Should a 75-year-old man with T2DM, HTN, and stable COPD proceed with elective knee replacement surgery?

Proceed with Elective Knee Replacement Surgery for the 75-Year-Old Man with Stable COPD

The patient should proceed with elective knee replacement surgery (option D) as his COPD is stable and his overall clinical status does not warrant delaying the procedure.

Assessment of Pulmonary Function and Surgical Risk

The patient presents with:

• Stable COPD requiring home oxygen (2L/min)
• FEV1 of 40% of predicted and FEV1/FVC ratio of 0.55 from testing 6 months ago
• Normal vital signs with oxygen saturation of 93% on supplemental oxygen
• Normal complete blood count
• Normal renal function (creatinine 1.30 mg/dL, eGFR 58 mL/min/1.73 m²)

Pulmonary Function Considerations

According to the BTS guidelines 1, patients with FEV1 >40% predicted and transfer factor (TLCO) >40% predicted with oxygen saturation >90% on air are considered average risk for pulmonary resection surgery. While this patient's FEV1 is at the borderline (40% of predicted), several factors support proceeding:

1. The patient has stable respiratory status with adequate oxygenation
2. The procedure is a knee replacement, which carries lower pulmonary risk than thoracic surgery
3. His vital signs are stable and laboratory values are normal

Surgical Timing for Osteoarthritis

The 2023 American College of Rheumatology and American Association of Hip and Knee Surgeons guidelines 1 conditionally recommend:

• Proceeding to total joint arthroplasty without delay for patients with symptomatic moderate-to-severe osteoarthritis for whom nonoperative therapy has been ineffective
• Not delaying surgery for additional nonoperative treatments when a patient has been indicated for surgery

Management Algorithm

1. Preoperative Assessment:

   • Patient's COPD is stable with adequate oxygenation
   • No signs of acute exacerbation or infection
   • Normal laboratory values

2. Risk Stratification:

   • Moderate pulmonary risk due to COPD with FEV1 of 40%
   • Knee replacement is not thoracic or upper abdominal surgery (lower risk)
   • No need for additional pulmonary function testing as recent results are available

3. Perioperative Management:

   • Continue home oxygen therapy
   • Optimize bronchodilator therapy
   • Consider regional anesthesia if possible
   • Implement early mobilization and pulmonary rehabilitation post-surgery

Why Additional Testing Is Not Indicated

• Repeat PFTs (Option A): Not necessary as PFTs from 6 months ago are recent enough and the patient's respiratory status is stable 1. Repeating tests would unnecessarily delay beneficial surgery.

• Arterial Blood Gas (Option C): Not indicated as the patient has stable oxygen saturation and no signs of acute respiratory distress 1.

• Recommending Against Surgery (Option B): Not appropriate as the patient's COPD, while significant, is stable and controlled. The 2023 ACR/AAHKS guidelines 1 support proceeding with surgery for patients with osteoarthritis when nonoperative therapy has been ineffective.

Potential Pitfalls and Caveats

1. Postoperative Monitoring: The patient will require careful monitoring for respiratory complications after surgery due to underlying COPD.

2. Anesthesia Considerations: Regional anesthesia may be preferred over general anesthesia to minimize respiratory complications 2.

3. Diabetes Management: While proceeding with surgery is recommended, the patient's diabetes should be optimized perioperatively as the ACR/AAHKS guidelines conditionally recommend delaying surgery for improved glycemic control 1.

4. Early Mobilization: Critical to implement early postoperative mobilization and pulmonary care to prevent complications.

By proceeding with surgery rather than delaying for additional testing, the patient can receive treatment for his severe osteoarthritis pain, which will likely improve his mobility and quality of life while avoiding unnecessary delays that could lead to further functional decline.