Final answer:
Swelling of the extremity with the fistula and warmth and erythema over the fistula site are signs that require intervention by the nurse as they may indicate serious complications such as a blocked fistula or infection.
Step-by-step explanation:
When a nurse is caring for a client with an arteriovenous fistula for dialysis, certain observations require intervention. A bruit over the fistula site and a thrill over the fistula site are generally expected findings as they represent the sound and feel of blood rushing through the fistula, respectively. However, swelling of the extremity with the fistula and warmth and erythema over the fistula site are cause for concern and require intervention by the nurse.
Swelling in the extremity can be indicative of a blocked fistula or venous hypertension, prompting the need to assess for potential complications and, if necessary, refer for further intervention. Warmth and erythema, similar to that seen in a case of localized infection, such as the one described with Barbara, or more severe conditions such as the necrotizing fasciitis experienced by Mark, suggest an infection at the site of the fistula, which is a serious complication that requires immediate treatment to prevent further complications such as sepsis.