This document discusses acid-base disorders and provides examples of how to interpret arterial blood gas results. It defines the normal ranges for pH, HCO3, and PCO2. It then gives several examples of interpreting ABG values to determine if a patient has metabolic acidosis, metabolic alkalosis, respiratory acidosis, or respiratory alkalosis. It also discusses anion gap, compensatory responses, causes of high and non-gap metabolic acidosis, and using the delta ratio to evaluate for mixed acid-base disorders.
3. Example 1
PH=7.31 ,HCO3=19 ,Pco2=36
first look for PH Less than normal range(7.35-7.45)
So, ACIDOSIS confirmed
Now look for Hco3 , is less than normal range(22-28)
So, Metabolic acidosis confirmed
Also look at pco2 is normal(35-45)
So. Ans : Metabolic acidosis.
9. ANION GAP
Anion gap=measured anion +unmeasured anion=measured cation+ unmeasured
cation
[cl+Hco3]+ [unmeasured anion]=[Na]+[unmeasured cation]
AG=Unmeasured anion-unmeasured cation
AG=Na-[cl+Hco3]
Anion gap means increase in unmeasured anions or decrease in unmeasured
cation
Unmeasured anions=
acetate,lactate,formate,oxalate,sulfate,phosphate,salicylate,albumin.
Unmeasured cations = k,ca,mg,lithium,IG.
NORMAL AG = 6-12 mmol/l
10. Example 5
PH=7.29 ,Hco2=14 ,pco2=24,Na=140,k=4.0,cl=106
Ans.
1)PH low =acidosis confirmed
2) look Hco3 is low =metabolic acidosis confirmed
3) look pco2 is low =co2 means acid = acid low .so,
Respiratory acidosis is not here.
4)calculate expected pco2=(1.5×Hco2)+8±2=(1.5×14)+8±2=21+8±2=29±2=27-31
now, patient pco2 < expected pco2.
so, respiratory alkalosis .
5) Anion gap=Na-[cl+hco3]=140+[106+14]=140-120=20
Normally AG=6-12 mmol/l,
so, High AG metabolic acidosis[HAGMA] with Respiratory alkalosis
IF cl=117
Then AG=Na-[cl+hco3]=140+[117+14]=140-131=9
So,Normal AG metabolic acidosis with respiratory alkalosis
13. Example 7
PH=7.30 ,Hco3=18, pco2=38 ,Na=140,cl=102
1) High AG Metabolic acidosis,Respiratory alkalosis
2) Non AG Metabolic acidosis,Respiratory alkalosis
3) High AG metabolic acidosis ,respiratory acidosis
4) Non AG metabolic acidosis ,respiratory alkalosis
Guide::1) PH first
2)then Hco3
3)expected pco2
4)ANION GAP
14. High Anion Gap Metabolic Acidosis
If AG>12 mmol/l….>HAGMA
If AG between 6-12 mmol/l …..NAGMA
CAUSES OF HAGMA
15. Non Anion Gap Metabolic Acidosis
AG=Na-[cl+Hco3]
Hco3 loss is compensated by cl gain
Urinary Anion Gap is used to diff GIT cause from RENAL cause of NAGMA
UAG=unmeasured anion-unmeasured cation
Total anion= Total cation
Measured anion + unmeasured anion= measured cation +unmeasured cation
[Cl]+ unmeasured anion= [Na+k] + unmeasured cation
UAG=Unmeasured anion-unmeasured cation= Na+k-cl
UAG= Hco3 - NH4
IN Renal loss :UAG POSITIVE(Hco3 in urine more ,NH4 less)
IN GI loss :UAG NEGETIVE (Hco3 in urine less, NH4 more)
20. EXAMPLE 10
35 year male unknown male patient (*Apudo) brought
to emergency in fully conscious oriented state with
breathlessness plus vomiting and he is not giving proper
history
P;132/min,bp:110/78 mmhg,spo2:96 room air,Rbs:79
mg/dl ,ecg; sinus tachycardia,not such significant pallor.
PH=7.42,Hco3=25,pco2=40,po2=82,so2=93,Na=140
,k=3.0,cl=95
???????
21. DELTA RATIO
Delta ratio is calculated in case of high anion gap metabolic acidosis , to
evaluate mixed disorder.
Delta gap=[patient AG-12]/[24-Patients Hco3]
Interpretation
<0.4 :NAGMA
0.4- 0.8 :NAGMA + HAGMA
0.8-2.0 : pure HAGMA
>2.0 : mixed HAGMA + Metabolic alkalosis
