Patho Electrolytes & Fluid

intracellular fluid

• fluid in cells

• 2/3 of body water

extracellular fluid

• interstitial

• intravascular

  • plasma/serum

transcellular fluid

• CSF

• fluid in peritoneal, pericardial, & pleural spaces

• fluid in joint spaces

body fluid transport

• helps transport gases, nutrition, and waste

• generates electrical activity

• food → energy

cell membrane

• O2 and CO2 pass directly through

• Ions need transport mechanisms (or can be exchanged if they have the same charge)

• water uses osmosis

diffusion

movement of charged or uncharged particles along a concentration gradien

osmosis

movement of water across a semipermeable membrane

primary solute in body

sodium

primary solvent in body

water

what does the distribution of fluids between ICF and ECF rely on

concentration of ECF sodium and water content

low osmolarity

• less than 275

• low amounts of solutes → dilute

elevated osmolarity

• greater than 295

• large amounts of solutes → concentrated

changes in sodium are usually present by proportionate changes in

water volume

tonicity

effective osmolarity of a solution

osmoreceptors: water & Na regulation

• sensory neurons located in/near hypothalamus

• shrink/swell based on osmolarity

• increase thirst response & increase ADH release when stimulated

baroreceptors stimulate

• sympathetic response

• ADH release

sympathetic response water & Na regulation

• dec GFR, slows Na filtration from blood

• stimulates kidneys to release renin

ADH water & Na regulation

tells kidneys to hold onto H2O at renal tubules → inc volume

heart: water & Na regulation

• ANP released in response to atrial stretch & overfilling

• BNP stimulates kidneys to rid body of Na

renin: water & Na regulation

• released from either SNS stimulation or dec in blood flow to organ occurs

• aldosterone promotes Na & H2O absorption in kidneys

isotonic fluid volume deficit

dec in ECF with equal losses of H2O & sodium

causes of isotonic fluid volume deficit

• GI = vomiting, diarrhea, NG tubes, fistulas

• urine = diuretics, hyperglycemia

• skin = sweating (fever/exercise)

• endocrine = low aldosterone → Na lost in urine

• transcellular fluid accumulation

symptoms of isotonic fluid volume deficit

• weight loss

• inc thirst

• dec urine output

• dec skin & tissue turgor

• dry mucous membranes

• sunken eyeballs

• depressed fontanels in infants

• postural hypotension

• weak, rapid pulse

• dec capillary refill

• severe - hypovolemic shock

isotonic volume overload

• isotonic expansion of ECF compartment

• inc interstitial & vascular volumes

when does isotonic volume overload occur

• Na excess with proportionate inc in H2O

• circulatory overload

causes of isotonic volume overload

• heart failure

• renal failure

• liver failure

• corticosteroid excess

symptoms of isotonic volume overload

• weight gain

• edema

• bounding pulses

• venous distension

• pulmonary edema

causes of edema

• inc capillary filtration/hydrostatic pressure

• dec capillary oncotic pressure

• inc capillary permeability

• lymph obstruction

causes of inc capillary filtration/hydrostatic pressure

• inc arterial pressure

  • dependent edema

• inc resistance to outflow - venous obstruction

  • thrombophlebitis

• capillary distension

  • inc vascular volume (CHF, kidney disease)

what does capillary hydrostatic pressure do

pushes water out of capillary into interstitial spaces

capillary distension symptoms

• edema

• excessive Na and water retention

  • dyspnea

  • crackles

  • SOB

  • non-productive cough

what causes dec capillary oncotic pressure

• inadequate production or loss of proteins (albumin)

  • liver failure, malnutrition, extensive burns

what does capillary oncotic pressure do

pulls water back into capillary

what type of edema is caused by dec capillary oncotic pressure

generalized edema

what type of edema is caused by inc capillary filtration/hydrostatic pressure

dependent edema

what happens when cap permeability is inc?

cap pores enlarge → proteins leak interstitially

what causes inc cap permeability

• allergic reactions

• inflammation

• burns

lymphedema

• edema due to impaired lymphatic flow

• honeycomb appearance

what does impaired lymph flow lead to

lymphedema

causes of lymphedema

• cancer

• lymph node removal

• trauma

• infection

edema

palpable swelling from inc interstitial fluid volume

types of peripheral edema

• pitting

• non-pitting

pitting edema

accumulation of interstitial fluid exceeding absorbing capacity of surrounding tissue

non-pitting edema

condition in which plasma proteins have accumulated in the tissue spaces & coagulated

what does non-pitting edema look like

firm & discolored

transcellular edema (third spacing)

trapping of ECF into transcellular compartments and serous cavities

types of transcellular edema

• ascites

• pleural effusuion

• pericardial effusion

what is the major cation of ECF

sodium (Na+)

what regulates sodium levels

• kidneys

• aldosterone

• natriuretic peptides

when is aldosterone secreted

• depressed Na levels

• inc K levels

• dec renal perfusion

what do natriuretic peptides do

inc Na and water excretion

sodium is necessary for which body functions

• osmotic transfer

• acid base balances

• neuromuscular and muscular excitability

• depolarization of cell membranes of excitable cells

hyponatremia

low blood sodium levels

hypotonic hyponatremia

dilution

• excessive sweating, GI losses, SIADH, HF

hypertonic hyponatremia

• sodium in the ECF becomes diluted as water moves out of body cells in response to the osmotic effects of the elevated blood glucose level.

• osmotic shift from ICF to ECF

  • hyperglycemia

hyponatremia manifestations

alters ability of cells to normally depolarize/repolarize

• muscle cramps/motor weakness

• weakness/fatigue

• headache, lethargy, confusion

• seizures

rapid correction of sodium can cause

osmotic demyelination syndrome = destruction of myelin sheath of axons passing through brain stem

hypernatriemia

high sodium blood levels

causes of hypernatriemia

• disproportionate loss of body water in relation to Na

  • through urine, GI tract, lungs

  • H20 not replaces

• Na gain

hypernatriemia manifestations

• thirst

• low urine output

• inc urine osmolarity

• weak, thready, elevated pulse

• dec BP

• dry mucus membranes, rough tongue, trouble swallowing

• irritability, restlessness, dec reflexes, headache

• seizures & coma can occur

what does K do

• maintains intracellular osmolartity

• maintains acid-base balance

• catalyst to transform CHOs into energy

• converts glucose into glycogen

• convert amino acids into proteisns

• critical in conduction of nerve impulses and muscle excitability

regulation of K

• renal

  • aldosterone (lowers levels)

  • K/H exchange mechanism

• transcellular buffer system - redistributes btwn ECF & ICF

  • removes K+ from or releases K into serum as needed

  • K temporarily shifted into RBCs, muscle, liver & bone   

what happens to the resting potential when K levels are low

it moves away from the threshold → takes a greater stimulus to reach threshold potential & open up sodium channels

hypokalemia

low K blood levels

causes of hypokalemia

• inadequate intake

  • fad diets, ED, elderly

• excessive loss

  • diuretic therapy, metabolic acidosis, excessive GI loss from vomiting/diarrhea

hypokalemia manifestations

• neuro

  • weakness

  • fatigue

  • paresthesia

• CV

  • ECG changes

  • arrythmias

  • delayed ventricular depolarization & freq of action potentials

• GI

  • nausea/vomiting

  • distension

• GU

  • polyuria

what happens to the resting potential when K levels are high

resting potientia; moves toward threshold → cells fire more easily → cannot depolarize

hyperkalemia

high K blood levels

causes of hyperkalemia

• dec renal elimination

  • CRF, ARF

  • depressed aldosterone

• movement of K from ICF to ECF

  • acidosis, tissue injury

• excessive rapid rate of administration

mild hyperkalemia symptoms

• restlessness

• intestinal cramping

• diarrhea

• ECG changes, peaked T waves

• weakness

• paresthesia

severe hyperkalemia symptoms

• muscle weakness

• loss of muscle tone

• possible paralysis

• lethal arrhythmias (vfib)

• cardiac arrest

• severe bradycardia

what hormone helps to maintain calcium concs in ECF

PTH

PTH functions

• tells kidneys to get rid of phosphorus and keep calcium

• inc renal activation of vitamin D → acts on intestines to absorb more Ca during digestion

hypoparathyroidism

deficient PTH secretion

causes of hypoparathyroidism

• congenital

• autoimmune

• surgery

• hypomagnesemia

what does hypoparathyroidism result in

• low serum ionized Ca

• low serum calcium

symptoms of hypoparathyroidism

• neuro = paresthesia, muscle spasms, tetany, hyperactive reflexes

• CV = hypotensison, HF, long QT, arrhythmias

• skeletal = fractures

hyperparathyroidism

inc PTH secretion

types of hyperparathyroidism

• primary

  • hyperplasia

  • adenoma/cancer of gland

• secondary

  • chronic renal failure

  • chronic malabsorption of Ca

hyperparathyroidism results in

• high Ca levels

• renal osteodystrophy

symptoms of hyperparathyroidism

hypocalcemia

low blood Ca levels

causes of hypocalcemia

• nutritional deficiencies

• lack of vitamin D

• renaal failure

• hypoparathyroidism

• alkalosis

hypocalcemia manifestations

• neuro = paresthesia, muscle spasms, tetany, hyperactive reflexes

• CV = hypotensison, HF, long QT, arrhythmias

• skeletal = fractures

assessment of hypocalcemia

• Chvostek – tapping facial nerve – spasm of lip, nose, face.

• Trousseau – BP cuff inflated 10mmHg above SBP for 3 minutes

  • See contraction of hand and fingers

hypercalcemia

high Ca levels

causes of hypercalcemia

• malignancy

  • cancer destroys bone → Ca released

  • tumors produce PTH

• hyperparathyroidism

• prolonged immobility

• excessive doses of vitamin D

• medications

hypercalcemia manifestations

• neuro = lethargic, behavioral changes, coma

• CV = HTN, inc contractility, arrhythmias

• GI = nausea, vomiting, constipation

• GU = high output, renal calculi

phosphorus is needed for

• bone formation

• many cellular functions (ATP, metabolism, nucleic acids, phospholipid membrane formation)

• acid-base buffer

• normal WBC & platelets

hypophosphatemia

high phosphorus levels

hypophosphatemia symptoms

• neuro, paresthesia, ataxia, confusion, stupor, coma, seiziures, tremors

• musculoskeletal = joint stiffness, bone pain, osteomalacia

• blood = hemolytic anemia, platelet dysfunction w/ bleeding, imapired WBC function

causes of hypophosphatemia

• inadequate absorption in intestines

• malnutrition (increases phosphate excretion)

• alcohol abuse

• diabetic ketoacidosis

hyperphosphatemia

high phosphorus levels

hyperphosphatemia symptoms

• neuro = paresthesia, tetany

• cv = hypotension, arrhythmias

causes of hyperphosphatemia

• kidney failure

• phabdomyolysis & massive tissue injury

hyperphosphatemia will cause

hypocalcemia

magnesium functions

• required for cellular energy metabolism

• functioning of Na/K pump

• membrane stabilization

• nerve conduction

• ion transportation (K and Ca)

• smooth muscle relaxant

hypomagnesemia symptoms

• inc neuromuscular excitability = personality changes, weakness & tremors, hyperactive reflexes, seizures

• CV = tachycardia, HTN, ventricular arrhythmias

causes of hypomagnesemia

• diarrhea

• prolonged NG suction

• malnutrition & malabsorption

• chronic alcoholism

hypermagnesemia symptoms

• neuromuscular = lethargy, hyporeflexia & weakness, confusion, coma

• CV = hypotension, arrhythmias, cardiac arrest