ACID-BASE SITUATIONS
Objectives
• After today’s presentation you will:
• List the primary causes of respiratory acidosis
• List the primary causes of respiratory alkalosis
• Given a set of electrolytes, determine the
anion gap
• List the primary causes of a metabolic acidosis
with an increased anion gap
• List the primary causes of a metabolic acidosis
with a normal anion gap
• List the primary causes of a metabolic
alkalosis
ACID-BASE DISTURBANCES
Respiratory Disturbances
Metabolic Disturbances
Metabolic Acidosis
General Causes of Metabolic
Acidosis
• Failure of kidneys to excrete metabolic
acids normally found in the body.
• Formation of excess quantities of metabolic
acids in the body.
• Addition of metabolic acids to the body by
ingestion or infusion of acids.
• Loss of base from the body fluids.
Anion Gap
• Two ways to
evaluate
• Na+ - Cl- HCO3• Normal is
6 to 12
mEq/L
• Na+ + K+ Cl- - HCO3• Normal is
10 to 16
Anion Gap
• http://www.thedrugmonitor.com/acidbase.ht
ml
Increased Anion Gap
• Greater than 20 = Accumulation of Fixed Acids
• NORMAL CHLORIDE LEVEL
• MUD PILERS
• Methanol
• Uremia (Azotemic Renal Failure)
• Elevated BUN/Creatinine
•
•
•
•
•
•
•
Diabetic Ketoacidosis
Paraldehyde (Formaldehyde and Toluene)
Isopropyl alcohol
Lactic (and Formic) Acidosis
Ethylene Glycol
Rhabdomyolysis
Salicylates
Methanol
Paraldehyde
Isopropyl Alcohol
Ethylene Glycol
Salicylates
Rhabdomyolysis
ARF
Lactic
Acidosis
DKA
Normal Anion Gap
• INCREASED CHLORIDE LEVEL – LOSS OF
BASE
• Renal Tubular Acidosis
• No reabsorption of HCO3-
• Enteric Drainage Tubes
• Small intestine drainage – Large amounts of base in
stool
• Diarrhea
• Urinary Diversion
• Surgical alteration of ureters
• Carbonic Anhydrase Inhibitors
• Poor reabsorption of bicarbonate
Low Anion Gap
• Look at albumin
• Hypoalbuminemia causes a low anion gap.
• Normal Albumin is 4.4 g/dL
• For every 0.4 g/dL decrease in albumin, the anion gap
will decrease by 1 mEq/L
Albumin (g/dL)
Maximum Anion Gap (mEq/L)
4.4
16
4.0
15
3.6
14
3.2
13
2.8
12
Example of Extreme
Compensation
• On 2 L/min NC
•
•
•
•
•
pH: 6.96
PaCO2: 6.8 mm Hg
PaO2: 158 mm Hg
HCO3-: 1.5 mEq/L
BE: -32.6 mEq/L
Metabolic Alkalosis
• Most common acid-base abnormality?
• Aggressive treatment of partially compensated
respiratory acidosis?
• Causes
• Loss of Acid
• Vomiting
• NG Drainage
• Gain of Alkali
• Increased ingestion of alkaline substances
• Excessive licorice ingestion
• Hypokalemia
Advance Acid Base Interpretation
Classification vs. Interpretation
• Classification: Identification of acid-base
disturbance and the causative element
along with any compensation that may be
present.
• Interpretation: Use of calculations to
determine if compensation is appropriate or
if multiple disorders are present.
Compensation
• There is no such thing as overcompensation.
• This usually means there is a second primary disorder
at work in the opposite direction.
• If there is no compensation OR the compensation
is less than expected:
• Compensation is not possible because the
compensatory organ is not functioning appropriately.
• There has not been sufficient time for compensation
(renal).
• Another primary disorder is present and is working in
the same direction.
PaCO2
pH
HCO3-
Acute
↑10
↓ 0.08
↑ 1 mEq/L
Chronic
↑10
↓ 0.03
↑ 4 mEq/L
Acute
↓10
↑ 0.08
↓ 2 mEq/L
Chronic
↓10
↑ 0.03
↓ 5 mEq/L
HCO3-
pH
PaCO2
METABOLIC ACIDOSIS
↓1
↓ 0.015
↓ 1.2
METABOLIC ALKALOSIS
↑1
↑0.015
↑ 0.7
RESPIRATORY ACIDOSIS
RESPIRATORY ALKALOSIS
Degree of Variation
• Allow for some degree of variation as
follows:
• pH: +0.03
• PaCO2: + 5 mm Hg
Oakes’ Approach
• Primary Problem (Acidemia or Alkalemia)
• Primary Cause
• CO2
• HCO3-
• Compensation
• Initial Classification (Technical and Functional)
• Determine extent of compensation and the presence of
other abnormalities
• Determine Anion Gap for metabolic acidemia
• Determine Oxygenation
• Assess Patient
• Check for Accuracy
• Final Interpretation
Factors That May Complicate
Acid-Base Determination
•
•
•
•
Chronic Lung Disease
Chronic Renal Disease
Therapeutic interventions
Mixed Acid-Base Problems
COPD
• Typical picture is fully compensated,
respiratory acidosis.
•
•
•
•
•
pH: 7.38
PaCO2: 55 mm Hg
HCO3-: 31 mEq/L
BE: 5 mEq/L
PaO2: 55 mm Hg
• Let’s go through the process….
7.38, 55, 31
• Acidosis
• CO2 is elevated, so there is a respiratory
cause.
• HCO3- is out of normal range, but is not the
cause.
• The body is compensating.
• Technical Classification: Fully
compensated respiratory acidosis.
• Functional Classification: Chronic
respiratory acidosis.
7.38, 55, 31
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
55
Disorder #2
7.38, 55, 31
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
55
For every 10 torr
change in PaCO2 there
is a 0.03 change in
pH.
pH D = (1.5 x
.03)=0.045
7.40-0.045=7.36
Disorder #2
7.38, 55, 31
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.36
55
For every 10 torr
change in PaCO2 there
is a 0.03 change in
pH.
pH D = (1.5 x
.03)=0.045
7.40-0.045=7.36
Disorder #2
7.38, 55, 31
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.36
55
For every 10 torr
change in PaCO2 there
is a 4 mEq/L change
in HCO3-.
HCO3- D = (1.5 x
4)=6
24+6=30 mEq/L
Disorder #2
7.38, 55, 31
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.36
55
30
For every 10 torr
change in PaCO2 there
is a 4 mEq/L change
in HCO3-.
HCO3- D = (1.5 x
4)=6
24+6=30 mEq/L
Disorder #2
7.38, 55, 31
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
Actual HCO3- (31)
doesn’t match the
predicted change in
HCO3-, so there must
be an underlying
metabolic alkalosis
superimposed on the
compensation.
Disorder #2
7.36
55
30
31
7.38, 55, 31
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
For every 1 mEq/L
change in HCO3there is a 0.015
change in pH.
pH D = (1 x .015) =
0.15~0.2
7.36 + 0.2 = 7.38
Disorder #2
7.36
55
30
31
7.38, 55, 31
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
For every 1 mEq/L
change in HCO3there is a 0.015
change in pH.
pH D = (1 x .015) =
0.15~0.2
7.36 + 0.2 = 7.38
Disorder #2
7.36
7.38
30
31
55
7.38, 55, 31
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
Disorder #2
7.36
7.38
30
31
55
COPD
• So our final interpretation is a fully
compensated, respiratory acidosis with a
secondary metabolic alkalemia.
•
•
•
•
•
pH: 7.38
PaCO2: 55 mm Hg
HCO3-: 31 mEq/L
BE: 5 mEq/L
PaO2: 55 mm Hg
• This may be due to hypochloremia and
hypokalemia associated with steroids and
diuretics.
COPD – Relative Hyperventilation
• If the patient below develops a hypoxemic episode
(e.g. pneumonia), the resulting hypoxemia may
cause the patient to hyperventilate, the PaCO2 to
return to “normal”, and a metabolic alkalosis to be
diagnosed.
• This is often seen when first starting the patient on
BiPAP or mechanical ventilation
pH: 7.38
PaCO2: 55 mm Hg
HCO3-: 31 mEq/L
BE: 5 mEq/L
PaO2: 55 mm Hg
pH: 7.52
PaCO2: 40 mm Hg
HCO3-: 31 mEq/L
BE: 5 mEq/L
PaO2: 50 mm Hg
Solution is to only correct the PaCO2 to 52 mm Hg
COPD with Lactic Acidosis
• COPD + Reduced Cardiac Output =
Cellular hypoxia and Lactic Acidosis
• Don’t be fooled by “normal” ABGs
pH: 7.38
PaCO2: 55 mm Hg
HCO3-: 31 mEq/L
BE: 5 mEq/L
PaO2: 55 mm Hg
pH: 7.38
PaCO2: 40 mm Hg
HCO3-: 24 mEq/L
BE: 1 mEq/L
PaO2: 44 mm Hg
Loss of HCO3- due to lactic acidosis.
Chronic Renal Failure
• Chronic renal failure can distort ABG
results.
• Renal ability to manipulate HCO3-,
electrolyte and fluid levels is impaired.
• Always evaluate with a metabolic acidosis
as a possible cause.
Therapeutic Interventions
• Multiple therapeutic interventions can affect
acid-base balance:
•
•
•
•
•
•
Diuretics
Steroids
Electrolytes
Oxygen
Sodium Bicarbonate
Mechanical Ventilation
Let’s try another…
• Interpret this ABG:
•
•
•
•
•
pH: 7.44
PaCO2: 18 mm Hg
[BE]: -12 mEq/L
[HCO3-]: 12 mEq/L
PaO2: 64 mm Hg
7.44, 18, 12
• Normal, but on alkalotic side.
• CO2 is reduced, so there is a respiratory cause.
• HCO3- is out of normal range, but is not the
cause as a lowered HCO3- would not cause an
alkalosis.
• The body is compensating.
• Technical Classification: Fully compensated
respiratory alkalosis.
• Functional Classification: Chronic respiratory
alkalosis.
7.44, 18, 12
• Change in CO2: -22 torr
• Change in pH: +0.04
• Change in HCO3-: -12 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
18
Disorder #2
7.44, 18, 12
• Change in CO2: -22 torr
• Change in pH: +0.04
• Change in HCO3-: -12 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
18
For every 10 torr
change in PaCO2 there
is a 0.03 change in
pH.
pH D = (2.2 x
.03)=0.066
7.40+0.066=7.47
Disorder #2
7.44, 18, 12
• Change in CO2: -22 torr
• Change in pH: +0.04
• Change in HCO3-: -12 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.47
18
For every 10 torr
change in PaCO2 there
is a 0.03 change in
pH.
pH D = (2.2 x
.03)=0.066
7.40+0.066=7.47
Disorder #2
7.44, 18, 12
• Change in CO2: -22 torr
• Change in pH: +0.04
• Change in HCO3-: -12 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.47
18
For every 10 torr
change in PaCO2 there
is a 5 mEq/L change
in HCO3-.
HCO3- D = (2.2 x
5)=11
24-11=13 mEq/L
Disorder #2
7.44, 18, 12
• Change in CO2: -22 torr
• Change in pH:+0.04
• Change in HCO3-: -12 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.47
18
13
For every 10 torr
change in PaCO2 there
is a 5 mEq/L change
in HCO3-.
HCO3- D = (2.2 x
5)=11
24-11=13 mEq/L
Disorder #2
7.44, 18, 12
• Change in CO2: -22 torr
• Change in pH: +0.04
• Change in HCO3-: -12 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
Actual HCO3- (12)
doesn’t match the
predicted change in
HCO3-, so there must
be an underlying
metabolic acidosis
superimposed on the
compensation.
Disorder #2
7.47
18
13
12
7.44, 18, 12
• Change in CO2: -22 torr
• Change in pH: +0.04
• Change in HCO3-: -12 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
For every 1 mEq/L
change in HCO3there is a 0.015
change in pH.
pH D = (1 x .015) =
0.15~0.2
7.47 - 0.2 = 7.45
Disorder #2
7.47
18
13
12
7.44, 18, 12
• Change in CO2: -22 torr
• Change in pH: +0.04
• Change in HCO3-: -12 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
For every 1 mEq/L
change in HCO3there is a 0.015
change in pH.
pH D = (1 x .015) =
0.15~0.2
7.47 - 0.2 = 7.45
Disorder #2
7.47
7.45
13
12
18
7.44, 18, 12
• Change in CO2: -22 torr
• Change in pH: +0.04
• Change in HCO3-: -12 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
The predicted pH of
7.45 is within the
degree of variation of
+ 0.03 for pH.
Disorder #2
7.47
7.45
13
12
18
Interpretation
• Fully compensated respiratory alkalosis
with simultaneous metabolic acidosis.
Mixed Acid-Base Disturbances
• Sometimes a simple compensatory
mechanism isn’t the reason for the
normalized acid-base status.
• If two opposing problems co-exist (ARF
causing metabolic acidosis and pain
causing respiratory alkalosis), you may
have what looks like one compensating for
the other.
• Interpret this ABG:
•
•
•
•
pH: 7.38
PaCO2: 20 mm Hg
[HCO3-]: 17 mEq/L
PaO2: 89 mm Hg
7.38, 20, 17
• Normal, but on acidotic side.
• CO2 is reduced, which would not cause an
alkalosis.
• HCO3- is reduced and would cause an
alkalosis.
• The body is compensating.
• Technical Classification: Fully
compensated metabolic acidosis.
• Functional Classification: Metabolic
acidosis.
7.38, 20, 17
• Change in CO2: -20 torr
• Change in pH: -0.02
• Change in HCO3-: -7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
17
For every 1 mEq/L
change in HCO3there is a 0.015
change in pH.
pH D = (7 x
.015)=0.105
7.40-0..105=7.30
Disorder #2
7.38, 20, 17
• Change in CO2: -20 torr
• Change in pH: -0.02
• Change in HCO3-: -7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.30
17
For every 1 mEq/L
change in HCO3there is a 0.015
change in pH.
pH D = (7 x
.015)=0.105
7.40-0.105=7.30
Disorder #2
7.38, 20, 17
• Change in CO2: -20 torr
• Change in pH: -0.02
• Change in HCO3-: -7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.30
17
The calculated
change in pH (7.30)
differs from the
actual measured pH,
so there must be
some additional acidbase disturbance.
Disorder #2
7.38, 20, 17
• Change in CO2: -20 torr
• Change in pH: -0.02
• Change in HCO3-: -7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.30
17
For every 1 mEq/L
change in HCO3there is a 1.2 change
in PaCO2.
PaCO2 D = (7 x
1.2)=8.4
40-8.4=31.6~32
Disorder #2
7.38, 20, 17
• Change in CO2: -20 torr
• Change in pH: -0.02
• Change in HCO3-: -7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.30
32
17
The calculated
change in PaCO2 (32)
differs from the
actual measured
PaCO2, so there must
be a respiratory
disturbance present.
Disorder #2
7.38, 20, 17
• Change in CO2: -20 torr
• Change in pH: -0.02
• Change in HCO3-: -7 mEq/L
BASELINE
Disorder #1
pH: 7.40
7.30
PaCO2: 40
torr
HCO3-: 24
mEq/L
31.6
17
The difference
between the
calculated change in
PaCO2 (32) and the
actual PaCO2 (20),
indicates that there
must be a respiratory
disturbance present.
Disorder #2
20
7.38, 20, 17
• Change in CO2: -20 torr
• Change in pH: -0.02
• Change in HCO3-: -7 mEq/L
BASELINE
Disorder #1
pH: 7.40
7.30
PaCO2: 40
torr
HCO3-: 24
mEq/L
31.6
17
For every 10 torr
change in PaCO2 there
is a 0.08 change in
pH.
pH D = (1.2 x
.08)=0.096
7.30+.096=7.396
Disorder #2
20
7.38, 20, 17
• Change in CO2: -20 torr
• Change in pH: -0.02
• Change in HCO3-: -7 mEq/L
BASELINE
Disorder #1
The predicted pH is
within the level of
variability of 0.03
units.
Disorder #2
pH: 7.40
7.30
7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
31.6
20
17
Interpretation
• Mixed metabolic acidosis and simultaneous
respiratory alkalosis.
Can you have a triple disorder?
Anion & Bicarbonate Gaps
• Anion Gap: Na+ - Cl- - HCO3• Normal value is 6 to 12
• Above 20 considered High
• Bicarbonate Gap: HCO3- + (AG-12)
• Normal is 20 to 28 – AG Metabolic Acidosis
• Less than 20 – AG Metabolic Acidosis + NonAG Metabolic Acidosis
• Greater than 28 – AG Metabolic Acidosis +
Metabolic Alkalosis
7.52, 30, 21
• Alkalemia.
• CO2 is reduced, which would cause an alkalosis.
Primary respiratory alkalosis.
• HCO3- is reduced and would not cause an
alkalosis.
• The body is compensating (HCO3- decreasing)
• Technical Classification: Partially compensated
respiratory alkalosis.
• Functional Classification: Chronic respiratory
alkalosis.
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
30
For every 10 torr
change in PaCO2 there
is a 0.03 change in
pH.
pH D = (1 x
.03)=0.03
7.40+.03=7.43
Disorder #2
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.43
30
For every 10 torr
change in PaCO2 there
is a 0.03 change in
pH.
pH D = (1 x
.03)=0.03
7.40+.03=7.43
Disorder #2
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.43
30
The calculated
change in pH (7.43)
differs from the
actual measured pH,
so there must be
some additional acidbase disturbance.
Disorder #2
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.43
30
For every 10 torr
change in PaCO2 there
is a 5 mEq/L change
in HCO3-.
HCO3- D = (1 x 5)=5
24-5=19 mEq/L
Disorder #2
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
7.43
30
19
For every 10 torr
change in PaCO2 there
is a 5 mEq/L change
in HCO3-.
HCO3- D = (1 x 5)=5
24-5=19 mEq/L
Disorder #2
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
The calculated
change in HCO3differs from the
actual measured
HCO3-, so there must
be some additional
acid-base
disturbance.
Disorder #2
7.43
30
19
21
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
For every 1 mEq/L
change in HCO3there is a 0.015
change in pH.
pH D = (2 x
.015)=0.03
7.43+0.03=7.46
Disorder #2
7.43
30
19
21
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
For every 1 mEq/L
change in HCO3there is a 0.015
change in pH.
pH D = (2 x
.015)=0.03
7.43+0.03=7.46
Disorder #2
7.43
7.46
19
21
30
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
Note that the pH still
is not fully explained
by the change in
bicarbonate due to
compensation. Some
additional metabolic
alkalosis must be
present.
Disorder #2
7.43
7.46
19
21
30
Look to Anion & Bicarbonate
Gaps
• Na+: 142 mEq/L
• Cl-: 98 mEq/L
• AG: Na+ - Cl- - HCO3- = 142-98-21 = 23
• This means we have an Anion Gap Metabolic
Acidosis
• BG: HCO3- + (AG-12) = 21 + (23-12) =
21+11 = 32
• AG Metabolic Acidosis + Metabolic Alkalosis
Interpretation
• Primary respiratory alkalosis and metabolic
acidosis and metabolic alkalosis.
• Huh?
• An example would be a patient with
pneumonia who is hyperventilating
secondary to hypoxemia, who also has
azotemic renal failure and has hypokalemia
secondary to aggressive diuretic therapy.
7.52, 30, 21
• Change in CO2: -10 torr
• Change in pH: +0.12
• Change in HCO3-: -3 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
30
Disorder #2
Can you have a quadruple
disorder?
Acid-Base Map
Fig 14-1
pH: 7.35 PaCO2: 60 mm Hg
pH: 7.60 PaCO2: 30 mm Hg
pH: 7.38 PaCO2: 70 mm Hg
pH: 7.35 PaCO2: 30 mm Hg
Fun reading…
• Last part of Chapter 14 in Malley.
7.43, 34, 22
• Change in CO2: +15 torr
• Change in pH: -0.02
• Change in HCO3-: +7 mEq/L
BASELINE
Disorder #1
pH: 7.40
PaCO2: 40
torr
HCO3-: 24
mEq/L
55
Disorder #2