1. Interpretation of bloodInterpretation of blood
gasesgases

2. Kidney fixes respiratory derangement, except if kidney malfunctioning
occur (e.g. sepsis, dehydration, prematurity or renal pathology)
Lung fixes metabolic derangement, except if lung malfunctioning occur
(e.g. infection, ARDS, or any lung pathology )
Renal mechanism is slow, that’s why respiratory derangement is
slowly fixed. While, respiratory mechanism is fast,
that’s why metabolic derangement is rapidly fixed.
Fixation ( compensation ) never brings acid-base balance to normal,
but near normal
Hassel Bach equation: pH = 6.2 + log ( Bicarbonate / PaCO2)
For simplification: pH = B/C
by dr M Osama Husseinby dr M Osama Hussein

3. Compensation is an evidence of chronicity
During compensation, bicarbonates & PaCO2 follow each other,
so, both are changed & in the same direction.
The one with the bigger magnitude of change, is the one who started
the derangement ( the chronic element which is to be compensated,
confirm with the resultant pH).
The one with the lesser magnitude of change, is the compensating
element.
Bicarbonates & PaCO2 serve the pH ( 2 servants & 1 lady ).
Bicarbonates & base deficit are nearly the same in both arterial &
venous samples.
by dr M Osama Husseinby dr M Osama Hussein

4. According to the equation:
B
pH=
C
C = CO2 B= bicarbonate
by dr M Osama Husseinby dr M Osama Hussein

5. NORMAL VALUES
Arterialized Capillary
& Arterial Samples
Venous Samples
PH 7.35 - 7.45 7.25 - 7.35
PO2 70 - 90 mmHg 60 - 80 mmHg
PCO2 35 - 45 mmHg 45 - 45 mmHG
Bicarbonates 18 - 25 meq/L
Don't complete reading & interpretation of the
result of the blood gas
analysis when pH is within the normal range.
by dr M Osama Husseinby dr M Osama Hussein

6. Derangement pH B & C
Acute Affected Only one is affected
Chronic
Minimally affected (near
normal)
Both are affected,
in the same
direction,
following each other.
Mixed Highly affected
Both are affected,
in opposite
directions,
not following each
other.
Derangement Where is the error?
Metabolic Error in the Metabolite: Bicarbonate (B)
Respiratory Error in the Respiratory gas: PaCO2 (C)
Derangement pH H+
AcidosisAcidosis LowerLower than normal rangethan normal range HigherHigher H ionsH ions
AlkalosisAlkalosis HigherHigher than normal rangethan normal range LowerLower H ionsH ions
by dr M Osama Husseinby dr M Osama Hussein

7. Acute
Metabolic
Acidosis
▼▼ B
---------------
◄► C
= ▼▼ pH
Acute
Respiratory
Acidosis
◄► B
---------------
▲▲ C
= ▼▼ pH
Acute
Metabolic
Alkalosis
▲▲ B
---------------
◄► C
= ▲▲pH
Acute
Respiratory
Alkalosis
◄► B
---------------
▼▼ C
= ▲▲ pH
pH is affected, Only B or C is affected
In metabolic derangement: B goes with pH
In respiratory derangement: C goes the opposite direction.
ACUTE DERANGEMENTS
by dr M Osama Husseinby dr M Osama Hussein

8. CHRONIC (COMPENSATING) DERANGEMENTSCHRONIC DERANGEMENT
Compensated
by
ACUTE
DERANGEMENT ► RESULTANT
Chc. Met. Acidosis + Ac. Resp.
Alkalosis
▼▼▼B
----------- = ▼▼▼pH
◄►C
+
◄►B
----------- = ▲▲pH
▼▼C
►
▼▼▼B
----------- = ▼pH
▼▼C
Chc. Resp. Acidosis + Ac. Met. Alkalosis ► ?
◄►B
----------- = ▼▼▼pH
▲▲▲C
+
▲▲B
----------- = ▲▲pH
◄►C
►
▲▲B
----------- = ▼pH
▲▲▲C
Chc. Met. Alkalosis + Ac. Resp. Acidosis ► ?
▲▲▲B
----------- = ▲▲▲pH
◄►C
+
◄►B
----------- = ▼▼pH
▲▲C
►
▲▲▲B
----------- = ▲pH
▲▲C
Chc. Resp. Alkalosis + Ac. Met. Acidosis ► ?
◄►B
----------- =▲▲▲pH
▼▼▼C
+
▼▼B
----------- =▼▼pH
◄►C
►
▼▼B
----------- =▲pH
▼▼▼C
..
by dr M Osama Husseinby dr M Osama Hussein

9. CHRONIC DERANGEMENT
Compensated
by
ACUTE
DERANGEMENT ► RESULTANT
Chc. Met. Acidosis + Ac. Resp.
Alkalosis
▼▼▼B
----------- = ▼▼▼pH
◄►C
+
◄►B
----------- = ▲▲pH
▼▼C
►
▼▼▼B
----------- = ▼pH
▼▼C
Chc. Resp. Acidosis + Ac. Met. Alkalosis
◄►B
----------- = ▼▼▼pH
▲▲▲C
+
▲▲B
----------- = ▲▲pH
◄►C
►
▲▲B
----------- = ▼pH
▲▲▲C
Chc. Met. Alkalosis + Ac. Resp. Acidosis ► ?
▲▲▲B
----------- = ▲▲▲pH
◄►C
+
◄►B
----------- = ▼▼pH
▲▲C
►
▲▲▲B
----------- = ▲pH
▲▲C
Chc. Resp. Alkalosis + Ac. Met. Acidosis ► ?
◄►B
----------- =▲▲▲pH
▼▼▼C
+
▼▼B
----------- =▼▼pH
◄►C
►
▼▼B
----------- =▲pH
▼▼▼C
..
by dr M Osama Husseinby dr M Osama Hussein

10. CHRONIC DERANGEMENT
Compensated
by
ACUTE
DERANGEMENT ► RESULTANT
Chc. Met. Acidosis + Ac. Resp.
Alkalosis
▼▼▼B
----------- = ▼▼▼pH
◄►C
+
◄►B
----------- = ▲▲pH
▼▼C
►
▼▼▼B
----------- = ▼pH
▼▼C
Chc. Resp. Acidosis + Ac. Met. Alkalosis
◄►B
----------- = ▼▼▼pH
▲▲▲C
+
▲▲B
----------- = ▲▲pH
◄►C
►
▲▲B
----------- = ▼pH
▲▲▲C
Chc. Met. Alkalosis + Ac. Resp. Acidosis
▲▲▲B
----------- = ▲▲▲pH
◄►C
+
◄►B
----------- = ▼▼pH
▲▲C
►
▲▲▲B
----------- = ▲pH
▲▲C
Chc. Resp. Alkalosis + Ac. Met. Acidosis ► ?
◄►B
----------- =▲▲▲pH
▼▼▼C
+
▼▼B
----------- =▼▼pH
◄►C
►
▼▼B
----------- =▲pH
▼▼▼C
..
by dr M Osama Husseinby dr M Osama Hussein

11. pH is mildly affected,
Both B & C are affected in the same direction, (following each other(
CHRONIC DERANGEMENT
Compensated
by
ACUTE
DERANGEMENT ► RESULTANT
Chc. Met. Acidosis + Ac. Resp.
Alkalosis
▼▼▼B
----------- = ▼▼▼pH
◄►C
+
◄►B
----------- = ▲▲pH
▼▼C
►
▼▼▼B
----------- = ▼pH
▼▼C
Chc. Resp. Acidosis + Ac. Met. Alkalosis
◄►B
----------- = ▼▼▼pH
▲▲▲C
+
▲▲B
----------- = ▲▲pH
◄►C
►
▲▲B
----------- = ▼pH
▲▲▲C
Chc. Met. Alkalosis + Ac. Resp. Acidosis
▲▲▲B
----------- = ▲▲▲pH
◄►C
+
◄►B
----------- = ▼▼pH
▲▲C
►
▲▲▲B
----------- = ▲pH
▲▲C
Chc. Resp. Alkalosis + Ac. Met. Acidosis
◄►B
----------- =▲▲▲pH
▼▼▼C
+
▼▼B
----------- =▼▼pH
◄►C
►
▼▼B
----------- =▲pH
▼▼▼C
by dr M Osama Husseinby dr M Osama Hussein

12. pH is markedly affected,
Both B & C are affected, but in 2 different directions (away
from each other(
MIXED DERANGEMENTS
Metabolic
Derangement
plus
Respiratory
Derangement
► Resultant
Metabolic Acidosis +
Respiratory
Acidosis
► Mixed Acidosis
▼▼B
----------- = ▼▼pH
◄►C
+
◄►B
----------- = ▼▼pH
▲▲C
►
▼▼B ▼
----------- = ▼ ▼ pH
▲▲ C ▼
Metabolic Alkalosis +
Respiratory
Alkalosis
► Mixed Alkalosis
▲▲B
----------- = ▲▲pH
◄►C
+
◄►B
----------- = ▲▲pH
▼▼C
►
▲▲B ▲
----------- = ▲▲ pH
▼▼C ▲
by dr M Osama Husseinby dr M Osama Hussein

13. CORRECTION OF METABOLIC ACIDOSISCORRECTION OF METABOLIC ACIDOSIS
pH < 7.2 (7.25( Bicarb. < 15 meq/L BE > -10 meq/L
Contraindicated when there is Hypercarbia
CO2 wash can br induced by increasing RR either on ventilator, or
applying few breaths by the Ambu bag.
by dr M Osama Husseinby dr M Osama Hussein

14. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
by dr M Osama Husseinby dr M Osama Hussein

15. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.25 ▼ 10 ▼ ◄ 40 ► ▼▼B
-----------
◄►C
PH
▼▼
Ac. Met. Acidosis
by dr M Osama Husseinby dr M Osama Hussein

16. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.25 ▼ 10 ▼ ◄ 40 ► ▼▼B
-----------
◄►C
PH
▼▼
Ac. Met. Acidosis
7.25 ◄ 20 ► ▲ 60 ▲ ◄►B
-----------
▲▲C
PH
▼▼
Ac. Resp. Acidosis
by dr M Osama Husseinby dr M Osama Hussein

17. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.25 ▼ 10 ▼ ◄ 40 ► ▼▼B
-----------
◄►C
PH
▼▼
Ac. Met. Acidosis
7.25 ◄ 20 ► ▲ 60 ▲ ◄►B
-----------
▲▲C
PH
▼▼
Ac. Resp. Acidosis
7.55 ▲ 30 ▲ ◄ 40 ► ▲▲B
-----------
◄►C
▲▲
pH
Ac. Met. Alkalosis
by dr M Osama Husseinby dr M Osama Hussein

18. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.25 ▼ 10 ▼ ◄ 40 ► ▼▼B
-----------
◄►C
PH
▼▼
Ac. Met. Acidosis
7.25 ◄ 20 ► ▲ 60 ▲ ◄►B
-----------
▲▲C
PH
▼▼
Ac. Resp. Acidosis
7.55 ▲ 30 ▲ ◄ 40 ► ▲▲B
-----------
◄►C
▲▲
pH
Ac. Met. Alkalosis
7.55 ◄ 20 ►
▼ 20 ▼
B
-----------
▼▼C
▲▲
pH
Ac. Resp. Alkalosis
by dr M Osama Husseinby dr M Osama Hussein

19. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.3 10▼▼ 30▼ ▼▼B
-----------
▼C
pH▼ Chr. Met. Acidosis
& Ac. Resp. Alkalosis
by dr M Osama Husseinby dr M Osama Hussein

20. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.3 10▼▼ 30▼ ▼▼B
-----------
▼C
pH▼ Chr. Met. Acidosis
& Ac. Resp. Alkalosis
7.3 ▲26 ▲60▲ ▲B
-----------
▲▲C
pH▼ Chr. Res. Acidosis
& Ac. Met. Alkalosis
by dr M Osama Husseinby dr M Osama Hussein

21. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.3 10▼▼ 30▼ ▼▼B
-----------
▼C
pH▼ Chr. Met. Acidosis
& Ac. Resp. Alkalosis
7.3 ▲26 ▲60▲ ▲B
-----------
▲▲C
pH▼ Chr. Res. Acidosis
& Ac. Met. Alkalosis
7.5 ▲30▲ ▲50 ▲▲B
-----------
▲C
▲
pH
Chr. Met.Alkalosis
& Ac. Resp. Acidosis
by dr M Osama Husseinby dr M Osama Hussein

22. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.3 10▼▼ 30▼ ▼▼B
-----------
▼C
pH▼ Chr. Met. Acidosis
& Ac. Resp. Alkalosis
7.3 ▲26 ▲60▲ ▲B
-----------
▲▲C
pH▼ Chr. Res. Acidosis
& Ac. Met. Alkalosis
7.5 ▲30▲ ▲50 ▲▲B
-----------
▲C
▲
pH
Chr. Met.Alkalosis
& Ac. Resp. Acidosis
7.5 13▼ ▼20▼ ▼B
-----------
▼▼C
▲
pH
Chr. Res. Alkalosis
& Ac. Met. Acidosis
by dr M Osama Husseinby dr M Osama Hussein

23. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.1 ▼10▼ ▲60▲ ▼▼B
---------
▲▲C
▼▼
pH
▼▼
Mixed Acidosis
by dr M Osama Husseinby dr M Osama Hussein

24. pH Bicarb. PCO2
? B
-----------
? C
pH? Derangement
How you
Should feel?
7.4 20 40 ◄►B
-----------
◄►C
◄
pH
►
NORMAL
7.1 ▼10▼ ▲60▲ ▼▼B
---------
▲▲C
▼▼
pH
▼▼
Mixed Acidosis
7.6 ▲30▲ ▼20▼ ▲▲B
---------
▼▼C
▲▲
pH
▲▲
Mixed Alkalosis
by dr M Osama Husseinby dr M Osama Hussein

25. by dr M Osama Husseinby dr M Osama Hussein