A nurse is assessing a patient 24 hours after total knee replacement surgery. Which assessment finding requires the most immediate nursing intervention?

Absence of pedal pulses indicates vascular compromise, a surgical emergency requiring immediate intervention to prevent limb loss. Other findings (pain, drainage, swelling) are expected post-op concerns managed with standard care.

Clinical Reasoning and Priority Setting

This question tests your ability to apply the nursing process and prioritize care using a clinical urgency framework. After a total knee replacement (TKR), you must distinguish between expected postoperative findings and complications that signal a threat to limb viability. The key is to identify which assessment finding represents an immediate physiological crisis.

Analysis of Each Option

Option 1: Pain level of 7/10 with movement and 4/10 at rest.
Moderate to severe pain is an expected finding 24 hours after a major orthopedic surgery like a TKR. While pain management is a core nursing responsibility and requires intervention, it is not the most immediate priority when compared to a finding that indicates a loss of arterial perfusion. Pain is a subjective symptom, whereas the absence of pulses is an objective sign of a potentially limb-threatening emergency.

Option 2: Serosanguineous drainage of 50 mL in the surgical drain over 8 hours.
Serosanguineous drainage is a normal and expected type of wound exudate in the early postoperative period. The volume of 50 mL over 8 hours is within an acceptable range for a surgical drain after a TKR. This finding requires continued monitoring and documentation but does not signal an immediate crisis. It is not the priority.

Option 3: Absence of dorsalis pedis and posterior tibial pulses in the affected extremity.
This is the correct answer. The absence of previously palpable pedal pulses is a cardinal sign of acute arterial occlusion. This is a surgical emergency because it indicates a complete cessation of arterial blood flow to the distal extremity. Without immediate intervention, irreversible tissue ischemia, necrosis, and potential limb loss can occur within hours. The 2024 ACC/AHA Guideline for the Management of Lower Extremity Peripheral Artery Disease defines acute limb ischemia (ALI) as a rapid decrease in limb perfusion that threatens limb viability and requires urgent evaluation [3, 4]. The classic presentation includes the "six Ps": pain, pallor, pulselessness, poikilothermia, paresthesia, and paralysis. Pulselessness is the most critical objective finding that confirms a complete loss of arterial inflow. This finding must be reported to the surgeon immediately.

Option 4: Knee circumference increased by 2 cm compared to pre-operative measurement.
An increase in knee circumference indicates postoperative swelling, which is an expected inflammatory response to surgical trauma. A 2 cm increase is a relatively small amount of generalized edema and does not, by itself, suggest compartment syndrome or massive hemorrhage. While the nurse should continue to monitor for excessive swelling, firmness, or disproportionate pain that could indicate a developing compartment syndrome, this finding is a lower priority than the complete loss of arterial flow.

Pathophysiology and Clinical Application
The core concept here is the difference between venous/lymphatic compromise and arterial compromise. Swelling (Option 4) and drainage (Option 2) relate to the venous and lymphatic systems. While a large hematoma could theoretically cause external compression of arteries, a simple 2 cm increase in circumference is not diagnostic of this. In contrast, the absent pulses (Option 3) directly prove that arterial inflow is blocked. This could be due to an embolus, thrombus, or direct arterial injury during the surgery. The clinical priority framework is clear: a threat to arterial perfusion always takes precedence over pain, expected drainage, or mild swelling. The guidelines for managing lower extremity peripheral artery disease emphasize that a rapid clinical assessment for ALI is paramount because the therapeutic window for limb salvage is short [3, 4]. Your immediate action as the nurse is to notify the rapid response team or the attending surgeon without delay, as this patient may require emergent revascularization.