Blood Gases Ios Kuma

Front 1

T/F
Blood gas readings are used primarily for prophylaxis?

Back 1

False.
Blood gases are used for DIAGNOSTIC purposes

Front 2

How are blood gases reported?

___/___/___/___

Back 2

pH/ pCO2/ pO2/ HCO3

Front 3

What is the normal pH lab values range?

Back 3

7.35-7.45

Front 4

What is the normal pCO2 lab values range?

Back 4

35-45 mmHg

Front 5

What is the normal pO2 lab values range?

Back 5

80-100 mmHg

Front 6

What is the normal HCO3 lab values range?

Back 6

22-26 mEq/L

Front 7

What is the normal base excess lab values range?

Back 7

-2--+2

Front 8

normal pH range?

Back 8

7.38-7.42
because ECF contains [H+] b/w 38-42 mEq/L

Front 9

Acidemia defn.

Back 9

pH <7.38
below normal blood pH

Front 10

Alkalemia defn.

Back 10

pH >7.42
above normal blood pH

Front 11

What problem results from a primary decrease in HCO3?

Back 11

metabolic acidosis

Front 12

What problem results from a primary decrease in H+?

Back 12

respiratory alkalosis

Front 13

What problem results from a primary increase in HCO3?

Back 13

metabolic alkalosis

Front 14

What problem results from a primary increase in H+?

Back 14

respiratory acidosis

Front 15

What problem results from hypoventilation?

Back 15

respiratory acidosis

Front 16

What problem results from hyperventilation?

Back 16

respiratory alkalosis

Front 17

which type of physiological buffer is able to accomodate approximately half of the acid load?

Back 17

Intracellular and bone buffers

Front 18

which physiological buffers normally buffer a total of 2% of renally excreted H+?

Back 18

ammonia-ammonium, and filtered phosphate

Front 19

what are the two types of metabolic compensatory mechanisms?

Back 19

1. HCO3(base) controlled by carbonic anhydrase (brushborder in PCT of kidney)
2. intravascular-intracellular exchange of H+/K+

Front 20

During intravascular-intracellular compensatory mechanism, which way do H+ and K+ flow during acidosis? alkalosis?

Back 20

Acidosis-->
H+ into cell
K+ out of cell into bloodstream

Alkalosis-->
H+ out of cell into bloodstream
K+ into cell

Front 21

How do you equate an anion gap?
What do the results mean?

Back 21

AG= (Na + K) - (Cl +HCO3)
normal AG = 6-12 mEq/L
AG if > or = 20 mEq/L

Front 22

Anion Gap Causes
(metabolic acidosis)

Back 22

Methanol(A)
Uremia(A/C)
Diabetic ketoacidosis(A)
Paraldehyde(A), protease inhibtor(C)
Isonazid(INH)(A/C), iron(A)
Lactate(A)
Ethanol(A), ethylene glycol(A)
Salicylates(A), starvation(C)

Front 23

Non-Anion Gap Causes
(metabolic acidosis)

Back 23

Hyperalimentation(C)
Acid ingestion(A), Addison's
Renal tubular acidosis(C)
Diarrhea(A), diuretics(A/C), drugs(A/C)
Uretosigmoidostemy/(C)
Pancreatitis(A/C)

Front 24

Metabolic Acidosis Compensation Mechanisms:
respiratory
metabolic
positive Osm Gap

Back 24

Respiratory: hyperventilation to decrease pCO2(24 hrs)

Metabolic: 1. increase renal production of HCO3(5 days)
2. intracellular exchange H+/K+(fast)

Osm Gap with MeOH, ethylene glycol, paraldehye. calculated
2Na + BUN/2.8 + glucose/18 + EtOH/4.3

Front 25

Metabolic Acidosis Treatment
Chronic

Back 25

acetate in TPN(if they don't have enough acetate)
***sodium bicarb tablets*** to replenish HCO3
325-650 mg (12mEq HCO3/g) or Shol's soln.(1mEq/ml) in divided doses. Total daily dose 24-48 mEq

Front 26

Metabolic Acidosis Treatment
Acute

Back 26

IV Sodium Bicarb if.....
pH < 7.2 orHCO3 < 15 mEq/L
3 amps NaHCO3 per 1 L D5W @ 75 ml/hr
OR...
THAM buffer--IV proton binder that does not supply Na+

Front 27

Why is replacing HCO3 controversial in metabolic acidosis?

Back 27

1. May induce more acidosis
HCO3+H <--> Co2 +H
2. fluid overload
3. Hemoglobin-O2 curve
4. Ca2+--albumin binding

Front 28

Types of Metabolic Alkalosis

Back 28

Cl responsive
Cl unresponsive

Front 29

Cl Responsive Causes
(metabolic alkalosis)

Back 29

increase HCO3 in response to losing Cl
HCl loss(vomiting, suctioning)
Diuretics(loop, thiazide)

Front 30

Cl Nonresponsive Causes
(metabolic alkalosis)

Back 30

increase in HCO3, irrespective of Cl concentration
Hyperaldosteronism(too much aldosterone)
severe hypokalemia
Iatrogenic alkali admin (TPN)

Front 31

Metabolic alkalosis compensation:
Respiratory
Metabolic

Back 31

respiratory: hypoventilation to increase pCO2 (fast)

Metabolic: 1. increase renal excretion of HCO3 (fast)
2. intravascular exchange of H+ for K+ (fast)

Front 32

Main treatment for metabolic alkalosis

Back 32

acetazolamide
(carbonic anhydrase inhibitor)
250-500 mg po/IV q 8 hrs for 3-4 doses
promotes renal excretion of HCO3

Front 33

treatments for metabolic alkalosis

Back 33

1. correct hypokalemia(20-60 mEq K+ infused over 3 hrs)
2. vol. replacement w/ NS or Cl replacement(if Cl responsive). Kidney will excrete HCO3 to preserve neutrality w/ Cl.
3. acetazolamide(see other card)
4. H2 antagonists or PPI to prevent HCl secretion, reduce HCl loss assoc. w/ vomiting/suctioning
5. severe/emergency: IV HCl or arginine HCl (142.5 mEq HCl/300 ml) or ammonium Cl if pH > 7.6

Front 34

Respiratory Acidosis Causes:

Back 34

increased pCO2 due to decreased ventilation/ventilation-perfusion mismatch
COPD(C)
PE(A)
Interstitial Lung Disease
Over sedation/NM blockade
Hypothyroidism(C)
NM Disorders(Myasthenia gravis, GB syn., CNS injury)
Hypoventilation w/ ventilator
Pickwickian syn.--obesity(C)

Front 35

Respiratory acidosis compensation:
respiratory
metabolic

Back 35

Respiratory: limited, since diseases freq. assoc. w/ irrev. lung damage

Metabolic: 1. increased renal H+ secretion(onset12-24 hrs, max effect 5 days)
2. intracellular shift of H+ for K+(fast)

Front 36

Respiratory Acidosis treatment

Back 36

O2 replacement w/w/out intubation
Increase ventilatory rate as long as O2 not adversely affected
***replace HCO3 if pH < 7.2 but use caustiously b/c increased HCO3 will worsen hypoventilation to promote retention of pCO2
NEVER GIVE BICARB TO TREAT ACUTE Resp. Acidosis

Front 37

why shouldn't you give bicarb to treat ACUTE respiratory acidosis???

Back 37

7.11/70/50/23
(low pH, high pCO2, norm HCO3)

--give pt. HCO3---->
7.2/70/50/30
lab values shift further
---> 7.11/90/40/30
Acidosis worsens!!!!

Front 38

Respiratory Alkalosis Causes

Back 38

Decreased pCO2 due to increased ventilation

Hypoxia(C/A)
nervousness/anixiety/pain(A)
PE(A)
interstitial lung disease(C)
Hyperventilation w/ ventilator
Hyperthyroidism(C)
pregnancy(C)
CNS injury(A)
Fever(A)
severe anemia(C)
CHF, hepatic insuff.(C)
Stimulants(A)

Front 39

Respiratory Alkalosis Compensation:
Respiratory
Metabolic

Back 39

respiratory: need removal of exacerbating stimulus

metabolic: 1. decrease renal production of HCO3(2 wks) 2. intravascular shift of H+ for K+(fast)