4th Example – ABG Report of the Patient

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
H⁺ & HCo3^– move in same direction. so, respiratory cause.
Step: 5
So, 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.