A 4-day-old with a "forward bend pose"

You look at the baby and note that she is jaundiced. You take her from her mother's arms and perform a full exam. The first thing that you notice is how completely floppy she feels. The remainder of her exam is significant for a 2/6 systolic ejection murmur and a poor unsustained suck. Her vitals are: temperature 97.4° F, respiration 35 bpm, heart rate 119 bpm, and 99% saturation on room air. Since you woke up the baby, mom decides to feed her. It takes a lot of effort to feed the baby, and to keep her awake. During the feeding, the O₂ saturation monitor alarms, and you look up to see her oxygen saturation has dropped to 50%. The baby appears cyanotic. You calmly ask mom to stop feeding the baby, suction out the baby's mouth, and give her a little blow-by oxygen. You are able to quickly wean the oxygen.

Family history

The baby lives with her parents and her healthy eight-year-old sister in a Chinatown apartment. The baby had an uneventful nursery stay, and was discharged home on day of life two. Mom explains that she started to worry when she began having a harder time waking the baby to feed. She never noticed the baby having any episodes of choking or turning blue. Your pager goes off, and you excuse yourself for a moment.

As you head to the phone you think about the symptoms...jaundice, poor suck, increased sleepiness, poor tone, heart murmur, and episode of desaturation while feeding. Sepsis could be the cause of all the symptoms. But what else could it be?