Just mentioning congenital heart disease (CHD) to most physicians causes an involuntary tightening of muscles in regions we dare not mention; yet, given the fact you are often the only one standing at the bedside, you have learned to work through the reflexive desire to run and hide in the closet (perhaps I am only speaking for myself). So when that hypoxic neonate presents in your ED, while you want to blame it on the lungs (“it is likely bronchiolitis”) or sepsis (it most often is), make sure you consider CHD.
Congenital Heart Disease (CHD)
- can be grossly separated into two groups: Cyanotic and Acyanotic
The Hyperoxia Test
- often spoken of) can help begin to differentiate hypoxia due to cardiac vs. noncardiac etiologies (but it isn’t the end of the story).
- Traditional teaching:
- Check ABG from right arm (pre-ductal) on Room Air.
- Place patient on 100% oxygen for 10 minutes.
- Check ABG from right arm while on 100% oxygen.
- If PaO2 on second ABG is less than 100 mgHg, then CHD is likely present
- If PaO2 on second ABG is greater than 200 mmHg, then respiratory issue likely exists.
- The problem(s) with this test:
- It is two ABGs in a tiny neonate who is sick… not the easiest thing in the world to do.
- Even if you are the ABG Master, this still takes time to do.
- Isn’t perfect…
- Kids with CHD may still have increases in PaO2, so it may be falsely normal.
- Kids with very bad pulm disease (Pulm hypertension) can have low PaO2, so it may be falsely abnormal.
- Another approach:
- Use the pulse Ox to determine whether there was any response to your increased oxygen.
- Be Careful: This is not the same as the Hyperoxia Test and has even more room for error, but it can be useful and will likely be what you are doing anyway.
- Consider: The child comes in hypoxic (Pulse Ox in 70’s), you will naturally want to give Oxygen (or one of your proficient nurses will). With the pulse ox, you can note whether there are no changes despite the big change (from 21% to 100%) in FiO2. No change should make you consider CHD much more rapidly and order the PGE1 early!
- If there is a significant change in pulse ox, you still may have CHD causing a shunt [an infant receiving 100% inspired oxygen may have an arterial PO2 of 80 mmHg (which would be abnormal) or an arterial PO2 of >500 mmHg (which would be normal), both leading to a pulse ox reading of 100%], but you have bought yourself time to think more.
- Now you can check you Pre-Ductal Sats (right arm) and Post-Ductal Sats (lower extremity), Upper and Lower limb blood pressures, CXR, and ECG.
- If you are still considering CHD, first, order your PGE1 and consult a peds cardiologist to get he ball rolling for an echo.
- Then you can go ahead and check the ABG in the right arm will on 100% oxygen (the kid will thank you for not going back to room air and you won’t mess up your Hyperoxia Test terribly).
BUT ABOVE ALL, don’t be afraid to start the prostaglandins in the neonate who presents in shock!
** PGE1 0.05 mcg/kg bolus, followed by 0.05mcg-0.1mcg/kg/min.