Third Example - ABG Report of the Patient

Third Example - ABG Report of the Patient

Example:- (3)

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

       So, metabolic acidosis with fully compensatory respiratory alkalosis.

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 .