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
Q

IV Fluids & Management

what are 2 isotonic crystalloid solutions?

A
  • Normal saline (0.9% NaCl)
  • Lactated Ringer’s (LR)
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26
Q

IV Fluids & Management

what are 2 hypotonic crystalloid solutions?

A
  • Dextrose solutions (D5W or D10W)
  • Saline Solutions (0.45% NaCl, .22% NaCl)
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27
Q

IV Fluids & Management

what are two types of hypertonic crystalloid solutions?

A
  • 3% NaCl
  • 5% NaCl
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28
Q

IV Fluids & Management

what are mixed crystalloid solutions?

2

A
  • dextrose in saline solutions
  • Isotonic bicarbonate
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29
Q

IV Fluids & Management

2 concentrated crystalloid solutions?

A
  • 8.4% sodium bicarbonate
  • 50% dextrose in water (D50W)
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30
Q

IV Fluids & Management

describe normal saline

A
  • 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
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31
Q

IV Fluids & Management

describe lactated ringers

A
  • 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)
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32
Q

IV Fluids & Management

describe use of dextrose solution

A
  • 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
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33
Q

IV Fluids & Management

describe use of 1/2 or 1/4 normal saline solutions

A
  • 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
Q

IV Fluids & Management

describe use to hypertonic crystalloid solutions

A
  • 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
Q

IV Fluids & Management

describe use of dextrose in saline (mixed crystalloid)

A
  • 5% dextrose iin 0.9% NaCl (isotonic) or 5% dextrose in 0.45% NaCl (hypotonic)
  • indications: fluid resuscitation, maintenance therapy
36
Q

IV Fluids & Management

describe use of isotonic bicarb (1.3% NaHCO3)

A
  • 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
Q

IV Fluids & Management

describe use of 8.4% sodium bicarb

A
  • indications: antidote for sodium channel blocker toxicity, severe metabolic acidosis
  • Risks: metabolic alkalosis, hypernatremia
38
Q

IV Fluids & Management

describe use of 50% dextrose in water (D50W)

A
  • 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
Q

IV Fluids & Management

describe use of colloidal solutions

A
  • solutions that contain large proteins or cells
  • do not readily cross capillary membranes and therefore remain in the intravascular space
40
Q

IV Fluids & Management

describe use of albumin as a colloidal solution

A
  • naturally occuring colloid and most abundant protein in plasma
  • increases extracellular volume
  • indications: cirrhosis, critically ill pts
  • risks: fluid overlaod, allergic rxns
41
Q

Volume Depletion & Dehydration

what are cell membranes composed of?

A

lipids and proteins (phospholipid bilayer)

42
Q

Volume Depletion & Dehydration

functions of cell membrane?

A
  • separates the interior of the cell from the outside environment
  • provides protection to the cell
  • allows for selective transport of molecules
43
Q

Volume Depletion & Dehydration

active vs passive transport

A
  • lipid soluble molecules pass thru the membrane (passive transport)
  • water soluble molecules require a channel for pass through (active transport)
44
Q

Volume Depletion & Dehydration

describe passive diffusion

A
  • 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
Q

Volume Depletion & Dehydration

describe active transport

A
  • 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
Q

Volume Depletion & Dehydration

differentiate endo and exo cytosis

A
  • endocytosis: into the cell
  • exocytosis: out of the cell
47
Q

Volume Depletion & Dehydration

define volume status

A

balance between water and solutes

48
Q

Volume Depletion & Dehydration

define volume depletion (hypovolemia)

A
  • 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
Q

Volume Depletion & Dehydration

define dehydration

A
  • refers to total body water loss across all compartments
  • decreased circulating volume, decreased intracellular volume
  • caused by decreased oral water intake
50
Q

Volume Depletion & Dehydration

causes of dehydration?

A
  • dehydration: decreased oral intake, acute/critical illness, altered thirst mechanisms, dementia
51
Q

Volume Depletion & Dehydration

causes of volume depletion due to:
* decreased oral Na intake
* increased volume loss

A
  • 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
Q

Volume Depletion & Dehydration

define total body water

A
  • ~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
Q

Volume Depletion & Dehydration

pathophys for dehydration

A
  • fluid shifts with illness/disease
  • occurs due to diffusion across semipermeable membrane
  • regulated by difference in plasma osmolality between ECF and ICF
54
Q

Volume Depletion & Dehydration

“flow chart” for dehydration pathophys?

A
  • 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
Q

Volume Depletion & Dehydration

pathophys for hypotonic volume depletion

A
  • water loss > Na+ loss
  • hypotonic fluid is lost from ECF
  • ECF osmolality increases
  • H2O diffuses from ICF to ECF
56
Q

Volume Depletion & Dehydration

pathophys of isotonic volume depletion

A
  • 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
Q

Volume Depletion & Dehydration

pathophys of hypertonic volume depletion

A
  • 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
Q

Acid Base

what is normal pH for body

A

7.35 to 7.45

59
Q

Acid Base

define acidemia

A
  • more hydrogen ions (H+) in blood
  • pH < 7.35
60
Q

Acid Base

define alkalemia

A
  • more hydroxide ions (OH-) in blood
  • pH > 7.45
61
Q

Acid Base

differentiate strong and weak acids

A
  • strong: fully ionize in water, greater effect on pH
  • weak: partially ionize in water, smaller effect on pH
62
Q

Acid Base

differentiate volatile and nonvolatile acids

A
  • 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
Q

Acid Base

differentiate strong and weak bases

A
  • 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
Q

Acid Base

eqn for most physiologically important buffer

A

HCO3- + H+ –> H2CO3 –> CO2 + H2O
can go either way.

65
Q

Acid Base

what are buffers

A

substances that consume or release hydrogen ions to stabilize pH

66
Q

Acid Base

what is acid base balance maintained by?

3

A
  • chemical buffering
  • pulmonary activity (acid- CO2)
  • renal activity (base- HCO3)
67
Q

Acid Base

causes of left shift (alkalosis) on oxygen-hemoglobin dissociation curve

A
  • decreased pCO2/H+
  • decreased temp
  • increased affinity for O2
68
Q

Acid Base

causes of right shift (acidosis) on oxygen-hemoglobin dissociation curve

A
  • increased pCO2, H+
  • increased temp
  • decreased affinity for O2
69
Q

Acid Base

what can pH changes impact in the body?

A

protein configuration/function

70
Q

Acid Base

ABG test purposes?

6 components

A

Vital
* pH
* PaCO2 (partial pressure CO2)
* Bicarb (HCO3)

Supplemental
* O2CT (oxygen content)
* PaO2 (partial pressure O2)
* O2Sat (oxygen saturation)

71
Q

Acid Base

normal values for ABG?

A
  • pH: 7.35 to 7.45
  • PaCO2: 35-45 mmHg
  • HCO3: 22-26 mEq/L
  • pO2: 75-100 mmHg
  • SaO2: 95-100%
72
Q

Acid Base

Allen’s test before ABG?

A

used to assess collateral blood flow to the hands

73
Q

Acid Base

what is VBG?

A

venous blood gas

74
Q

Acid Base

normal values VBG

A
  • pH: 0.03-0.04 lower
  • pCO2: 7-8 mmHg higher
  • HCO3: 2 mEq/L higher
75
Q

Acid Base

ultimate acid base regulator

A

kidneys!

76
Q

Acid Base

how to determine respiratory disturbance to balance?

A
  • change in CO2
  • elevated: acidic
  • decreased: alkalotic
77
Q

Acid Base

how to determine metabolic disturbance to balance?

A
  • change in HCO3
  • elevated: alkalotic
  • decreased: acidic
78
Q

Acid Base

What formula is used to determine the degree of compensation?

A

Winter’s formula

79
Q

Acid Base

Describe use of anion gap

A

calculated for primary metabolic disturbances

80
Q

Acid Base

anion gap for metabolic alkalosis? for metabolic acidosis?

A
  • alkalosis: low
  • acidosis: high
81
Q

Acid Base

how to calculate anion gap?

A

Na + K - (Cl + HCO3)