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pharm 2 > Electrolytes > Flashcards

Electrolytes Flashcards

1
Q

Total body water and the compartment model

A

-Intracellular fluid (ICF)-> fluid enclosed w/in cells-> tightly regulated and remains pretty stable - regulated by cellular membrane

-Extracellular fluid (ECF)-> fluid surrounds all the cells in the body-> Plasma (fluid component of blood) and Interstitial fluid (surrounds all cells not in blood-> MAINTENANCE IS CRITICAL TO TISSUE PERFUSION

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2
Q

What is third spacing?

A

intracellular fluid

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3
Q

Composition of Body fluids

A

Extracellular fluid
-Plasma -> Sodium, Chloride, Protein, Bicarbonate
-Interstitial fluid-> sodium, chloride, bicarbonate
Intracellular fluid
potassium, phosphate, protein

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4
Q

Pressure- 2 pressure forces act to cause fluid shifts in our bodies

A
  1. Hydrostatic Pressure-> any pressure that a fluid in a confined space exerts
  2. Osmotic/Oncotic pressure-> pressure exerted by the MOVEMENT OF WATER in relation to the molar conc of solutes

the RELATIVE DIFFERENCES in osmolality BTWN FLUID COMPARTMENTS will drive osmotic fluid shift

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5
Q

What is Oncotic pressure? (Colloid osmotic pressure)

A

Big part of Osmotic pressure
-derived from large molecules (albumin)-> oncotic pressure
-25-30 mm Hg range or 0.5% of total osmotic pressure-> small contribution to KEEP WATER IN THE VASCULAR COMPARTMENT

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6
Q

Albumin

A

What is it? Protein made by the liver
Why is it important? maintains consistent amount of fluid in the blood and carries a variety of substances thru body (hormones, vitamins, enzymes)
How do you evaluate it? via CMP
What do the levels mean clinically?
-High levels: dehydration and severe diarrhea
-Low levels: liver disease, kidney disease, malnutrition, infection, IBD, thyroid disease

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7
Q

Main point of albumin

A

major contributor to the oncotic pressure-> 75%

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8
Q

Conditions that can cause a shift in body fluid: increase in fluid

A

edema and effusions
-sodium & water retention-> CHF or Renal failure
-increased hydrostatic pressure-> DVT or CHF
-Decreased plasma osmotic pressure-> decreased Plasma albumin -> malnutrition, liver failure, nephrotic syndrome
-lymphatic obstruction-> trauma, fibrosis, invasive tumors, infectious agents

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9
Q

Conditions that can cause a shift in body fluid: Loss of fluid

A

Sweating
Diarrhea->increased NaCl or LOSS OF ECF WATER LEADS TO SHIFT FROM ICF TO ECF
VOMITING

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10
Q

IV- Parenteral fluids/therapy

A

Definition: tharpy involving IV administration of crystalloids, colloidal solutions, and/or blood products

Purpose:
-hydration
-IV access for better admin of meds-> rapid therapeutic action needed and pts who are unable/restricted from taking oral preparation
-provides a patent IV line in cases of blood loss and electrolyte depletion

Type of fluids-> generally classified according to molecular weight & oncotic pressure
-CRYSTALLOIDS-> molecular weight < 8000 and low oncotic pressure
-COLLOIDS-> molecular weight >8000 and high oncotic pressure

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11
Q

Types of Fluids

A
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12
Q

Crystalloid vs colloid overview

A
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13
Q

Isotonic crystalloids: Lactated Ringers and Normal Saline

A

MOST COMMON FLUIDS GIVEN, ESPECIALLY DURING ACUTE SITUATIONS
Properties:
-SAME OSMOLALITY AS PLASMA-> DO NOT PROMOTE SHIFTS OF FLUID
-EQUAL TONICITY as plasma-> will NOT cause cells to shrink or enlarge

Use: EXPAND ECF VOLUME-> will cause an INCREASE OF OVERALL FLUID VOLUME -> severe fluid loss- dehydration

EX:
-Normal saline- 0.9% Sodium Chloride
-Lactated Ringer’s solution- water, sodium chloride, sodium lactate, potassium chloride, calcium chloride (more mainstay bc most like body)
–aka LR, Ringer’s lactate, sodium lactate solution, hartmann’s solution

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14
Q

Lactated Ringers- Properties, uses, SE

A

Properties: MOST SIMILAR TO BODY’S PLASMA & SERUM CONCENTRATION
-contains: water, sodium chloride, potassium chloride, calcium chloride, SODIUM LACTATE-> body metabolizes to bicarb-> ACTS AS A BUFFER-> useful when in sepsis and acidic
Uses:
1. RESTORE FLUID BALANCE AFTER SIGNIFICANT BLOOD LOSS OR BURN
2. Irrigating trauma wounds, or surgical procedures
3. Keep vein open
4. SEPSIS MANAGEMENT
5. used when large volumes of fluid needed- RESUSCITATION
SE:
-FLUID OVERLOAD-> SWELLING AND PERIPHERAL EDEMA, in pts who cannot handle extra fluid= CHF, CKD, CIRRHOSIS-> pts cant process large volumes of lactate
-hypokalemia
-hyponatremia

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15
Q

Normal Saline- properties, uses, side effects

A

Properties: MOST COMMONLY USED SOLUTION FOR INITIAL REPLETION

Uses: Dehydration, Hypovolemia, DKA, Hyperosmolar hyperglycemic state, headaches, trauma, sepsis

SE:
1. Hyperchloremic acidosis-> secondary to high chloride content relative to plasma
2. Peripheral edema->2ndary to significant extravascular distribution of normal saline

use w/ extreme caution w/ cardiac, renal compromise bc potential for sodium induced fluid retention

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16
Q

Normal saline vs lactated ringers

A

Normal saline
- lasts longer than lactated ringers
-high chloride content

Lactated ringers
-does not not last as long in the body as NS
-contains additive sodium lactate-> body metabolizes to bicarbonate
-contains many of the same electrolytes as blood
HARMFUL FOR CIRRHOSIS

Both
-Isotonic IV FLUIDS
-Same osmotic pressure as blood
-can cause fluid overload/edema

17
Q

Crystalloids: hypotonic

A

Hypotonic solutions-> cause water to shift from ECF to ICF
MAIN INDICATIONS ARE FOR FLUID MAINTENANCE->DOSE= 4:2:1 RULE

4 mL per kg per hour for first 10 kg then 2 mL/kg per hour for every kg over 20
1. D5W-> dextrose in water
-glucose for quick energy for cells - free water to all compartments-> often used for diabetic pts who are NPO but may impair glucose control
-AVOID FOR RENAL FAILURE, CARDIAC COMPROMISE, RISK OF INCREASED INTRACRANIAL PRESSURE

  1. 1/2 Normal Saline- 0.45% NaCl
    -used for Hypernatremia (long term use) or DKA
    -Avoid in pts w. burns, trauma, or liver disease
    -increased risk of IV infiltration vs. isotonic
  2. D5 1/2 NS-> Dextrose in half normal saline
    post surg pts who are NPO
18
Q

Crystalloids: hypertonic

A

Hypertonic-> cause water to shift from ICF to ECF
~3% NaCl~
Indication: SEVERE SYMPTOMATIC HYPONATREMIA
Caution: Osmotic demyelination syndrome with TOO RAPID CORRECTION
>12 mEq/L/d for acute hyponatremia— never- 5-10
> 8 mE/L/d for chronic hyponatremia

ALWAYS GO SLOW

19
Q

IV solutions: Colloids

A

What are they? Large molecules w/ the inability to pass thru semipermeable membranes thus they stay in the blood vessels

Why are they useful?
-aka volume/plasma expanders-> draw fluid from interstitial space back into BV as they have increased Oncotic pressure
-require less Volume than crystalloids-> good for pts who can’t handle large fluid volumes

Indications: shock, external burns, pancreatitis, peritonitis, post op albumin loss

Types:
1. protein
-ALBUMIN
-Gelatin
2. Starch
-Dextran
-Hydroxyethyl starches

20
Q

Protocols for IV Fluids in the adult

A

5 R’s
Resuscitation
Reassess
Routine maintenance
Replacement
Redistribution

21
Q

5 R’s- Resuscitation

A

pt w. obvious Fluid deficit IN NEED OF URGENT FLUIDS: (baby cry w/out tears)
1. Assess Volume Status via PE, Vitals, Labs
-hypotension, tachy, prolonged cap refill, cool extremities, skin turgor, electrolyte levels

Fluids:
-GIVE 500 mL BOLUS of crystalloid (NS or LR) over 15 minutes
REASSESS-> does pt still need resuscitation
-repeat fluid bolus in 250-500 mL increments up to 2500 mL PRN
REASSESS

22
Q

5R’s Routine maintenance

A

pt cannot meet routine fluid needs orally but is otherwise stable
NORMAL MAINTENANCE NEEDS:
-25-30 mL/kg/day H2O
-1mmol/kg/day K+
50-100 g/day glucose

usually short term and low volume-> pts will only 1- 2 L
NS is adequate if admin slowly
pt w/ longer term needs-> may need to alternate with D5W or a mixed NS/glucose solution

REASSESS

23
Q

5R’s- Replacement & Redistribution

A

Pt has existing fluid and/or electrolyte imbalances
-dehydration, fluid overload, HYPER/HYPO - LYTE –> Estimate deficits or excess
Ongoing losses
-vomiting, sweating/fever, Urinary —> Estimate amounts lost

Prescribe REPLACEMENT fluids by adding or subtracting from routine maintenance amount
Check for REDISTRIBUTION
-peripheral edema, heart failure, severe sepsis–> fluid depends on clinical scenario
REASSESS

24
Q

Hyponatremia

A

MC electrolyte disorder-> acute or chronic-> elderly and hospitalized pt
Na < 135
Causes: a failure to excrete water normally-> excess water retention> too little sodium
-iatrogenic-> excess hypotonic IV Fluid 0.45% NaCl
-volume depletion- GI causes, diuretics
-edamatous states-> HF, liver disease
SIADH

Symptoms: nausea, malaise, headache, disorientation, eventual brainstem herniation

Confirm that pt has hypotonic hyponatremia-> evaluate volume states
1. Hypovolemic
-replace intravasc volume with 0.9% NaCl or LR
2. Euvolemic
-restrict fluid intake
-tx underlying cause-> demeclocycline for chronic SIADH or conivaptan for acute SIADH
3. Hypervolemia
-Restrict fluid & salt intake
-diurese pt
-tx underlying cause -> conivaptan or Tolvaptan to target ADH

25
Q

Hyponatremia Management

A

Acute hyponatremia w/ severe symptoms-> 3% NaCl
-hypertonic solution-> admin IV NaCl 0.5-1 mEq/L/hr
ex: raise serum Na from 115 to 125 over 24 hours

What happens if hyponatremia is corrected too quickly?
-Osmotic Demyelination syndrome aka Central Pontine Demyelination
spastic or flaccid quadriplegia
dysarthria
dysphagia
importanttttt
Not 100% reversible-> goes back hyponatremic then slowly back up

26
Q

Hypernatremia

A

Na+ > 145 mEq/L -> approx 1% pts
ALL PTS ARE HYPEROSMOLAL-> OFTEN HYPOVOLEMIC

Causes:
1. Hypodipsia-> defect in thirst mechanism or access to water
2. Excessive salt intake
3. Diabetes insipidus-> loss of water, but not solute
4. Osmotic diuretics-> DM w/ glucosuria

Symptoms:
GI- anorexia, nv
Integumentary- dry skin, mucous mem, inc body temp
neuro- restlessness, agitation, irritability, lethargy
cardio- tachy, hyp or hypertn, erratic heart rate

Management: first two are highlighted
1. Hypotonic fluids-> D5W 0.45% NaCl, 0.2% NaCl- > Rate less than or equal to 0.5 to prevent cerebral edema -> monitor Na+ 4-6 hours
2 Desmopressin DDAVP-> 1st line Central Diabetes INsipidus w/ fluid resusc
3. Hydrochlorothiazide-> 1st line for Nephrogenic Diabetes Insipidus
4. Indomethacin-> used w/ HCTZ to tx NDI
5. Amiloride- alternative to Indomethacin

Monitor all and restrict sodium in diet

27
Q

Hypokalemia

A

K+<3.5 –Moderate is 2.5-3 and Severe is <2.5
20% of hospitalized patients

Causes:
1. Increased K+ excretion- MC cause = 1. enhanced sodium delivery to collecting duct (diuretics) 2. Mineralocorticoid excess- hyperadosteronism 3. Increased urine flow- osmotic diuresis
2. inadequate potassium intake
3. GI losses-> vomiting, diarrhea, NG tube suction
4. SHIFT OF K+ FROM ECF TO ICF

Symptoms: WEAKNESS, FATIGUE, CONSTIPATION, ileus, resp muscle dysfxn

Tx:
1. Reduce K+ loss
2. Replenish K+ stores
3. determine cause

-GIVE KCl-> ORAL IF POSSIBLE-> better absorption than IV

Rule: every 0.1 mEq deficit in K+ = 10 mEq supplemented
-give K+ sparing diuretic if severe= Spironolactone

may use phosphate salt (K-Phos) if hypophosphatemia
ALWAYS CHECK FOR HYPOMAGNESEMIA-> POTASSIUM CANNOT BE REPLENISHED IF MAG IS LOW

28
Q

Hyperkalemia

A

MC is bad blood draw
K+> 5 –10% of hospitalized pts

Causes:
Drugs-> diuretics, succinylcholine (NMB), insulin, ACE/ARBS, NSAIDs, bactr
Pseudohyperkalemia-> botched venipuncture, clenching
Intra to extracellular shift-> acidosis, hyperosmolality, digoxin
Decreased Distal delivery-> CHF, volume depletion, CKD, diabetic neuropathy

Symptoms: “peaked T waves”
usually asym
muscular or cardiac presentations-> palpitations, cp, sinus brady, sinus arrest, vtach, vfib, asys
weakness, fatigue, n/v

Tx:
1st approach- IV infusion of calcium gluconate—support cardiac membrane
2nd: Drive K+ from extra to intracellular-> Insulin, albuterol, sodium bicarb
3rd: remove excess K+ from body-> diuretics, Kayexalate, dialysis

29
Q

tx of hyperkalemia acronym

A

C BIG K DROP
Calcium gluconate
Bicarbonate
Insulin
Glucose
Kayexalate
Diuretic

30
Q

Hypomagnesemia- rare

A

Mg2+ < 1.8
Severe hypmag= hypocalcemia bc Mg and Ca are linked

Causes:
-Gi loses- malabsorption (alcoholics, celiac), diarrhea, vomiting, laxatives, vita d deficiency
-Renal losses- diuretics, diabetes, RTA
-Meds- PPIs, aminoglycosides

Symptoms:
-neurovasc- AMS, lethargy, weakness, muscle cramps, seizures
-Cardiovasc- arrhythmias, palpitations

Hypocalcemia 2/2 impaired PTH
stones, thrones, groans

Tx:
-asympt/min symp= ORAL MAG 240-1000 qd/qid with meals, Extended Release preferred to avoid abrupt elevations, requires days of replacement bc lose 50% in urine
-Severe symp (seizures, arrhyth)- IV magnesium sulfate over 12-24 hrs w/ CONTINUOUS CARDIAC MONITORING

31
Q

Hypermagnesemia- rare

A

Mg2+ > 3
Causes:
RENAL FAILURE MC BC CANT EXCRETE
Iatrogenic -> torsades, eclampsia
excess ingestion
rapid mobilization from tissue-> trauma, shock, cardiac arrest
extracellular shifts-> DKA, TLS, rhabdo
LITHIUM THERAPY

Symptoms:
NV, skin flushing, dizziness, muscle weakness, AMS, decreased DTRs

Tx: Depends on renal fxn
Normalish Kidney fxn (>45 mL/min)= 1. interrupt source of mg 2. Loop or thiazide diuretics to increase excretion
Moderate Kd impairment (ckd, ak)= 1. interrupt source 2. IV isotonic fluids (0.9% NS) 3. Loop diuretic
Severe impairment (chronic dialysis) <15%= 1. interrupt source 2. Dialysis

Severeeee cases= 100-200 mg IV Calcium Gluconate over 1-2 hrs can provide temporary improvement

32
Q

Acid base disorders

A

either metabolic or respiratory
1. Acidosis (pH <7.40)
2. Alkalosis (pH > 7.0)

Metabolic disorders:
imbalance in HCO3-

Respiratory disorders:
imbalances in PCO2

33
Q

Metabolic Acidosis

A

Decreased HCO3-
pH <7.5
acute or chronic
Causes:
MUDPILES (high anion gap acidosis)
HARDASS (normal anion gap acidoses)
Tricyclic antidepressant overdose

Symptoms:
flushed, warm skin, nv, headaches, kussmaul resp, decreased BP, changes in level of consciousness

Tx:
Sodium Bicarbonate (baking soda) for pH 7.1-7.2
Goal of therapy: raise arterial pH to 7.2-> increase pH not normalize pH

34
Q

MUDPILES (CAT)

A

High anion gap
M- Methanol
U-Uremia
D-DKA
P- Paraldehyde
I- Iron, isoniazid
L- Lactic acidosis
E- Ethanol
S- Salicylate/ASA/Aspirin

C-Carbon Monoxide
A- Aminoglycosides
T- Theophylline

35
Q

HARDASS

A

Normal anion gap
H- Hyperalimentation
A- Addison’s disease
R- Renal tubular acidosis
D- Diarrhea
A- Acetazolamide
S-Spironolactone
S- Saline infusion

36
Q

Metabolic Alkalosis

A

Increased HCO3-
pH > 7.45
Causes:
Chloride sensitive
-Gastric fluid loss, Volume Depletion, past use of diuretics
Chloride resistant
-Current use of diuretics, profound hypokalemia, hyperaldosteronism, exogenous steroids

Symptoms:
-shallow breathing, dysrhythmias, muscle cramps, n/v/d, dizziness, restlessness and lethargy

37
Q

Metabolic Alkalosis: Chloride Sensitive

A

Problem: Sustained loss of Cl–> loss of Na+ from renal or GI
Na+ conservation leads to corresponding REABSORPTION OF HCO3-

Tx:
1. check uric chloride= if Urcl < 10 mEg= Choride Sensitive
2. Assess volume status
-decreased intravascular volume-> Give NS
-Adequate or increased Volume-> 250-375 mg PO ACETAZOLAMIDE = blocks bicarb
3. still alkaline after 1 and 2=
-Hydrochloric acid
-ammonium chloride

38
Q

Metabolic Alkalosis: Chloride Resistant

A

Problem: Direct stimulation of kd TO RETAIN BICARB irrespective of electrolyte intake and loss (exogenous cause)
Tx:
1. Check urine chloride
-Urcl >15-20 -> chloride resistant
2. Adjust any therapies contributing to alkalosis
3. Surgical removal of mineralocorticoid producing tumor
4. Potassium <3
-ORAL OR IV POTASSIUM SUPPLEMENTATION
-stop K+ losses
-give aldosterone inhibitor

pharm 2 (15 decks)

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