Third Example – ABG Report of the Patient

Example:- (3)

Third Example - ABG Report of the Patient
Third Example – ABG Report of the Patient

A young adult of 30 Years suffering from Type 1 Diabetes mellitus from last 5 years, not taking insulin, admitted in emergency department of DMCH with the complain of vomiting, loose motion drowsiness and found tachycardia, hypotension, dehydration , increased rate of respiration (34/m). ABG was done on 12/02/15 at 4.36 PM.

ABG Analysis:

(i) Gas Analysis
Step:1
PaO2 – 139.0 mm of Hg –> High due to use of High Fio2
Step:2
PAO2 – 139.0 mm of Hg –> Above normal alveolar oxygen content due to high Fio2 .
Step:3
 P(A-a)O2   = (139.0-139.0) mm of Hg
= 0 mm of Hg –> No Parenchymal
lung disease.
Step:4
   PaCo2 ->  11.3 mm of Hg –> Hyperventilation


Step:5
   No Hypoxemia/No respiratory failure.
Step:6
   P/F = 661.8 –> No ALI/ARDS –> gas exchange is very good.
Step:7
   SPO2 = 96.5 –> Probably due to increase H+ there is Rt shift of the Hb dissociation curve. So, PaO2 increase and SpO2 relatively Low.
Step:8
   CaO2 = 15.9X10X1.34X96.5/100+0.003X139.0
= 205.60 + 0.417
= 206.01 ml/L
Normal value for this 40 Mg adult man should be approximate  111 ml/L. So oxygen to be avoided to protect from oxygen toxicity.

(ii) Electrolyte Analysis


Upper limit – due to loss of body water content & Cl- is a bit high due to metabolic acidosis.
Ca++ -> 1.172 – High
K+     ->  4.18 – normal , but its value should be high due to decrease blood pH.
For 0.10 decrease of pH.
Increase of K+ should approximate 0.6 mmol/L.
So for 7.029 of pH –> K+ should have increased value upto (N+2.226)mmol/L.
Low level is due to GIT and / or Renal loss.

Anion Gap

AG = 144.9-(116.7+2.9)
=144.9-119.6 = 25.3/29.5 (derived by machine)
Perhaps K+ is also taken in consideration by the machine.

Delta Gap


Delta gap+ measured HCo3 = 17.5 +2.9=20.4 –> low (normal 22-26 mmol/L)
i.e. non anion gap metabolic acidosis.

Gap – Gap Ratio
Gap -gap ratio = (29.5-12) / (24-2.9) = 17.5 / 21.1 = 0.83 <1
i.e. normal AG metabolic acidosis and treatment with N/S (Hyperchloronic).
In this case patient had been gives 3L of N/S before the ABG was done.

Base Excess

BE = 2.9-24 = -21.1 (Derived value by machine -25.8)
Negative value suggestion metabolic acidosis. (So non respiratory cause of Acidosis).

(iii) Acid – Base Analysis

Step:1
        pH = 7.029
H+ = 93.6 nmol/L
So acidemia.
Step:2
        HCo3 = 2.9 mmol/L (< 24 mmol/L) so, metabolic acidosis.
Step:3
        PaCo2 = 11.3 mm of Hg (< 40 mm of Hg) so, respiratory alkalosis.
Step:4


H+ & HCo3 moves in opposite direction.
so, metabolic cause.
Step:5


So, PaCo2 & HCo3 moves in same direction.
so, simple cause.
So, the patient have metabolic acidosis (primary cause) with compensatory  respiratory alkalosis.
Step:6  

 Compensation – Expected PaCo2 fall = 1.2 X (24-2.9)
                                                             = 1.2 X 21.6
                                                             = 25.32
                           So, expected PaCo2 = 40-25.32
                                                             = 14.68

Final Diagnosis

High and normal AG metabolic acidosis with fully compensatory respiratory alkalosis with hyperventilation with low value of K+ is this condition.

Causes of high AG  metabolic acidosis

M – Methanol                                 – No history in this patient
U – Uraemia                                   – Blood urea/ s.creatinine/spot urinary ACR / Input- output chart.
D – Diabetes mellitus                    – This is the cause
P – Paraldehyde                           – No history
I – Infection,Ischaemia,Isoniazide – CBC,ECG required
L – S.lactate                                  – to be estimated
E – Ethanol                                  – No history
S – Starvation,                             – Present for 2 days
Salicylat                                   – No history.

Causes of Normal AG  metabolic acidosis 

  • Gastrointestinal loss of HCO3 in diarrhoea (which was presenting problem).
  •  Renal Tubular Acidosis -> to be excluded by normal AG with no evidence of gastrointestinal disturbance and urinary pH is inappropriately high >5.5 .
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