Shunts might be produced in this setting by:
- Large cardiac defects
- Pulmonary vascular defects
- Lung tissue that is perfused but not ventilated
In a shunt of this size, the first two possibilities should produce sounds (bruits or murmurs) clearly
distinguishable on ausculation of the heart and lung fields (these sounds were not present in this infant).
As an aside, would you expect a large patent ductus arteriosus to produce a blood gas pattern like this in
an infant? Could the pattern change if the defect persisted into later life?
I'll let you figure this one out on your own. If you really get stuck, send me email--J. Harrison
