When to use 02 on a newborn

CCHD is the acronym for critical congenital heart defect. Neonates are being discharged home earlier and earlier, resulting in a rise in the number of newborns rapidly decompensating at home. Some of these babies die needlessly and others have much more complicated courses than those diagnosed prenatally or within the first 2 days of life. The American Association of Pedatrics has developed a screening process to reduce the odds of this happening. FAQs about the program are here: Newborn Screening for CCHD

Now to respond to the OP. The screening is done after 24 hours of life, or just before discharge if the baby is going home before they reach 24 hours. Pulse oximetry is measured on the right hand and both feet in a CCHD screen. If possible they should be recorded simultaneously, but sequentially is permitted where resources require it. If the sats are > 95% and the difference between the right hand and foot is 90% but 3% they're to be rechecked in one hour. Which is what happened with your baby. Rarely, some babies need three separate screens, each an hour apart to ensure validity. If after the third screen the sats are still > 90% but

So let's think about the physiology of this screening. Why do we check right hand and both feet? Think about fetal circulation. In the first hours of life, partial pressures of oxygen and carbon dioxide shift as blood is finally allowed to circulate to the lungs. These partial pressure changes are responsible for the closure of the ductus arteriosus and the foramen ovale. Once these structures close, there is normally no shunting of deoxygenated blood into the systemic circulation or of oxygenated blood into the pulmonary circulation. The right hand is pre-ductal and the lower limbs are post-ductal. If there's a right-to-left (blue to red) shunt then there will be a difference between upper and lower limb saturations with the hand being higher than the feet. The opposite is noted in defects creating a left-to-right (red-to-blue) shunt, seen in defects such as coarctation of the aorta or Interrupted Aortic Arch with concurrent Transposition of the Great Arteries. Cyanotic defects include Patent Foramen Ovale, Patent Ductus Arteriosus, Tetralogy of Fallot, Transposition of the Great Arteries, Pulmonary Atresia, Total Anomalous Pulmonary Venous Return, Hypoplastic Left Heart Syndrome and a few others. (I've capitalized the letters that compose the acronyms of these defects for clarity.)

The use of oxygen in the neonate with CCHD is contraindicated in any of the defects creating a right-to-left shunt because it speeds up the closure of the ductus and foramen ovale, thereby drastically reducing the amount of oxygenated blood circulating through all areas of the body. Once these shunts are closed, PaO2 falls fast, while PaCO2 rises. Anaerobic metabolism causes a rapid rise in lactic acid and severe acidosis follows. Hard on the heels of a rising lactate comes circulatory collapse. This is what happens to those babies who have gone home undiagnosed, and it's why the screening program requires three failed sat tests before interventions are initiated. Without rapid access to a tertiary care NICU these babies will die. Initial treatment includes a continuous infusion of Prostin (alprostadil or PGE2) to maintain or reopen those shunts (closure isn't usually irreversible for about a week), fluid resuscitation, reversal of acidosis and diagnostic imaging. Accepting lower sats is the norm. Even in post-operative children with HLHS we're happy with sats of 80-90% - because they're shunt-dependent.

I think my reply is a lot more information than you were seeking, but I feel it's important to understand the whys as well as the whats.

The screening is usually only done on "normal, healthy" newborns who are being discharged home so it's no surprise you haven't heard about it before. I wish there was some sort of universal screening program like this in Canada. My unit is the busiest pediatric cardiovascular ICU in the country and some of the kids who slip by and come in shocky and near death are the scariest patients I've ever seen. The last code I was involved in was one of these - a 7 month old with ALCAPA (aberrant left coronary artery to pulmonary artery) who crashed right after that very first echo.

I know what CCHD is and why we do it. It was the full term newborn's first screen so it was done in the hospital at around 40 hours of life. Again I will ask should O2 have been put on the baby even though she was asymptomatic?

I guess you stopped reading my post above, the longer one. I explained why O2 wasn't indicated for this baby in it.