Which device is commonly used to assess a child with Tetralogy of Fallot?

A pulse oximeter is the correct choice for assessing a child with Tetralogy of Fallot because this device measures the oxygen saturation level in the blood. Children with this congenital heart defect often experience low oxygen levels due to the mixing of oxygenated and deoxygenated blood caused by the structural abnormalities of the heart. Monitoring oxygen saturation helps healthcare providers evaluate the severity of the condition, determine if the child is experiencing cyanotic spells (often described as "tet spells"), and decide on interventions that may be needed to ensure adequate oxygenation.

The other devices mentioned serve different purposes. A blood pressure cuff measures blood pressure but does not provide information on oxygen saturation. A stethoscope is used for auscultation of heart sounds and lung sounds, which can give insights into cardiovascular and respiratory status but does not specifically assess oxygen levels. A glucose meter is designed for measuring blood glucose levels, which is unrelated to the assessment of cardiac conditions. Thus, the pulse oximeter is the most relevant and commonly used device in this context.