Volume Depletion and Dehydration

Definitions and Etiology

Definitions

Dehydration refers only to a loss of water, while volume depletion refers to a loss of both water and Na⁺. 

Etiology

• Dehydration due to decreased oral water intake:
  • Acute or critical illness 
  • Decreased access to water
  • Altered thirst mechanisms in childhood or old age
  • Dementia Dementia Major neurocognitive disorders (NCD), also known as dementia, are a group of diseases characterized by decline in a person’s memory and executive function. These disorders are progressive and persistent diseases that are the leading cause of disability among elderly people worldwide. Major Neurocognitive Disorders

• Volume depletion ( hypovolemia Hypovolemia Sepsis in Children) due to decreased oral Na intake:
  • Acute or critical illness
  • Eating disorders
  • Dementia Dementia Major neurocognitive disorders (NCD), also known as dementia, are a group of diseases characterized by decline in a person’s memory and executive function. These disorders are progressive and persistent diseases that are the leading cause of disability among elderly people worldwide. Major Neurocognitive Disorders
• Volume depletion due to increased volume losses: 
  • Bleeding
  • GI losses:
    • Diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
    • Vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia
    • Drains (e.g., nasogastric tube Nasogastric tube Malnutrition in children in resource-limited countries)
  • Renal:
    • Osmotic diuresis (diabetic ketoacidosis Ketoacidosis A life-threatening complication of diabetes mellitus, primarily of type 1 diabetes mellitus with severe insulin deficiency and extreme hyperglycemia. It is characterized by ketosis; dehydration; and depressed consciousness leading to coma. Metabolic Acidosis)
    • Diuretic therapy
    • Diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus insipidus
    • Postobstructive/postacute tubular necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage diuresis
  • Third-space losses:
    • Burns Burns A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Burns
    • Severe pancreatitis Pancreatitis Inflammation of the pancreas. Pancreatitis is classified as acute unless there are computed tomographic or endoscopic retrograde cholangiopancreatographic findings of chronic pancreatitis. The two most common forms of acute pancreatitis are alcoholic pancreatitis and gallstone pancreatitis. Acute Pancreatitis
  • Insensible losses:
    • Skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions/mucous membranes (e.g., fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever)
    • Respiratory tract

Pathophysiology

The relative differences between losses of water and Na determine how water shifts between the fluid compartments of the body. With volume depletion and dehydration, there are fluid shifts between the compartments.

Fluid compartments of the body

• Total body water Total body water Body Fluid Compartments ( TBW TBW Body Fluid Compartments):
  • 50% of body weight for adult women and 60% of body weight for adult men
  • Varies with muscle mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast (more water) and fat (less water)
  • Decreases in the elderly, as muscle mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast is replaced with fat 
  • Decreases in obesity Obesity Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Obesity
• Intracellular fluid Intracellular fluid The fluid inside cells. Body Fluid Compartments ( ICF ICF The fluid inside cells. Body Fluid Compartments): fluid enclosed within cells = ⅔ of TBW TBW Body Fluid Compartments
• Extracellular fluid Extracellular fluid The fluid of the body that is outside of cells. It is the external environment for the cells. Body Fluid Compartments (ECF): fluid outside the cells = ⅓ of TBW TBW Body Fluid Compartments
  • Divided into 2 subcompartments 
  • Intravascular fluid Intravascular fluid Body Fluid Compartments = plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products (in blood)
    • ¼ of the ECF
    • Approximately 8% of TBW TBW Body Fluid Compartments (⅓ x ¼)
  • Interstitial fluid Interstitial fluid Body Fluid Compartments (IF)
    • Fluid between cells; not in the blood
    • ¾ of the ECF
    • Approximately 25% of TBW TBW Body Fluid Compartments (⅓ x ¾)

Fluid shifts with illness/disease

• Occur due to diffusion Diffusion The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially facilitated diffusion, is a major mechanism of biological transport. Peritoneal Dialysis and Hemodialysis across a semipermeable membrane Semipermeable membrane Peritoneal Dialysis and Hemodialysis 
• Regulated by a difference in plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation between ECF and ICF ICF The fluid inside cells. Body Fluid Compartments
• Plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation ＝ total body sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia (TBNa⁺)/ TBW TBW Body Fluid Compartments
• Dehydration: 
  • Water is lost, but Na is not.
  • ICF ICF The fluid inside cells. Body Fluid Compartments contracts more than ECF.
    • Water is lost from ECF → ECF osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation increases → water diffuses from ICF ICF The fluid inside cells. Body Fluid Compartments to ECF
    • ⅔ of total lost water is from ICF ICF The fluid inside cells. Body Fluid Compartments, ⅓ is from ECF.
    • Net effect: ECF hypertonicity and hypernatremia Hypernatremia Hypernatremia is an elevated serum sodium concentration > 145 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled by the hypothalamus via the thirst mechanism and antidiuretic hormone (ADH) release. Hypernatremia occurs either from a lack of access to water or an excessive intake of sodium. Hypernatremia 
  • Example: ↓ water intake or inadequate water replacement in critical illness
• Hypotonic Hypotonic Solutions that have a lesser osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid. Renal Sodium and Water Regulation loss of fluid:
  • Water loss exceeds Na loss.
  • ECF and ICF ICF The fluid inside cells. Body Fluid Compartments both contract:
    • Hypotonic Hypotonic Solutions that have a lesser osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid. Renal Sodium and Water Regulation fluid is lost from ECF → ECF osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation increases → water diffuses from ICF ICF The fluid inside cells. Body Fluid Compartments to ECF
    • Less water shifts from ICF ICF The fluid inside cells. Body Fluid Compartments to ECF compared to the loss of only water (with dehydration).
    • Net effect is ECF hypertonicity and hypernatremia Hypernatremia Hypernatremia is an elevated serum sodium concentration > 145 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled by the hypothalamus via the thirst mechanism and antidiuretic hormone (ADH) release. Hypernatremia occurs either from a lack of access to water or an excessive intake of sodium. Hypernatremia.
  • Examples:
    • Increased insensible losses ( fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination, excessive sweating)
    • Polyuria Polyuria Urination of a large volume of urine with an increase in urinary frequency, commonly seen in diabetes. Renal Potassium Regulation ( diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus insipidus, postobstructive diuresis)
    • Osmotic diuresis (diabetic ketoacidosis Ketoacidosis A life-threatening complication of diabetes mellitus, primarily of type 1 diabetes mellitus with severe insulin deficiency and extreme hyperglycemia. It is characterized by ketosis; dehydration; and depressed consciousness leading to coma. Metabolic Acidosis)
• Hypertonic Hypertonic Solutions that have a greater osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid. Renal Sodium and Water Regulation loss of fluid:
  • Na loss exceeds water loss.
  • Can result in either hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia or hypernatremia Hypernatremia Hypernatremia is an elevated serum sodium concentration > 145 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled by the hypothalamus via the thirst mechanism and antidiuretic hormone (ADH) release. Hypernatremia occurs either from a lack of access to water or an excessive intake of sodium. Hypernatremia
  • ECF contracts and ICF ICF The fluid inside cells. Body Fluid Compartments expands:
    • Fluid is lost from ECF → ECF contracts and ECF osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation decreases
    • ↓ ECF osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation causes water to shift from ECF to ICF ICF The fluid inside cells. Body Fluid Compartments via diffusion Diffusion The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially facilitated diffusion, is a major mechanism of biological transport. Peritoneal Dialysis and Hemodialysis.
    • Normal ⅔-to-⅓ relationship between ICF ICF The fluid inside cells. Body Fluid Compartments and ECF is lost
  • Examples:
    • Loop diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication ( furosemide Furosemide A benzoic-sulfonamide-furan. It is a diuretic with fast onset and short duration that is used for edema and chronic renal insufficiency. Loop Diuretics, bumetanide Bumetanide A sulfamyl diuretic. Loop Diuretics, torsemide Torsemide A pyridine and sulfonamide derivative that acts as a sodium-potassium chloride symporter inhibitor. It is used for the treatment of edema associated with congestive heart failure; chronic renal insufficiency; and liver diseases. It is also used for the management of hypertension. Loop Diuretics)
    • Salt-wasting nephropathy ( Bartter syndrome Bartter syndrome Bartter syndrome is a rare autosomal recessive disorder that affects the kidneys and presents either antenatally with severe or life-threatening manifestations or in childhood or adulthood with a milder course, depending on the genetic defect. Clinical disease results from defective renal reabsorption of sodium chloride in the thick ascending limb of the loop of Henle. Bartter Syndrome, Gitelman syndrome Gitelman syndrome Gitelman syndrome is a rare genetic autosomal recessive disorder that affects the sodium-chloride cotransporter in the distal convoluted tubule of the nephron and causes electrolyte abnormalities. The syndrome presents clinically with symptoms of hypokalemia and hypomagnesemia. Gitelman Syndrome)
    • Primary adrenal insufficiency Primary adrenal insufficiency An adrenal disease characterized by the progressive destruction of the adrenal cortex, resulting in insufficient production of aldosterone and hydrocortisone. Clinical symptoms include anorexia; nausea; weight loss; muscle weakness; and hyperpigmentation of the skin due to increase in circulating levels of acth precursor hormone which stimulates melanocytes. Adrenal Insufficiency and Addison Disease (Addison disease)
• Isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation loss of fluid:
  • Na and water lost at the same rate
  • ECF contracts, ICF ICF The fluid inside cells. Body Fluid Compartments does not change.
  • Isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation fluid is lost from ECF → ECF osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation does not change → no gradient for diffusion Diffusion The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially facilitated diffusion, is a major mechanism of biological transport. Peritoneal Dialysis and Hemodialysis with ICF ICF The fluid inside cells. Body Fluid Compartments
  • Plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation and serum Na do not change.
  • Examples:
    • Diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
    • Loss of whole blood
    • Third-space losses

Clinical Presentation

The clinical presentation of dehydration and volume depletion varies greatly depending on the severity, from asymptomatic to potentially fatal hypovolemic shock Hypovolemic Shock Types of Shock.

Clinical history

• Can be asymptomatic
• Symptoms with mild and moderate hypovolemia Hypovolemia Sepsis in Children are often nonspecific:
  • Fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia
  • Dizziness Dizziness An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness. Lateral Medullary Syndrome (Wallenberg Syndrome)
  • Thirst
  • Muscle cramps Cramps Ion Channel Myopathy
• Symptoms with severe hypovolemia Hypovolemia Sepsis in Children are mostly related to hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension:
  • Chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways ( coronary artery Coronary Artery Truncus Arteriosus ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage)
  • Abdominal pain Abdominal Pain Acute Abdomen (mesenteric ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage)
  • Altered mental status Altered Mental Status Sepsis in Children/severe dizziness Dizziness An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness. Lateral Medullary Syndrome (Wallenberg Syndrome) (cerebral ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage)

Physical exam

• Signs of dehydration and hypovolemia Hypovolemia Sepsis in Children:
  • Dry mucous membranes
  • Dry skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions
  • Decreased skin turgor Skin turgor Malnutrition in children in resource-limited countries ( skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions tenting when pinched)
  • Mildly decreased supine blood pressure
  • Orthostatic hypotension Orthostatic hypotension A significant drop in blood pressure after assuming a standing position. Orthostatic hypotension is a finding, and defined as a 20-mm hg decrease in systolic pressure or a 10-mm hg decrease in diastolic pressure 3 minutes after the person has risen from supine to standing. Symptoms generally include dizziness, blurred vision, and syncope. Hypotension
  • Weight loss Weight loss Decrease in existing body weight. Bariatric Surgery
• Signs of shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock:
  • Hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension (systolic blood pressure < 100 mm Hg)
  • Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children (> 90–100 beats/min)
  • Tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination ( respiratory rate Respiratory rate The number of times an organism breathes with the lungs (respiration) per unit time, usually per minute. Pulmonary Examination > 20)
  • Cool extremities
  • Altered mental status Altered Mental Status Sepsis in Children
  • Prolonged capillary refill time Capillary Refill Time Cardiovascular Examination > 2 seconds
  • Decreased urine output
  • Decreased jugular venous pressure Jugular Venous Pressure Portal Hypertension
• Findings are less reliable in the elderly:
  • Orthostatic hypotension Orthostatic hypotension A significant drop in blood pressure after assuming a standing position. Orthostatic hypotension is a finding, and defined as a 20-mm hg decrease in systolic pressure or a 10-mm hg decrease in diastolic pressure 3 minutes after the person has risen from supine to standing. Symptoms generally include dizziness, blurred vision, and syncope. Hypotension may be due to autonomic dysfunction Autonomic Dysfunction Anterior Cord Syndrome.
  • Skin turgor Skin turgor Malnutrition in children in resource-limited countries is typically lost with age. 
• Urine output may be paradoxically high with specific etiologies:
  • Diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus insipidus
  • Osmotic diuresis 
  • Salt-wasting nephropathy ( Bartter syndrome Bartter syndrome Bartter syndrome is a rare autosomal recessive disorder that affects the kidneys and presents either antenatally with severe or life-threatening manifestations or in childhood or adulthood with a milder course, depending on the genetic defect. Clinical disease results from defective renal reabsorption of sodium chloride in the thick ascending limb of the loop of Henle. Bartter Syndrome, Gitelman syndrome Gitelman syndrome Gitelman syndrome is a rare genetic autosomal recessive disorder that affects the sodium-chloride cotransporter in the distal convoluted tubule of the nephron and causes electrolyte abnormalities. The syndrome presents clinically with symptoms of hypokalemia and hypomagnesemia. Gitelman Syndrome)
• Evaluation of TBNa⁺:
  • Normal TBNa⁺ → normal blood pressure and skin turgor Skin turgor Malnutrition in children in resource-limited countries (normal physical exam)
  • Decreased TBNa⁺ → signs of volume depletion

Diagnosis

Determining the volume status Volume Status ACES and RUSH: Resuscitation Ultrasound Protocols is often challenging, and the history, physical exam, and lab results must be integrated. Outside of extremes, signs and symptoms of dehydration are subtle and unreliable and should not be used alone for detecting dehydration and volume depletion.

Laboratory evaluation

• Blood tests:
  • BUN/creatinine ratio:
    • Normal: approximately 10:1
    • Elevated ratio (> 20:1) suggests hypovolemia Hypovolemia Sepsis in Children.
    • Inaccurate if glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids or GI bleeding (unrelated causes of elevated BUN)
  • Serum Na⁺:
    • Can be high or low, depending on the tonicity Tonicity Plasma tonicity refers to the concentration of only the osmotically active solutes in blood Renal Sodium and Water Regulation of fluid lost
    • Hypovolemia Hypovolemia Sepsis in Children stimulates antidiuretic hormone Antidiuretic hormone Antidiuretic hormones released by the neurohypophysis of all vertebrates (structure varies with species) to regulate water balance and osmolarity. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a cystine. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the kidney collecting ducts to increase water reabsorption, increase blood volume and blood pressure. Hypernatremia (ADH) secretion Secretion Coagulation Studies (contributes to hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia).
  • Serum K⁺:
    • Can be high or low, but is usually low
    • Elevated: if there is decreased secretion Secretion Coagulation Studies from renal dysfunction or decreased distal Na⁺ delivery
    • Low: if K⁺ is lost in GI fluids or if there is increased secretion Secretion Coagulation Studies from high aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia state 
  • Acid–base disorders:
    • Metabolic alkalosis Alkalosis A pathological condition that removes acid or adds base to the body fluids. Respiratory Alkalosis: if hypovolemia Hypovolemia Sepsis in Children is due to diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication or upper GI losses
    • Metabolic acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis: with bicarbonate Bicarbonate Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the ph of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity. Electrolytes loss due to diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea, lactic acidosis Lactic Acidosis Oxazolidinones with shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock, or ketoacidosis Ketoacidosis A life-threatening complication of diabetes mellitus, primarily of type 1 diabetes mellitus with severe insulin deficiency and extreme hyperglycemia. It is characterized by ketosis; dehydration; and depressed consciousness leading to coma. Metabolic Acidosis with diabetic ketoacidosis Ketoacidosis A life-threatening complication of diabetes mellitus, primarily of type 1 diabetes mellitus with severe insulin deficiency and extreme hyperglycemia. It is characterized by ketosis; dehydration; and depressed consciousness leading to coma. Metabolic Acidosis ( DKA DKA Diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS) are serious, acute complications of diabetes mellitus. Diabetic ketoacidosis is characterized by hyperglycemia and ketoacidosis due to an absolute insulin deficiency. Hyperglycemic Crises)
  • Albumin Albumin Serum albumin from humans. It is an essential carrier of both endogenous substances, such as fatty acids and bilirubin, and of xenobiotics in the blood. Liver Function Tests and hematocrit Hematocrit The volume of packed red blood cells in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, anemia shows a low value; polycythemia, a high value. Neonatal Polycythemia:
    • Concentration increases with hypovolemia Hypovolemia Sepsis in Children
    • Must consider baseline values 
• Urine studies:
  • Urine sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia (UNa⁺): < 20 mEq/L suggests hypovolemia Hypovolemia Sepsis in Children
  • UNa⁺ is inaccurate with:
    • Metabolic alkalosis Alkalosis A pathological condition that removes acid or adds base to the body fluids. Respiratory Alkalosis: UNa⁺ > 20 mEq/L due to Na⁺ being paired with filtered HCO₃^–
    • Edematous states (low effective arterial blood volume Effective arterial blood volume Renal Sodium and Water Regulation): HF, cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic parenchymal necrosis and scarring (fibrosis) most commonly due to hepatitis C infection and alcoholic liver disease. Patients may present with jaundice, ascites, and hepatosplenomegaly. Cirrhosis can also cause complications such as hepatic encephalopathy, portal hypertension, portal vein thrombosis, and hepatorenal syndrome. Cirrhosis, nephrotic syndrome Nephrotic syndrome Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and peripheral edema. In contrast, the nephritic syndromes present with hematuria, variable loss of renal function, and hypertension, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephrotic Syndrome
    • AKI AKI Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury/ CKD CKD Chronic kidney disease (CKD) is kidney impairment that lasts for ≥ 3 months, implying that it is irreversible. Hypertension and diabetes are the most common causes; however, there are a multitude of other etiologies. In the early to moderate stages, CKD is usually asymptomatic and is primarily diagnosed by laboratory abnormalities. Chronic Kidney Disease (unable to conserve Na⁺)
    • Diuretic use
    • Bilateral renal artery Renal artery A branch of the abdominal aorta which supplies the kidneys, adrenal glands and ureters. Glomerular Filtration stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS)
    • Very-low-sodium diet
    • Salt-wasting nephropathy ( Bartter syndrome Bartter syndrome Bartter syndrome is a rare autosomal recessive disorder that affects the kidneys and presents either antenatally with severe or life-threatening manifestations or in childhood or adulthood with a milder course, depending on the genetic defect. Clinical disease results from defective renal reabsorption of sodium chloride in the thick ascending limb of the loop of Henle. Bartter Syndrome, Gitelman syndrome Gitelman syndrome Gitelman syndrome is a rare genetic autosomal recessive disorder that affects the sodium-chloride cotransporter in the distal convoluted tubule of the nephron and causes electrolyte abnormalities. The syndrome presents clinically with symptoms of hypokalemia and hypomagnesemia. Gitelman Syndrome)
  • Fractional excretion of Na⁺ (FENa⁺):
    • Useful only if AKI AKI Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury is also present
    • FENa⁺ < 1 suggests hypovolemia Hypovolemia Sepsis in Children
  • Urine osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation: > 450 mOsm/kg suggests hypovolemia Hypovolemia Sepsis in Children
  • Urine osmolality Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Renal Sodium and Water Regulation is inaccurate with:
    • AKI AKI Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury/ CKD CKD Chronic kidney disease (CKD) is kidney impairment that lasts for ≥ 3 months, implying that it is irreversible. Hypertension and diabetes are the most common causes; however, there are a multitude of other etiologies. In the early to moderate stages, CKD is usually asymptomatic and is primarily diagnosed by laboratory abnormalities. Chronic Kidney Disease (unable to concentrate urine)
    • Diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication
    • Diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus insipidus
  • Urine specific gravity:
    •  > 1.015 suggests hypovolemia Hypovolemia Sepsis in Children
    • Inaccurate if recent IV contrast or severe proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children

Other diagnostic tools

• If it is unclear that hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension is due to hypovolemia Hypovolemia Sepsis in Children:
  • Test volume responsiveness:
    • IV fluid test bolus 250–500 mL over 5–10 minutes
    • Passive leg Leg The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg: Anatomy raising may be used as a maneuver to assess whether a individual is fluid-responsive.
    • Volume responsiveness implies an improvement in cardiac output Cardiac output The volume of blood passing through the heart per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with stroke volume (volume per beat). Cardiac Mechanics and tissue perfusion.
  • Hemodynamic monitoring devices may be used to assist in volume management by measuring:
    • Cardiac output Cardiac output The volume of blood passing through the heart per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with stroke volume (volume per beat). Cardiac Mechanics
    • Pulse pressure variation
    • Stroke volume Stroke volume The amount of blood pumped out of the heart per beat, not to be confused with cardiac output (volume/time). It is calculated as the difference between the end-diastolic volume and the end-systolic volume. Cardiac Cycle variation
• Chest x-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests:
  • Expected to be clear of signs of pulmonary edema Pulmonary edema Pulmonary edema is a condition caused by excess fluid within the lung parenchyma and alveoli as a consequence of a disease process. Based on etiology, pulmonary edema is classified as cardiogenic or noncardiogenic. Patients may present with progressive dyspnea, orthopnea, cough, or respiratory failure. Pulmonary Edema in hypovolemia Hypovolemia Sepsis in Children
  • Inaccurate if chronic or unrelated lung disease
• Point-of-care bedside ultrasonography Bedside Ultrasonography ACES and RUSH: Resuscitation Ultrasound Protocols/ echocardiography Echocardiography Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic. Tricuspid Valve Atresia (TVA):
  • For individuals with undifferentiated hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension in the ED
  • Occasionally used for difficult-to-determine volume status Volume Status ACES and RUSH: Resuscitation Ultrasound Protocols
  • Vena cava assessment:
    • Euvolemia/ hypovolemia Hypovolemia Sepsis in Children: IVC IVC The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs. Mediastinum and Great Vessels: Anatomy diameter decreases during inspiration Inspiration Ventilation: Mechanics of Breathing.
    • Hypervolemia Hypervolemia Renal Sodium and Water Regulation: IVC IVC The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs. Mediastinum and Great Vessels: Anatomy diameter decreases less or not at all during inspiration Inspiration Ventilation: Mechanics of Breathing.
  • Elevated systolic EF EF Cardiac Cycle:
    • Hypovolemia Hypovolemia Sepsis in Children → less blood in the ventricle → higher fraction is ejected to maintain the stroke volume Stroke volume The amount of blood pumped out of the heart per beat, not to be confused with cardiac output (volume/time). It is calculated as the difference between the end-diastolic volume and the end-systolic volume. Cardiac Cycle
    • Can be inaccurate if the baseline EF EF Cardiac Cycle is unknown

Management

The primary management of hypovolemia Hypovolemia Sepsis in Children is to replace the fluids lost with similar tonicity Tonicity Plasma tonicity refers to the concentration of only the osmotically active solutes in blood Renal Sodium and Water Regulation of fluids; electrolytes Electrolytes Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions. Electrolytes must also be monitored.

Hypovolemic shock Hypovolemic Shock Types of Shock management

• Aggressive administration of isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids:
  • Usually 0.9% normal saline Normal saline A crystalloid solution that contains 9. 0g of sodium chloride per liter of water. It has a variety of uses, including: as a contact lens solution, in ophthalmic solutions and nasal lavage, in wound irrigation, and for fluid therapy. Intravenous Fluids
  • Blood transfusion if there is bleeding
• Monitor blood pressure closely:
  • Decrease IV fluid rate when blood pressure improves.
  • Consider vasopressors Vasopressors Sepsis in Children if blood pressure does not improve with large volumes of IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids.
• Address electrolytes Electrolytes Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions. Electrolytes when blood pressure improves.

Moderate-to-severe hypovolemia Hypovolemia Sepsis in Children management

• Initial rehydration Rehydration Dengue Virus:
  • Bolus of 1–2 L isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids to start (usually normal saline Normal saline A crystalloid solution that contains 9. 0g of sodium chloride per liter of water. It has a variety of uses, including: as a contact lens solution, in ophthalmic solutions and nasal lavage, in wound irrigation, and for fluid therapy. Intravenous Fluids)
  • Treat aggressively to prevent possible progression to shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock.
• Na management:
  • Normal serum Na⁺ (sNa⁺):
    • Continue isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids until signs/symptoms improve.
    • May need continuous maintenance IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids if there are ongoing losses (e.g.,  diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea) 
  • Hypernatremia Hypernatremia Hypernatremia is an elevated serum sodium concentration > 145 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled by the hypothalamus via the thirst mechanism and antidiuretic hormone (ADH) release. Hypernatremia occurs either from a lack of access to water or an excessive intake of sodium. Hypernatremia:
    • Switch to hypotonic Hypotonic Solutions that have a lesser osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid. Renal Sodium and Water Regulation fluids (0.45% NaCl or 5% dextrose Dextrose Intravenous Fluids in water) once hypovolemia Hypovolemia Sepsis in Children symptomatically improves.
    • Exception: may need to use 5% dextrose Dextrose Intravenous Fluids in water earlier if there is severe hypernatremia Hypernatremia Hypernatremia is an elevated serum sodium concentration > 145 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled by the hypothalamus via the thirst mechanism and antidiuretic hormone (ADH) release. Hypernatremia occurs either from a lack of access to water or an excessive intake of sodium. Hypernatremia
    • Monitor closely to avoid overcorrection.
  • Hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia:
    • Acutely symptomatic hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia → give 3% NaCl ( hypertonic saline Hypertonic saline Hypertonic sodium chloride solution. A solution having an osmotic pressure greater than that of physiologic salt solution (0. 9 g NaCl in 100 ml purified water). Hyponatremia) until symptoms improve
    • Moderate-to-severe hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia, but not acutely symptomatic → give isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation fluids ( normal saline Normal saline A crystalloid solution that contains 9. 0g of sodium chloride per liter of water. It has a variety of uses, including: as a contact lens solution, in ophthalmic solutions and nasal lavage, in wound irrigation, and for fluid therapy. Intravenous Fluids) at a more conservative rate than if sNa⁺ is normal
    • Mild hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia → give isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation fluids at a similar rate as with normal sNa⁺

Mild hypovolemia Hypovolemia Sepsis in Children management

• If sNa⁺ is high or low: address before replacing fluid specifically for hypovolemia Hypovolemia Sepsis in Children.
• If sNa⁺ is normal:
  • Give gentle isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids (usually normal saline Normal saline A crystalloid solution that contains 9. 0g of sodium chloride per liter of water. It has a variety of uses, including: as a contact lens solution, in ophthalmic solutions and nasal lavage, in wound irrigation, and for fluid therapy. Intravenous Fluids; less likely to need transfusion).
  • Increased oral intake of fluids alone may be sufficient if very mild.

Follow-up and monitoring

• Identify and treat other electrolyte abnormalities.
• Identify and treat underlying diseases contributing to hypovolemia Hypovolemia Sepsis in Children.
• Monitor closely to determine when IV fluid rate adjustment is needed:
  • Clinical signs:
    • Blood pressure
    • Heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology
    • Urine output
  • Labs:
    • BUN
    • Creatinine
    • BNP BNP A peptide that is secreted by the brain and the heart atria, stored mainly in cardiac ventricular myocardium. It can cause natriuresis; diuresis; vasodilation; and inhibits secretion of renin and aldosterone. It improves heart function. It contains 32 amino acids. Renal Sodium and Water Regulation
    • Lactic acid

Clinical Relevance

• Edematous states: conditions such as heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR), cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic parenchymal necrosis and scarring (fibrosis) most commonly due to hepatitis C infection and alcoholic liver disease. Patients may present with jaundice, ascites, and hepatosplenomegaly. Cirrhosis can also cause complications such as hepatic encephalopathy, portal hypertension, portal vein thrombosis, and hepatorenal syndrome. Cirrhosis, and nephrotic syndrome Nephrotic syndrome Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and peripheral edema. In contrast, the nephritic syndromes present with hematuria, variable loss of renal function, and hypertension, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephrotic Syndrome with total body fluid overload (↑ ECF) but decreased effective arterial blood volume Effective arterial blood volume Renal Sodium and Water Regulation. Still, the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy paradoxically react as if the body is volume depleted and continue to maximize the reabsorption of Na⁺ and water, leading to a vicious cycle of fluid retention. Loop diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication are required for clinical volume overload, which manifests with pitting edema Pitting edema Edema caused by excess fluid without excess colloid. Leaves “pits” due to fluid displacement when pressure is applied to the area Edema, ascites Ascites Ascites is the pathologic accumulation of fluid within the peritoneal cavity that occurs due to an osmotic and/or hydrostatic pressure imbalance secondary to portal hypertension (cirrhosis, heart failure) or non-portal hypertension (hypoalbuminemia, malignancy, infection). Ascites, and weight gain.
• Hypovolemic shock Hypovolemic Shock Types of Shock: Loss of intravascular volume is so severe that tissue perfusion is compromised. Clinical signs include low blood pressure, tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children, cool extremities, altered mental status Altered Mental Status Sepsis in Children, and decreased urine output. Lactic acidosis Lactic Acidosis Oxazolidinones can be a helpful indicator Indicator Methods for assessing flow through a system by injection of a known quantity of an indicator, such as a dye, radionuclide, or chilled liquid, into the system and monitoring its concentration over time at a specific point in the system. Body Fluid Compartments of compromised tissue perfusion. Treatment is aggressive isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation IV fluid resuscitation Resuscitation The restoration to life or consciousness of one apparently dead. . Neonatal Respiratory Distress Syndrome. If this treatment does not restore the hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension and tissue perfusion, then vasopressors Vasopressors Sepsis in Children are indicated.  
• Acute blood loss: Bleeding is an isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation loss of fluid. The decrease in hemoglobin and hematocrit Hematocrit The volume of packed red blood cells in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, anemia shows a low value; polycythemia, a high value. Neonatal Polycythemia that accompany hemorrhage is due to the kidney’s response to the hypovolemia Hypovolemia Sepsis in Children. This response is to reabsorb more water, which then dilutes the ECF and causes the concentration of hemoglobin and hematocrit Hematocrit The volume of packed red blood cells in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, anemia shows a low value; polycythemia, a high value. Neonatal Polycythemia to fall. This renal compensation Renal compensation Respiratory Alkalosis also explains the time lag from when the bleeding stops to when the hemoglobin and hematocrit Hematocrit The volume of packed red blood cells in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, anemia shows a low value; polycythemia, a high value. Neonatal Polycythemia stabilize.
• Insensible losses: small amounts of fluid normally lost throughout the day via respiration Respiration The act of breathing with the lungs, consisting of inhalation, or the taking into the lungs of the ambient air, and of exhalation, or the expelling of the modified air which contains more carbon dioxide than the air taken in. Nose Anatomy (External & Internal) and sweating. These volumes are usually very small and clinically inconsequential. However, if the individual has tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination or fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, the volume losses can become clinically significant and lead to hypovolemia Hypovolemia Sepsis in Children. Hypovolemia Hypovolemia Sepsis in Children may occur even in critically ill individuals who are intubated and mechanically ventilated. Treatment is to replace these ongoing losses with maintenance hypotonic Hypotonic Solutions that have a lesser osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid. Renal Sodium and Water Regulation IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids.
• Third spacing: fluid moving from the intravascular space into the interstitial, or “third,” space. This movement can involve large volumes of fluids in individuals with large burns Burns A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Burns or severe pancreatitis Pancreatitis Inflammation of the pancreas. Pancreatitis is classified as acute unless there are computed tomographic or endoscopic retrograde cholangiopancreatographic findings of chronic pancreatitis. The two most common forms of acute pancreatitis are alcoholic pancreatitis and gallstone pancreatitis. Acute Pancreatitis. The movement is important because this fluid does not quickly mobilize back into the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment and is essentially considered “lost.” Treatment is to aggressively replace the lost fluid volume with isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids, as third spacing can be extensive enough to cause severe hypovolemia Hypovolemia Sepsis in Children.
• Postobstructive polyuria Polyuria Urination of a large volume of urine with an increase in urinary frequency, commonly seen in diabetes. Renal Potassium Regulation: brisk diuresis that can occur after the resolution of AKI AKI Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury caused by severe urinary tract Urinary tract The urinary tract is located in the abdomen and pelvis and consists of the kidneys, ureters, urinary bladder, and urethra. The structures permit the excretion of urine from the body. Urine flows from the kidneys through the ureters to the urinary bladder and out through the urethra. Urinary Tract: Anatomy obstruction. Polyuria Polyuria Urination of a large volume of urine with an increase in urinary frequency, commonly seen in diabetes. Renal Potassium Regulation can also be caused by impaired urinary concentrating ability from acute tubular necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage (ATN) with osmotic diuresis from the high levels of solutes (e.g., Na and urea Urea A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids. Urea Cycle) that accumulate during AKI AKI Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury. Management is with hypotonic Hypotonic Solutions that have a lesser osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid. Renal Sodium and Water Regulation IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids given at half the volume of the urine output, with caution not to cause increased urine output from overaggressive hydration.
• Diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus insipidus ( DI DI Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of di: central di (CDI) and nephrogenic di (NDI). Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus): genetic or acquired condition of impaired urinary concentrating ability due to either the lack of ADH (central DI DI Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of di: central di (CDI) and nephrogenic di (NDI). Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus) or resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing to it by the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy (nephrogenic DI DI Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of di: central di (CDI) and nephrogenic di (NDI). Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus). Both conditions result in the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy being unable to concentrate urine, leading to polyuria Polyuria Urination of a large volume of urine with an increase in urinary frequency, commonly seen in diabetes. Renal Potassium Regulation and polydipsia Polydipsia Excessive thirst manifested by excessive fluid intake. It is characteristic of many diseases such as diabetes mellitus; diabetes insipidus; and nephrogenic diabetes insipidus. The condition may be psychogenic in origin. Diabetes Insipidus. Diagnosis is by measurement of ADH levels and response to the water-deprivation test. Central DI DI Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of di: central di (CDI) and nephrogenic di (NDI). Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus is treated with desmopressin Desmopressin Hemophilia; nephrogenic DI DI Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of di: central di (CDI) and nephrogenic di (NDI). Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus is treated with diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication and dietary salt restriction.