Chapter 8: fluid, electrolytes, and acid base balance Flashcards
What ratio of the body’s fluid is ICF (intracellular fluid)
2/3 of the body’s water
What ratio of the body’s fluid is ECF (extracellular fluid)
1/3 of the body’s measure
What are the two sub categories of extracellular
fluid?
plasma
interstitial fluids
What is ICF abundant in?
K+
phosphate
some Mg2+
What is the ECF abundant in?
Na+, Cl-, Ca2+ and some bicarbonate
What type of body fluid do lab tests evaluate?
ECF
What happens when a cell is in a hypertonic solution?
The cell becomes crenated:
water leaves the cell and follows to the solutes in the solution
What happens when a cell is placed into a hypotonic solution?
It swells: water moves from solution into the cell towards the solutes
What is edema?
increased interstitial fluid volume
What are the four general causes of edema?
1) Increased capillary pressure
2) decreased capillary colloidal osmotic pressure
3) Increased capillary permeability
4) Obstruction to lymph flow
List 3 ways the capillary pressure could increase to cause edema.
1) inc vascular volume
2) venous obstruction
3) decreased arterial resistance (meds)
List 2 ways the capillary colloidal osmatic pressure could decrease to cause edema
1) loss of plasma proteins
ex burns, renal disease
2) decreased production of plasma proteins
ex. malnutrition, liver disease
What are some things that could cause increased capillary permeability?
inflammation, allergic reaction, and burnsf
What are some things that could cause an obstruction to lymph flow?
malignancy
lymph node removal
Give an example of something that can cause localized edema
histamine release causing hives and dilation
What is an example of something that can cause generalized edema?
CHF
Renal failure
What is another name for generalized edema?
Anasarca
What are the six areas of the body that can be life threatening if edema forms there?
Brain Larynx Lungs Pericardial sac Pleural cavity
List 4 consequences of edema.
1) increased distances for diffusion of oxygen, nutrients and waste. Therefore, dec efficiency.
2) tissues more susceptible to injury (pressure ulcers)
3) compresses blood vessels and nerves (like a tourniquet)
4) disfigurement
Describe how to determine if edema is pitting or non pitting. What is a pitting +5 edema
push on the area with your finger for 15-30 s and remove
+5 if it remains indented 20-30 seconds
Describe the 3 types of spacing of edema
1ST SPACE: intravascular (in vessels)
2ND SPACE: extravascular (interstitial and extracellular)
3RD SPACE: areas where fluid doesn’t normally collect in large amounts. (causes them to be physiologically non-functional)
Give some examples of areas that would be considered 3rd spacing edema.
Peritoneal cavity
Pleural cavity
Pericardial sac
What is edema in the peritoneal cavity called?
ascites
What is edema in the pleural cavity called?
hydrothorax or pleural effusion
What is edema in the pericardial sac called?
pericardial effusion
List six treatments of edema
1) elevation
2) diuretics
3) albumin
4) massage
5) elastic support stockings
6) ROM exercises
Define Hypodipsia and list some things that can cause it.
Decrease in ability to sense thirst
Causes:
Age
hypothalamus dmg/lesion
Define polydipsia and give some things that can cause it
Excessive thirst
Causes:
diabetes mellitus and insipidus
polyuria
What is psychogenic polydipsia
it is a psychologic cause of extreme thirst with no pathological reason.
Describe what diabetes incipidus is.
It is an ADH disorder where their is a deficiency in ADH or response to it
1) NEUROLOGIC/CENTRAL DI:
defect in synthesis/release of ADH
2) NEPHROGENIC DI: kidneys unable to respond
result in inability to concentrate urine; 3-20 L/day output.
list 5 symptoms of diabetes insipidus
1) polyuria
2) dec fluid volume in the body
3) intense polydipsia
4) hypernatremia
5) dehydration
Describe treatment for diabetes insipidus
ADH therapy
DIURETICS (b/c it pulls sodium and then the body tries to retain it and fluid) WTF…. check this
Describe what Syndrome of Inappropriate ADH is. (SIADH)
It is the failure of the negative feedback system regulating ADH
results in water retention and dilutional hyponatremia
What are some causes or triggers of SIADH?
stress, temp changes, surgery, lung tumors
Describe the bodies response to high osmolality in the blood (high protein and low water content). What about when the blood has low osmolality?
THIRST: to inc water intake
ADH release: inc water reabsorption from urin
opposite effect for low
What is the normal level for sodium?
135 to 145 mEq/L
What are the two types of hyponatremia?
HYPERTONIC hyponatremia
HYPOTONIC hyponatremia
Describe hypertonic hyponatremia and list some causes
Water shifts from ICF to ECF
Some causes:
elevated blood glucose
decreased renal function
diuretics
Describe hypotonic hyponatremia and list some causes.
It is dilutional, resulting in cellular edema.
Some causes:
Heart failure/water retention, excessive intake of water
What is more common, hypertonic or hypotonic hyponatremia?
Hypotonic hyponatremia is more common
Describe the 7 manifestations of hyponatremia
1) fingerprint edema
2) cramps
3) weakness
4) fatigue
5) disorientation
6) seizures
7) coma
List three causes of hypernatremia
1) water loss
2) sodium gain
3) not replacing water
Describe the manifestations for hypernatremia.
ECF Fluid Loss: thirst, fever, tachycardia
Cellular Dehydration: dry skin and mucous membranes, decrease salivation/lacrimation
CNS: dec reflexes, agitation, headache, seizures, coma
What are the normal levels for potassium?
3.5 - 5.0
List 3 things that potassium is necessary for.
1) maintaining intracellular osmolality
2) needed for Na/K pump
3) exchanged for H+ to buffer changes in pH
List 3 general causes of hypokalemia.
1) inadequate intake
2) excessive loss (diuretics)
3) movement of K from bloodstream (alkalosis, insulin elevation)
What is one type of medication that can cause excessive loss of potassium resulting in hypokalemia.
Diuretics
Describe how insulin can cause hypokalemia.
Insulin pushes K into cells resulting in hypokalemia
Describe the manifestations of hypokalemia
usually gradual
GI: anorexia, nausea, vomiting, constipation
CNS: muscle weakness, fatigue, paresthesia, paralysis
CVS: ventricular arrhythmias
ECG changes: digoxin toxicity
What is paresthesia?
decreased sensation.
List three general causes for Hyperkalemia
1) decreased excretion
2) increased intake
3) increased movement of K from cells into blood stream
What can cause hyperkalemia related to decreased excretion?
Adrenal insufficiency
ACE inhibitors
Chronic disease
What can cause hyperkalemia related to increased movement of K from cells into bloodstream?
Acidosis
Tissue injury
Dec insulin
B-blockers
Describe the manifestations of hyperkalemia
CVS: bradycardia, cardiac arrest
CNS: weakness, paresthesia, paralysis
GI: cramps, diarrhea, N and V
What does parathyroid hormone do?
increases blood Ca2+ by stimulating release from bone by osteoclasts
stimulates activation of Vit D by kidney to increase Ca2+ absorption
What vitamin deficiency can result in hypoparathyroidism?
Magnesium deficiency
Describe the common causes of primary hyperparathyroidism.
usually d/t tumor or hyperplasia
Describe the common causes of secondary hyperparathyroidism.
VIT D deficiency: which is necessary for absorption of Ca in GI
RENAL failure: can’t reabsorb
What are the three things that regulate Ca
Parathyroid hormone
Calcitonin
VIt D
Describe the manifestations of hypocalcemia
Muscular-skeletal:
tetany, muscle cramps, bone pain, cardopedal spasm (trousseau’s sign)
CNS:
Chvostek’s sign
Parathesia
Confusion, lethargy, anxiety
CVS
prolonged QT
resistance to digitalis
hypotension
Describe what Trousseau’s sign is.
spasms of the hand when BP cuff is inflated.
Hand curls and thumb tucks in
Describe what Chvostek’s sign is.
Tap the face just anterior to the ear
see twitching of the ipsilateral facial muscles
list 3 common causes of hypercalcemia
Neoplasms of parathyroid glands
Immobilization
Poor absorption
Describe the effects of calcium on Skeletal muscle, nerves, and smooth muscle.
SKELETAL: calcium is involved in creating the resting membrane potential (it is in the ECF) therefore dec Ca results in a dec in resting membrane potential approaching threshold therefore inc excitation.
NEURONS: same as skeletal
SMOOTH MUSCLE: influx is of Ca and not Na. Therefore greater Ca results in increase excitation
Describe the manifestations of hypercalcemia.
Musculoskeletal: muscle weakness, ataxia
CNS: lethargy, personality changes, stupor, coma
GI: anorexia, N and V, constipation
GU: interferes with ADH so can’t concentrate urine
List 3 ways that you can have hypomagnesium.
1) insufficient intake
2) excessive losses
3) movement between ECF and ICF
What might cause hypermagnesia?
1) excessive intake
2) renal insufficiency
What is the definition of an acid?
a molecule that dissociates to release a hydrogen ion
What is the definition of a base?
Ion or molecule that can accept or combine with a hydrogen ion
Described the 3 forms that CO2 is found in the body.
1) dissolved pase pCO2
2) as bicarbonate HCO3-
3) as carbaminohemoglobin
What is the normal pH of the ECF (body’s pH)?
7.35 - 7.45
What is it called when you have an increased pH? What about lower?
INCREASED: alkalemia
DECREASED: acidemia
What is the formula for pH?
pH = - log(H+)
What are the three ways that the body regulates pH in the body? Discuss their relative speed
1) CHEMICAL BUFFER: fast but short acting
2) LUNGS: eliminates CO2, faster than kidneys
3) KIDNEYS: controls elimination of H+ ions and absorption/generation of HCO3-
Describe the Henderson-hasselbach equation.
CO2 + H20 H2CO3 HCO3- + H+
Explain how the kidneys and respiratory system compensates for eachother.
Resp: by doing to CO2 what was done to HCO3-
Kidney: by doing to HCO3- what was done to CO2
if one inc, the other will inc to compensate. If one dec, the other will dec to compensate
How are pH imbalances described?
first by cause, resp or metabolic. then acidosis or alkalosis
there is a 5th type called combined
What are 3 general ways that can cause metabolic acidosis?
1) loss of bicarbonate via kidney or GI tract (diarrhea)
2) access accumulation/production of acids (hepatic disease, ketoacidosis, drugs, rhabomyolysis (breakdown of skeletal muscle)
3) inability of kidney to excrete excess acids (renal disease)
What values would you expect for pH and HCO3- for metabolic acidosis?
pH < 7.35
HCO3- < 22 mEq/L
What is the normal range for HCO3-?
22-26
What is the normal range for PaCO2?
35-45
List the adverse effects of metabolic acidosis.
CNS: H/A, lethargy, stupor, kussmaul’s respirations
RESPIRATORY: hyperventilation
CVS: hypotension
GI: anorexia
What are the 3 ways that you can get metabolic alkalosis?
1) excess H+ ion loss
- vomiting or suctioning
2) Excess HCO3- gain
- ingestion of base, IV HCO3-
3) Loss of K+ related to renal excretion
- hyperaldosteronism, diuretics
List the manifestations for metabolic alkalosis.
CNS: hyperactive reflexes, tetany, confusion, seizures
Carphology (picking) and troussou’s sign
RESP: shallow, bradypnea
CVS: hypotension, arrhythmia
GI: N and V
List the three general ways that respiratory acidosis can occur.
1) Overproduction
- sepsis, burns, hyperthermia
2) inhalation of CO2
3) dec exhalation of CO2
List 5 ways that you can have decreased expiration of CO2
1) obstruction
2) lung/chest wall damage
3) Hypoventilation, asphyxia
4) Denervation of muscles
5) Damage to muscles
What is something that could cause denervation of respiratory muscles leading to resp acidosis?
Brain stem infarct
Opiates
Peripheral nerve disease (gullaine-barre)
What is something that could damage the resp muscles leading to resp acidosis?
Myasthenia gravis
What are the 2 causes of respiratory alkalosis?
Hyperventilation
- anxiety, pain, fever, anemia, altitude
- medullary stimulation
- mechanical ventilation
- disease processes
Medication
What type of medication overdose commonly causes resp alkalosis?
Salicylates
In respiratory alkalosis, how does the body attempt to compensate?
by pulling H+ out of cells to attempt to maintain pH
H+ binds to HCO3- to create CO2
List the manifestations of resp alkalosis
CNS: dizziness, agitation, parathesia, tetany, twitching, muscle weakness
RESP: deep rapid respirations
CVS: increase HR
What test is used to assess respiratory and metabolic function
arterial blood gas analysis
