1 INTRODUCTION: Fluids are vital to all forms of life. The skin, the lungs, and the kidneys work together to maintain the proper balance of fluids, or homeostasis. To maintain that balance, the amount of fluid gained throughout the day must equal the amount the lost. Maintaining the equilibrium would be easy if all losses could be measured, but they can’t. In good health, a delicate balance of fluids, electrolytes, and acids and bases is maintained in the body. BODY FLUIDS COMPARTMENTS AND EXCHANGE Water is the major body component, accounting for approximately 60% of adult body weight. The body gains water primarily from eating and drinking, and a small amount is generated from metabolism. Water is lost from the body as urine faeces, sweat and insensibly from respiration and skin surface. Within the body water is in one of two compartments. Two third of the body water us within the cells (intracellular fluid), and one third of body water is out of the cells (extracellular fluid).water can freely cross the cell membrane and move from one compartment to other The extracellular fluid compartment is more complex. Most of the extracellular fluid is in the space between the cells (the interstitial fluid). Some of the fluid is the plasma of vascular space (intravascular fluid).exchange between the interstitial and vascular space is determined by the balance of proteins. The plasma is a key extracellular space because compounds and fluids entering and exiting the body must first pass through the plasma before entering the cells .the other compartments of ECF are the
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Fluids are vital to all forms of life. The skin, the lungs, and the kidneys work together to maintain the proper balance of fluids, or homeostasis. To maintain that balance, the amount of fluid gained throughout the day must equal the amount the lost. Maintaining the equilibrium would be easy if all losses could be measured, but they can’t. In good health, a delicate balance of fluids, electrolytes, and acids and bases is maintained in the body.
BODY FLUIDS COMPARTMENTS AND EXCHANGE
Water is the major body component, accounting for approximately 60% of adult body weight. The body gains water primarily from eating and drinking, and a small amount is generated from metabolism. Water is lost from the body as urine faeces, sweat and insensibly from respiration and skin surface.
Within the body water is in one of two compartments. Two third of the body water us within the cells (intracellular fluid), and one third of body water is out of the cells (extracellular fluid).water can freely cross the cell membrane and move from one compartment to other
The extracellular fluid compartment is more complex. Most of the extracellular fluid is in the space between the cells (the interstitial fluid). Some of the fluid is the plasma of vascular space (intravascular fluid).exchange between the interstitial and vascular space is determined by the balance of proteins. The plasma is a key extracellular space because compounds and fluids entering and exiting the body must first pass through the plasma before entering the cells .the other compartments of ECF are the lymph and transcellular fluid. Examples of transcellular fluid include cerebrospinal, pericardial, pancreatic, pleural, intraocular, biliary, peritoneal, and synovial fluids.
Intracellular fluid is vital to normal cell functioning. It contains solutes such as oxygen, electrolytes and glucose, and it provides a medium in which metabolic processes of the cell takes place.
COMPOSITION OF BODY FLUIDS
Extracellular and intracellular fluid contains oxygen from the lungs, dissolved nutrients from the gastrointestinal tract, excretory products of metabolism such as carbon dioxide and charged particles called ions.
MOVEMENT OF BODY FLUIDS
Fluids and electrolytes constantly shift from compartment to compartment to meet a variety of metabolic needs. The movement of fluids depends on cell membrane permeability. The methods by which electrolytes and other solutes move are osmosis, diffusion, filtration and active transport.
CELLULAR LEVEL MOVEMENTS:cell membranes are semi-permeable, meaning that they allow some solutes to pass through but not others. Solutes exist within the intracellular, interstitial, and intravascular compartments and they use three processes to move through the various compartments: diffusion, osmosis and active transport.
Diffusion is a process in which a solute in a solution moves from an area of higher concentration to an area of lower concentration, evenly distributing the solutes in the solution. The difference between two concentrations is known as a concentration gradient. Fluids and electrolytes diffuse across cell membranes. For a substance to cross the membrane, the membrane must be permeable to it. Diffusion is a form of passive transport because no extra energy input is needed to make it happen. Diffusion occurs naturally.
Osmosis is the movement of water across semi permeable membranes, from the less concentrated solution to the more concentrated solution. In other words water moves toward the higher concentration of solute in an attempt to equalize the concentrations. In this process, hypotonic and hypertonic solutions seek an isotonic balance.
When you have a more concentrated solution on one side of a selectively permeable membrane and a less concentrated solution on the other side, there is a pull called osmotic pressure that draws water where through the membranes to the more concentrated side. When the solution on both sides of the semi permeable membrane have established equilibrium, or are equal in concentration, they are isotonic. The measure of a solutions ability to create osmotic pressure and thus affect the movement of water is Osmolality
This occurs when solutes move from an area of lower concentration to higher concentration. Active transport requires extra energy input in the form of ATP (adenosine triphosphate), which is stored in cells. Some solutes such as sodium and potassium use ATP
to move in and out of the cells in form of active transport called the sodium- potassium pump. Other solutes that need active transport to cross the cell membranes include calcium ions, hydrogen ions, amino acids, and certain sugars.
MOVEMENT WITHIN THE VASCULAR SYSTEM: Movement of fluids and electrolytes through capillary wall is called capillary filtration and plays a critical role in the body’s fluid balance. Within the vascular system, only capillaries have walls thin enough to let solutes pass through.
Blood pushes against the capillary wall and produces hydrostatic (or fluid pushing) pressure, which forces fluids and solutes through the capillary wall. When the hydrostatic pressure inside a capillary is greater than the pressure in the surrounding interstitial space, fluids and solutes inside the capillary are forced into interstitial space. When the pressure inside the capillary is less than the pressure outside of it, fluids and solutes move back into capillary.
Reabsorption (or resorption) prevents too much fluid from leaving the capillaries no matter how much hydrostatic pressure exists within the capillaries. When fluid filters through a capillary, the protein albumin– a large molecule that normally can’t pass through the capillary membranes- remains behind the diminishing volume of water. As the concentration of albumin inside a capillary increases, fluids begin to move back into the capillaries through osmosis. The specific process of osmosis in the intravascular space is called the plasma colloid osmotic pressure. In the arteries, this pressure averages about 25 mm of Hg.
Maintenance of capillary blood pressure:
As long as the hydrostatic pressure, which is capillary blood pressure, exceeds plasma colloid osmotic pressure, water and solutes can leave the capillaries and enter the interstitial fluid. When capillary blood pressure falls below plasma colloid osmotic pressure, water and diffusible solutes return to the capillaries. Normally, a capillary has an arteriole end and a venule end. Capillary blood pressure is greater than plasma colloid osmotic pressure at the venule end.
Capillary filtration occurs along the first half of the vessel and Reabsorption occurs along the second half of the vessel. As long as capillary blood pressure and plasma albumin levels remain normal, the amount of water that moves into the vessel equals the amount that moves out. Occasionally, extra fluid filters out of the capillary. When that happens, the excess fluid shifts into the lymphatic vessels located just outside the capillaries and eventually returns to the heart of recirculation.
One of the kidney’s vital functions is fluid balance. Nephrons are the workhorses of the kidneys and are responsible for filtering waste products from the blood and producing urine as well as constantly working to maintain fluid balance. If the kidneys don’t work properly, the body has a difficult time controlling fluid balance.
Each nephron consists of a glomerulus and a tubule. Bowman’s capsule, a vast vascular bed, surrounds the glomerulus, which attaches to a collecting duct by way of a proximal tubule, a descending limb, the loop of Henley, an ascending limb and distal tubule.
Capillary blood pressure forces fluid through the capillary walls and into Bowman ’s capsule at the proximal end of the tubule. Along the length of the tubule, water and electrolytes are either excreted or retained depending on the body’s needs. If the body needs more fluid, for instance it retains more. If it needs less, it reabsorbs les and excretes more. Electrolytes, such as sodium and potassium, are either filtered or reabsorbed throughout the same area. The end result is filtrate, which eventually becomes urine, and flows through the tubule into the collecting ducts and empties into the bladder.
Nephrons filter about 125 ml of blood every minute, or about 180 L daily. That rate, called the glomerular filtration rate, leads to the production of 1 to 2 L of urine per day. The nephrons reabsorb the remaining 178 L (or more) of fluid. If the body loses more than 1% to 2% of its fluid, the kidneys take steps to conserve water. Perhaps the most important step involves reabsorbing more water from the filtrate, which produces more concentrated urine.
If the body has excess fluid, the kidneys respond by excreting more diluted urine, which rids the body of fluid and conserves electrolytes.
The kidneys must continue to excrete at least 20 ml of urine every hour (about 500 ml per day) to eliminate body wastes. A urine excretion rate of less than 20 ml/hr usually indicates renal diseases. The minimum urine excretion rate varies with age.
Ant diuretic hormone (ADH), also known as vasopressin, plays a major role in regulating body fluid balance. The hypothalamus produces ADH and the posterior pituitary gland stores and releases it. The body senses the Osmolality of the blood and either stimulates ADH release or inhibit the release of ADH with the goal of restoring normal Osmolality levels.
The amount of ADH released varies throughout the day, depending on the body’s needs. The body holds water when fluid levels drop and releases water when fluid levels rise. It’s a constant cycle that keeps fluid levels in balance all day long.
When blood volume is decreased (increased serum Osmolality), ADH is released, which increases the kidney’s Reabsorption of water. Less water is lost through urine, so the urine is more concentrated.
When blood volume is increased (decreased serum Osmolality), ADH secretion is inhibited, which decreases the kidney’s Reabsorption of water. More water is lost through the urine, so the urine is less concentrated.
RENIN – ANGIOTENSIN – ALDOSTERONE SYSTEM:
Each glomerulus has a special cluster of cells, called juxtaglomerular cells. When the kidneys detect hypovolemia (a decrease in circulating blood volume such as occurs during haemorrhage) and the resulting low blood pressure, the juxtaglomerular cells release rennin. The presence of rennin triggers the production of angiotensin II. Angiotensin II is a potent peripheral vasoconstrictor. Its production also stimulates the production of hormone aldosterone from the adrenal cortex. Aldosterone triggers the kidneys to reabsorb more sodium, therefore reabsorbing water. All of these processes help raise the blood pressure. When blood pressure is returned to normal, the body inhibit release of rennin.
The amount of rennin secreted depends on blood flow and the level of sodium in the blood stream. If blood flow to the kidneys diminishes, as happens in a patient who’s haemorrhaging, or if the amount of sodium reaching the glomerulus drops, the juxtaglomerular cells secrete more rennin causing vasoconstriction and a subsequent increase in blood pressure.
Conversely, if the blood flow to the kidneys increases, or if the amount of sodium reaching the glomerulus increases, juxtaglomerular cells secrete less rennin, causing a reduction in vasoconstriction and a subsequent decrease in blood pressure.
SODIUM AND WATER REGULATION:
Aldosterone also plays a role in maintaining blood pressure and fluid balance. Secreted by the adrenal cortex, aldosterone regulates the Reabsorption of sodium and water within the nephrons.
ACTIVE TRANSPORT INITIATION:
When blood volume drops, aldosterone initiates the active transport of sodium from the distal tubules and the collecting duct into the blood stream. When sodium is forced into the bloodstream, more water is reabsorbed and blood volume expands.
ATRIAL NATRIURETIC PEPTIDE:
Atrial natriuretic peptide (ANP) is a cardiac hormone that helps maintain fluid balance. ANP is stored in the cells of the atria and released when atrial pressure increases. The hormone counteracts the effects of the rennin-angiotensin-aldosterone system by reducing intravascular blood volume and decreasing blood pressure. Increased atrial pressures can be seen with heart failure, chronic renal impairment, orthostatic changes, atrial arrhythmias, and use of drugs that may cause vasoconstriction.ANP is released in relation to the amount of atrial stretching (atrial pressure) that is sensed.
ANP is a powerful hormone that:
Suppresses serum rennin levels Decreases aldosterone release from the adrenal glands Increases glomerular filtration, which increases urine excretion of sodium and water. Decreases ADH release from the posterior pituitary gland Reduces vascular resistance by causing vasodilatation.
The primary mechanism for maintaining fluid balance is thirst. Thirst occurs as a result of even small losses of fluid. Losing body fluids or eating highly salty foods leads to an increase in extracellular fluid Osmolality. This increase leads to the drying of mucous membranes in the mouth, which in turn stimulates the thirst centre in hypothalamus.
The normal response when a person is thirsty is to drink fluid. The ingested fluid is absorbed from the intestine into the blood stream, where it moves freely between fluid compartments. This movement leads to an increase in the amount of fluid in the body and a decrease in the concentration of solutes, thus balancing fluid levels throughout the body.
RECORDING FLUID BALANCE:
The nursing assessment of fluid balance should include: the patient’s history, physical examination, clinical observation and interpretation of laboratory results (Place and Field, 1997).
A detailed account of the patient’s history should be taken especially the fluid intake and output. The nurse may have to rely on relatives and carers to give this information if the patient is unable to.
A clinical assessment of the patient should be carried out including vital observations such as measuring the blood pressure, pulse, respiration and temperature. The patient’s physical appearance should be noted: attention should be paid to the skin, tongue and face. The general well being of the patient is also a good indication of fluid loss or gain.
Central venous pressure (CVP) is a measurement of pressure in the right atrium of the heart. The CVP recording is a good indication to determine the amount of fluid contained within the body.
FLUID IMBALANCE :
Sodium is the most prevalent electrolyte in the ECF. Therefore changes in the ECF volume are often associated with the alterations in sodium balance and may be described in the context of that abnormality.
When a change occurs in the sodium or water ratio, a disturbance in Osmolality results; that is the ECF become hypo osmolar or hyperosmolar. When the change in ECF volume occurs, with a proportionate change in extracellular solutes the ECF remains isotonic. Loss of fluid balance may occur as a result of fluid excess or deficit.
The fluid imbalance can be
Extracellular fluid volume deficitIntracellular fluid volume deficitExtracellular fluid volume excessIntracellular fluid volume excess; water intoxicationExtracellular fluid volume shift; third spacing
Extracellular fluid volume deficit
It is commonly called dehydration, is a decrease in intravascular and interstitial fluids. It is a common and serious fluid imbalance that results in vascular fluid volume loss. (Hypovolemia)
Losses can be mild, with a loss of 1 to 2 L of water (2% of body water); moderate, with a loss of 3 to 5 L of water (5% of body water); or severe, when 5 to 10 L of water (8% of body water)
Fluid balance is maintained in the body because the intake of fluids equals the excretion of fluids. a lack of fluid intake, excessive fluid output, or both can lead to dehydration. Conversely, excessive fluid intake and lack of fluid excretion can lead to over hydration.
Furthermore, alteration in any of the regulators of fluid balance- thirst, hormones, lymphatic system, kidneys – increases the risk for or can cause an actual fluid imbalance.
Lack of fluid intake
Cognitive and physical impairments can quickly reduce water intake.
Impaired thirst mechanism can also decrease fluid intake. The thirst mechanism usually triggered by low blood pressure or a fluid volume depletion as small as 0.5%.the sensation of a dry mouth also stimulate thirst.
Several disorders can leads to inappropriate thirst mechanism. People with excess fluid in the interstitial space but depleted fluid in the vascular space are commonly thirsty.
Any stimulant that results increased rennin- angiotensin- aldosterone response causes sodium retention that, in turn stimulates the thirst mechanism.
Osmolality also influences thirst. Hypo-Osmolality inhibits the thirst response.
Excess fluid loss. Unmonitored use of potent diuretics Severe vomiting and diarrhoea Fever, diaphoresis Hyperglycaemia Gastrointestinal suction Ileostomy Fistulae Burns Blood loss Hyperventilation Hyperthyroidism Decreased anti diuretic hormone secretion Diabetes insipidous Addison’s disease or adrenal crisis Diuretic phase of acute renal failure
PATHOPHYSIOLOGYFluids are found in three spaces: inside the cells (intracellular), around the cells (interstitial), and in the blood stream(intravascular).how the body reacts to a fluid deficit depends on whether it is due to an isotonic, hyperosmolar, or hyperosmolar imbalances.
Isotonic imbalances occur when the change in ECF volume occurs with a proportionate change in extracellular solutes. The water/sodium ratio remain unchanged .e.g.: haemorrhage
When fluid volume deficit occurs as a result of isotonic imbalance, the thirst centre is stimulated to increase water consumption, ADH secretion is increased to increase water Reabsorption from the renal tubule, and the rennin-angiotensin-aldosterone system is also stimulated to increase sodium and water reabsorption.since the imbalance is isotonic, the Osmolarity between the extracellular and intracellular components are the same, there is no water movement by osmosis between the two compartments .the cells neither swell nor shrink as a result of the isotonic fluid volume deficit.
A fluid volume deficit may also occur with sodium loss or sodium excess. When the extra cellular sodium content is low, renal absorption of water is diminished in an attempt to restore normal proportion of sodium to water in the ECF. The resulting fluid deficit occurs as a result of the hypo osmolar state. Fluid lost through vomiting, diarrhoea, and sweating have a high sodium content, which may precipitate hyponatremia. Diuretics may also contribute to sodium loss. In a hypo osmolar state, the osmolarity in the ECF compartment is lower than that in the ICF compartment. As a result water moves by osmosis from the ECF compartment to the ICF compartment resulting in cellular swelling.
Fluid deficit may occur in hypernatremia as well. For e.g.: in diabetes insipidous large amount of urine are excreted and the sodium content of the ECF becomes more concentrated.
CLINICAL MANIFESTATION: Loss of body weight: fairly rapid weight loss is a common result of fluid loss, because
water is a major portion of body weight. Changes in intake and output: intake and output measurement provides another
means of assessing fluid balance. These data provide insight into the cause of fluid imbalance.(such as decreased fluid intake or increased fluid loss. Urine output usually decreases with ECFVD because of the effects of ADH and aldosterone. Urine is usually concentrated ,with a specific gravity greater than 1.030 and urine Osmolality greater than 1000 mOsm/kg.for many years it was thought that the kidney’s had to excrete at least 30 ml of urine per hour as a mechanism for waste removal. Currently a urine output of 400 to 500 ml/day is considered as oliguria and indicates a marked compromise in kidney function.
Changes in vital signs: inadequate fluid volume also leads to
o a decrease in blood pressure,o a weak pulse, ando A decrease in CVP and pulmonary capillary wedge pressure (PCWP).o For every litre of fluid lost, the cardiac output decreases by 1L/min, the heart
rate increases 8 beats/min and the core temperature increases by 0.3oC(0.6oF) postural hypotension is a classic sign of decreased fluid volume. It is defined as a decrease in systolic blood pressure of more than 25 mm of Hg, a decrease in
diastolic pressure of more than 20 mm of Hg and a pulse increase of 30 beats/min or more when the client stands up.
Sympathetic nervous system stimulation leads to
Vasoconstriction and increases the heart rate to compensate for the altered tissue perfusion.
o Flat jugular veins in a supine position and a prolonged peripheral venous filling time of more than 5 seconds are also noted.
Manifestations of cellular dehydration:
o The mucous membranes of eyes and mouth become dry even though fluid is recruited from the interstitial spaces.
o The lips can crack, and furrows may be seen on the tongue. o Decreased skin turgor occurs because of decreased interstitial fluid.o Muscle weakness from an imbalance of sodium and potassium occurs early
and become worse as it progresseso Feces become hard and decreased in number
Cerebral signs are always considered serious because it means that ICF compartmental shifting has occurred. Early signs include apprehension, restlessness, and head ache. As the deficit progresses hallucination, maniacal behaviour, and confusion occur, followed by coma.
DIAGNOSTIC FINDINGS:In hyperosmolar fluid deficit, more solvent is lost than solutes, which creates hemoconcentration.
Plasma sodium concentration increases>145mEq/L BUN >25 mg/dl Osmolality greater than 295mOsm/kg Plasma glucose greater than 120 mg/dl Hematocrit greater than 55% Urine specific gravity greater than 1.030.
Specific gravity is a numerical value of urine concentration using solute solvent relationship. Very concentrated urine has a high specific gravity. High specific gravity reading indicates dehydration or increased ADH. Glucose, protein, and dyes falsely elevate specific gravity.
Hypernatreamia usually indicates hyperosmolality, and hyponatremia usually indicates hypo Osmolality.
MANAGEMENT:The seriousness of a client’s manifestations and the aggressiveness of treatment are related to both the amount and acuteness of the fluid loss, and the client’s state of health at the time of loss.
Goals of treatment: to restore normal fluid volume by using fluids similar in composition to those lost, to replace ongoing losses, and to correct the underlying problem.
oral reydration:if the fluid lost is mild, the thirst mechanism is intact and the client can drink fluids, replace the fluid orally. Oral glucose replacement solutions are palatable, inexpensive, and a good source of fluid, glucose, and electrolytes.
Intravenous rehydration: when the fluid loss is severe and life threatening, I.V. fluids are used for replacement. The volume of fluid is calculated on the basis of the client’s weight and other co morbidities. The type of solution used is based on the type of fluid lost from the body.
Monitor for complications of fluid restoration: a client with severe ECFVD accompanied by severe heart, pulmonary, liver, or kidney diseases cannot tolerate large volumes of fluid or sodium without the risk for development of heart failure.
Correction of the underlying problem: antiemetic and anti diarrhoeal drugs are prescribed to correct problems with nausea, vomiting and diarrhoea. Antipyretic agents are used to reduce the high temperature associated with fluid loss.
Obtain the client’s history of fluid loss. If the cause is infectious, isolation may be needed
Assess the client’s vital signs every 2-4 hours, depending on the severity of fluid loss; compare them with a baseline vital signs and report marked variations. Assess for postural blood pressure and pulse changes by taking blood pressure and pulse with the client lying down. Report a drop in standing blood pressure of 25mm of Hg or more from the supine blood pressure; report pulse increases of more than 30 beats/min.
Assess the peripheral vein filling time daily. Veins with normal fluid volume should fill in 3-5 seconds when the arm is lowered below the level of heart.
Monitor intake, output, and daily weight accurately in high risk clients. Whenever the urine output decreases to less than 0.5 ml/kg/hr for two consecutive hours, urine output should be assessed hourly.
Assess the oral cavity between the gums and cheek for dryness of the mucous membranes and the tongue for dryness and longitudinal furrows.
Check skin turgor by pinching and lifting the skin. A slower response may indicate loss of interstitial fluids. Generalised weakness may develop because of changes in sodium levels.
Monitor plasma sodium, urea/nitrogen (BUN), and glucose and Hematocrit levels to determine plasma Osmolality. Assess for confusion an early manifestation of ICF involvement.
Determine the history of chronic illnesses that may impair the ability to tolerate fluids at rapid speeds. Lung, renal, and heart diseases reduce the body’s ability to move fluids through the vascular system. Record the client’s lung sounds on admission to serve as a baseline for later comparison.
Assess the client’s weight and height; do not rely on the client’s stated weight on admission. Weigh the client daily on the same scale, at the same time on day, with the client wearing clothing of the similar weight. Analyse changes in daily weights. A loss of 2.2 pound is equivalent to 1 L of fluid. Therefore an 8 pound weight loss equals about 3.5 L of fluid, or a moderate fluid volume deficit.
Deficient fluid volume related to insufficient fluid intake, vomiting, diarrhoea, haemorrhage, or third space fluid loss such as ascitis or burns
The desired outcome is return of normal levels of body fluids. The goal statement may be that the client will have restoration of normal fluid volume, improvement in fluid volume, or no further fluid losses depending on the clinical situation. Indicators of adequate fluid volumes include the following:
Oral intake between 1500 and 2500 ml or more in 24 hours. Urine out put greater than 0.5 ml/kg/hr. Stable blood pressure and pulse in the
Impaired oral mucous membrane related to lack of oral intake or other causes
INTRA CELLULAR FLUID VOLUME DEFICIT: Dehydration can become so severe that the cells become dehydrated. This condition is relatively rare in a healthy adult, but it occurs common in older people and in those with conditions that result in acute water loss. Thirst and oliguria are the most common compensatory signs. Cellular manifestations are due to the dysfunction in the cerebral cells
and include fever and CNS changes, such as confusion, and if not corrected can lead to cerebral haemorrhage and coma.
The desired outcome is restoration of fluid volume, which is initially addressed through IV replacement. Once the client become stable, the focus of medical management is correction or control of the underlying cause. The focus of nursing management is on prevention or early detection of complication secondary to the pathology or treatment.
EXTRA CELLULAR FLUID VOLUME EXCESS: ECFVE is fluid over load or over hydration. Excess fluid can be found in the vascular system, a problem called hypervolemia, or in the interstitial space, a problem usually called ‘third spacing’. The water and sodium retained is in the same proportions as it exists in other ECF, and therefore is referred to as iso osmolar (isotonic) fluid volume excess.
Compromised regulation of fluid movement and excretion. E.g.: in case of cirrhosis of liver, decreased plasma protein, heart failure, hypothyroidism, lymphatic or venous obstruction, and renal disorders.
Excessive ingestion of fluids or food containing sodium Increased anti diuretic hormone and aldosterone
PATHOPHYSIOLOGY: When a fluid volume excess, the hydrostatic pressure of the fluid is higher than usual at the arterial end of capillary, pushing excess fluid into interstitial space. The fluid is not absorbed at the end of the capillary because the oncotic pressure is too low to pull the fluids back across the capillary membrane. Usually the residual fluids are removed by the lymphatic, but in case of oedema, the fluid volume overloads the lymph system and stays in the interstitial space, leading to peripheral oedema.
Fluid volume excess in the lungs leads to coughing, dyspnoea and crackles that can be auscultated over the involved lung area.
Pallor, cyanosis, decreased tissue perfusion, and increased CO2 blood gas abnormalities.
Decreased emptying and filling of right ventricle leads to systemic venous engorgement, including signs of jugular venous distension, peripheral vein filling time greater than 5 seconds
Bounding pulse and elevated BP Increased CVP and PCWP Oedema Signs of organ dysfunction specific to the tissues involved Rapid weight gain Cerebral dysfunction
Restriction of sodium and fluids: a mildly restricted sodium diet containing 4-5 gm of sodium, a moderately restricted diet contains 2 gm of sodium, and a severely restricted diet contain 0.5 gm of sodium
Promoting urine output: mild diuretics and digitalis promote fluid loss and improve myocardial contractility.
Monitor the client’s vital signs for a bounding pulse, elevated BP, or both every 4-8 hours.
Assess breath sounds every 4-8 hours for crackles Assess for changes in respiratory effort related to activity Palpate the sacrum for pitting oedema in the morning, and bilateral neck vein
engorgement. Assess the condition of the skin and legs Compare I&O every 4-8 hours Weigh the client daily Monitor plasma Osmolality, sodium level, Hematocrit, and urine specific gravity. Observe for changes in level of consciousness
ICFVE results from either water excess or solute deficit, primarily sodium. In water excess, the number of solutes is normal but they are diluted by excessive water.
Administration of excessive amounts of hypo osmolar IV fluids SIADH
Cellular oedema Neurological manifestations
The first priority is to reduce ICP with steroids and osmotic diuretics If SIADH is an impending risk, early administration of IV fluids containing some
sodium chloride may prevent it. Perform neurologic checks periodically Monitor weights daily
Prevention is the best intervention for water intoxication. However, if your patient develops this condition, take the following nursing actions:
Check neurologic status; watch for deterioration, especially changes in personality or LOC
Monitor vital signs and intake and output to evaluate the patient’s progress. Maintain oral and I.V fluid restrictions, as prescribed Alert the dietician and the patients’ family to the restrictions Post a sign in the patient’s room to alert staff to fluid restrictions Maintain an I.V catheter as ordered; monitor infusion of hypertonic solutions via
an infusion pump. Observe the patients response to therapy Weigh the patient daily to detect water retention Monitor laboratory test results such as serum sodium levels Provide a safe environment for the patient who has an alteration in neurologic
status and teach his family to do the same Institute seizure precautions in severe cases Document your data collection and interventions
Document: physical examination findings, laboratory values, intake and output, noting fluid restrictions, daily weight, nursing interventions and the patient’s response.
Reinforce teaching and evaluate the patient’s understanding of
The nature of the condition and its causes
The need for fluid restrictions Warning signs and symptoms and when to report them Prescribed medications The importance of being weighed regularly
EXTRA CELLULAR FLUID VOLUME SHIFT: THIRD SPACING
An extracellular fluid volume shift is basically a change in the location of ECF between the intravascular and interstitial spaces. Fluid shifts are if two types
1. Vascular: fluid shifts to interstitial spaces2. Interstitial: fluid shifts to vascular spaces
Fluid shifts to vascular spaces and remained there is referred to as third space fluid. It reflects not only pathologic conditions but also inability of the lymphatic system to compensate.
Pleural cavity Peritoneal cavity Pericardial sac
Fluids can move to interstitial spaces because of increased hydrostatic pressure, increased capillary permeability, decreased serum protein levels, obstruction of the venous portion of capillary, or non functional lymphatic drainage system.
Any pathologic process triggers the inflammatory or ischemic processes can lead to fluid shifting.
Decreased protein intake Altered lymphatic function Decreased colloidal osmotic pressure
Cold extremities Weak and rapid pulse Hypotension Oliguria Decreased level of consciousness Bounding pulse Crackles Increase in BP Engorgement of peripheral and jugular veins
Replace fluid: large volumes of isotonic IV fluids are required to replace intra vascular volume.
Stabilize other problems
Assess vital signs every hour until the blood pressure is greater than 90 mm of Hg.Monitor IV fluid replacement needsAssess for early signs of fluid overloadMonitor urine output Measure the client’s abdominal girth every 8 hourly
Assessing fluid balance:
Scales and Pilsworth (2008) identified three elements to assessing fluid balance and hydration status:
Clinical assessment; Review of fluid balance charts; Review of blood chemistry.
Patients should be asked if they are thirsty, although this is only effective for patients who are able to control their fluid intake.
Patients with impaired ability to control fluid intake include those with speech difficulties, confusion or depression (McMillen and Pitcher, 2010). Thirst perception can also be impaired in older people (Cannella et al, 2009).
Dehydration will cause the mouth and mucous membranes to become dry, and the lips to become cracked so an assessment of the mouth and oral mucosa can be useful at this stage (McMillen and Pitcher, 2010; Scales and Pilsworth, 2008).
Vital signs, such as pulse, blood pressure and respiratory rate, will change when a patient becomes dehydrated.
Dehydrated patients may become tachycardic and, when a lying and standing blood pressure is recorded, they will show a postural drop, known as postural hypotension, which often accompanies a fluid deficit (Waugh, 2007). The respiratory rate may become rapid but only if fluid loss is severe.
These observations should be measured as part of the clinical assessment (Mooney, 2007; Large, 2005).
Capillary refill time
Capillary refill time (CRT) is a good measure of the fluid present in the intravascular fluid volume (Large, 2005). It is measured by holding the patient’s hand at heart level and pressing on the pad of their middle finger for five seconds. The pressure is released and the time measured in seconds until normal colour returns. Normal filling time is usually less than two seconds (Resuscitation Council UK, 2006). It should be noted that CRT assessment can sometimes be misleading, particularly in patients with sepsis (Scales and Pilsworth, 2008).
The elasticity of skin, or turgor, is an indicator of fluid status in most patients (Scales and Pilsworth, 2008).
Assessing skin turgor is a quick and simple test performed by pinching a fold of skin. In a well-hydrated person, the skin will immediately fall back to its normal position when released. It is best practice to pinch the skin over the sternum or the inner thigh (Davies, 2010).
However, this assessment can be an unreliable indicator of dehydration in older people as skin elasticity reduces with age (Large, 2005).
A good alternative to skin turgor is tongue turgor, as this is not age-dependent. In a well-hydrated individual, the tongue has one longitudinal furrow, but a person with depleted fluids will have additional furrows (Metheny, 2000)
Acute changes in body weight, after imposed fluid restrictions or exercise, is a good indicator of hydration status. However, this can be affected by bowel movements, as well as food and fluid, and would be difficult and unethical to measure in sick, immobile stroke
patients (Vivanti et al, 2010). McMillen and Pitcher (2010) argued that to maximise the accuracy of weight assessment in fluid balance, the measurement should be performed at the same time of day using the same scales, which should be calibrated regularly.
In healthy people, urine should be a pale straw colour. It should be clear, with no debris or odour (Smith and Roberts, 2011).
In dehydrated patients the kidneys conserve water, producing urine that is dark, concentrated and reduced in volume (Scales and Pilsworth, 2008). Normal urine output is around 1ml/kg of body weight per hour, in a range of 0.5-2ml/kg per hour. The minimum acceptable urine output for a patient with normal renal function is 0.5ml/kg per hour. Anything less should be reported (McMillen and Pitcher, 2010; Scales and Pilsworth, 2008).
When recording urine output on a fluid balance chart, it is not acceptable practice to record it as “passed urine +++” or “up to the toilet”. Notes such as these are uninformative and do not give a clear indication of the amount of urine passed (Mooney, 2007).
The colour of the urine should not be relied on as a marker of fluid balance as some drugs, such as tuberculosis medication, can alter urine colour and give a false indication of urine concentration (Scales and Pilsworth, 2008).
If a patient has a urinary catheter and the output is low, it is sensible to check whether the catheter or tubing is blocked or occluded in any way (McMillen and Pitcher, 2010).
Fluid balance chart
Monitoring a patient’s fluid balance to prevent dehydration or over hydration is a relatively simple task, but fluid balance recording is notorious for being inadequately or inaccurately completed (Bennett, 2010).
A study by Reid (2004), which audited the completion of fluid balance charts on different wards, found the major reasons fluid balance charts were not completed appropriately were staff shortages, lack of training, and lack of time.
According to the Nursing and Midwifery Council (2007), record keeping is an integral part of nursing care, not something to be “fitted in” where circumstances allow. It is the responsibility of the nurse caring for a patient to ensure observations and fluid balance are recorded in a timely manner, with any abnormal findings documented and reported to the nurse in charge (Scales and Pilsworth, 2008).
Smith and Roberts (2011) said that all fluid intake and output, whatever the source, must be documented using quantifiable amounts. This means it is important to know how many millilitres of fluid are in an intravenous medication, a glass of water or a cup of tea. How frequently the fluid balance chart data should be recorded – such as hourly or two hourly – should be clearly documented. It is not acceptable practice to use shorthand.
Fig 3 shows best practice when completing a fluid balance chart and Fig 4 shows an example of unacceptable practice (Smith and Roberts, 2011).
The use of fluid balance charts that show cumulative input and output is now being debated in the literature (Bennett, 2010). A recent study by Perren et al (2011) suggested that for a large proportion of patients, especially those in critical care, cumulative fluid balance charts are not accurate and their use should be questioned.
Blood chemistry and hydration status
While Scales and Pilsworth (2008) suggest that the analysis of blood chemistry may be useful in the assessment of hydration status, the evidence surrounding this is equivocal. According to Wolfson (2009) sodium, potassium, chloride, bicarbonate, blood urea nitrogen (BUN) are helpful blood electrolytes to measure when determining hydration status. Wolfson proposes that if any of these electrolytes are found to be outside normal parameters, their levels should be used to guide the prescription of intravenous fluids required to restore homeostatic fluid balance.
In contrast, Vivanti et al (2008) argue that there is limited value in the analysis of biochemical indicators such as these for less severe dehydration, particularly in older people, and suggest that physical signs may be more promising indicators
Fluid imbalances are common problem, especially in high risk patients. Many health care disciplines work collaboratively toward maintaining or restoring fluid volume. The role of nursing in this collaborative effort is focused on health promotion activities including teaching positive health behaviour, health maintenance activities and prevention and early detection of complication from the underlying diseases.