients should receive 1 to 2 liters of isotonic fluids as quickly as possible to restore adequate tissue perfusion. For adults with sepsis or severe hypovolemic shock, the recommended treatment is to administer 30 mL/kg of fluid in 500 milliliters boluses during the initial hours of treatment.

Fluid resuscitation should continue rapidly until signs of hypovolemia, such as low blood pressure, reduced urine output, or altered mental status, show improvement. Rapid fluid administration is unnecessary for patients with mild-to-moderate hypovolemia. Instead, fluids should be given at a rate that exceeds ongoing losses, including urine and insensible losses—typically 30 to 50 mL/h—along with any additional ongoing losses. A common approach is to administer fluids at a rate of 50 to 100 mL/h above the estimated fluid losses to achieve a positive fluid balance.

Patients with severe hypovolemia or hypovolemic shock may experience better outcomes with lactated Ringer solution or 1/2NS. Normal saline contains a higher chloride concentration than plasma, which can lead to hyperchloremia. If clinicians administer significant volumes of normal saline, patients may be at risk for developing hyperchloremic metabolic acidosis. However, administering large volumes of lactated Ringer can cause metabolic alkalosis. For these reasons, guidelines recommend minimizing the use of IV fluids in the resuscitation of trauma patients and suggest limiting fluids until blood products are available. Patients with hypernatremia typically receive hypotonic solutions, whereas those with hyponatremia are usually given isotonic or hypertonic solutions. In cases of hypokalemia, potassium supplementation may be required, and bicarbonate may be beneficial in severe acidosis.

Adding dextrose has not been proven to benefit or harm most patients. However, adding dextrose is appropriate in certain situations, such as for children receiving maintenance fluids, individuals with hypoglycemia, those with alcohol-related or fasting-induced ketoacidosis, and patients with hyperkalemia without hyperglycemia, when used in conjunction with insulin. Dextrose solutions are not recommended for individuals with uncontrolled diabetes or hypokalemia, as dextrose can stimulate insulin release, potentially worsening hypokalemia by driving potassium into cells.

Colloid-containing solutions, such as albumin, are rarely used as first-line treatments for patients with hypovolemia or hypovolemic shock. However, albumin may be beneficial for patients who do not respond to crystalloid solutions, particularly in cases of hypoalbuminemia. Clinicians should avoid hyperoncotic starch solutions due to the risk of acute kidney injury.[21]

Infants and Children

Maintenance fluid: Clinicians must consider a child's size when determining the maintenance fluid rate in the pediatric population. For example, the fluid requirements of an infant aged 3 months differ significantly from those of a child aged 8. Clinicians can utilize the 4-2-1 rule to determine the hourly maintenance fluid rate required for a child based on their body weight.[22]

The formula outlined below illustrates how to calculate fluid maintenance rates based on a child’s weight, as mentioned below.

• First 10 kilograms: 4 mL/kg/h
• Next 10 to 20 kilograms: 40 mL/h for the first 10 kilograms, plus 2 mL/h for each additional kilogram
• Any remaining weight more than 20 kilograms: 60 mL/h for the first 20 kilograms of body weight, plus 1 mL/h for any weight exceeding 20 kilograms

For example, a child with a body weight of 22 kilograms would require maintenance fluids at hourly rates mentioned below.

• First 10 kg: 4 mL/kg/h × 10 kg = 40 mL/h
• Next 10 to 20 kg: 2 mL/kg/h × 10 kg = 20 mL/h
• Remaining 2 kg: 1 mL/kg/h × 2 kg = 2 mL/h

Total hourly maintenance fluid rate: (40+20+2) mL/h = 62 mL/h

Another commonly used formula that predicts fluid requirements over 24 hours is based on the following parameters:

• First 10 kg: 100 mL/kg/d
• Next 10 to 20 kg: Additional 50 mL/kg/d
• Any remaining weight more than 20 kg: Additional 20 mL/kg/d

For example, the maintenance fluid requirements for a child with a body weight of 15 kilograms include:

• First 10 kg: 100 mL/kg/d × 10 kg = 1000 mL/d
• Next 10 to 20 kg: 50 mL/kg/d × 5 kg = 250 mL/d
• Remaining weight (50 kg): As the child is 15 kg, no additional weight over 20 kg applies. Thus, 20 mL/kg/d × 0 = 0 mL/d
• Total fluids per day: 1000 + 250 = 1250 mL/d
• Hourly fluid rate: 1250/24 = 52 mL/h

In the pediatric population, electrolyte requirements vary according to weight and age. Sodium and chloride needs typically range from 2 to 3 mEq per 100 mL of water per day, while potassium requirements fall between 1 and 2 mEq per 100 mL of water per day. Children with a body weight of less than 10 kg, who have normal serum potassium levels and kidney function, usually receive 10 mEq/L of potassium. In contrast, children with a body weight of more than 10 kg receive 10 to 20 mEq/L of potassium.[23] Children have higher glucose needs than adults, and a 5% to 10% dextrose solution is generally considered safe for maintenance fluids in pediatric patients.

Due to the increased risk of hyponatremia and inappropriate antidiuretic hormone secretion (ADH) in hospitalized children, the American Academy of Pediatrics recommends the use of normal saline or lactated Ringer for most pediatric patients.[24][25][26] These guidelines regarding the use of isotonic fluids do not apply to infants, children, and adolescents with certain conditions, including neurosurgical disorders, congenital or acquired cardiac disease, hepatic disease, cancer, renal dysfunction, diabetes insipidus, profuse watery diarrhea, severe burns, or for neonates aged 28 days or younger, or those in the neonatal intensive care unit (NICU).[24] 

Clinicians should exercise caution when applying weight-based formulas, particularly in older patients or those with obesity.[27] As with adults, monitoring serum sodium levels is an effective way to assess the body’s free water status. Additionally, tracking serum sodium levels alongside daily weight measurements can provide valuable insight into the patient’s volume status, helping clinicians make informed decisions regarding fluid management.

Replacement fluid: The management of hypovolemia begins with the urgent replenishment of fluids, followed by a less critical phase that includes continued IV fluid administration or oral rehydration.

Severe hypovolemia: In pediatric patients, severe hypovolemia is typically defined as a volume depletion of 10% or more. Initial management involves administering a 20 mL/kg bolus of isotonic saline without dextrose, followed by clinical reassessment. Boluses may be repeated as needed until the patient’s volume status stabilizes. After emergent volume repletion, subsequent fluid selection should be guided by the patient’s serum sodium concentration. Clinicians may continue isotonic saline at doses of 20 to 40 mL/kg over 2 to 4 hours. Once the patient achieves euvolemia, therapy transitions to standard maintenance fluid rates.

Moderate hypovolemia: Infants and children with moderate hypovolemia, typically defined as approximately 7% volume depletion, may be treated with a 10 mL/kg bolus of isotonic saline without dextrose. If the patient is able to tolerate it, they may then receive an additional bolus or transition to oral rehydration.[28] Indications for continued IV therapy include an inability to tolerate oral rehydration, a caregiver's inability to administer oral fluids, persistent electrolyte disturbances requiring frequent monitoring, or ongoing fluid losses that prevent adequate hydration through oral rehydration alone. Similar to adults, colloid solutions such as albumin are not considered first-line but may be helpful in pediatric patients with nephrotic syndrome or sepsis. In these cases, the recommended dosage of albumin is 0.5 mg to 1 g/kg.

Mild-to-moderate hypovolemia: Ideally, children with mild to moderate hypovolemia should receive oral rehydration therapy. Caregivers provide frequent, small amounts of fluid through a syringe or spoon. 

Newborns

Fluid management in newborns is significantly more complex than in adults, older infants, or children. Clinicians must consider gestational age, postnatal physiologic changes in renal function, shifts in total body water, birth weight, environmental conditions in the healthcare setting, and the severity of the illness. As mentioned earlier, water balance is influenced by renal function along with fluid intake and losses. In the postnatal period, the combination of immature renal function, changes in body water composition, and increased insensible water losses makes fluid management in newborns particularly challenging.

Fluid requirements: Due to the increased insensible fluid losses, smaller and less mature neonates have higher fluid needs. Most neonates receive fluids as a 10% dextrose solution to ensure adequate glucose delivery. However, extremely preterm infants, who are often glucose intolerant, may require a 5% dextrose solution instead.

The list below provides the suggested fluid administration rates for neonates during the first 2 days of life, based on the newborn's birth weight.  

• Less than 1000 grams: 90 to 120 mL/kg/d
• 1001 to 1250 grams: 80 to 100 mL/kg/d 
• 1251 to 1500: 80 mL/kg/d
• 1501 to 2000 grams: 60 to 80 mL/kg/d
• Greater than 2000 grams: 60 to 80 mL/kg/d

On day 3 of life, neonatal fluid requirements increase, and the fluid administration rates are mentioned below.

• Less than 1000 grams: 140 mL/kg/d 
• 1001 to 1250 grams:120 mL/kg/d 
• 1251 to 1500: 100 mL/kg/d
• 1501 to 2000 grams: 100 mL/kg/d
• Greater than 2000 grams: 100 mL/kg/d

Beyond day 3 of life, the recommended fluid administration rates are mentioned below.

• Less than 1000 grams: 150 mL/kg/d 
• 1001 to 1250 grams: 150 mL/kg/d 
• 1251 to 1500: 150 mL/kg/d
• 1501 to 2000 grams: 140 to 160 mL/kg/d
• Greater than 2000 grams: 140 to 160 mL/kg/d

For assessing fluid status, monitoring changes in body weight alongside serum sodium concentrations offers the most reliable indicators. Hyponatremia indicates an excess of free water, whereas hypernatremia indicates dehydration or excessive loss of free water. In neonates weighing less than 1500 grams, fluid requirements should be increased by 20 mL/kg/d if they are placed in an open warmer or receiving respiratory support with non-humidified gas. Adjustments should be made based on the infant’s ongoing clinical condition.

Electrolytes: Neonates do not receive electrolytes on their first day of life. Starting on day 2, clinicians administer electrolytes to maintain daily maintenance levels of 3 mEq/kg/d of sodium and 2 mEq/kg/d of potassium. Additionally, clinicians must replace any electrolyte losses from gastric, small intestine, or thoracostomy fluid. For reference, thoracostomy fluid has an electrolyte composition similar to serum. Gastric output typically contains 20 to 80 mEq/L of sodium, 5 to 20 mEq/L of potassium, and 100 to 150 mEq/L of chloride. Small bowel output contains 100 to 140 mEq/L of sodium, 5 to 15 mEq/L of potassium, and 40 to 75 mEq/L of bicarbonate.

Complications

Although fluid management is crucial for ensuring quality patient care, it can also lead to complications that necessitate careful consideration and ongoing monitoring.

Hyponatremia

Hyponatremia requires regular monitoring of serum sodium levels, with an increased risk associated with the use of hypotonic solutions. Many hospitalized patients are particularly vulnerable due to inappropriate ADH release, which can lead to volume retention and worsen hyponatremia.[29]

Symptoms of hyponatremia typically manifest when serum sodium levels drop acutely within 24 hours, as water shifts from the cerebrospinal fluid and plasma into the brain. Early symptoms, such as nausea, vomiting, and malaise, typically occur when the serum sodium level falls below 125 to 130 mEq/L. As the serum sodium continues to decline further, below 120 to 115 mEq/L, patients may experience headaches, lethargy, obtundation, seizures, coma, and possibly respiratory arrest. Clinicians should avoid correcting severe hyponatremia rapidly to avoid osmotic demyelination syndrome.[30] 

Hypernatremia

Hypernatremia can result from the administration of hypertonic saline or improperly formulated hyperalimentation solutions. Early symptoms include lethargy, weakness, and irritability. As serum sodium levels rise—particularly above 158 mEq/L—patients may develop twitching, seizures, and coma. Additional complications can include intracerebral and subarachnoid hemorrhage, resulting from cerebral vein rupture due to a rapid reduction in brain volume.[31] 

Hyperkalemia

Hyperkalemia can be a significant concern for patients with renal failure who receive potassium-containing solutions. The impaired ability to clear potassium effectively in these patients can lead to life-threatening cardiac arrhythmias. As a result, clinicians generally avoid using potassium-containing solutions, such as lactated Ringer, in patients with hyperkalemia. 

Hypokalemia

Hypokalemia can lead to cardiac arrhythmias and impaired glucose tolerance. Severe cases, typically with potassium levels below 2.5 mEq/L, may result in muscle weakness, potentially causing respiratory failure and paralytic ileus. 

Volume Overload

Clinicians should closely monitor patients for signs of peripheral and pulmonary edema or hepatomegaly.[30] Patients with underlying cardiac dysfunction or renal failure require careful evaluation and appropriate adjustments to their fluid volume to prevent complications.

Compartment Syndrome

Abdominal compartment syndrome, characterized by oliguria, a tense abdomen, and increased airway pressure, is a potential complication in patients receiving fluid volumes exceeding 5 liters in 24 hours.[32]

Metabolic Acidosis

Normal saline is slightly acidic compared to the body's physiological pH and may contribute to the development of metabolic acidosis.[33][34] Although lactated Ringer solution more closely approximates the body’s normal pH, the decision to use lactated Ringer or normal saline for fluid maintenance is often influenced by the availability of these solutions at individual institutions.

Metabolic Alkalosis

Lactated Ringer solution can contribute to metabolic alkalosis due to the conversion of lactate to bicarbonate in the body.

Other Complications

Additional complications associated with fluid management include:

• Hematoma formation
• Phlebitis
• Thrombophlebitis
• Air embolism
• Infiltration;
• Extravascular and intra-arterial injections
• Catheter-related bloodstream infection
• Local infections
• Nerve injury
• Acute kidney injury due to hyperoncotic starch solutions
• Hypothermia
• Worsening hemorrhage due to the dilution of clotting factors and disruption of thrombus formation in trauma patients
• Device embolism [35][36]

Clinical Significance

Maintaining adequate intravascular volume is crucial for ensuring organ perfusion and preserving electrolyte and pH balance. Fluid management can range from addressing basic daily fluid and electrolyte needs to meeting the complex requirements of patients with severe trauma, surgical injuries, burns, sepsis, or critical illness. Insufficient volume can lead to shock, ischemic stroke, myocardial infarction, renal or hepatic injury, multiple organ failure, and death. Conversely, excessive fluid administration can result in complications such as pulmonary edema, heart failure, and abdominal compartment syndrome.

An individualized fluid management plan should be guided by the patient’s clinical condition and medical history. This tailored approach helps prevent iatrogenic complications such as dehydration, fluid overload, electrolyte imbalances, and acid-base disturbances. Ongoing assessment, including the monitoring of vital signs, daily weights, and relevant laboratory values, combined with effective communication among the healthcare team, is essential to minimizing risks and optimizing patient outcomes.

Enhancing Healthcare Team Outcomes

Fluid management is a critical component of inpatient care, and healthcare professionals must individualize fluid replacement according to each patient's specific needs and clinical status. Patients may require maintenance, replacement, or resuscitative fluids, or a combination of these. Maintenance therapy replenishes normal daily losses through urine, sweat, respiration, and stool, typically at a rate of around 1600 mL per day in adults. Replacement therapy addresses fluid and electrolyte deficits resulting from conditions such as vomiting, diarrhea, bleeding, burns, or third-space fluid shifts. Resuscitative therapy is needed for patients with severe hypovolemia or hypovolemic shock, often resulting from sepsis or injury.

The choice and rate of fluid administration depend on the severity of the patient’s volume depletion and clinical presentation. In cases of severe hypovolemia or shock, rapid fluid resuscitation with isotonic crystalloids may be necessary. In contrast, patients with mild-to-moderate fluid loss benefit from more controlled replacement based on ongoing fluid losses. Clinicians rely on clinical indicators, such as skin turgor, capillary refill, blood pressure, urine output, and jugular venous pressure, to guide therapy, as there is no precise formula to calculate fluid deficits. Crystalloids, including normal saline (NS), 1/2NS, and lactated Ringer solution, are most commonly used, with the specific choice influenced by the patient's electrolyte and acid-base status. Colloids, such as albumin, may be considered appropriate for patients who do not respond adequately to crystalloids or who have hypoalbuminemia. However, hyperoncotic starch solutions should be avoided due to their association with acute kidney injury.

A thorough understanding of fluid management is essential to avoid complications such as volume overload, hyponatremia, hypernatremia, and cerebral edema, particularly in vulnerable populations such as children. Effective fluid management requires a coordinated, multidisciplinary approach that combines the skills and expertise of physicians, advanced practitioners, nurses, pharmacists, and other healthcare professionals. Each healthcare team member plays a vital role in assessing, planning, delivering, and monitoring fluid therapy to ensure patient-centered care and optimal outcomes.

Physicians and advanced practitioners are primarily responsible for evaluating the patients' fluid status, identifying deficits, and determining the appropriate type and volume of fluid based on the patient's condition and clinical needs. Nurses contribute by initiating IV access, closely monitoring fluid input and output, tracking vital signs, and observing for clinical signs of fluid imbalance—all while providing real-time updates on the patient’s response to treatment. Pharmacists support safe and effective fluid management by reviewing the composition of fluids, monitoring for potential drug interactions, recommending electrolyte replacement strategies, and helping to prevent complications such as hypernatremia, acidosis, or medication-related adverse effects.

Strategic decision-making is crucial for tailoring fluid therapy to each patient’s unique needs, especially in complex cases involving comorbidities or substantial fluid losses. Coordinated care enhances fluid management by incorporating input from various specialists, including nephrology, cardiology, emergency medicine, trauma, dietetics, and critical care, when appropriate. Effective transitions of care, including handoffs between shifts or units, are crucial for maintaining continuity and avoiding mismanagement of fluids. A collaborative, team-based approach enhances patient safety, reduces the risk of complications such as fluid overload and electrolyte imbalances, and strengthens overall team performance. By fostering mutual respect, promoting shared decision-making, and ensuring clear communication, healthcare teams can deliver high-quality, patient-centered fluid management that leads to improved clinical outcomes.

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Disclosure: Mark Castera declares no relevant financial relationships with ineligible companies.

Disclosure: Mahesh Borhade declares no relevant financial relationships with ineligible companies.