Electrolytes Flashcards
Function of fluid
- transports nutrients and waste to and from cells
- acts as solvent for electrolytes/non electrolytes
- helps maintain body temp, digestion/elimination, acid-base balance, lubrication of joints and body tissue
Composition of body fluid
Water that contains dissolved or suspended substances
- 50-60% of body wt is water
Fluid compartments
- intracellular: inside the cells
- extracellular: outside the cell
- interstitial fluid: between the cells
- intravascular fluid: plasma (part of blood)
Movement of fluid and electrolytes
- diffusion
- facilitated diffusion
- active transport
- osmosis
Osmosis
Movement of water down its concentration gradient
- from low solute env to high solute env across a semipermeable membrane
- stops when conc differences disappear or hydrostatic pressure builds and opposes further movement
Diffusion
Movement of molecules from an area of high conc to low conc
- movement stops when conc are equal
Osmotic pressure
Amount of pressure needed to prevent the movement of water across a cell membrane
Colloids
Substances that inc colloid oncotic pressure
- move fluid from interstitial compartments to plasma compartment
3 primary colloids
- albumin
- globulin
- fibrinogen
How to measure colloids
Total protein level
-not an indicator of protein nutrition
Colloid oncotic pressure dec w
Age
Overall malnutrition
- can be replaces with colloid replacements
Hydrostatic pressure
Force of fluid in compartment pushing against the cell membrane (or vessel wall)
- generated by bp
- at capillary level—> major force that pushes water out of vascular into interstitial
Oncotic pressure
Aka colloid oncotic pressure
Caused by plasma colloids in solution
- plasma has lots of colloids and the interstitial space has few so plasma proteins attract water and pull fluid from tissues into vascular space
Hydrostatic and oncotic
Hydro pushes fluid out of capillaries
Oncotic pulls fluid into capillary
Electrolyte influence
Fluid balance, acid base balance, nerve impulses, muscle contractions, heart rhythm, other cell functions
- function collaboratively so a change in one is going to influence changes in others
Electrolytes
Substances that are electrically charged when in solution
Conc of electrolytes depend on
- intake
- absorption
- distribution
- excretion
Where do we find electrolytes
Intracellular
- K, Mg, Ph
Extracellular
- Na, Cl, bicarbonate
What happens if electrolyte imbalance occurs
We replace abnormal losses with a fluid and electrolyte similar to that which was lost
Normal Na level
136-145 med/L
K levels
3.5-5.0 meq/L
Mg levels
1.7-2.2 mg/dl
Ca levels
9-11 mg/dL
Ph levels
3.2-4.3 mg/dL
Hypo/hypernatremia
-below 136 and above 145
Sodium key points
Main ECF cation which governs osmolality and influences water distribution
- sodium sucks water towards it
- activates muscle and nerve cells —> important for AP
Causes of hyponatremia
- GI loss: vomiting/etc. fistulas, NG suction
- renal losses: diuretics, adrenal insufficiency
- skin loss: burn skin, wounds
- fasting diets or polydipsia
- excess hypotonic fluid
S/s of hyponatremia
- confusion/ altered LOC
- anorexia, muscle weakness
- can lead seizure
Hyponatremia altered LOC explained
Cells in the brain swell
- more solutes in the cells than vascular space
Dilutional hyponatremia
hypervolemic: too much volume in the vascular space
- extra fluid dilutes the Na down
- increase bp, wt gain, bounding/rapid pulse, inc urine sp gravity
Depletion hyponatremia
Hypovolemic: Low Na
- hypovolemia, dec bp, tachy pulse, dry skin, wt loss, dec urine sp gravity
Treatment of hyponatremia
- slow Na replacement PO/IV
- can do normal saline
- fluid restrictions
- treating underlying problem
Why is Na replacement slow
Too much Na too fast will in Na in vascular space, so fluid moves out of cells (specifically brain) and dehydrate the cell causing the altered LOC
Causes of hypernatremia
-IV fluids, tube feeds, near drownings in salt water—> excess Na intake
- not enough water intake or too much water loss due to cog impairment, diarrhea, high fever, heatstroke
- profound dieresis
S/s of hypernatremia
- altered LOC, confusion, seizure, coma
- extreme thirst (hyperosmolaity)
- dry, sticky mucous membranes
- muscle cramps
Hypernatremia treatment
If water is lost to quickly, then add water
If na is in excess, then remove na
- gradually adjust over 48 hr period to avoid edema of cerebral cells
Potassium
Intracellular ion that helps regulate the excitability and electrical status
- helps control intracellular osmolality
- diet is main source
- kidneys main source of loss
Normal values of k
3.5-5 mEq/L
Causes of hypokalemia
Renal or GI losses like diuresis
Acid base disorders —> k leaves ECF into ICF
S/s of hypokalemia
- cardiac rhythm disturbance (heart attack)
- muscle weakness, leg cramps
- dec bowel motility, constipation, nausea, lieu’s
- potassium and ATP pump *
Hypokalemia treatment
Potassium chloride
Hyperkalemia cause
- dec potassium output (renal failure, not peeing)
- burns, crash, injuries, sepsis (K lives in cells, so when many die they release K into blood)
- drugs (K sparing, ACE, ARBS, NSAIDS)
Hyperkalemia s/s
Cardiac rhythm disturbance
- muscle weakness, cramps
- abdominal cramping
Hyperkalemia treatment
Diuretics or drugs
Magnesium
Helps stabilize cardiac muscle cells by blocking/controlling movement of K OUT of cardiac muscles
- also helps stabilize smooth muscles
Hypomagnesium causes
- diuresis
- GI or renal losses
- limited intake (fasting/starvation)
- alc abuse
- pancreatitis
- hyperglycemia
Hypomagnesium treatment
- Treat cause
- replacement oral or IV
Hypomagnesium s/s
- hyperactive reflexes
- confusion
- cramps
- tremors
- seizures
- nystagmus
Hyper magnesium cause
Increased intake accompanies with renal failure
- renal failure and OB pts
- healthy ppl pee it out
Why can OB pts get hyper magnesium
Given mg sulfate to prevent pre eclampsia, eclampsia and seizures
Hyper magnesium s/s
- lethargic
- floppiness
- muscle weakness
- dec reflexes
- flushed/warm skin
- dec pulse/BP
Hyper magnesium treatment
Stop replacement
- if chronic, then dialysis
Calcium
Hormones released from thyroid and parathyroid glands control amount of Ca absorbed/released from bone
When is majority of Ca
Bone
Ca functions
- enzyme rxns
- effects membrane potentials and nerve excitability
- helps in release of hormones, NTs, and chemical mediators
- influences cardiac contractility and automaticity
- necessary for blood clotting
Hypocalcemia cause
- unable to mobilize Ca from bone
- hypoparathyroidism
- hypomagnesium
- increase renal loss
- inc binding
- dec intake of absorption, dec vitamin D
- acute pancreatitis
- thyroid/parathyroid surgery
Hypocalcemia s/s
Increased neuromuscular excitability
- parasthesias (numbness/tingling)
- muscle cramps, bone pain, tetany, laryngeal spasms, hyperactive reflexes
- prolonged QT interval
- positive Chvostek’s and Trousseau
Chovsteks
Ipsilateral twitching of the circumoral muscles in response to gentle tapping of the facial nerve just anterior of the ear
Trousseau
Carpal spasm upon inflation of BP cuff to 20 mmHg Obote pts sbp for 3 mins
Treatment of hypocalcemia
IV: ca chloride/ca gluconate., given through central line typically
Oral: elemental Ca, Ca carbonate (tums), may also need vitamin D (active form in impaired liver and or kidney function)
Hypercalcemia causes
Hyperparathyroidism
Cancer (breast, lung, hemotological)
S/s of Hypercalcemia
Calcium acts like a sediative, fatigue, lethargic, confusion, weakness, leading to seizure/coma, kidney stones
- dec excitability
Treatment of hypercalcemia
Adequate hydration
- inc urine output
- diuretics and NaCl (na excretion accompanied w Ca)
- dialysis in renal failure
Phosphorus location
Mostly found in bone, some intracellular
- tiny amount in blood
Forms of P
Organic: intracellular
Inorganic: circulating and measured
Function of P
- role in bone formation
- essential for ATP formation and enzymes need for glucose, protein, fat metabolism
- part of RNA, DNA
- acid base buffer
- normal function of WBC and platelet
Hypophsophatemia cause
- dec absorption
- antacids OD
- severe diarrhea
- inc kidney elimination
- malnutrition (alcoholism, TPN, recovery)
Hypophosphatemia s/s
Tremor, parasthesia, confusion to coma, seizure, muscle weakness, joint stiff, hemolytic anemia, platelet dysfunction, impaired WBC
Causes of hyperphosphatemia
Kidney failure
- laxative/enemas with P
- shift form intracellular to extracellular due to trauma or heat stroke
- hypoparathyroidism
S/s hyperphosphatemia
Usually asymptomatic
- usually the symptoms of hypocalcemia: muscle spasms, parathesia, tetany
Treatment for p imbalance
Hypophosphatemia: oral or IV replacement given over a long period of time, inc risk of calcification
Hyperphosphatemia: treat cause, ca based p binders, hemodialysis
