Wednesday 25 February 2015

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 .

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