Fluids Pathophys Flashcards

1
Q

IV Fluids & Management

what makes up intracellular fluid

A
  • all fluid enclosed in cells by plasma membranes
  • makes up ~2/3 of body water
  • fluid volume is stable
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2
Q

IV Fluids & Management

what makes up extracellular fluid

A
  • fluid outside of the cells
  • Intravascular fluid (plasma): fluid component of blood
  • interstitial fluid: fluid surrounding cells
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3
Q

IV Fluids & Management

what is the term that describes the distribution of water present in the body?

A

fluid spacing

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4
Q

IV Fluids & Management

what is first spacing?

A
  • normal distribution of fluid in the intracellular and extracellular compartments
  • extracellular fluids are distributed between the interstitial (tissue) and intravascular (plasma) compartments 75-25%
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5
Q

IV Fluids & Management

describe second spacing

A
  • abnormal accumulation of interstitial fluid in the body (edema)
  • can move back to first spacing
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6
Q

IV Fluids & Management

describe third spacing

A
  • mobilization of body fluid to a non-contributory space rendering it unavailable to the circulatory system (ascites)
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7
Q

IV Fluids & Management

define osmosis

A
  • spontaneous movement of water across semi-permeable membrane
  • water moves from region of high solute concentration to a region of low solute concentration
  • tries to equalize concentrations
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8
Q

IV Fluids & Management

define osmotic pressure

A
  • hydrostatic pressure necessary to counteract the process of osmosis
  • depends on the solut concentration (increases osmotic pressure with high solute concentration)
  • NOT dependent on mass/size of molecules
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9
Q

IV Fluids & Management

describe tonicity

A

the capability of a solution to modify the volume of cells by altering their water content

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10
Q

IV Fluids & Management

define isotonic, hypertonic, and hypotonic

A
  • isotonic: IV fluid concentration = plasma concentration
  • hypertonic: IV fluid concentration > plasma concentration
  • hypotonic: IV fluid concentration < plasma concentration
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11
Q

IV Fluids & Management

what would happen if a patient received IV water instead of normal saline?

A

RBCs would swell and burst

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12
Q

IV Fluids & Management

what is osmolar concentration

A

how much of a solute is present

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13
Q

IV Fluids & Management

osmolarity vs osmolality

A
  • osmolarity: solute in solution based on 1L
  • osmolality: solute in solution based on kilogram
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14
Q

IV Fluids & Management

major intracellular vs extracellular ions?

A
  • intracellular: potassium
  • extracellular: sodium
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15
Q

IV Fluids & Management

describe water balance in the body

A
  • our body wants intake and excretion to be equal
  • majority of intake: GI tract
  • majority of output: urine
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16
Q

IV Fluids & Management

what center helps regulate water intake/output?

A
  • hypothalmic thirst center
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17
Q

IV Fluids & Management

describe activation of hypothalamic thirst center

A
  • stimulated when osmoreceptors detect an increase in plasma osmolality or a decrease in blood volume/pressure
  • body releases ADH and aldosterone
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18
Q

IV Fluids & Management

describe feedback loop of hypothalamic thirst center

A
  • drinking water inhibits thirst center
  • inhibitory feedback: relief of dry mouth, activation of stomach/intestinal stretch receptors
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19
Q

IV Fluids & Management

role of anti-diuretic hormone (ADH) in thirst response

A
  • hypothalamus stimulates release of ADH from posterior pituitary gland when dehydrated
  • ADH works on the kidneys to recover water from urine
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20
Q

IV Fluids & Management

describe role of aldosterone with thirst

A
  • kidneys increase production of angiotensin II which stimulates thirst and stimulates the release of aldosterone from the adrenal galnds
  • aldosterone tells the kidneys to increase resorption of sodium in distal tubules (water will follow sodium)
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21
Q

IV Fluids & Management

common indications of IV fluid administration

4

A
  • fluid resuscitation
  • correction of electrolyte imbalances
  • maintenance of fluids for patients that cannot take fluids enterally
  • IV med delivery
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22
Q

IV Fluids & Management

2 categories of fluid administration

A
  • crystalloid solutions
  • colloid solutions
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23
Q

IV Fluids & Management

two components of:
* crystalloid
* colloid

A
  • crystalloid: small molecular weight solutes (minerals, dextrose) and sterile water (more commonly used)
  • colloid: large molecular weight solutes (albumin, blood products) and sterile water
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24
Q

IV Fluids & Management

describe what crystalloid solutions do in the body

3 components

A
  • consist of aqueous electrolyte solutions w/ varying concentrations
  • do not readily cross plasma membranes, but will cross capillary membranes
  • can be isotonic, hypotonic, hypertonic, mixed, and concentrated
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25
# IV Fluids & Management what are 2 isotonic crystalloid solutions?
* Normal saline (0.9% NaCl) * Lactated Ringer's (LR)
26
# IV Fluids & Management what are 2 hypotonic crystalloid solutions?
* Dextrose solutions (D5W or D10W) * Saline Solutions (0.45% NaCl, .22% NaCl)
27
# IV Fluids & Management what are two types of hypertonic crystalloid solutions?
* 3% NaCl * 5% NaCl
28
# IV Fluids & Management what are mixed crystalloid solutions? | 2
* dextrose in saline solutions * Isotonic bicarbonate
29
# IV Fluids & Management 2 concentrated crystalloid solutions?
* 8.4% sodium bicarbonate * 50% dextrose in water (D50W)
30
# IV Fluids & Management describe normal saline
* 0.9% NaCl * contains equal mEg/L of Na+ and Cl- * increase extracellular volume w/ no change in intracellular volume * indicated: fluid resuscitation, maintenance of fluid therapy, IV drug admin * risks: hyperchloremic non-anion gap metablic acidosis, fluid overload
31
# IV Fluids & Management describe lactated ringers
* contains Na+, Cl-. K+, Ca2+, lactate * increases extracellular volume, minimally increases intracellular volume * mild buffering action which prevents acidosis * indicated: fluid resuscitation, maintenance fluid therapy * risks: hyperkalemia, fluid overload, accumulation of lactate (only in liver failure)
32
# IV Fluids & Management describe use of dextrose solution
* can be 5% or 10% dextrose (D5W, D10W) * increases extracellular and intracellular volume * indications: correction of free water deficit (hypernatremia), maintenance fluid therapy (hypoglycemia, ketosis) * risks: hyponatremia, hypokalemia, hyperglycemia, cerebral/pulm edema
33
# IV Fluids & Management describe use of 1/2 or 1/4 normal saline solutions
* 0.45% NaCl (1/2 NS) or 0.22% NaCl (1/4 NS) * increases both extracellular and intracellular volume * indications: correction of hypernatremia, maintenance fluid therapy * Risks: hyponatremia, cerebral/pulm edema
34
# IV Fluids & Management describe use to hypertonic crystalloid solutions
* infuse very slowly * contains high Na+ and Cl- * decreases intracellular volume and increases extracellular volume * indications: severe hyponatremia, tx of cerebral edema * risks: osmotic demyelination syndrome
35
# IV Fluids & Management describe use of dextrose in saline (mixed crystalloid)
* 5% dextrose iin 0.9% NaCl (isotonic) or 5% dextrose in 0.45% NaCl (hypotonic) * indications: fluid resuscitation, maintenance therapy
36
# IV Fluids & Management describe use of isotonic bicarb (1.3% NaHCO3)
* mixed crystalloid * indications: corrects severe metabolic acidosis, urinary alkalinization (decreases toxicity of drugs), correction of bicarb deficit (severe diarrhea, renal tubular acidosis) * Risks: metabolic alkalosis, hypernatremia, hyperglycemia
37
# IV Fluids & Management describe use of 8.4% sodium bicarb
* indications: antidote for sodium channel blocker toxicity, severe metabolic acidosis * Risks: metabolic alkalosis, hypernatremia
38
# IV Fluids & Management describe use of 50% dextrose in water (D50W)
* available in ampules of 25 mL or 50 mL * indications: rapid reversal of hypoglycemia, adjunctive treatment of hyperkalemia when combined with insulin (enhances uptake of K+) * Risks: hyperglycemia
39
# IV Fluids & Management describe use of colloidal solutions
* solutions that contain large proteins or cells * do not readily cross capillary membranes and therefore remain in the intravascular space
40
# IV Fluids & Management describe use of albumin as a colloidal solution
* naturally occuring colloid and most abundant protein in plasma * increases extracellular volume * indications: cirrhosis, critically ill pts * risks: fluid overlaod, allergic rxns
41
# Volume Depletion & Dehydration what are cell membranes composed of?
lipids and proteins (phospholipid bilayer)
42
# Volume Depletion & Dehydration functions of cell membrane?
* separates the interior of the cell from the outside environment * provides protection to the cell * allows for selective transport of molecules
43
# Volume Depletion & Dehydration active vs passive transport
* lipid soluble molecules pass thru the membrane (passive transport) * water soluble molecules require a channel for pass through (active transport)
44
# Volume Depletion & Dehydration describe passive diffusion
* no ATP required * movement of molecules from high to low conentration along electrochemical gradient * involves simple diffusion (movement of small or lipophilic molecules), osmosis (simple diffusion of water), facilitated diffusion (movement of large/charged molecules via chanell/carrier protein)
45
# Volume Depletion & Dehydration describe active transport
* requires ATP * movement against gradient (low concentration to high concentration) * Primary Active: direct, use to ATP to mediate transport * Secondary Active: indirect, coupling the molecule w/ another moving along gradient
46
# Volume Depletion & Dehydration differentiate endo and exo cytosis
* endocytosis: into the cell * exocytosis: out of the cell
47
# Volume Depletion & Dehydration define volume status
balance between water and solutes
48
# Volume Depletion & Dehydration define volume depletion (hypovolemia)
* refers to extracellular fluid loss (loss of water and Na) * decreased circulating volume * caused by decreased oral Na intake and/or increased volume losses
49
# Volume Depletion & Dehydration define dehydration
* refers to total body water loss across all compartments * decreased circulating volume, decreased intracellular volume * caused by decreased oral water intake
50
# Volume Depletion & Dehydration causes of dehydration?
* dehydration: decreased oral intake, acute/critical illness, altered thirst mechanisms, dementia
51
# Volume Depletion & Dehydration causes of volume depletion due to: * decreased oral Na intake * increased volume loss
* decreased Na: acute/critical illness, eating disorders, dementia * Increased volume loss: bleeding, GI (diarrhea, vomiting, drains), renal (diabetic ketoacidosis, diuretics, diabetes insipidus), third space losses (burns, severe pancreatitis), insensible lossses (skin/mucous membranes)
52
# Volume Depletion & Dehydration define total body water
* ~55% of body weight for women, ~60% of body weight for men * varies with muscle mass (more H2O) and fat mass (less H2O) * decreases in elderly and obesity
53
# Volume Depletion & Dehydration pathophys for dehydration
* fluid shifts with illness/disease * occurs due to diffusion across semipermeable membrane * regulated by difference in plasma osmolality between ECF and ICF
54
# Volume Depletion & Dehydration "flow chart" for dehydration pathophys?
* H2O is lost, Na+ is retained * H2O lost from ECF which increases ECF osmolality * H2O diffuses from ICF to ECF * Net effect: ECF hypertonicity and cellular hypernatremia
55
# Volume Depletion & Dehydration pathophys for hypotonic volume depletion
* water loss > Na+ loss * hypotonic fluid is lost from ECF * ECF osmolality increases * H2O diffuses from ICF to ECF
56
# Volume Depletion & Dehydration pathophys of isotonic volume depletion
* Na+ loss = H2O loss * isotonic fluid is lost from ECF * ECF osmolality does not change because there is no gradient for diffusion with ICF * caused by diarrhea, loss of whole blood
57
# Volume Depletion & Dehydration pathophys of hypertonic volume depletion
* Na+ loss > H2O loss * fluid is lost from ECF * ECF contracts and ECF osmolality decreases * H2O shifts from ECF to ICF via diffusions * Example: loop diuretics, primary adrenal insufficiency
58
# Acid Base what is normal pH for body
7.35 to 7.45
59
# Acid Base define acidemia
* more hydrogen ions (H+) in blood * pH < 7.35
60
# Acid Base define alkalemia
* more hydroxide ions (OH-) in blood * pH > 7.45
61
# Acid Base differentiate strong and weak acids
* strong: fully ionize in water, greater effect on pH * weak: partially ionize in water, smaller effect on pH
62
# Acid Base differentiate volatile and nonvolatile acids
* volatile: can change phase into a gas, produced via aerobic metabolism, removable via lungs (CO2) * non-volatile: cannot change phase into a gas, removed by the kidneys, produced via anaerobic metabolism or the GI tract
63
# Acid Base differentiate strong and weak bases
* strong: fully ionize in water, more OH- released into water, greater effect on pH * weak: partially ionize in water, less OH- released into water, smaller effect on pH (HCO3)
64
# Acid Base eqn for most physiologically important buffer
HCO3- + H+ --> H2CO3 --> CO2 + H2O can go either way.
65
# Acid Base what are buffers
substances that consume or release hydrogen ions to stabilize pH
66
# Acid Base what is acid base balance maintained by? | 3
* chemical buffering * pulmonary activity (acid- CO2) * renal activity (base- HCO3)
67
# Acid Base causes of left shift (alkalosis) on oxygen-hemoglobin dissociation curve
* decreased pCO2/H+ * decreased temp * increased affinity for O2
68
# Acid Base causes of right shift (acidosis) on oxygen-hemoglobin dissociation curve
* increased pCO2, H+ * increased temp * decreased affinity for O2
69
# Acid Base what can pH changes impact in the body?
protein configuration/function
70
# Acid Base ABG test purposes? | 6 components
Vital * pH * PaCO2 (partial pressure CO2) * Bicarb (HCO3) Supplemental * O2CT (oxygen content) * PaO2 (partial pressure O2) * O2Sat (oxygen saturation)
71
# Acid Base normal values for ABG?
* pH: 7.35 to 7.45 * PaCO2: 35-45 mmHg * HCO3: 22-26 mEq/L * pO2: 75-100 mmHg * SaO2: 95-100%
72
# Acid Base Allen's test before ABG?
used to assess collateral blood flow to the hands
73
# Acid Base what is VBG?
venous blood gas
74
# Acid Base normal values VBG
* pH: 0.03-0.04 lower * pCO2: 7-8 mmHg higher * HCO3: 2 mEq/L higher
75
# Acid Base ultimate acid base regulator
kidneys!
76
# Acid Base how to determine respiratory disturbance to balance?
* change in CO2 * elevated: acidic * decreased: alkalotic
77
# Acid Base how to determine metabolic disturbance to balance?
* change in HCO3 * elevated: alkalotic * decreased: acidic
78
# Acid Base What formula is used to determine the degree of compensation?
Winter's formula
79
# Acid Base Describe use of anion gap
calculated for primary metabolic disturbances
80
# Acid Base anion gap for metabolic alkalosis? for metabolic acidosis?
* alkalosis: low * acidosis: high
81
# Acid Base how to calculate anion gap?
Na + K - (Cl + HCO3)