At this point we need to remember the Alveolar-arterial A-a gradient. This may be acute, chronic or acute on chronic.
Patients may walk around with a fully compensated Type 2 Respiratory Abg ten such as COPD but then decompensate and become acidotic again despite the raised bicarbonate - acute on chronic failure.
The oxygen content and the percentage saturation of arterial blood taken at close intervals from three different peripheral arteries of a normal individual have shown values agreeing within the limits of error, Abg ten.
Abg ten can be none, partial there is an attempt but pH remains deranged or full pH back within normal limits, Abg ten. Make sure the FiO2 or oxygen delivery is documented on the gas. Causes of Type 2 Respiratory Failure can be pulmonary such as COPD ; peripheral such chest wall deformities or peripheral nervous diseases such as Motor Neuron Disease or central such as overdose of opiates or benzodiazepines causing respiratory depression.
I find this is a very quick way of identifying the cause, being aware of course that you can have Abg ten acidosis due to combined high PaCO2 and low bicarbonate and mixed alkalosis low PaCO2 and high bicarbonate, Abg ten. In three persons with severe anemia the saturation of the arterial blood has not differed from the normal.
The carbon dioxide content of the arterial blood from ten normal individuals has varied between That of the venous blood has varied between No deviations from the normal values for oxygen and Abg ten dioxide were found in venous and arterial blood from cardiac patients without arrhytiunias, well compensated, Abg ten, and at rest in bed.
This is the gradient between the PaO2 of inspired air and that in the blood, Abg ten. This process takes days to hours.
Robot or human?
The percentage saturation of the arterial blood has varied between and The Abg ten is The oxygen consumption has varied between 2. Analyses of the blood gases of a normal individual, Abg ten, at rest and after exercise, have shown a lowering of the percentage oxygen saturation of the arterial blood and a diminished carbon dioxide content after exercise.
If the problem is respiratory then there will be metabolic compensation compensating high PaCO2 with high bicarbonate and Abg ten versa - this takes a long time remember. The raised PaCO2 will lower pH acutely; the blood will respond by buffering this by increasing bicarbonate production in the kidneys. In a healthy adult it should be about mmHg. PaCO2: 4. CO2 is acidic when dissolved in solution.
Life's A (Blood) Gas — Take Aurally
Increasing respiration rate blows off CO2 while reducing respiration rate means we retain CO2, Abg ten. PaO2: Abg ten if this is low then the patient is hypoxia - this is cause of cardiac arrest and so must be identified early. Why is it important?
Very low absolute values were found for the oxygen content of the venous blood, but the normal oxygen consumption has been maintained. Chronic Type 2 Respiratory Failure fully compensated :.
Once you're happy with the ABG being for the right patient etc it's now time to first look at the pH - is it normal, Abg ten, high alkalotic or low acidotic? If the BE is below -2 then the patient has a base deficit and so has metabolic acidosis. Abg ten the amount of bicarbonate however takes hours to days whereas it's almost instantaneous to alter respiration rate.
