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Flashcards in Acid/Base Physiology Deck (18)
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1
Q

What is the Henderson-hasselbalch equation for Bicarb/CO2

A

pH= 6.1 + Log (HCO3-/.03PaCO2)

2
Q

What are the normal values for pH, Paco2, and HCO3- in the blood?

A

HCO3-= 24mEq/L

PaCO2= 40 Torr

pH= 7.4 (7.38-7.43)

pH venous (7.34-7.37)

3
Q

True or False: Compensation for alkalosis/acidosis will NEVER completely correct to normal pH.

A

TRUE

This was in RED on his slides and is important

4
Q

What are the 4 acid Base Disorders and how does the body compensate for each of them?

A

Compensations are in blue.

Mnuemonic= Metabolic Mimics pH

5
Q

What causes Respiratory Acidosis?

A

Almost always due to ineffective or decreased ventilation:

Acute Causes

  • CNS depressants
  • Respiratory muscle fatigue

Chronic Causes

  • Central hypoventilation
  • Neuromuscular disease (ALS)
  • Chronic Lung disease
  • Hypothyroidism
6
Q

What are the compensation rules for pH reguarding acute and chronic changes in respiratory disorders?

A

Acute

  • For every 10 Torr increase in CO2 pH decreases by .08 (notice the inverse relationship)

Chronic

  • every 1 Torr decrease in CO2, HCO3- decreases about .4 meq/L.

*note the inverse of each is true a well.

7
Q

What causes Respiratory Alkalosis?

A

Almost always due to INCREASED ventilation:

Acute Causes

  • Pain Anxiety, fever,
  • Mechanical Ventilation

Chronic Causes

  • Altitude
  • Brain Injury
  • Pregnancy
  • Chronic Salicylate Toxicity
8
Q

How does expected pCO2 relate to HCO3- for Metabolic Acidosis Compenastion Rules?

A

pCO2= 1.5[HCO3-] + 8 ± 2

  • This is Winter’s formula and is important to know. You will NOT have this given on a test.
  • You use winters formula with reguards to compensation in METABOLIC ACIDOSIS
9
Q

How can we calculate Anion Gap? What does it mean if we have an increased Anion Gap? Which acid/base disorder do anion gaps go under?

A

Anion Gap= Na+ - (Cl- + HCO3-)

  • Normal value is 12-14

If increased, then it means we have an unknown acid being buffered by HCO3-

Belongs to Metabolic Acidosis, along with non-anion gap MA.

10
Q

What are the casues for Anion Gap? What is the mneumonic?

A

THIS IS IMPORTANT TO KNOW!!!

MUD PILES

  • Methanol
  • Uremia
  • DKA (diabetic ketoacidosis, ETOH and Starvation)
  • Propylene Glycol
  • INH (Isoniazid)
  • Lactate
  • Etheylene Glycol (antifreeze)
  • Salicylates
11
Q

What causes Non-Anion Gap MA?

A
  • GI losses (diarrhea)
  • Renal Losses
  • Too much IV saline

Important card

12
Q

True or False: Respiratory compensation for Metabolic Alkalosis is generally ineffective.

A

True

The body will not hypoventilate to the point of hypoxemia. You still gotta breathe sucka.

13
Q

What is the Compenation Rule for Metabolic Acidosis with reguards to HCO3- and PaCO2?

A

Inc of 1 mEq/L of HCO3- = Inc PaCO2 by .7 Torr

14
Q

So in summary… What are the 4 types of acid/base disorders, how do you identify them, and what are the compensations?

A
15
Q

A pt presents with a broken arm with the following values:

pH= 7.52

PaCO2= 25 Torr

PaO2= 85 Torr

HCO3= 21 meq/L

What is it? What caused it?

A

ACUTE Respiratory Alkalosis.

  • Inc pH, Dec PCO2
  • Bicarb is not Significatly reduced (it follows the acute change of .08 pH per 10 Torr change)
  • Caused by Pain of breaking harm and hyperventilation
16
Q

A pt presents with nausea and vomiting with the following values:

pH= 7.53

PaCO2= 42 Torr

PaO2= 110 Torr

HCO3= 36 meq/L

What is it? Is the compenation appropriate? What caused it?

A
  1. Metabolic Alkalosis
  2. Incomplete Compenastion: expected PaCO2 increase of 8.4Torr (12 meq HCO3 x .07)
  3. Caused by getting vomiting up stomac acid and ingestion of (EtOH)

Bonus: elevated O2 is because of supplemental oxygen

17
Q

A pt is brought to the ED by a friend because he is stuporous. He has the following values:

pH= 7.31

PaCO2= 48 Torr

PaO2= 55 Torr

HCO3=23 meq/L

What is it? Acute or chronic?

A

Respiratory Acidosis

Acute: Bicarb is normal and the 10 Torr for .08 dec in pH is very close.

18
Q

A pt is brought to the ED with nausea/vomiting. He has the following values:

pH= 7.07

PaCO2= 18 Torr

PaO2= 78 Torr

HCO3=5 meq/L

Glucose= 560

What is it? What else do we need to ask? What is the most likely cause of this disorder? Is it compensated?

A
  1. Metabolic Acidosis
  2. Ask is this anion gap or non? (labs Na=132 Cl=94 Glucose= 560)
    • Gap of 33
  3. This is anion gap Caused by DKA
    • Expected PaCO2 = 1.5 (5) + 8 +/- 2 = 14-18 Torr (pt is 18)
    • Adequate Compensation despite low pH