Thursday 22 January 2015

First Example - ABG Report of the Patient

ABG Report of the Patient
Example: (1)      

A known case of chronic kidney disease admitted in EOPD, D.M.C.H. with the c/o Breathlessness with decreased urine output.

ABG Analysis:                                          

(i) Gas Analysis                                                              

Step:1
  PaO2 =36.9 mm of Hg.                                                        
  SPO2 =52.4 %
  Severe Hypoxemia.

Step: 2
   PAO2 =114.9
   Normal.  
        
Step: 3  
    P(A-a)O2=(114.9-36.9)
                   =78 -> increased
    Parenchymal lung disease.

Step: 4
      PaCo2=30.2 mm of Hg -> low           
      So, Type 1 respiratory failure.

Step: 5
      O2 therapy (6 L/m through C-PAP) for 2 hrs
       Improved to some extent. So the causes may be
       Ventilation / perfusion mismatch i.e.
  •  Airway disease .
  •  Interstitial lung disease.
  • Alveolar disease.
  • Pulmary vascular disease.
Step: 6
      P/F=36.9/21 X 100
             = 175.7 mm Hg.     
             
ALI/ARDS to be decided by excluding, pneumonia or heart failure. There should be (progressive diffuse pulmonary infiltration in x-ray) and  arterial hypoxemia.                                                            
Step: 7                                                                                                
            Relation of PaO2 and SPO2 is normal.

Step: 8
      CaO2 = 10X5.6(gm/L)X1.34X52.4/100+0.003X36.9 ml/L
                = 39.32+0.11
                = 39.43 ml/L
       Wt. Of the patient is 58 kg.
       So,expected CaO2 = 161.11 ml/L
       Available CaO2       = 39.43 ml/L

       So, Blood transfusion is also indicated.

*********************************************************************************************
           

(ii) Electrolyte Analysis

            S.Na    – Normal
            S.Cl     – raised -> may be due to metabolic acidosis.
            S.Ca++  - low    -> may be due to hypoalbuminemia.
            S.K+        - high    -> may be due to acidosis/Renal Dysfunction

Anion Gap :-
        AG = 140.5-[110.7+11.4]
              = 140.5-122.1
              = 18.4  but it is 25.6 as derived by machine. It may be due to hypoalbuminemia.
        AG > 20 so, primary metabolic acidosis.

Delta Gap :-
      Delta Gap = 25.6-12
                       = 13.6
      Delta Gap + HCo3- = 13.6+11.4
                                     = 25 -> Normal range
Gap-Gap Ratio :-
      Gap/Gap ratio = 13.6/12.6 >1
       But delta gap + HCo3 is normal.
       So their is less chance of associated metabolic alkalosis.

BE :-
        BE = 11.4-24
              = -12.6  ->  Base deficit
        So, Metabolic acidosis.


*********************************************************************************************

(iii) Acid-Base Analysis

Step: 1
     pH = 7.193
     H+ = 64.1 nmol/L
     So acidemia.

Step: 2
     HCo3 = 11.4 mmol/L
     (< 24 mmol/L) so, metabolic acidosis.

Step: 3
     PaCo2 = 30.2 mm of Hg
     (< 40 mm of Hg) so, respiratory alkalosis.

Step: 4
    


                       





Step: 5
   










Step: 6     
        Compensation -
        Expected, PaCo2 fall = 1.2 X (24-11.4 )
                                          = 1.2 X 12.6
                                          = 15.12
        So, expected PaCo2 = 40-15.12
                                         = 24.88
So, metabolic acidosis with incomplete compensatory respiratory alkalosis.

Step: 7
       AG = 25.6
       High anion gap metabolic acidosis.
       Delta gap + HCo3 -> normal.
       So, no normal anion gap metabolic acidosis and no metabolic alkalosis.
           
Step: 8
Final diagnosis – High anion gap metabolic acidosis with incomplete compensatory respiratory alkalosis with type 1 respiratory failure with Hyperkalaemia with Hypocalcaemia.


Causes of High Anion Gap Metabolic Acidosis

M – Methanol                     - No history in this patient
U – Uraemia                       - Present
D – Diabetes mellitus         - Not present
P – Paraldehyde                - No history
I – Infection, Ischaemia, Isoniazide – Infection present, No Ischaemia , No H/O Isoniazide
L – S.lactate                      - Not done
E – Ethanol                       - No history
S – Starvation, Salicylate  - Starvation present, No H/O Salicylate intoxication
  
So, Acidosis is most probably due to Infection, Uraemia.

Cause of Type 1 RF

X – Ray chest suggest pneumonia.

     


Prognosis:- 

Since hypoxemia is severe and there is associated Anaemia, hyperkalaemia, pneumonia and uraemia, so prognosis is not good even with haemodialysis, blood transfusion and close monitoring of the patient.






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