Which of the following parameters is expected to change with a clenched fist during Doppler assessment?

When a patient clenches their fist during Doppler assessment, there is typically an increase in blood flow velocity due to the increased demand for oxygen and nutrients by the muscles engaged in clenching. This demand causes a more pronounced systolic phase and leads to greater variations in blood flow during the cardiac cycle, which is reflected in the pulsatility index.

The pulsatility index is a measure that reflects the changes in blood flow dynamics, influenced by both the heart's pumping action and resistance in the vascular bed. With a clenched fist, resistance can increase initially, but the resulting increased flow, especially in the arterial system, will often lead to a greater degree of pulsatility as vessels react to changes in flow and pressure.

In contrast, other parameters like diastolic flow might not show significant changes or could decrease as blood is preferentially directed during the systolic phase. Blood pressure could also either remain stable or rise, depending on individual cardiovascular responses to muscle exertion. Therefore, the increase in pulsatility index during this activity is anticipated due to the dynamic changes in arterial flow characteristics as a result of muscle contraction.