After surgical repair of Tetralogy of Fallot, which finding most suggests low cardiac output?

• A. Bounding pulses and mottled skin
• B. Altered level of consciousness and thready pulses
• C. Capillary refill 2 seconds and BP 96/67 mm Hg
• D. Extremities warm to the touch and pale skin

Answer: (B)

After tetralogy of Fallot repair, recognizing low cardiac output hinges on perfusion status. Changes in mental status reflect reduced cerebral perfusion, which can occur quickly when cardiac output falls. Thready, weak pulses indicate diminished stroke volume and overall systemic perfusion.

The combination of an altered level of consciousness and thready pulses most strongly signals low cardiac output because it directly links brain perfusion with weak peripheral perfusion. The other options are less specific: bounding pulses with mottled skin can be inconsistent with low output, normal-capillary refill and a reasonable blood pressure don’t point to inadequate perfusion, and warm extremities with pale skin suggest better perfusion or peripheral vasodilation rather than poor cardiac output.