What is the recommended anesthesia plan for a 75-year-old male patient with obesity, diabetes, and poorly controlled Obstructive Sleep Apnea (OSA) who recently stopped using Continuous Positive Airway Pressure (CPAP) therapy and is undergoing a left total knee arthroplasty?

Anesthesia Plan for a 75-Year-Old Male with Obesity, Diabetes, and Poorly Controlled OSA Undergoing Left Total Knee Arthroplasty

For this high-risk patient with multiple comorbidities, a regional anesthesia technique with neuraxial anesthesia (spinal) combined with peripheral nerve blocks should be the primary approach, avoiding general anesthesia if possible to minimize respiratory complications. 1

Pre-operative Considerations

• Assume this patient has significant sleep-disordered breathing due to his poorly controlled OSA and recent CPAP discontinuation 1
• Ensure CPAP machine is available for immediate postoperative use 1
• Site two intravenous cannulae while in pre-op area; ultrasound guidance may be necessary due to obesity 1
• Consider unusual sites for IV access such as upper arm or anterior chest wall if needed 1

Anesthetic Technique

Primary Approach: "SDB-Safe" Anesthetic

• Spinal anesthesia with an opioid adjunct (low-dose intrathecal morphine) as the primary anesthetic technique 1, 2
• Continuous adductor canal block for postoperative analgesia rather than femoral nerve block to preserve quadriceps function 2
• If general anesthesia becomes necessary:
  • Use short-acting agents only 1
  • Employ depth of anesthesia monitoring to limit anesthetic load 1
  • Choose desflurane over sevoflurane for faster emergence and return of airway reflexes 1

Intraoperative Management

• Position in slight head-up/sitting position to improve respiratory mechanics 1
• If mechanical ventilation required, use pressure-controlled ventilation with sufficient PEEP and recruitment maneuvers to reduce atelectasis 1
• Implement neuromuscular monitoring to maintain appropriate block level and ensure complete reversal 1
• Administer multimodal non-opioid analgesia:
  • Periarticular local anesthetic infiltration by surgeon 3, 4
  • IV acetaminophen 3
  • COX-2 inhibitor (if no contraindications) 3
  • Ketamine (low dose) 5
  • Dexamethasone 3

Emergence Plan

• Have nasopharyngeal airway available before emergence to mitigate partial airway obstruction 1
• If general anesthesia was used:
  • Ensure complete reversal of neuromuscular blockade using quantitative monitoring 1
  • Extubate only when patient is fully awake with return of airway reflexes 1
  • Perform extubation with patient in sitting position 1

Postoperative Care

• Reinstate CPAP therapy immediately in PACU 1
• Provide supplemental oxygen via CPAP mask if needed 1
• Implement multimodal opioid-sparing analgesia:
  • Continue peripheral nerve block 2
  • Scheduled acetaminophen and NSAIDs (if not contraindicated) 3
  • Avoid intramuscular injections due to unpredictable pharmacokinetics in obesity 1

PACU Monitoring and Discharge Criteria

• Observe patient while unstimulated for signs of hypoventilation, apnea, or hypopnea 1
• Monitor oxygen saturation continuously 1
• Transfer to ward only when:
  • Routine discharge criteria are met 1
  • Respiratory rate is normal with no periods of apnea for at least one hour 1
  • Oxygen saturation returns to pre-operative values 1

Ward Care

• Consider level-2 care (step-down unit) if:
  • Long-acting opioids are required 1
  • Patient-controlled analgesia is needed 1
• Continue oxygen therapy until baseline saturations are maintained without supplementation 1
• Continue pulse oximetry until oxygen saturations remain at baseline and parenteral opioids are no longer required 1
• Implement early mobilization as part of enhanced recovery protocol 1

Special Considerations and Pitfalls

• Avoid patient-controlled analgesia if possible due to increased risk of respiratory depression; if required, use only with increased monitoring in level-2 care 1
• Be vigilant for postoperative tachycardia as it may be the only sign of a complication 1
• Recognize that anesthetic type (regional vs. general) has not shown significant differences in outcomes specifically for OSA patients undergoing TKA, but regional techniques generally offer advantages for respiratory function 6