Fluids And Electrolytes

Front 1

range of normal values for Na, K, HCO3- and Cl- in serum

Back 1

Na: 135-145
K: 3.5 - 5.0
HCO3: (CO2 content): 24-30
Cl-: 95-105

Front 2

range of normal values for Na, K, HCO3- and Cl- in gastric aspirate

Back 2

Na: 10-150
K: 10-20
HCO3-: 0
Cl-: 120-160

Front 3

range of normal values for Na, K, HCO3- and Cl- in bile

Back 3

Na: 135-145
K+: 5-10
HCO3-: 30-40
Cl-: 80-120
ISOTONIC TO SERUM

Front 4

range of normal values for Na, K, HCO3- and Cl- in ileostomy aspirate (from small intestine)

Back 4

Na: 120-140
K+: 5-10
HCO3-: 30-40
Cl-: 20-40

Front 5

what is the normal serum osmolarity?

Back 5

290 mOsm/L
extracellular osmolarity is calculated by osmolarity = {2 x [Na]s} + [glucose(mg)/dL / 18] + (BUN /2.8) -> normal if 290 +- 10

Front 6

what is the total body sodium level (mEq/kg)

Back 6

40 mEq/L

Front 7

whaty is the normal adulst sodium requirement?

Back 7

1-2 mEq/kg/day

Front 8

what are 4 hormones/substrates that affect renal absorption and excretion of sodium and water?

Back 8

Aldosterone
Antidiuretic hormone

Front 9

what is the role of aldosterone?

Back 9

controls sodium resorption in exchange for K+ and H+ secretion in distal tubules -> maintains both extracellular volume and osmolarity

Front 10

what is the role of ADH?

Back 10

increases tubular resorption of water at the collecting ducts
released from the posterior pituitary

Front 11

what is the normal total body store of K+? where is the majority located?

Back 11

normal total body store of K+ = 50-55 mEq/kg
98% is located intracellularly at concentraction of 150 mEq/L
extracellularly, concentration is 3.5-5.0 mEq/L

Front 12

what regulates potassium levels and excretion?

Back 12

circulating levels of aldosterone
cellular and extracellular K+
tubular urine flow rates
also acid-base disturbances

Front 13

how do you relation bicarb buffering system to pH?

Back 13

Henderson-Hasselbach eqn:
pH = 6.1+ log ([HCO3-]/[0.03xPaCO2])
7.4= 6.1+ log (24/1.20)

Front 14

what effect does acidosis have on K+?

Back 14

acidosis -> H+ moves from area of high concentration (extracellular) to low concentration (intracellular) causes K+ to move OUT of the cell
Alkalosis is the opposite

Front 15

what is the K+ status in acidosis vs. alkalosis

Back 15

acidosis -> hyperkalemia
alkalosis -> hypokalemia

Front 16

what are the 3 components of F&E managment in op pts?

Back 16

1. resuscitation = recognize and repair imbalances and defecits already present
2. replacement = provide for ongoing and additional losses that occur during course of therapy
3. maintenance = meet requirements for F&E intake that balance daily obligatory losses

Front 17

what are ranges of different types of output?

Back 17

12-15 ml/kg/day of urine
3 ml/kg stool water
0-1.5 ml/kg sweat
10 ml/kg combined insensible losses from lung and skin (increased with fever or higher ambient temps)

Front 18

if all you need are maintainance fluids (IV), what can you use? and why?

Back 18

5% dextrose in water
because kidney reabsorbs all NaCl that it needs

Front 19

what should you use for replacement fluids?

Back 19

0.45% or 0.9% normal saline + 20 mEq KCl

Front 20

what preop test should you do in someone with COPD

Back 20

ABGs

Front 21

what preop test should you do in someone with chronic renal disease

Back 21

BUN, serum creatinine, electrolytes

Front 22

what condition should you susptect in someone who is vomiting or has had prolonged gastric drainage?

Back 22

Hypokalemic, Hypochloremic Metabolic Alkalosis
(remember: hypokalemia is associated with alkalosis)
pt needs replacement of volume, K+ and Cl-

Front 23

in this situation, what happens if the urine pH is acidic?
what is this called?

Back 23

profound K+ depletion if urine pH is acidic
= Paradoxical Aciduria

Front 24

name 4 situtations in which 3rd space fluid losses can be present

Back 24

peritonitis (bacterial or chemical)
intestinal obstruction
extensive soft tissue inflammation
trauma

Front 25

what kind of loss is this (___tonic)
what should be used for replacement?

Back 25

this is an isotonic loss
LR (a balanced salt solution) should be used for replacement

Front 26

what are some clinical signs of hypovolemia?

Back 26

Hemodynamic changes: tachycardia, narrowed pulse pressure, hypotension
Decreased urine output (<0.5 ml/kg/hr)
Lab evidence: increasing hematrocrit, serum BUN:creatinine > 20:1, urine Na concentration < 20mEq/L

Front 27

what are hte F&E goals during surgery?

Back 27

Goal: Tissue perfusion and maintain circulating volumes

Front 28

How are these monitored?

Back 28

Urine flow rates
central venous or pulmonary arterial pressures

Front 29

when does 3rd spaced fluid accumulation usually resolve post-operatively?

Back 29

POD 3 -> expect diuresis and wt loss

Front 30

how can you differentiate prerenal azotemia (low intravascular volume) from acute renal injury?

Back 30

Prerenal azotemia:
Urine Na <20 mEq/L
BUN:creatinine >20:1
urine osmolality > 400 mOsm/L
Acute Renal Injury:
Urine Na increases (>40mEq/L)
BUN:creatinine <10:1 (because creatinine starts to rise)
urine osmolality approaches plasma osmolality

Front 31

when should LR NOT be use for a replacement fluid? why not?

Back 31

LR should not be used to replace gastric loss d/t vomiting or NG tube sxn
Because there isn't enough Cl- in LR, so it won't correct the Hypochloremic hypokalemic metabolic alkalosis that occurs

Front 32

what should be used instead?

Back 32

1/2 NS + 20 mEq KCL/L

Front 33

Note:

Back 33

Glucose solns should not be used to correct volume deficits d/t osmotic diuresis induces by hyperglycemia

Front 34

what is a good indication of adequate repletion of vascular volume

Back 34

urine output at rates greater than 0.5ml/kg/hr

Front 35

what are 3 major groups of cuases of Hyponatremia. give a few examples of each

Back 35

1. Dilution (accumulation of excess water): hypotonic fluid replacement for GI or 3rd space losses, too much ADH
2. Excessive renal loss of Na: Thiazide diuretics, Metabolic alkalosis, Ketoacidosis, Adrenal insufficiency, Salt-wasting nephropathy
3. Artifactual: hyperlipidemia, hyperproteinemia

Front 36

what are the primary clinical manifestations of Hyponatremia?

Back 36

CNS dysfunction

Front 37

what are cut-off levels of Na and what S/Sx do you expect?

Back 37

Serum Na od 130-120 (acute drop) -> irritability, weakness, fatigue, increased deep-tendon reflexes, and muscle twitches
But completely ASx if developed slowly
Serum Na < 120, if untreated -> seizuers, coma, areflexia, and death

Front 38

what diuretic causes hyponatremia and how?

Back 38

Thiazide diuretic - blocks reabsorption of NaCl in cortical-diluting segment.
But there is still resorption of salt in ascending loop of Henle, so urine can be very concentrated.
so there is water retention with loss of Na, K, and Cl

Front 39

what endocrine disorder can cause hyponatremia?

Back 39

SIADH
tx: Demeclocyline or Lithium carbonate

Front 40

how do you estimate the amount of sodium needed to correct hyponatremia?

Back 40

mEq Na+ needed = (140- measured serum Na+) x TBW
where TBW = 0.6 x body wt(kg)

Front 41

at what rate should this be given?

Back 41

not more thatn 1/2 the total calculated amt of Na needed is give in the first 12-18 hours
the rest can be given over the next 24-48 hours with normal saline

Front 42

what can happen if correction is too rapd? what rate is too rapid?

Back 42

Too rapid = > 12 mEq/L/day
can cause Osmotic Demyelination Syndrome

Front 43

what are signs of acute volume loss (hypovolemia) vs. chronic water loss?

Back 43

Acute volume loss: tachycardia, hypotension, and decreased urine output
Gradual water loss: loss of skin turgor, thirst, altered body temp, and changes in mental status

Front 44

what is the consequence of hypervolemia in most people?

Back 44

high urin output

Front 45

what are possible complications? in whom do these occur?

Back 45

complications can occur in elderly and those retaining fluid
complications: CHF and acute peripheral edema

Front 46

how does CHF occur in young people

Back 46

occurs with sudden fluid excess. can occur in young people with compromised cardiac function d/t shock with trauma, acid-base disturbances, or blood transfusions

Front 47

what happens if fluid excess occurs more slowly?

Back 47

can get pulmonary or peripheral edema instead of CHF

Front 48

what can be a complication of Acute Peripheral edema?

Back 48

usually causes little harm
but if it pesists, can lead to pulm edema --> decreased oxygenation
edema also breaks down tight jxns --> further edema

Front 49

Definition of hyponatremia

Back 49

serum sodium < 130 mEq/L

Front 50

what are the symptoms of hyponatremia

Back 50

irritability
increased TDReflexes
muscle twitching
seizures if severe

Front 51

causes of hyponatremia (4)

Back 51

Hyperglycemia --> artifact
Total body sodium defecit
Total body sodium excess
Normal body sodium level

Front 52

how can total body sodium excess cause hyponatremia?

Back 52

these pts have inability to excrete Na and H2O correctly
Occurs with renal failure, cirrhosis, and stress
Can see evidence of fluid overload: pulm and pitting edema

Front 53

how can pts with normal body sodium level become hyponatremic?

Back 53

if patient is unable to voluntarily control sodium and water intake
also SIADH - do not excrete excess free water appropriately

Front 54

what is the definition of hypernatremia?

Back 54

serum sodium > 145

Front 55

what are S/Sx of hypernatremia

Back 55

volume depletion sx: tachy, hypotension, lethargy, agitation
and signs of dehydration: dry mucus membranes and decreased skin turgor

Front 56

what can cause hypernatremia

Back 56

often in hospitalized pt d/t administration of salt-containing fluids(NS)
loss of water can also be d/t NGtube drainage, sweating, trach, diarrha, diuresis

Front 57

how do you know how and when to treat hypernatremia?

Back 57

calculate the Free Water Defecit =
0.6 x body wt x [1-(140/Na)]

Front 58

what do you to treat hypernatremia?

Back 58

free water infusions --> monitor signs of volume defecit
but if total body water is already increased, decrease the amount of sodium that is being administered

Front 59

what is the definition of hypokalemia?

Back 59

serum K < 3 mEq/L

Front 60

what are the S/Sx of Hypokalemia?

Back 60

Depression of neural, cardiac, and muscle fxn

Front 61

what do you see on the EKG in hypokalemia?

Back 61

Arrhythmias
Flattened or inverted T waves
then U waves
ST segment depression
PR interval elongates
QRS complex widens

Front 62

what are the neuromuscular changes of hypokalemia?

Back 62

weakness

Front 63

what is the GI problem with hypokalemia?

Back 63

can develop an ileus

Front 64

what are the causes of hypokalemia?

Back 64

unusual in healthy person because there are large body stores
can be causes by starvation, anorexia, or diuretics
can also lose K through NG tubes, diarrhea, and fistulas

Front 65

what is the treatment for hypokalemia?

Back 65

FIRST correct the deficit of K
then correct the underlying problem
can do a central infusion (not peripheral, because that causes irritation)

Front 66

what is the definition of hyperkalemia?

Back 66

serum K+ > 6 mEq/L

Front 67

what are the S/Sx of Hyperkalemia?

Back 67

Hyperexcitability
GI tract: hypermobility --> nausea, cramping, diarrhea, vomiting
Heart: peaked T waves and widened QRS. can lead to heard block and eventually diastolic cardiac arrest

Front 68

how likely is hyperkalemia to occur?

Back 68

almost impossible in someone with normal functioning kidneys

Front 69

what are causes of hyperkalemia?

Back 69

in hospital: insufficient renal function and excess K+ (iatrogenic or endogenous)
Can occur with massive blood transfusions and GI bleeding
Acidosis can cause acute severe hyperkalemia

Front 70

what is the treatment for hyperkalemia?

Back 70

1. Calcium --> stabilizes cell membranes, avoid arrhythmias
2. Bicarb and insulin --> lowers serum K+ levels by moving K+ back into cells
3. Ion-exchange resins --> to remove excess K+ from body by exchanging K+ for Na+ ions
4. Dialysis - very effective, but invasive

Front 71

what ist the definition of hypochloremia?

Back 71

chloride < 90 mEq/L

Front 72

what can cause hypochloremia?

Back 72

high GI fluid losses (prolonged vomiting, NG tube sxn) --> loss of lots of H+ and Cl- ions
can also be due to dilutional states after admin of hypotonic fluids

Front 73

what are S/Sx of hypochloremia?

Back 73

Loss of H+, Cl-, or water causes kidneys to retain sodium --> loss of K+ and Cl- and retention of HCO3- --> severe HYPOCHLOREMIC HYPOKALEMIC METABOLIC ACIDOSIS

Front 74

what is the treatment for hypochloremia?

Back 74

NaCl solutions and with KCl if K is low

Front 75

what is the definition of hyperchloremia?

Back 75

Cl > 110 mEq/L

Front 76

what are the causes of hyperchloremia in hospitalized patients?

Back 76

to much Cl- in IV solutions
Note: Chloride in normal saline (154 mEq/L) is much higher than in plasma (90-100 mEq/L)

Front 77

what are S/Sx of hyperchloremia?

Back 77

increased Cl- causes HCO3- to go into cells to keep plasma electrically neutral --> METABOLIC ACIDOSIS
this metabolic acidosis can also be caused by aggressive diuresis after giving NS by concentrating the plasma

Front 78

what is the treatment for hyperchloremia?

Back 78

stop giving high levels of Cl-
may need to give ree water to return plasma to normal so that kidneys can then correct the electrolyte abnormality

Front 79

what causes of deficit of bicarb (leading to metabolic acidosis)?

Back 79

Lack of O2 delivery to tissues --> production of Lactic Acid that is then buffered with HCO3-
With Renal Failure, kidneys can't excrete metabolic acids produced and cannot prodice HCO3-

Front 80

What is the treatment for low bicarb?

Back 80

Correct the oxygen delivery problem
If there is severe acidosis (pH <7.2) may need to administer bicarb to raise pH and allow for normal organ fxn
If renal failure cannot be corrected, then diuresis

Front 81

what is the common role of Magnesium?

Back 81

Co-factor for many enzymes
Also affects neuromuscular function

Front 82

Where is magnesium stored?

Back 82

At least half in bone
Most of the remaineder is INTRAcellular
Note: Mg++ is the commonest intracellular divalent cation and most is bound to ATP

Front 83

what is the normal range of serum Mg++?

Back 83

1.5-2.5 mg/dL

Front 84

what causes hypomagnesemia to be common in surgical patients?

Back 84

They are often in starvations tates and may also have GI losses or absorption defects

Front 85

what happens to some other ions when Mg++ is low?

Back 85

these is alos loss of Potassium and Phosphorys - the 2 other major elents in cells --> cells end up decreasing in size to maintain normal intracellular composition
Low Mg++ also causes hypocalcemia by causing a decrease in PTH secretion

Front 86

what are some other causes of hypomagnesemia?

Back 86

chronic alcoholism (esp during withdrawl)
malabsorption (esp steatorrhea)
acute pancreatitis
improper hyperalimentation
endocrine disorder
can be a side effect of many drugs

Front 87

what are S/Sx of low Mg++?

Back 87

Increased deep tendon reflex
Tetany
Asterixis
Tremor
Chvostek's sign
Ventricular ectopy
Vertigo
Tachycardia
Arrhythmias

Front 88

what is the treatment?

Back 88

Acute Tx: MgSO4 IV
Chronic Tx: Magnesium oxide PH (but causes diarrhea)
correct the underlying cause

Front 89

what can cause Hypermagnesemia?

Back 89

Renal failure
Injury that causes rhabdomyolysis (crush injuries, severe burns)
Dehydration
Severe metabolic acidosis
After treatment for eclampsia

Front 90

what are S/Sx of hyperMg++?

Back 90

Respiratory failure
CNS depression
Decreased deep tendon reflexes

Front 91

what is the Tx for HyperMg?

Back 91

Calcium gluconate IV
insulin + glucose
Dialysis
(similar to treatment of hyperkalemia)
Furosemide (lasix)