4th Example – ABG Report of the Patient

4th Example of ABG Analysis
4th Example of ABG Analysis

A male patient aged 65 years of COPD and cor pulmonale admitted with the complain of increase in Breathlessness. ABG was done before giving oxygen therapy on 12/02/2015 at 6.13 PM.

ABG Analysis
1. Gas Analysis :-
Step: 1
PaO2 = 47.1 mm of Hg – Moderate Hypoxenia.
Step: 2
PAO2 = 72.5 – decrease Alveolar oxygen content.
Step: 3
P(A-a)O2 = 72.5-47.1
= 25.4
Nearly Normal = age/4+4
= 65/4+4 = 16+4 = 20
Supposed to be no paregnel lup disease.
Step: 4
PaCo2 = 66.5 Increased more than 49.
So, Hypoventilation.
So, Hypoxemia with Hypercapnia
= Type 2  Respiratory failure.
Step: 5
Since PaCo2 is increased and P(A-a)O2    not increased so, hypo ventilation alone and important cause of it is decrease respiratory drive and neuromuscular disease.
Step: 6
P/F = 224.3 – there are features of heart failure so is not an  indication of ALI.
Step: 7
PaO2 of (40 – 60) mm of Hg  Correspond to SPO2 of (75 – 91)%. Here, SPO2 69.7% & PaO2 47.1 mm of Hg.  So, SPO2 a bit low.
Step: 8
Cao2 = 17.1 X 10 X 1.34 X 69.7/100 + 0.003 X 47  ml/L
= 159.71 + 0.1413
= 159.85 ml/L
 

2. Electrolyte Analysis :-

Ca++ -> 0.561 – low – Cause, Pancreatis, hypoalbuminemia, Renal failure, Vit deficiency and alkalosis to be searched.
K+     -> 4.90   – normal
Anion Gap :-
AG = 12.5 – near normal
Delta Gap :-
Delta gap = 12.5 – 12 = 0.5
Gap – Gap ratio :-
Delta gap / HCo3 gap = 0.5/(30.6-24) = 0.5/6.6 = 0.08 <1 (to be taken in consideration if there is metabolic cause.)
Base Excess :-
BE = 1.5 mm/L –> if metabolic cause it suggest metabolic alkalosis.

3. Acid Base Analysis :-
Step: 1

Step: 2
HCo3 = 30.6 mmol/L (> 24 mmol/L) metabolic alkalosis .
Step: 3
PaCo2 = 66.5 mm of Hg (> 40 mm of Hg) so, respiratory acidosis.
Step: 4
step-4H+ & HCo3 move in same direction. so, respiratory cause.
Step: 5
step-5So, PaCo2 & HCo3 move in same direction.so, simple cause.So, respiratory acidosis with compensatory metabolic alkalosis.

Step: 6    
Compensation in chronic cause of respiratory acidosis
HCo3 rise = (2.62 X 66.5)/7.50 = 23.23
So, expected HCo3 = 40 + 23.23 = 63.23 , so fully compensatory.
So, chronic respiratory acidosis with fully compensatory metabolic acidosis with Type 2 respiratory failure due to decrease respiratory drive in a patient of COPD.

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 .