RENAL- ACID/BASE

Question 1

Which ACID is powerful quick, harmful?

Answer 1

CO2

Question 2

Which ion is slow, complex, creative for ACIDs?

Answer 2

Bicarbonate
HCO3
TCO2 (on chem panel) ABG (essentially HCO3 is a byproduct of CO2>

Question 3

How do LUNGS compensate using CO2?

Answer 3

Exhale-fast flexible
INC RR- BLOW OFF CO2 (raises pH)
DEC RR
RESPIRTORY

Question 4

How do KIDNEYs compensate using HCO3?

Answer 4

save HCO3-inc pH
discard HCO3-dec pH
METABOLIC- RENAL
but OTHER system occure

Question 5

How dose our body use HCO3 and CO2?

Answer 5

Provides automatic and predictable outcomes

Question 6

What is the ratio to bicarb and acid?

Answer 6

20 parts bicarb to one part acid (carbonic acid).

pH (pH = potential of Hydrogen).

Question 7

What is the pH of our extracellular fluid?

Answer 7

7.35 – 7.45pH
Remember 7.40
Means fully compensated
Tells us the CONDITION of the Pt.

Question 8

What condition results in the accumulation of H+ ions? What is the result and pH?

Answer 8

ACIDOSIS
ACEDEMIA
LOWERED ARTERIAL pH.
too much acid or too little HCO3***

Question 9

What condition results in the excess of bicarbonate ions? What is the result and pH?

Answer 9

ALKALOSIS
ALKALEMIA,
ELEVATED ARTERIAL pH.
too much HCO3*** or too little acid

Question 10

What is significant about pH in regards to its value?

Answer 10

ANY small change outside of NORMAL 
is SIGNIFCANT
7.2 VERY SICK, UNCONSCIOUS
<7.0 LIFE THREATENING
<6.8 RARE SURVIVAL

PH>8.0 LIFE threatening

Question 11

How is Acidosis or Alkalosis actually harmful?

Answer 11

-Acidosis
-Shifts the oxyhemoglobin dissociation curve to the right (Bohr effect), most marks INC CO2, temp, H+, (low O2)
-Depression of CNS, hypercarbia
-Disorders of respiration
-Decreased cardiac contractility
-Decreased vascular response to catecholemines and
decreased vascular tone (low blood pressure)
-Interference with pharmacologic agents

• Alkalosis (lowered CO2 or too much HCO3)
• Shifts the oxyhemoglobin dissociation curve to the left- most marks DEC CO2, temp, H+, (high O2)
• Decreased cerebral blood flow, alterations of consciousness
• Over-excitation of CNS resulting in muscle spasm and tetany (severe)

Question 12

What Indicates need for ABG?

Answer 12

• significant hypoxemia, hypercapnia or Chem panel abnormalities
• Toxicology or the Mystery Patient
• Monitoring effects of therapy (intubated pt’s; DKA, COPD management, etc)

Question 13

How do we obtain an arterial blood gas?

Answer 13

-Venous (VBG) ok if pH is all you need now becoming common

• Radial artery, Femoral now (big target), Brachial is last
• **Allen’s test every time to verify patency of ulnar artery
• Arterial blood is bright red and fills the tube on it’s own
• LABEL Put specimen on ice
• 5 min. firm pressure at site - you’ve punctured an artery

Question 14

WHat are THE FOURS?

Answer 14

pH-7.40
CO2-40
HCO3-24

Question 15

What is “simple” “pure” primary entails?

Answer 15

Primary event results

Compensatory even that leads to min. effect

Question 16

Which compesatory event takes hours vs sec.

Answer 16

Metabolic take HRS-Kidney deciding

Respiratory takse sec- easy hypervenilation

Question 17

What are the common Primary Disorders?

Answer 17

RESPIRATORY ACIDOSIS
RESPIRATORY ALKALOSIS
METABOLIC ACIDOSIS (2 types)- w/ ANION GAP OR W/O ANION GAP
METABOLIC ALKALOSIS

Question 18

What are the FIVE QUESTIONS?

Answer 18

1- pH - acidosis or alkalosis or normal?

2. Respiratory or Metabolic?
3. Who should be compensating (CO2 or HCO3-)?
   - Look at the patient
4. Is there an anion gap? (automatic metabolic acidosis if AG >20). ALWAYS CALULATE

5 If a metabolic acidosis exists, is it a “pure” or “mixed” disorder?
-Respiratory process other than compensation?
-Rule of 15? Are the CO2 and last 2 digits of pH same?
NO-Winter’s formula?

-If an anion gap >20 exists, is there an additional Metabolic process? Winter’s formula? Calculate the Delta gap or Delta Ratio

Question 19

2. Is this a Primary Respiratory or Metabolic disorder?

Answer 19

Normal CO2 = 35 - 45 or 40
Normal HCO3- = 22 -26 or 24

Which one is abnormal?
HIGH OR LOW
For each, does indicate acidosis or alkalosis?
Which one caused the pH change?

ROME
For simple, single acute acid-base disorders:
LOW pH, HIGH CO2 (lots of acids) = RESPIRATORY ACIDOSIS
HIGH pH, LOW CO2 = RESPIRATORY ALKALOSIS

HIGH pH, HIGH HCO3- = METABOLIC ALKALOSIS
LOW pH, LOW HCO3- = METABOLIC ACIDOSIS

Question 20

If the CO2 drives the pH in the opposite direction,

Answer 20

primary respiratory disorder exists

Question 21

If the CO2 and pH move in the same direction (up or down)

Answer 21

primary metabolic disorder exists

Question 22

What begins immediately which may throw values into confusion?

Answer 22

-Are BOTH the CO2 and HCO3- abnormal?
Compensation begins immediately. CO2, HCO3- values are off a bit, reflecting the attempt.

pH abnormal = acute illness or partial compensation.
-Has there been time for compensation?

-If the compensation doesn’t make sense, there is “mixed disorder” – very common condition

Rare CO2 >55, a respiratory process also present

“Primary respiratory acidosis with adequate metabolic compensation”
“ pH adequate will see how treatment helps

Question 23

RESPIRATORY ACIDOSIS

Answer 23

pH - low (<7.35), CO2 - high, HCO3- normal or elevated compensation: acute or chronic
Inadequate ventilation - results in retention of CO2

CO2 retention: 
d/t lung disease or obstruction;
muscles  or chest wall aren’t working;
alveolar ventilation dfx, arterial CO2 goes up; 
you are unconscious 
you have stopped breathing (CPR).

• Pulmonary – COPD/emphysema, asthma, pneumonia, aspiration, pulmonary edema, pleural effusion, pneumothorax, smoke inhalation
• Cardiac – cardiac arrest, CHF
• Mechanical – Airway obstruction – infection, foreign body, bronchospasm
• Central/CNS – Neuromuscular Dz (Guilain-Barre, polio, myasthenia gravis, MS, etc), stroke, tumors, CNS infection, anesthetic/paralyzing drugs

Question 24

RESPIRATORY ALKALOSIS- Most common acid-base disorder.

Answer 24

pH - high (>7.45), CO2 - low, HCO3- normal or low compensation: acute or chronic
Inc RR- excessive removal of CO2.

hyperventilation.
Hypoxia also stimulates respiration - tachypnea.

Disorders

• airway obstruction/bronchospasm, CHF, infection, PE, altitude
• Drugs – stimulants, salicylates (OD), catecholamines
• Central/CNS – tumors, infection, trauma, stoke, fever, sepsis, pain
• Miscellaneous – pregnancy, hyperthyroid, liver failure, ventilator settings
• Anxiety, psychiatric

Question 25

METABOLIC ALKALOSIS

Answer 25

-pH - high, HCO3- is high, CO2 is usually elevated, compensating (quick) -Excess of serum HCO3- ions through H+ ion loss -retention of HCO3-, or - addition of alkali rich substances. Kidneys are overwhelmed or sick. No ABG needed Chloride Responsive (correction) Causes -Volume depletion (dehydrated), severe vomiting, diuretics, NG tube -Fix: IV hydration; replacing sodium/chloride balances the anion/cation pool -Be aware of hypokalemia. precursor and result Chloride Unresponsive Causes -mineralcorticoid excess and severe hypokalemia.

Question 26

METABOLIC ACIDOSIS

Answer 26

-pH - low, HCO3- low, CO2 is usually low depending on severity of acidosis and compensation. - Direct Depletion of bicarbonate - excessive use of Bicarb stores, - relative acid gain - decreased renal excretion of H+ ion.

Question 27

What should you considered in all HIGH anion GAPS during Metbolic acidosis?

Answer 27

M – Metformin, methanol (Sterno) ingestion U - uremia (think aminoglycosides, NSAID’s)-ARF D - diabetic ketoacidosis, alcoholic ketoacidosis P - paraldehyde (liquid sedative - rare anymore), phenphormin (diet pill RX) I - INH or iron overdose L - lactic acidosis (post-seizure, sepsis, carbon monoxide, cyanide, etc) E - ethylene glycol ingestion (antifreeze, wiper fluid) R – Renal failure, rhabdomyolysis S - salicylate overdose (aspirin), starvation

Question 28

What should you considered in an anion gap (>20)? How do you calculate it

Answer 28

a metabolic acidosis automatically, regardless of value of pH, CO2 or HCO3 Calculate all the time in head

Question 29

WHat is the RULE of 15

Answer 29

Add 15 to HCO3 if pH and CO2 #s are close if add 15, the sum should match the last #in pH and CO2 -CO2 and last two digits of the pH should be roughly the same (HCO3 10 or >) fifth question uncovers concurrent processes that may be missed-Determines if something other than just respiratory compensation exists.

Question 30

Is the anion GAP open or Closed?

Answer 30

calculation of unmeasured anions in the serum. - Anions negative charge acids. - In the face of depletion, the body will produce acids compensate. Thus acid disorders only - drug overdoses -Anion gap of >18 is significant Normal AG = 8 to 12 (or 15) Na- (Cl+HCO3)

Question 31

Non-Anion Gap (Normal Gap) Metabolic Acidosis.

Answer 31

Direct HCO3- loss (diarrhea most common), or kidney fails to excrete H+ ions. Another pneumonic – H.A.R.D.U.P. H – hypoaldosteronism/Addison’s, hyperalimentation A – acetazolamide (Diamox), spironolactone R – renal tubular acidosis, renal failure, nephritis D - diarrhea U – ureterosigmoidostomy/ileostomy P – pancreatic fistula low Delta Gap/Delta Ratio

Question 32

So how do you know if a mixed disorder exists?? Is there a chronic disorder?

Answer 32

if the CO2 and HCO3- are abnormal in the same direction, a mixed disorder is UNLIKELY but not ruled out, particularly with metabolic conditions and chronic conditions.

Question 33

Mixed Disorders - Rule Number One:

Answer 33

EXISTS if the pH is NORMAL and the CO2 is ABNORMAL (if no chronic condition exists)

Question 34

Mixed Disorders - Rule Number Two:

Answer 34

In a “pure” respiratory process: A change in the CO2 by 10 will change the pH by .08 in the OPPOSITE direction (CO2 changes by 20, pH changes by 1.6, etc) -If pH is higher than it should be, then a metabolic ALKalosis also exists -If pH is lower than it should be, then a metabolic acidosis also exists

Question 35

Mixed Disorders - Rule Number Three:

Answer 35

A change in HCO3- by 10 will change the pH by .15 in the SAME direction (HCO3- changes by 20, pH changes by .30, etc) -If the pH is higher or lower than it should be, then a respiratory or another metabolic process also exists

Question 36

CHRONIC ACID-BASE IMBALANCES

Answer 36

- baseline chronic acid base imbalance, but fine and walking a fine line. - Identify patients at risk for decompensation in the event of acute illness. - Follow rules for interpreting blood gases, tell us if the compensation attempted by the body is adequate, or acute or chronic.

Question 37

CHRONIC RESPIRATORY ACIDOSIS

Answer 37

COPD’ers, asthmatics, lung cancer/mass, neuromuscular dz pH - 7.36 almost normal – due to chronic compensation CO2->50-60’s HCO3- around 55 Rule-increase in CO2 by 10 will decrease pH by .03 and increase HCO3- by 3.5 If doesn’t roughly match the patient’s blood gas, there is another problem addition to the chronic problem.

Question 38

CHRONIC RESPIRATORY ALKALOSIS

Answer 38

hypoxia, CHF, CNS tumors, hyperthyroidism, pregnancy pH - almost normal CO2 - low HCO3- low as well Rule-decrease in CO2 by 10 will increase pH by .03 and decrease HCO3- by 5 If doesn’t roughly work out, something else

Question 39

Is this a “pure” metabolic acidosis or a mixed disorder?

Answer 39

-Determines if something OTHER than just respiratory compensation exists ASK ONLY if ANION GAP metabolic acidosis >20 -“Rule of 15”: 1. HCO3- plus 15 should equal CO2 and last 2 digits of pH, (HCO3 10 or >) 2. CO2 too low? = Primary Respiratory Alkalosis also exists 3. CO2 too high? = Primary Respiratory Acidosis also exists IF the RULE 15 not roughly the same, calculate if the respiratory compensation to this metabolic acidosis adequate: Winter’s formula: CO2 = 1.5 x HCO3 + 8 (±2) (use after 12-24hrs) CO2 too low? = Primary Respiratory Alkalosis also exists CO2 too high? = Primary Respiratory Acidosis also exists

Question 40

What Uncovers a hidden/chronic metabolic or respiratory process?

Answer 40

Use only if gap >20 All values are from the Chem panel: Delta Gap = HCO3 + change in the anion gap (Anion gap-12) (normal 24 +/- 1) >30 = metabolic alkalosis also exists <18= non-gap metabolic acidosis also exists 18-30=no addn chronic dz Example: Na 136, Cl 99, HCO3 10; AG = 136 – (99 + 10) = 27 Delta Gap = 10 + (27 – 12) 10 + 15 = 25