Fluid's electrolytes, acid-base physiology

Question 1

Henderson-Hasselbaclch euation

Answer 1

CalculatespH
relationship pH, PaCO2, serum bicarbonate

pH = 6.1+log (HCO3)/0.03 x PaCO2

Question 2

solubility coefficitent in blood of CO2

Answer 2

0.03

Question 3

pKa of carbonic acid

Answer 3

6.1

Question 4

Normal pH

Answer 4

7.35-7.45

Question 5

What divides intravascular fluid (IVF) ad interstitial space (ISF)

Answer 5

capillary membrane

Question 6

Starling forces role

Answer 6

determine motion across the membrane in the microcirculation

Question 7

Starling forces (4)

Answer 7

1.Capillary Pressure
2. ISF pressure
3. ISF colloid osmotic pressure
4. Plasma colloid osmotic pressure

Question 8

Most significant starling force is

Answer 8

plama colloid osmotic pressure

Question 9

Plasma colloid osmotic pressure is determined by

Answer 9

plasma protien concentration and serves to maintain the circulating fluid volume within the intravascular space

Question 10

How can you increase or decrease plasma protien concentration depending on

Answer 10

type and volume of IV Fluids

Question 11

Fluid movement betwenen intravascular space and interstitial space is determined by: (2)

Answer 11

1. Starling forces
2. glycocalyx (protective layer on interior wall of blood vessel) (gatekeeper of what can pass from vessel into interstitial fluid)

Question 12

Lymphatic system role

Answer 12

fluid scavenger- removes unwanted things that enter interstitium

Question 13

Hypovolemia is most often from

Answer 13

Loss of ECF leading to decreased circulating volume

Question 14

How to treat hypovolemia

Answer 14

isotonic crystalloids (NS, LR) because they are most similar to ECF

Question 15

Serum osmlality and osmolarity measure

Answer 15

balance between water and solutes in blood

evaluates hyponatremia etiology

Question 16

Normal serum osmolality

Answer 16

275-295 mmol/kg

Question 17

Normal plama osmolarity

Answer 17

280-290 mOsm/L

Question 18

Tonicity compares

Answer 18

osmolarity of a solution relative to osmolarity of the plasma

transfer of water move in direction of less solute concentration

Question 19

Isotonic

Answer 19

same as plasma, not water transfer

Question 20

Hypotonic

Answer 20

water enters and cell swells (leaves plasma)

Question 21

Hypertonic

Answer 21

Water exits and cell shrinks (enters plasma)

Question 22

Normal sodium level

Answer 22

135-145

Question 23

How fast should you correct hyponatremia? Why?

Answer 23

Slowly! 1-2 mEq/L per hour

Too aggressive correction (especially chronic) can lead to neurologic complication and coma d/t osmotic demyelination (myelinolysis)

Question 24

What is the principle electrolyte in ICF?

Answer 24

Potassium

Question 25

Why is potassium kept in ICF

Answer 25

d/t resting membrane potential of the cell

Question 26

Disease that cause potassium disturbances are often disorders disrupting

Answer 26

resting membrane potential

Question 27

normal potassium blood level

Answer 27

3.5-5.5

Question 28

Hyperventilation and potassium

Answer 28

Hyperventilation causes alkalosis = hypokalemia

Question 29

Treatment for loss of P wave and widening QRS (hyperkalemia)

Answer 29

Calcium chloride SOdium bicarbonate

Question 30

Calcium chloride MOA

Answer 30

membrane stabilization

Question 31

Sodium bicarbonate MOA

Answer 31

shifts potassium intracellularly

Question 32

Peaked T wave therapy/tx (hyperkalemia):

Answer 32

glucose and insulin

Question 33

glucose/insulin MOA (hyperkalemia)

Answer 33

shifts potassium intracellularly

Question 34

Normal serum calcium

Answer 34

8.5-10.5

Question 35

Mostly likely cause of hypocalcemia intraoperatively

Answer 35

hyperventilation and mass transfusion

Question 36

Normal blood magnesium range

Answer 36

1.3-2.5 mEq/L

Question 37

Patient fluid replacement should be treated according to

Answer 37

principles of goal-directed therapy that compensate for individual needs

Question 38

Know and replace (in fluid replacement):

Answer 38

Fluid deficit, fluid losses during surgery, intravascular volume lost until transfusion is warranted

Question 39

Gold standard for determining volume status

Answer 39

Maxamizing cardiac flow parameters as a surrogate for oxygen delivery improves outcomes pulse pressure variation

Question 40

How to calculate hourly fluid maintenance requirement (rule)

Answer 40

4:2:1

Question 41

Explain 4:2:1 rule

Answer 41

first 10 kg: 4mL/10kg/hr next 10 kg: 2ml/10kg/hr Each 1 kg above 20 kg add 1mL/kg/hr

Question 42

Calculating fluid deficeit

Answer 42

(IV fluid hourly rate x surgical hours) +NG suction or - bowel prep

Question 43

Blood loss: crystalloid replacement ratio

Answer 43

3:1

Question 44

Blood loss: Colloid replacement ratio

Answer 44

1:1

Question 45

Normal saline can cause

Answer 45

hyperchloremic metabolic acidosis

Question 46

LR can cause

Answer 46

metabolic alkalosis s/t metabolism of lactate

Question 47

Why can't you use LR with blood?

Answer 47

Calcium will bind to citrate in blood and occlude line

Question 48

Dextrose-containing solutions should be avoided in patients with___. Why?

Answer 48

neurologic injuries may cause hyper glycemia, cerebral acidosis, osmotic diuresis

Question 49

Which part of the startling curve best correlates with preload dependence?

Answer 49

upcurve

Question 50

artificial colloid administration is associated with

Answer 50

coagulopathy and clinical bleeding, most frequently in cardiac surgery patients receiving hydroxyethyl starch

Question 51

All colloids share these potential downsides (4):

Answer 51

1. volume overload 2. coagulopathy (especially hetastarch) 3. anaphylactoid reactions 4. interstitial edema

Question 52

Traditionally favored colloid in neurosurgical pts: however:

Answer 52

Albumin However, SAFE trial suggested higher mortality rate associated with albumin as compared to saline

Question 53

difference bewteen colloids and crystalloids ("long term" expansion)

Answer 53

long term expansion by colloids is a myth - risk of edema is no different btwn colloids and crystalloids no evidence that resuscitation with colloids reduces the risk of death compared to resuscitation with crystalloids (trauma and surgery) Colloids are more expensive than crystalloids