When do you like to get them? If you have a kid, neonate or otherwise, who comes in with respiratory distress whether it's due to ttnb, rds, or bronchiolitis, and how many hours of steady tugging ( no acute decompensation or change in status) do you let them do before you get an abg to assess acid/base status and co2 levels?
ABGs
- Thread starter TGAmed
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Neonate: when desaturated, ABG is part of your workup. Can help with hashing out PPHN vs. potential cyanotic congenital heart disease. Most blue CHD does not present early (first hours of life) with respiratory distress (in the absence of hypoperfusion). An exception would be TAPVR with obstructed veins which will present like PPHN. Anything that might lead to acidosis will eventually cause some respiratory symptoms (ex. HLHS with a closing ductus will be desaturated and hypoperfused).
Older: bronchiolitis and asthma-not unless the decision has been made to intubate based on clinical symptomatology and you want a baseline gas to guide post intubation vent management. If you are not going to intubate, then ABGs are not a useful tool and can cause more harm than good.
ABGs are more useful when used to detect metabolic derangement (often acidosis when it's a sick patient, though not always). Should always go with a basic metabolic panel at a minimum.
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You should always trust your clinical exam over any blood gas. Example, an asthmatic or bronchiolitic with severe retractions and tachypnea to the 80s needs to be intubated, even if the blood gas is normal (because it should show respiratory alkalosis in a patient with normal gas exchange and a respiratory rate in the 80s)
Blood gases are generally only helpful when you are on the fence in the non-intubated patient or if there is a metabolic reason for acidemia (DKA, branch-chain acidemias, MELAS, etc.)
Blood gases are generally only helpful when you are on the fence in the non-intubated patient or if there is a metabolic reason for acidemia (DKA, branch-chain acidemias, MELAS, etc.)
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Specific to neonates, both preterm and term, consider why you want to get an arterial sample and how you will obtain it. Assuming one isn't far enough along in the course of the disease to have an arterial line (UAC or peripheral), then it requires a stick. This is not all that easy to do in a tiny baby and also tends to lead itself to a drop in oxygenation, especially if one misses the first try.
If the issue is ventilation and pH, then a warmed capillary blood gas may suffice, especially if done by someone who knows how to do it properly. If the issue is overall respiratory status in a newborn infant, often in the first hours of life a pulse oximeter and a capillary gas will suffice. If the infant is getting sicker or there is serious concern of pulmonary hypertension, then a true peripheral ABG can be tried, but often it is most effective to place an arterial line in that circumstance.
Regardless, I do agree that in most circumstances, clinical judgment is important and blood gas results shouldn't be relied upon over that judgment. However, knowing pH is helpful clinically and certainly as oxygen requirements increase about 40-50% via hood, etc, a true arterial paO2 is helpful along with the pH.
If the issue is ventilation and pH, then a warmed capillary blood gas may suffice, especially if done by someone who knows how to do it properly. If the issue is overall respiratory status in a newborn infant, often in the first hours of life a pulse oximeter and a capillary gas will suffice. If the infant is getting sicker or there is serious concern of pulmonary hypertension, then a true peripheral ABG can be tried, but often it is most effective to place an arterial line in that circumstance.
Regardless, I do agree that in most circumstances, clinical judgment is important and blood gas results shouldn't be relied upon over that judgment. However, knowing pH is helpful clinically and certainly as oxygen requirements increase about 40-50% via hood, etc, a true arterial paO2 is helpful along with the pH.