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Difficulty: MediumSurgical and Procedural Interventions

A 62-year-old woman presents to the preoperative clinic for evaluation ahead of an elective right hemicolectomy scheduled in seven days. The surgery is indicated for a large, flat cecal adenoma that was unamenable to endoscopic resection. Her medical history includes a mechanical mitral valve replacement performed five years ago, type 2 diabetes mellitus, hypertension, and stage 3 chronic kidney disease. She leads an active lifestyle and reports walking at least two miles daily without experiencing chest pain, shortness of breath, or fatigue. Current medications include warfarin, metformin, and lisinopril. Vital signs are within normal limits. Laboratory studies reveal a serum creatinine of 1.5 mg/dL, an INR of 2.8, and an HbA1c of 7.1%. Which of the following procedural and perioperative management steps are indicated for this patient? (Select all that apply)

  1. Stop warfarin five days before surgery and initiate bridging therapy with low-molecular-weight heparinAnswer
  2. Withhold the morning dose of lisinopril on the day of the procedureAnswer
  3. C
    Discontinue warfarin two days prior to the surgery to ensure normalization of the prothrombin time
  4. D
    Instruct the patient to take her usual dose of metformin with a small sip of water on the morning of surgery
  5. E
    Order a preoperative myocardial perfusion imaging study for cardiovascular risk stratification

Answer

The indicated steps are to stop warfarin five days prior to surgery while initiating a low-molecular-weight heparin bridge, and to withhold the morning dose of lisinopril on the day of the procedure.
Appropriate perioperative management requires optimizing safety by balancing surgical bleeding risk with thromboembolic and physiologic risks. For a patient with a mechanical mitral valve (high thromboembolic risk), warfarin must be stopped 5 days prior to surgery to allow the INR to normalize, with a parenteral anticoagulant bridge instituted in the interim. Additionally, ACE inhibitors like lisinopril are generally held the morning of surgery to prevent severe, refractory hypotension during the induction and maintenance of general anesthesia.

Step-by-Step Solution

1
Assess the patient's thromboembolic risk to determine the need for anticoagulation bridging.
The patient has a mechanical mitral valve, placing her in a high-risk category for arterial thromboembolism.
High-risk conditions dictate that the patient cannot be off anticoagulation for a prolonged period, necessitating a bridge with LMWH or unfractionated heparin.
2
Determine the appropriate timeline for warfarin cessation.
Warfarin must be discontinued 5 days before the scheduled surgery.
It takes approximately 5 days for the synthesis of new vitamin K-dependent factors to normalize the INR to a safe level (<1.5) for major abdominal surgery.
3
Evaluate the patient's daily medications for preoperative continuation or cessation.
Lisinopril and metformin should both be withheld on the morning of surgery.
ACE inhibitors can cause severe intraoperative hypotension, and metformin poses a risk of hypoglycemia and lactic acidosis while the patient is fasting.
4
Evaluate the need for preoperative cardiac testing based on functional status.
No further cardiac testing is needed.
The patient is asymptomatic and achieves >4 METs (walking 2 miles daily), meaning she can proceed directly to intermediate-risk surgery without a stress test.

Key Concept

Preoperative management of chronic medications and risk stratification, including anticoagulation bridging for mechanical heart valves and withholding appropriate antihypertensives/hypoglycemics.
Estimated Time:1m 30s
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Topics

Surgical and Procedural Interventions

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