You obtain this information when assessing a 3-year-old with uncorrected tetralogy of Fallot who is crying. Which finding requires immediate action?
1) The apical pulse rate is 118 beats/min.
2) A loud systolic murmur is heard in the pulmonic area.
3) There is marked clubbing of all of the child's nail beds.
4) The lips and oral mucosa are dusky in color.