Fluid Imbalances Flashcards
The process by which solutes move from an area of higher concentration to one of lower concentration is called ________________________.
Diffusion
Tonicity is fluid _________________or the effect that osmotic pressure of a solution with impermeable solutes exerts on cell size because of water movement across the cell membrane.
Tension
TRUE or FALSE
The cardinal feature of metabolic acidosis is a decrease in the serum bicarbonate level.
True
TRUE or FALSE
A nurse should assess a patient with hypervolemia for indicators of hypotension, increased hematocrit and hemoglobin, and oliguria.
False
TRUE or FALSE
Body fluid is located in two fluid compartments: the intracellular space (fluid in the cells) and the extracellular space (fluid outside the cells).
True
TRUE or FALSE
Vital to the regulation of fluid and electrolyte balance, the kidneys of a well-hydrated adult excrete 1 to 2 L of urine per day.
True
The major electrolytes in the extracellular fluid are ________________ and chloride.
Sodium
________________ is the unintentional administration of a nonvesicant solution or medication into surrounding tissue.
Infiltration
________________ is the excretion of less than 400 mL or urine per day in an adult.
Oliguria
TRUE or FALSE
The nurse monitoring a patient’s potassium level knows tall, tented, “T” waves on an ECG are an indication of hypokalemia.
False
How much fluid is lost through the kidneys?
1 mL/kg/hr
What are the gerontological considerations for fluid imbalances?
- Clinical manifestations may be subtle
- Fluid deficit may cause delirium
- Level of conciousness may be affected
- Decreased cardiac reserve
- Reduced renal function
- Dehydration is common
- Blunted response to the thirst signal
- Age related thinning of the skin, loss of strength and elasticity = more fluid loss
What is intercellular fluid?
- Fluid in the cells
- Contained in skeletal muscle mass
- makes up 2/3 of bodily fluid
- 40% of typical adult body weight
What is extracellular fluid?
- Fluid in the Intravascular space (blood vessels)
- Fluid in the interstitial space (lymph)
- Transcellular fluid = cerebrospinal fluid, pericardial fluid, synovial fluid
- 20% of typical adult body weight
What is osmolality?
- Determined by the solutes in body fluid
- Normal serum = 280-295 mOsm/kg
- Normal urine = 100-1300 mOsm/kg
- Lots of solutes = high osmolality = water moves IN
- Fewer solutes = low osmolality = water moves OUT
What is osmosis?
Water moving from an area of low solute concentration to an area of high solute concentration
What determines fluid moving through capillary walls?
- Osmotic pressure = exerted by the proteins in plasma (draws water INTO the vessels)
- Hydrostatic pressure = exerted on walls of blood vessels by plasma (Pushes water and small particles OUT of the vessels)
How can you affect osmotic pressure?
Administering colloids or hypertonic solutions INCREASES osmotic pressure and draws more fluid INTO plasma from interstitial spaces
What mainly affects hydrostatic pressure?
Blood pressure
Higher blood pressure = higher hydrostatic pressure = more fluids LEAVE the vessels and enter interstitial space
Why does fluid shift into interstitial spaces in the body?
- Increase in venous pressure (pushing fluid out of vessels)
- Increase in interstitial oncotic pressure (drawing fluid into interstitial space)
- Decrease in plasma oncotic pressure
How are interstitial fluid shifts decreased?
- Reduce venous pressure = Administer colloids, mannitol, hypertonic solutions
- Increase tissue hydrostatic pressure = wear elastic stockings (TED hose)
What is first spacing?
Fluids in the normal distribution (ECF, ICF)
What is second spacing?
Abnormal accumulation of fluid in the interstitial space (edema)
What is third spacing?
Fluid is trapped where it is difficult or impossible for it to move back into cells or blood vessels
(ascites)
Explain the Hypothalmic-Pituitary regulation of water balance
- Osmoreceptors in the hypothalamus sense changes in body fluids
- In fluid deficit = stimulates thirst and triggers release of ADH
- In fluid excess = supresses release of ADH
Explain the Adrenal Cortical Regulation of Water Balance
- Hormones are released to regulate water and electrolytes
- Glucocorticoids = Cortisol = may cause Sodium and fluid retention
- Mineralcorticoids = Aldosterone = causes sodium retention (with water) and Potassium excretion
Explain the Renin-Angiotensin II Regulation of Fluid Balance
- Kidneys detect a drop in BP, loss in sodium, or low Blood Volume
- Kidneys release Renin
- Renin converts Angiotensinogen (made by liver) to Angiotensin I.
- Angiotensin I travels to lungs where enzyme ACE (Angiotensin converting enzyme) converts it to Angiotensin II
- Angiotensin II = powerful vasoconstrictor (raises BP), stimulates Aldosteronerelease (retain Na and water), stimulates ADH release (retain water), stimulates thirst signal
- Result = retained fluids, increase in BP and blood volume
Explain the Cardiac regulation of Water Balance
Natriuretic peptides antagonize the RAAS system
ANP and BNP are produced by cardiomyoctes in response to increased atrial pressure and/or high Na levels
End result = lower blood pressure and volume
Explain the gastrointestinal regulation of water balance
- Oral route accounts for most water intake
- Small amounts of water are eliminated by the GI tract in the feces
- Diarrhea and vomiting can lead to significant fluid and electrolyte loss
What is dehydration?
Loss of WATER ALONE with increased Na levels
More common in: children, elderly, confused, with overexertion
What is Fluid Volume Deficit (hypovolemia)?
- ECF fluid loss exceeds intake ratio of water
- Electrolytes lost in same proportion as they exist in normal body fluids
What is Fluid Volume Excess (hypervolemia)?
- Isotonic expansion of the ECF caused by abnormal retention of water and sodium (in the same proportions as they normally are)
What are possible causes of Fluid Volume Deficit (hypovolemia)?
- Abnormal fluid loss (vomiting, diarrhea, sweating, GI suctioning)
- Decreased Intake (nausea, lack of access to fluids)
- Third Space Fluid Shifts (due to burns or ascites, or edema)
- Diabetes insipidus
- Adrenal insufficiency
- Hemorrhage
- Trauma
What are some causes of Fluid Volume Excess (hypervolemia)?
- Heart failure
- Renal injury/failure
- Liver failure (cirrhosis)
- Excessive IV solutions and/or blood transfusions
- Excessive oral sodium intake
- Abnormal retention of fluids and sodium
- Fluid shift increasing to intravascular volume
- Pregnancy
- Medication side effects
- SIADH (Syndrome of Inappropriate Antidiuretic Hormone secretion)
What are colloids?
- Human plasma products (albumin, fresh frozen plasma, blood)
- Semisynthetics (dextran and starches, Hespan)
- Sometimes referred to as volume or plasma expanders
- Stays IN vascular space and increases osmotic pressure (Pulls fluid INTO blood vessels)
What are crystalloids?
- Solutions with small molecules which can move around easily when injected into body
- 0.9% NaCl (NS) isotonic
- Lactated Ringers (LR) isotonic
- 0.45% NaCl hypotonic
- 3% NaCl hypertonic
- 5% Dextrose in water (D5W) both hypotonic and isotonic)
What do hypotonic IV fluids do?
- ECF ➡️ ICF
- Moves water OUT of vessels and INTO cells
- 🦛 Hypo = “Hippo” = PLUMPS cells 🦛
- Contains more water than electrolytes
- Never inject pure water into a vein - will lyse RBCs
- Monitor for changes in mentation
What do isotonic IV fluids do?
Stays in the ECF
* Expands volume in ECF only
What do hypertonic IV fluids do?
- ICF ➡️ ECF
- Raises osmolality of ECF
- Pulls water out of cells and into blood vessels
- Cells shrink
- Requires frequent monitoring of: blood pressure, lung sounds, serum sodium levels
used for severe hyponatremia and cerebral edema
Clinical manifestations of FVD (hypovolemia)
- Hypotension
- Tachypnea
- Tachycardia
- lethargy, weakness
- dizziness
- seizures, coma
- increased thirst
- decreased skin turgor, cap refill, urine output
Treatment for FVD (hypovolemia)
- Correct underlying cause
- Oral route preferred
- Isotonic solutions (0.9% NS, LR)
- Blood Products
- Hypertonic Solutions (very carefully monitored)
FVD (hypovolemia)
Nursing Management
- Monitor I/O
- Daily weights
- Vital signs closely monitored
- Assess skin and tongue turgor, mucosa, urine output, mental status
- Minimize fluid loss
- Administer oral fluids
- Administer parenteral fluids
Clinical manifestations of FVE (hypervolemia)
- Hypertension
- Pulmonary edema
- crackles in lungs
- S3 heart sound
- headache
- increased urine output
- weight gain
- peripheral/sacral edema
- bounding pulse
Treatment for FVE (hypervolemia)
- Remove fluid while maintaining adequate electrolyte composition (osmolality) of ECF
- Diuretics
- Fluid restriction
- Restrict sodium intake
- Aquapheresis (ultrafiltration)
- For 24 hr fluid restriction: give ~ 70% during day hours, ~ 30% at night
Treatment for
second spacing hypervolemia
- Hypertonic fluids (mannitol, D5 1/2 NS)
- Plasma proteins (albumin) to shift water from interstitial space to vascular space; followed by diuretics
Treatment for
third spacing hypervolemia
- Thoracentesis
- Paracentesis
- Albumin
FVE (hypervolemia)
Nursing Management
- Monitor I/Os
- Daily weights
- Monitor VS
- Assess respiratory changes/lung sounds
- Assess CV status
- Monitor edema
- Monitor lab values
- Skin assessment (turgor, color, temperature)
