Indications:
The review used to assess the amount of haematosis in respiratory diseases, whether acute or chronic.
Principle:
It involves measuring blood pressure O2 and CO2, the bicarbonate ion concentration and arterial blood pH.
Sampling 3 mL of arterial blood via the femoral or radial puncture into a heparinized syringe sealed.
It is essential to ensure that the sampling is carried out in an artery and not into a vein.
If successive samples are needed, we can put in place a microcatheter.
By scarification, it is possible to take a sample at the ear lobe or heel in infants.
In any case, absolutely avoid air bubbles that distort the result.
Results:
Normal values to 30 years:
– PO2 (arterial oxygen pressure):> 90 mmHg;
– PCO2 (arterial pressure of carbon dioxide): 38-42 mmHg;
– SaO2 (O2 saturation): 95 to 98%;
– PH: 7.38 to 7.42.
PO2 decreases with age, and it is 75 mmHg to 80 years.
Pathological changes:
– Hypoxemia without hypercapnia (pressure drop in O2 but no CO2 pressure increase); the total “+ PO2 PCO2” is less than 130 mmHg in case of:
– pulmonary embolism,
– Pulmonary shunt effect with a poorly ventilated area,
– Alveolocapillary block (loss of permeability of the capillary cell);
– With hypercapnia hypoxemia (decreased oxygen, increased carbon dioxide); the total “PCO2 PO2 +” is between 130 and 150 mmHg in the case of:
– Depression of the respiratory centers (acute poisoning, head trauma, encephalitis)
– Paralysis of respiratory muscles,
– Chronic bronchitis with obstruction.
Hypoxia is severe, if PO2 is less than 40 mmHg and SaO2 less than 75%.
Cost:
B100.
Practical advice:
If venipuncture, we quickly realized the error handling to the following results: PO2 40 mmHg; PCO2 45 mmHg; SpO2: 75%; pH 7.35, which are those of a venous and arterial not.