Fluid + Electrolyte Imbalance

What does fluid balance at the capillary level rely on?

Relies on a balance between opposing forces
- The pushing force of hydrostatic pressure
- The pulling force of oncotic pressure

At the arterial end of the capillary, which type of pressure is higher?

- Hydrostatic pressure higher than oncotic pressure in the capillary, then fluid moves and is pushed out into the interstitial space
- Interstitial hydrostatic pressure has a small negative value, and contributes slightly to the movement of fluid from the capillary to the tissue

At the venous end of the capillary, which type of pressure is higher?

Fluid moves into the interstitial space, leaves solutes (plasma proteins in particular) behind, this creates a higher capillary osmotic pressure which pulls fluid from the interstitial space back into the vessel
- Glucose and electrolytes move from vessel into interstitial space and creates interstitial colloidal osmotic pressure which pulls a small amount of fluid into the interstitial space

How is fluid normally kept in balance in the capillaries?

- Excess interstitial fluid taken up by lymphatics and returned to central circulation
- Fluid balance determined by push/pull of fluids across the semi-permeable capillary membrane
- Normal movement of fluids depends on the integrity of the capillary membrane

How does imbalance occur with increase capillary hydrostatic pressure?

- Fluid imbalances at capillary level can be due to alterations in normal fluid movement
- Increased capillary hydrostatic pressure can cause higher amounts of fluid to leave the capillary
-if hydrostatic pressure continues to be high at the venous end, net fluid movement will be out of the capillary

What might cause increased fluid pressure?

- HTN
- Increase in fluid volume (sodium/water retention)

How can hydrostatic pressure increase?

If there is a back-up of blood flow, ex. DVT might obstruct venous blood flow, resulting in higher than normal pressure at the venous end of the capillary

How does imbalance occur with decreased capillary colloidal osmotic pressure?

- Lack of sufficient oncotic pressure to pull fluid back into the intravascular space (into the capillary) at the venous end of the capillary
- Albumin \= most prevalent colloid (solid) in the plasma, therefore decreased albumin can result in decreased capillary oncotic pressure
- Ex. low albumin d/t burns, liver disease, malnutrition and excessive wound drainage

How does imbalance occur with increased interstitial colloidal osmotic pressure?

- When solutes escape from the vessel to the interstitial fluid, they will take fluid with them and hold that fluid in the interstitial space
- Capillary membrane should only allow some solutes to escape
- Capillary permeability increases in response to the chemical mediators of the inflammatory process leads to "leaky capillaries"

How is imbalance caused by increased tissue hydrostatic pressure?

- Occurs when lymphatics are obstructed and do not remove excess fluid, complicated by increased tissue oncotic pressure which pulls more fluid from the vessel
- Lymphatic obstruction can occur in liver disease due to physical obstruction from surgery
- Lymphedema also creates increased interstitial colloidal osmotic pressure

What is edema?

Increase in fluid in the interstitial space

What are some mechanisms that can cause edema?

- Increased capillary hydrostatic pressure causes fluid to move to the tissue
- Decrease in plasma proteins results in decreased capillary oncotic pressure, lack of pull means that fluid stays in the interstitial space instead of going back to the vessel
- Leaky capillaries (increased permeability) causes loss of intravascular proteins/solids into the interstitial space. Movement accompanied by fluid and solutes hold fluid in the interstitial space
- Lymphatic obstruction results in decreased absorption of interstitial fluid

What is third spacing?

Transcellular fluid accumulation, small subdivision of the extra-cellular fluid compartment. Includes body spaces (ex. joint spaces, pericardial and pleural cavities, the peritoneum and ocular fluid)

How are the signs and symptoms of edema determined?

Signs, symptoms and effects determined by location

What are some manifestations/causes of edema in the brain?

- Edema associated with infections or trauma (both initiate inflammatory response)
- Skull enclosed, little space for extra fluid
- Cerebral edema life threatening
- Signs of increased ICP: headache, altered LOC/coma, abnormal pupil size/reflex, changes in patterns of breathing, change in muscle tone, abnormal posturing

What are some manifestations/causes of edema in the airway?

- Acute, life-threatening condition
- Frequently due to inflammatory response to allergens or microorganisms
- May cause difficulty swallowing, anxiety, stridor (harsh vibrating noise when breathing), possible airway obstruction and asphyxia

What are some manifestations/causes of edema in the lungs?

- Fluid forced out of the capillaries at the level of the lungs, accumulates around the alveoli, results in decreased gas exchange and decrease in ability of the lungs to inflate
- Manifestations: dyspnea, others may vary, anxiety, restlessness, diminished breath sounds and/or crackles on auscultation

What are some manifestations/causes of edema in the abdomen?

- Ascites (fluid collected around peritoneal cavity), ex. of third spacing
- Accumulation can be due to increased intravascular hydrostatic pressure results when the portal vein is affected by liver cirrhosis or perhaps results from significant inflammatory response to something like an abdominal tumor or pancreatitis
- May see increase in abdominal girth and protruding umbilicus, abdominal discomfort and if accumulation is considerable, SOB when expansion of the diaphragm is impeded by fluid

What are some of the causes of edema in the intestines?

- May experience third space loss of fluid inside the lumen and wall of the intestine if the intestine is obstructed

What are some of the causes/manifestations of peripheral edema?

- Due to obstruction of venous blood flow, increases capillary hydrostatic pressure, or to obstruction in lymphatic drainage, peripheral edema can occur predominantly in lower extremities in ambulatory patients
- Edema can occur in the sacral area
- Referred to as "dependent edema"
- Edema related to salt retention is usually pitting edema (finger pressed into oedematous area fluid shifts when the finger is removed a pit is evident)
- Overt edema only apparent after significant amounts of fluid have collected

How do you treat edema?

What you do depends on why the edema occurred:
- Correct the problem
- Control the underlying mechanism
- Treat symptoms
- Supportive measures

Explain why edema being related to malnutrition and lack of albumin may not be solved easily by the patient consuming adequate amounts of protein

- Mechanism for edema might be lack of albumin intravascularly, but the reason for that problem is that a massive inflammatory response has created increased capillary permeability, causing protein to leak from the vessels, this would make treatment more complex
- Client may require transfusions of albumin or other colloid solutions to increase capillary oncotic pressure, but unless increased capillary permeability is resolved, albumin will continue to move to the interstitial space and take fluid with it, increasing the edema
- Problem can be further complicated by the body's fluid conserving mechanisms. Kidneys will conserve water and sodium (increasing capillary hydrostatic pressure and increasing edema)

What type of treatment is often used for patients with increased extracellular fluid volume? (ex. patients with HTN)

Diuretic therapy

What other things may be implemented in the treatment of patients with F&E imbalances?

- Tx involves implementation of supportive measures
- Ex. pregnant female with swollen ankles (d/t increased hydrostatic pressure) may be taught to keep her legs elevated whenever possible and to avoid standing for long periods of time
- Clients with peripheral edema due to heart disease may be advised to wear compression stockings to increase interstitial fluid pressure and providing some resistance to the movement of fluid from the capillary to the interstitial space

What is the major regulator of sodium and water balance?

Amount of circulating blood volume

What are osmoreceptors? Where are they located?

- Keep track of osmolality (concentration) of the blood
- Located in the hypothalamus

What is the predominant osmotically active particle in the blood?

Sodium

What are baroreceptors? Where are they located?

- Measure the stretch in the vessel walls that is produced by blood volume and blood pressure
- Located in the blood vessel walls and in the kidneys

What are some of the mechanisms of fluid balance that the body uses in response to messages from the receptors?

- Thirst
- ADH
- Sympathetic nervous system
- RAAS
- Natriuretic peptides

What is the primary regulator of water intake?

Thirst
- Normally drink without needing to be reminded by the thirst mechanism

When would the thirst mechanism be initiated?

- The body can experience unanticipated decreases in blood volume or increases in osmolality that alert the body to correct them
- Ex. eat lots of salty food - thirst mechanism prompts you to drink more
- Thirst develops with men a small change in fluid volume or osmolality

Where is ADH (vasopressin) made?

Made in the hypothalamus, stored in the posterior pituitary

When would the release of ADH be triggered? What will this release cause?

- Hypothalamus senses low blood volume/increased osmolality and it sends signals to the posterior pituitary to release ADH
- ADH acts on the kidney tubules to retain water and therefore increases blood volume and reduces serum osmolality
- Once the problem has been corrected the hypothalamus gets the messages and stops the cycle (negative feedback loop)

How does the sympathetic nervous system respond to changes in arterial blood pressure and blood volume?

- Regulates constriction or relaxation of efferent and afferent arterioles in the kidney, the amount of glomerular filtrate can be controlled. If the SNS is stimulated, afferent arterioles will constrict, limiting the amount of blood flow to the kidney and lowering the glomerular filtration pressure
- Sympathetic activity regulates the reabsorption of sodium
- SNS stimulation results in the release of renin

What does the renin-angiontensin-aldosterone system do?

- Hormonal regulator of fluid volume
- Circulating blood volume drops, less blood flow to the glomerulus so less renal perfusion pressure
- Juxtaglomerular cells in the kidney sense reduced stretch of the afferent arteriole because of the reduced blood flow
- Causes an increase in release of renin (acts as an enzyme to convert angiotensinogen to angiotensin I)
- Angiotensin I converted to angiotensin II (active angiotensin) by ACE
- Active angiotensin II acts on the kidney tubules to increase sodium reabsorption, also stimulate production fo aldosterone in the adrenals
- Aldosterone works in the distal tubule of the kidney, promotes exchange of sodium and potassium: sodium reabsorbed and potassium lost
- When sodium is reabsorbed it brings water with it, resulting in an increase in circulating blood volume

What do natriuretic peptides do?

- Provide counterbalance in the activity of baroreceptors, ADH and RAAS
- In response to increased blood volume, these cells cause the kidney to increase sodium and water excretion by:
1. Suppressing renin levels
2. Decreasing aldosterone release
3. Causing vasodilation

Why are infants at risk for fluid imbalances?

- Have higher body water percentage than adults, more than half their total body water is in the extracellular component
- Infants ingest and excrete higher amounts of water daily than adults do
- Daily fluid exchange is greater in infants because of their high metabolic rate
- Also have immature kidneys to concentrate urine efficiently
- Greater fluid loss through the skin than adults because of their proportionally greater surface area, infants and young children have immature homeostatic regulating mechanisms so they don't respond as efficiently as adults to small changes in fluid balance

Why are the elderly at risk for fluid imbalances?

- Most at risk for fluid imbalance
- Agind kidneys have a decrease in glomeruli and a decrease in GFR
- Decrease in ability to concentrate urine
- Slower to respond to sodium and water imbalances, including having decreased response to Ash and a decrease in secretion of aldosterone
- Elderly have a reduction in total body water
- Thirst sensation decreases with age, therefore fluid intake is not regulated by thirst, it can instead be associated with food intake. If they are eating poorly, its possible they're drinking poorly too

Why are the obese at risk for fluid imbalance?

- Percentage of total body water is much less than that of a lean individual
- Less body water to lose

Why are the ill at risk for fluid imbalance?

- May be due to decreased intake of fluid or may be due to increase in fluid losses through fever, vomiting or diarrhea
- Inflammatory response causes intravascular fluid loss due to increased capillary permeability
- Even if the fluid loss is not external (ex. vomiting), fluid is not where it is supposed to be and that is what results in dehydration

How does thirst, mucous membranes, turgor and tearing indicate fluid balance?

- Dry mouth could be due to fluid volume deficit or might be the result of mouth breathing
- Trick to determine is to look in areas where cheeks and gums meet, in mouth breathing these areas will remain moist, in fluid volume deficit they will be dry
- Individuals with fluid volume deficit \= skin flattens more slowly after a pinch is release
- older clients/those with recent weight loss might show signs of decreased skin elasticity
- Obese infants maintain skin turgor even when in fluid volume deficit
- Tissue turgor varies with age, nutrition status and race/complexion
- In infants, tearing is considered a reliable indicator of fluid volume, with decreased tearing in patients with fluid volume deficits

How are pulse and blood pressure a reliable indicator of fluid imbalance?

- Tachycardia usually the earliest sign of decreased vascular volume
- Alterations in pulse rate, regularity and volume are present in several types of fluid or electrolyte imbalances
- Blood pressure also provides information, in suspected fluid volume imbalances we take the blood pressure when the client is lying and standing

How is edema an indicator of excessive amounts of interstitial fluid?

- Excessive amount of interstitial fluid will not become apparent until the interstitial volume has increased by at least 2.5 L
- Need to be sure to check for edema that is generalized, localized and dependent
- Manifestations of pulmonary edema: crackles and dyspnea
- Manifestations of peritoneal third spacing: increased abdominal girth

How is weight a reliable indicator of fluid imbalance?

- Daily weighing of patients with actual/suspected fluid imbalance \= very important
- Rapid changes in weight reflect changes in body fluid volume
- Weight measurements more accurate than I&O

When should patients with fluid imbalance be weighed?

- First thing in the morning, before breakfast but after voiding
- On the same scale
- In similar clothing

What is the normal urine output of an adult?

1000-2000 mL a day, 40-80 mL an hour

Why is measuring intake and output so important?

- Important to monitor output, but also important to remember all other sources of measurable output and recall that insensible losses in some patients can be considerable
- Need to know how much fluid the patient is receiving from all sources
- Careful I&O records for patient with real or potential F/E imbalance
- Urine concentration (specific gravity) measures the ability of the kidneys to concentrate urine
- In fluid volume deficit, body conserves water so solutes are excreted in a small, concentrated urine volume
- High urine levels of unexpected solutes such as glucose or albumin will falsely elevate SG readings

What neuromuscular signs could show F&E imbalances?

Some disturbances in fluid/electrolyte balance will create central and/or peripheral effects that include anxiety, headache, changes in LOC and twitching

What are disorders of NA+ and H20 balance?

- When looking at imbalances in the body, we always talk about changes in both sodium and water
- 2 main categories: changes in which gains or losses are of both sodium and water in proportion - changes which are isotonic - and changes in which sodium or water are gained or lost so that their normal concentrations are altered
- Isotonic changes can also be divided into two categories: proportionate losses of sodium and water, and proportionate gains

Loss of sodium and water

Isotonic fluid deficit

Gain of sodium and water

Isotonic fluid excess

What are the causes of isotonic fluid volume deficit?

- Both sodium and water are lost
- Plasma electrolyte concentrations unchanged, but circulating fluid volume decreased
INADEQUATE INTAKE:
- Fluids unavailable or withheld
- Thirst mechanism is impaired
EXCESSIVE OUTPUT:
- Lost through the skin (fever, exposure to heat, d/t wounds/burns
- Lost to third spacing (peritoneum/intestine)
- Lost to the GI tract (lose up to 10 L of fluid a day this way, secreted into the GI tract, mostly reabsorbed but vomiting or diarrhea can result in both large losses and in increased secretion of fluid into the GI tract
- Lost through the kidneys (disease or drug therapy, ex. diuretics that result in impaired sodium and water reabsorption

What are the manifestations of isotonic fluid volume deficit?

- Thirst
- Decrease in body weight
- Decreased urine output, increased specific gravity, osmolality
- Sunken eyes and loss of skin turgor
- Infants: tearing
- Changes in blood pressure/changes in pulse
- Hct/BUN

How does thirst show an isotonic fluid deficit?

- Body responds to small decreases in total fluid volume by initiating the thirst response
- May occur sometimes because it is unreliable in the elderly, not easily assessed in infants

How does decrease in body weight show an isotonic fluid deficit?

- When fluid volume is lost there will be a body weight decrease
- 1 L of water \= 1 kg of body weight
- Take care when weighing the patient, fluid volume deficit does not always result in a decrease in body weight, if fluid is lost to the third space, it still contributes to body weight even though it doesn't contribute to functional fluid volume

How does decreased urine output, increased specific gravity and osmolality show an isotonic fluid deficit?

- Baroreceptors sense a decrease in vascular volume, send a message to the pituitary to initiate compensatory secretion of ADH
- ADH causes reabsorption of water and sodium which results in decreased urine output
- Output decreases, urine is more concentrated
- Specific gravity and osmolality rise

How do sunken eyes and loss of skin turgor show an isotonic fluid deficit?

- Vascular fluid volume decreases, fluid will move from the interstitial space in an attempt to improve the vascular volume
- Tissues lose fluid \= tissues lose resiliency
- Eyes can look sunken and skin turgor decreases
- Not reliable indicts of dehydration in elderly populations due to the loss of skin elasticity that occurs with aging

How is tearing an indicator of isotonic fluid deficit in infants?

Contraction of fluid volume and body's effort to conserve vascular volume can be seen in decreased tearing

How do changes in blood pressure/changes in pulse indicate an isotonic fluid deficit?

- Blood volume decreases, then blood pressure decreases
- Early signs of fluid deficit is postal hypotension - drop in blood pressure on standing
- As blood pressure drops, heart rate will increase and the pulse will become weak and thready
- In severe volume depletion, the body experiences hypovolemic shock with vascular collapse

How do changes in Hct/BUN indicate an isotonic fluid deficit?

Sodium and water are decreased, the red cells and blood urea nitrogen become more concentrated

What is the treatment for isotonic fluid volume deficit?

- Tx for hypovolemia \= very straightforward and very important
- Can cause renal damage and circulatory collapse, important to replace fluids promptly
- When IV therapy is required, isotonic losses are replaced with isotonic fluids such as normal saline or lactated ringers (sodium lactate) solution
- Replacing fluids critical, but so is treating symptoms
- Health care team must also determine underlying cause of fluid loss and take measures to correct the problem

What is an isotonic fluid volume excess?

- Both sodium and water are retained in proportion, an isotonic fluid volume excess results
- Extracellular compartments expand - vascular volume and the interstitial volume
- Type of excess unusual in healthy individuals because the body's compensatory mechanisms for dealing with excess volume are usually sufficient to restore fluid balance

What causes isotonic fluid volume excess?

INADEQUATE ELIMINATION:
- Body unable to eliminate appropriate amounts of fluid due to poor kidney function
- If the heart is unable to effectively pump, decreased blood flow to the kidneys will result in fluid retention
EXCESSIVE INTAKE:
- Increase in the amount of sodium ingested will result in water retention as well. Normally the body will eliminate excess but if the kidneys or heart are not able to do there Jos properly hypervolemia may result
- If excessive amounts of IV fluids are given or if they are given too quickly, the body may be unable to manage the increase in circulating volume

What are the manifestations of isotonic fluid excess?

WEIGHT GAIN:
- Changes in weight may indicate fluid overload
- Watch patient and monitor if they are gaining weight over a short period of time
EDEMA:
- As a result of increased hydrostatic pressure, hypervolemia results in edema
BOUNDING PULSE:
- Increase in vascular volume can be seen in distended neck veins and in a full, bounding pulse
RESPIRATORY SYMPTOMS:
- When fluid accumulates in the lungs client will show signs of respiratory distress, listen for crackles and watch for a productive cough
DECREASE IN BUN AND HEMATOCRIT:
- BUN and hematocrit levels will decrease when both are diluted in the excess fluid

What is the treatment for isotonic fluid volume excess?

STOP INCREASING THE VOLUME:
- Restrict fluid intake/restrict sodium intake
- If IV fluids are contributing to volume overload, careful attention must be paid to the solution and the rate of administration
START DECREASING THE VOLUME:
- Diuretics can be even to increase sodium (and therefore water) elimination
TREAT THE CAUSE:
- Determine the cause for the volume excess so treatment of the problem can be initiated if possible
- Ex. heart failure may be treated with digoxin which strengthens cardiac contractions and can increase kidney perfusion

What are disorders of Na+ and H20 balance?

- Hypovolemia/hypervolemia are conditions in which sodium and water are gained or lost in equal proportions
- Sodium and water can be lost or gained independently of the other, resulting in changes in sodium concentration -\> hypo/hypernatremia
- Changes produce change in the osmolality of the ECF and results in fluid shifts between the ECF and the ICF
- Loss or sodium/gain of water \= hyponatremia
- Gain of sodium or loss of water \= hypernatremia

What is hyponatremia?

- Defined as a plasma concentration of sodium less than 135 mol/L
- Hyponatremia is a deficit in sodium in relation to the amount of body water

What are some reasons that sodium concentration drops?

- Too little ECF sodium
- Too much ECF water

What are some reasons for having too little ECF sodium (in hyponatremia)?

- Not enough sodium intake
- Too much sodium loss -\> related to renal problems (normally prevented through the use of aldosterone, failure to do so may indicate renal impairment or adrenal insufficiency or might indicate loss of sodium due to diuretic use)
- Sodium lost through sweating and GI losses such as vomiting, diarrhea, or NG suction. Fluid also lost in this manner but more sodium than water is lost
- Problem compounded when the client replaces losses with water as opposed to solutions containing electrolytes

What are some reasons for having too much ECF water (in hyponatremia)?

- Osmotic pull --\> blood sodium can be diluted when too much fluid moves to or stays in the vascular space. if other osmotically active particles in the bloodstream increase intravascular osmotic pull, fluid will move into the vessel. An example of this is hyperglycaemia
- Water retention -\> when water is retained, generally the kidneys are at fault Ex. high levels of ADH result in too much water retention, this is common during the post-op period and can be made worse if the clients are given electrolyte free IV fluids such as dextrose in water (D5W)
- Sometimes the high ADH levels are through inappropriate ADH secretion -\> mixed up messages in the body
- Water retention can also be caused by some medications, including several anti-psychotic medications

What do manifestations of hyponatremia depend on?

The cause of the problem and the speed of onset

What are the manifestations of hyponatremia?

FLUID SHIFTS TO CELLS - BRAIN SWELLING:
- Decreased vascular osmotic pressure, fluid shifts from extracellular space into the cells
- When the cells in the brain swell, the client will get headaches, with further swelling there will be changes in level of consciousness and coma
- Fluid shifts into the GI tract result in diarrhea
INADEQUATE SODIUM - NEUROMUSCULAR EFFECTS:
- Sodium plays a role in transmission of impulses in nerve and muscle fibres
- Sodium levels are too low -\> client will experience muscle cramping, weakness, fatigue and tremors
LABS - DECREASED SERUM OSMOLALITY:
- Lab values show decreased osmolality and a decrease in hematocrit and BUN because of the dilution of these substances by lots of extra fluid

How should we treat hyponatremia?

Determine and treat the cause, sometimes this isn't possible. Treat the symptoms of the problem instead
- Decrease the fluid excess
- Replace some sodium
- Monitor carefully

How would you decrease fluid excess (in hyponatremia)?

- Client placed on fluid restriction
- If a medication is causing water intoxication, it should be stopped
- if the client is hypervolemic it may be necessary to limit both water intake and salt intake until the cause of the problem has been determined and treated

How would you replace sodium (in hyponatremia)?

- If hyponatremia is severe, physician may order orals or IV sodium replacements
- Treatment should be gradual in order to avoid huge shifts of fluid that would occur in response to suddenly higher sodium levels

What should we monitor in patients receiving treatment for hyponatremia?

- Monitor vitals, neurological status, intake and output and daily weight
- This will provide information about the clients fluid balance status
- Monitor lab values as well

What is hypernatremia?

- Defined as a serum sodium concentration of more than 145 mol/L
- Change in concentration of sodium in the blood
- High levels of sodium can be caused by too much sodium in the ECF or by too little water

What causes too much sodium (leading to hypernatremia)?

- Rarely caused by too much sodium intake
- Sodium creates an increase in the osmolality of the blood which stimulates thirst
- Hypernatremia shouldn't persist unless there is no access to fluid
- Rarely the administration of IV fluids or of sodium bicarbonate in specific medical treatments will result in hypernatremia

What causes too little ECF water (leading to hypernatremia)?

- More commonly caused by water loss
- Clients lose water through insensible losses through the skin or lungs when they experience fever, heat, stroke or respiratory illnesses
- Significant amount of fluid can be lost when a client has diarrhea
- Sodium is also lost in this way, but the proportion lost is much less, and this causes the patient to have hypernatremia
- Sometimes this client will lose lots of water through osmotic diuresis (at the kidney, the loss of particles into the filtrate will cause a related loss water)
- Ex. Renal loss of glucose that occurs when blood glucose levels are high

What are the manifestations of hypernatremia?

- All related to increased osmolality of the blood, but symptoms
SHRUNKEN CELLS - BRAIN CELLS, SKIN AND MUCOUS MEMBRANES:
- If the problem is an increase in sodium, fluid will shift from the intracellular compartment to the vasculature d/t osmotic pull. Results in shrunken cells
- Shrunken brain cells \= restless, confused and weak
- If imbalance is not corrected, symptoms will worsen: stupor, seizures and coma
- Remember role of sodium in transmission of nerve and muscle impulses, loos for signs of neuromuscular excitability such as twitching
- When water is lost in greater proportion than sodium, your client will also show signs of volume depletion such as dry mucous membranes and orthostatic hypotension
LAB VALUES:
- Will show an increase in sodium concentration and osmolality
THIRST

What is the treatment for hypernatremia?

- Not common that hypernatremia comes from excessive intake because our bodies crave the fluid that would dilute the sodium
- Oral rehydration solution contains glucose and electrolytes along with water and is recommended for treated dehydration
- IV solutions can also be used
- Serum osmolality has to be corrected slowly, sudden decrease in osmolality would cause fluids to shift quickly to brain cells causing cerebral edema and potentially permanent neurological injury

What is potassium responsible for in the body?

- Important in regulating membrane potentials
- Controlling excitability of nerve and muscle cells
- Contractility of muscles

How do we lose potassium in the body?

Primarily through renal excretion

What is the normal concentration of potassium in the cells?

140-150 mol/L

What is the ECF concentration of potassium?

3.5-5 mol/L

What is hypokalemia?

Decrease in plasma potassium levels below 3.5 mol/L, and can occur for many reasons

What are some of the reasons that hypokalemia can occur?

INADEQUATE INTAKE OF POTASSIUM:
- Common cause
- Adults require at least 40 mol of potassium a day to balance renal losses
- Intake of food in general is low, will also intake too little potassium, people on fad diets may not eat sufficient potassium rich foods
- Elderly at risk for inadequate potassium intake if they are not able to purchase, prepare and eat potassium rich food
- Hospitalized patients getting IV fluids might have hypokalemia if receiving fluids without potassium in them
TOO MUCH POTASSIUM OUTPUT:
- Can be lost through the kidney either when aldosterone is high, or because of diuretic use (thiazide and loop diuretics increase the loss of potassium in the urine)
- Also lost through the GI tract, losses can become excessive with vomiting, diarrhea or GI suctioning
SHIFTS BETWEEN INTRACELLULAR OR EXTRACELLULAR COMPARTMENTS:
- Movement of potassium from the extracellular space into the intracellular space will decrease potassium levels
- Insulin promotes movement of potassium in the cells as do a number of medications such as bronchodilators and decongestants

Where are the deficits of hypokalemia seen?

Deficit can affect physiological functioning in many ways, most clients won't show signs of hypokalemia until levels fall below 3.0 mol/L and signs are usually gradual in onset so detecting the problem can take some time
- Kidneys
- GI tract
- Skeletal muscles
- Cardiovascular system

How is hypokalemia seen in the kidneys?

- Kidneys try to conserve potassium, creates inability for them to concentrate urine
- Output increases and therefore the plasma osmolality increases and the client will experience thirst

How is hypokalemia seen in the GI tract?

- Potassium deficit alters peristalsis so clients may have anorexia, nausea or vomiting
- Decrease in smooth muscle activity can cause constripation or in severe cases paralytic ileum

How is hypokalemia seen in skeletal muscles?

Abnormal muscle in skeletal muscles can cause fatigue, weakness and muscle cramping

How is hypokalemia seen in the cardiovascular system?

- Shows the most serious, even life threatening effects of hypokalemia
- Too little potassium interferes with normal electrical activity and contractility, so patients may experience postural hypotension and cardiac arrhythmias

How do we treat hypokalemia?

Best treatment is prevention:
- Patients at risk (patients on potassium wasting diuretics) should be taught to ingest foods with a high potassium content
Replacement:
- Once deficit has occurred, its hard to treat with high potassium foods
- Patients are prescribed oral potassium supplements which will slowly correct the problem
- Oral supplements contraindicated when the deficit is severe, potassium may be added to an IV solution
- Nurses must be aware of precautions necessary when administering administering any potassium replacement
CORRECT SLOWLY!

What is hyperkalemia?

Defined as plasma levels of potassium in excess of 5.0 mmol/L, not a common problem but can be serious

What are the three causes of hyperkalemia?

- Too rapid administration
- Too little output
- Shifts between intracellular and extracellular compartments

How does rapid administration cause hyperkalemia?

- Difficult to treat low potassium levels with oral supplements because the kidneys will excrete any overload
- If IV potassium-containing solutions are administered too quickly (especially in clients who's kidney function is impaired) hyperkalemia can result

How does too little output cause hyperkalemia?

- Potassium containing solutions should not be started util the health care team is sure that the patient has adequate function
- Decrease in aldosterone will cause elimination of sodium with accompanying decrease in elimination of potassium

How doe shifts between intracellular and extracellular compartments cause hyperkalemia?

- Movement of potassium out of the cells and into the plasma will cause hyperkalemia
- Movement can occur in response to tissue injury
- During periods of acidosis th body tries to compensate for a high number of hydrogen ions by shifting them into cells, in exchange potassium will move out of the cells and into the plasma
- During acidosis, renal function is decreased furthering the retention of potassium

When will you see signs of hyperkalemia?

Not noticeable until plasma levels exceed 6.0 mol/L, when they do they're related to problems of neuromuscular excitability

What are the GI signs of hyperkalemia?

- Nausea and vomiting
- Cramping
- Diarrhea