Fluid and Electrolytes: Sodium
Jimmy Durbin, MSN, RN
4 things electrolytes do:
1. Promote neuromuscular irritability
2. Maintain body fluid osmolality
3. Regulate acid/base balance
4. Regulate distribution of body fluids among body fluid compartments
Nursing:
1. Assess overall fluid balance by assessing weight changes and I&O
2. Assess the neurological status (LOC)
3. Evaluate sensor and motor function or their neuromuscular irritability
4. Monitor vital signs and electrolytes
5. Look at EKG to detect changes
6. Assess nutritional status (electrolytes are obtained through food intake)
7. Evaluate the health history for medical conditions that might affect fluid and
electrolytes
8. Evaluate medication history for prescriptions or OTC drugs that can interfere with
fluid and electrolytes
Body Fluids
• Factors that influence body fluid
Age - younger people have a higher % of body fluid that older people
Gender - men have more body fluid than women
Body fat –, obese people have less fluid than those who are thing because fat
cells contain very little water.
Skeleton or bone have very low water content
Highest amt of water is found in muscle, skin, and blood
• 60% of our body is fluid (water and electrolytes.
ICF vs. ECF
• Intracellular space (fluid in the cells) and Extracellular space (fluid outside a cell)
• 2/3rds located in ICF and is usually in skeletal mass.
• 1/3rd located in ECF.
• ECF further divided
– Intravascular-contains plasma (plasma makes up about 3 of the 6L of blood in
the body – the other 3 is made up of WBCs, RBCs, and thrombocytes)
– Interstitial-fluid that surrounds the cell (11-12L – the lymphatic system)
– Transcellular (1L – CSF, Pericardia, Synovial, Interocular, Pleural, Sweat,
Digestive secretions)
• Shifting of fluid
– Normal
• Third spacing – fluid is there, but it is not in a useable form
Third Spacing
• Manifestations
– ↓Urine output (even though they’re drinking plenty of water, water shifts out of
the intravascular space and the kidneys hold on to fluid so ur not losing it)
Other s/s
– ↑Heart rate
– ↓BP, ↓CVP, edema
– ↑Body weight
• Imbalances in I/O
Cause: Ascites, burns, peritonitis, bowel obstruction, massive bleeding
Electrolytes
• Active chemicals in body fluids
– Cations (+ charge)
• Na+, K+, Ca++, Mg+, H+
– Anions (- charge)
• Cl-, HCO3, Phos.
Regulation of Fluid
• Osmosis and Osmolality – movement of water through a permeable membrane from a
solution with a lower solute concentration to an increased solute concentration
• Diffusion – Particles in a fluid move from an area of high concentration to an area of
low concentration resulting in even distribution
• Filtration – separating out the unwanted material
• Sodium-Potassium Pump – protein that transports sodium and potassium ions across
cell membranes against their concentration gradients
Routes of Gains & Losses
• Kidneys
• Skin
• Lungs – lose about 400mL of water/day just by breathing
• Gastrointestinal Tract
Sodium
• Major electrolyte in ECF – primary regulator of body fluid
• Normal: 135-145 mEq/L
• ECF levels effect ICF levels:
– ↓ serum Na+ = dilute ECF
o H2O drawn into cells
– ↑ serum Na+ = concentrated ECF
o H2O pulled out of cells
• Na+ into cell then K+ moves out of cell
Function of Sodium
• Controls H2O distribution
• Determine ECF concentration
• Determine ECF volume
• Electrochemical state for proper muscle & nerve function
Hyponatremia
• Sodium < 135 mEq/L
• Causes
– Excessive Na loss
– Excessive H2O gain in ECF (dilutes Na)
– HF
– Liver failure
– Hypotonic IV fluids
– Nephrotic syndrome
Causes of Sodium Loss
• Loss of GI fluids or secretions
• Excessive sweating
• Medications
• Addison’s Disease – caused by partial or complete failure of the adrenocortical
functions, results from an autoimmune process from infection, neoplasm, hemorrhage.
U lose Na and H2O
– ↓ adrenocorticoid & ↓ aldosterone secretion
Water Gain
• Excess IVF (hypotonic)
• SIADH (Syndrome of Inappropriate Antidiuretic Hormone) – leads to dilutional
hyponatremia due to accumulation of water
• Continuous bladder irrigation
• Fresh H2O near drowning
• Psychogenic Polydipsia – excessive water drinking
S/S Hyponatremia
• S/S depend on the cause, magnitude and speed at which the deficit occurs.
– Poor skin turgor
– Dry mucosa
– Headache
– Decreased saliva production
– Orthostatic fall in BP
– Nausea
– Abdominal cramping
• Neurological changes – the biggest concern w/ acute rapid loss of Na is neurologic
status due to cellular swelling and cerebral edema associated with the hyponatremia
– Altered mental status
– Status epilepticus
– Obtundation – deadend to pain, reduces the irritation or pain, blocks sensibility
at some level of the CNS (narcotics, tranquilizers)
The more rapid the loss, the more severe and dangerous the signs.
• Usually due to sodium loss
– Anorexia
– Muscle Cramps
– Lethargy
• Severity of the symptoms also depend on the degree and speed in which it develops.
Wont see s/x until below 120, at 115 u get signs of increased ICP they get lethargic,
confusion, have muscle twitching, weakness, seizures, maybe coma
Hyponatremia: Lab Data
• Serum Na+ < 135 mEq/L
• Serum osmolality < 280 mOsm/kg
• Urinary Na+ < 20 mEq/L
• Urine specific gravity < 1.010
Medical Treatment for Hyponatremia
• Na replacement by mouth, IV, or NGT
• Replacement depends on the rate lost
– Can use LR, NS
– When replacing Na, watch for signs of fluid overload or pulmonary edema
• Rule of thumb: serum Na must not be increased > 12 mEq/L in 24 hours.
Water gain:
• Restrict H20 safer than giving Na (800ml/24hr)
• Hypertonic solution 3%-5% NaCL
• Edema only-restrict Na
• Edema and Na- restrict both
• Loop Diuretics – takes out the water but keeps the Na
Nursing Interventions for Hyponatremia
• Identify pt. at risk
– Monitor labs, I&O, daily weight
• Review medications
• GI manifestations
• Monitor for S/S of hyponatremia
• Monitor for neurological changes
• Oral hygiene
SIADH - Syndrome of Inappropriate Anti-Diuretic Hormone
• Body secretes too much antidiuretic hormone (ADH)
• Disturbs fluid and electrolyte balance • Major cause of low sodium levels
What happens:
• ADH increases the permeability of the renal tubules
• Increased permeability of renal tubules increases water retention and extracellular fluid
volume
• Leads to:
– Reduced plasma osmolality
– Dilutional hyponatremia
– Dimished aldosterone secretion
– Elevated GFR
• Increased sodium excretion and shifting of fluids into cells
Can result from:
• Sustained secretion of ADH from Hypothalamus
• Production of ADH-like substance from a tumor
S/S of SIADH
• Same as Hyponatremia
• Fingerprinting - When the finger is pressed over a bony prominence
Lab Values of SIADH
• Low BUN and Creatinine
• Due to overhydration,
– elevated urine sodium > 20 mEq/L
– elevated urine specific gravity > 1.012
Treatment of SIADH
• Treat the underlying cause
• Replace sodium
– Hypertonic solution –cannot be used alone to tx hyponatremia caused by SIADH
because excessive sodium would be excreted rapidly in concentrated urine
– Diuretic –Lasix
• If water restriction is difficult - Use lithium or demeclocycline (antagonist to ADA)
Nursing Management of SIADH
• Monitor I/O
• Daily weight
• Monitor for Neurological symptoms
• Monitor for lithium toxicity
• Ensure adequate sodium intake
• Avoid excess water supplements
• Monitor urine specific gravity
• Monitor serum sodium
Hypernatremia
• Na+ > 145 mEq/L
• Caused by a gain of sodium and excess water or a loss of water and excess sodium. - - ↓ H2O intake
– Hypertonic tube feeding with ↓ H2O supplement(Na+gain)
– IVF with ↑ Na+
– H2O loss (GI, burns, heat)
– CAPD (Continuous Alternating Peritoneal Dialysis)
– Diabetes Insipidus
– Partial salt water drowning
S/S Hypernatremia
• Primarily neurological – most important sign will be neurologic because of the effects
fluid shifts have on brain cells
S – Skin flushed
• Moderate hypernatremia - Restlessness, weakness
• Severe hypernatremia - Disoriented, delusion, hallucinations,
A - Agitation
• Dehydration
• Thirst – strong defender of serum sodium levels in healthy people
L – Low grade fever
• Dry, swollen tongue, sticky mucous membranes
• Flushed skin
T – Thirst
• Mild increase in temperature
• Peripheral and pulmonary edema
• Postural hypotension
• Increased deep tendon reflexes and nuchal rigidity (cant flex your neck down)
Hypernatremia Lab Data
• Serum Na+ > 145 mEq/L
• Serum osmolality > 300 mOsm/L
• Urine specific gravity > 1.015
Hypernatremia Medical Treatment
• ↓ serum Na+ level gradually – if u introduce water too quickly to fix it, water will shift
into the brain cells causing cerebral edema
• ↓ approx. 0.5-1mEq/L/hr over 48 hrs
• Monitor for neuro changes & cerebral edema
• Hypotonic solution D5W or 0.45% NS
• Desmopressin (DDAVP)
Hypernatremia Nsg Interventions
• Identify pt at risk
• Monitor fluid loss / gain
• Neuro precautions and behavior changes
• Monitor labs
• Monitor oral Na intake
• Offer fluids
• Note medication with ↑ Na+ content