n325 fluids

intracellular fluid

• fluid inside the cells

• 2/3 of body fluid

• primarily in skeletal muscle

• transports nutrients, electrolytes, and waste

• assists with cell metabolism

extracellular fluid

• fluid outside cells

• intravascular, interstitial, transcellular

extracellular fluid - intravascular

• in the vascular space (bloodstream)

extracellular fluid - interstitial

• fluid in spaces between the cells, fluid reservoir

• not in cells, not in bloodstream..

• in the space between cells

extracellular fluid - transcellular

• cerebral spinal fluid, pericardial fluid, synovial joints, intraocular space fluids

hydrostatic pressure

• force within a fluid compartment that pushes fluid to follow diffusio/osmotic gradients

• force that pushes into the capillaries

• pulling force from capillary to tissue

oncotic pressure

• force exerted by plasma proteins to keep fluid in the vasculature

• holds fluids together in the vessels

• pulling force from tissue to capillary

osmolality

• measure of fluid concentration

• reflects hydration status

• normal serum value = 280-295 mOsm/kg

• <240 or >320 mOsm/kg is critically abnormal

ways that fluid balance is regulated

• renal

• endocrine

• cardiac

• GI

renal regulation

• ANG II is a potent vasoconstrictor

  • vasoconstriction

  • thirst

  • ADH release

  • aldosterone release

• baroreceptors in the kidneys detect fluid volume imbalances

  • drop in BP → release ANG I → end result is ANG II to vasoconstrict and get more blood

endocrine regulation of H2O: ADH

• the pituitary gland regulates fluid volume by controlling the release of ADH

• increases reabsorption of H2O by real tubules

• ADH is released when:

  • decr blood volume

  • incr plasma osmolality

  • incr serum Na+

  • pain/stress

  • incr catecholamines

cardiac regulation of H2O - ANP

• released by the heart cells when atrial walls stretch

cardiac regulation of H2O - BNP

• released by heart cells when ventricle walls stretch

• use as a measure when there is too much volume in the heart

• high BNP = too much volume in the blood stream

• cause increased Na+ excretion to cause waterloss

GI regulation of H2O

• involved in losses of fluids related to vomiting, diarrhea

• can act to reabsorb normally secreted fluids and electrolytes when the patient is depleted

third spacing

• fluid where it is not supposed to be and cannot be easily exchanged

• 1st spacing = intravascular

• 2nd spacing = interstitial and intracellular

third spacing assessment

• fluid may be deep inside body structures

• caused by cardiac, renal, liver damage, pancreatitis, decreased plasma proteins, increased capillary permeability

• S/S:

  • renal: decreased urine output with adequate intake

  • cardiac: increased HR, decreased BP, decreased CVP

  • weight gain

  • pitting edema

  • ascites

third spacing - interventions/evaluations

• interventions:

  • monitor edema

  • daily weights

  • intake and outputs

  • monitor VS

  • HOB > 30 degrees

  • monitor underlying cause

• evaluations:

  • stabilized I&O

  • stabilized weight

  • VS normal

  • resolution of third-spacing/underlying cause

hypovolemia

• not enough fluid in the vasculature

• causes:

  • fluid loss:

    • increase insensible water loss (high fever, heatstroke, perspiration)

    • diabetes insipidus

    • diabetic ketoacidosis

    • osmotic diuresis (increased urination due to excess solutes in the kidney’s filtered fluids)

    • overuse of diuretics

    • third-space fluid shifts: burn, pancreatitis

  • inadequate fluid intake:

    • altered mental status

    • difficulty swallowing

    • decreased thirst (elderly)

    • inadequate access

hypovolemia assessment

• thirst

• acute weight loss

• decreased skin turgor

• oliguira/concentrated urine

• weak, rapid pulse

• longer capillary refill

• decreased blood pressure (BP)

• increased respiratory rate

• increased HGB, HCT, osmolality

• urine S.G. > 1.030

• dry mouth, mucous membranes

• weakness, dizziness, muscle cramps

• confusion, restlessness, lethargy

older adults assessment

• may be related to medications, so check med list

• may be result of additional health problems

• elderly have blunted thirst

• vein filling better indicator than skin turgor → check cap refill..

• if checking skin turgor, check on sternum instead of hand

normal HCT (hematocrit) range

• 41-50%

• high HCT = fluid loss = more concentrated

• low HCT = fluid gain = more dilute

normal BUN levels

• 8-24 mg/dL

• kidney function

• should be in proportion to Cr

  • 10:1 - 20:1

  • >20:1 is bad

normal creatinine levels

• 0.3 - 1.2 mg/dL

serum osmolality normal levels

• 280-295 mOsm/kg

• <240 or >320 is critically abnormal

urine osmolality normal levels

• 50-1400 mOsm/kG

urine specific gravity normal levels

• 1.005 - 1.030

urine volume normal levels

• at least 0.5 ml/kg/hr

• ~ 30 mLs/hr

lab trends of hypovolemia

• increased HCT

• increased BUN

• BUN out of proportion to Cr

• increased creatinine

• high serum osmolality

• high urine osmolaltiy

• increased urine specific gravity

• decreased urine volume

hypovolemia interventions

• goal: prevent/correct abnormal fluid volume status before acute renal failure (ARF occurs)

• assess/monitor: daily weights, VS, mental status, skin turgor, I&O

• interventions: encourage PO fluids, IV fluid replacement, monitor for fluid overload, fall precautions, oral care, moisturize skin

• evaluation: normal skin turgor, increased urine output, normal SG, normal labs

isotonic fluid

• keeps osmolality the same while increasing overall volume in the vasculature

• we’re just adding volume.. no shifting of solutes

• 0.9% NS

• lactated ringers

• indications:

  • mild hyponatremia

  • maintenance fluid replacement

  • rehydration/resuscitation

• caution:

  • can cause fluid volume overload in individuals with cardiac, renal, and even liver problems

hypertonic fluid

• more concentrated than isotonic

• fluid will shift out of cells → into the bloodstream to dilute → cells will shrink

• 3% or 5% saline

• indications:

  • cerebral edema

  • hyponatremia (sometimes)

• cautions:

  • fluid overload in the vasculature

  • pulmonary edema

hypotonic fluid

• less concentrated than isotonic

• fluid will shift into cells from the vasculature to dilute the cells → cells will swell

• 0.45% of 0.33% saline

• DO NOT USE FOR PTS WITH BRAIN SWELLING/PEDIATRICS

• indications:

  • dehydration from gastric losses

  • conditions in which cells are dehydrated

• cautions:

  • can cause cell lysis

  • can worsen edema

  • may cause hyponatremia

  • depletes intravascular volume (can cause hypovolemia)

D5W

• 5% dextrose in water

• isotonic in the bag, hypotonic in the body

• dextrose gets metabolized in the body → left with just hypotonic water

• hypotonic effects → NEVER USE IN BRAIN AND PEDIATRIC PATIENTS

• bonus if use in hypoglycemic pt so they get some dextrose

D5NS

• 5% dextrose in 0.9% saline

• hypertonic in the bag, isotonic in the body

• dextrose is metabolized in the body, you’re left with NS..

• bonus if use in hypoglycemic pt so they get some dextrose

plasma volume expanders (PVEs)

• stay in the vascular space

• “volume expander”

• helps to increase volume in the bloodstream → provides oncotic pressure

• go to for hemorrhage… we prefer blood products compared to IV bc IV fluids will just wash away clotting factors

• 3 types:

  • crystalloids: has glucose/electrolytes

  • colloids: has proteins/starches that exert oncotic pressure

  • whole blood/packed RBCs

patients at risk for fluid volume deficit

• hemorrhage

• vomiting

• diarrhea

• burns

• diuretic therapy

• fever

• impaired thirst

causes of hypervolemia

• cardiovascular: heart failure

• renal: kidney failure

• SIADH - too much ADH → too much retention of water

• liver failure

• excess IV fluids

• high sodium intake

• excess water ingestion

• cancer, thrombus, drug therapy, hypertonic fluid infusion, too much aldosterone

assessment of hypervolemia

• third spacing

• pulmonary congestion

  • SOB, decreased O2 sat, increased HR, crackles in the lungs

• peripheral edema

  • +3 or +4 pitting edema.. bounding bouncy sounding pulse

• brisk cap refll

• increased CVP

• increased BP

• JVD

• confusion, altered mental status

peripheral vs pulmonary edema

• peripheral edema = usually right sided HF

• pulmonary edema = usually left sided HF → back into the lungs

pitting vs non-pitting edema

• non-pitting: usually r/t thyroid or lymphatics

• pitting: when someone has too much fluid

bilateral vs unilateral edema

• bilateral: fluid everywhere.. fluid volume overload

• unilateral: indicates a likely vessel blockage (DVT) instead of FVE