What is the recommended dosage of levobupivacaine for a subarachnoid block in an elderly woman scheduled for right partial hip arthroplasty?

Dosage of Levobupivacaine for Subarachnoid Block in Elderly Patients Undergoing Hip Arthroplasty

For an elderly woman undergoing right partial hip arthroplasty, a lower dose of intrathecal levobupivacaine (< 10 mg) is recommended to reduce the risk of hypotension while providing adequate anesthesia. 1

Dosage Recommendation

The optimal dosage for subarachnoid block with levobupivacaine in elderly patients undergoing hip arthroplasty should follow these guidelines:

• Recommended dose: 7.5-10 mg of levobupivacaine 0.5%
• Consider using the lower end of this range (7.5 mg) for very elderly or frail patients
• Position patient laterally with the operative (right) hip uppermost during administration

Rationale for Lower Dosage

Lower doses of intrathecal local anesthetic are particularly important in elderly patients for several reasons:

• Reduced doses (< 10 mg) significantly decrease the incidence of hypotension 1
• Elderly patients have limited physiological reserve and often multiple comorbidities 1
• Hemodynamic stability is crucial for reducing morbidity and mortality
• Research shows that levobupivacaine provides better hemodynamic stability compared to bupivacaine, with significantly lower incidence of intraoperative hypotension (13.3% vs 38.3%) 2

Administration Technique

1. Position the patient in lateral decubitus position with the operative (right) side uppermost
2. Perform lumbar puncture at L3-L4 or L4-L5 interspace
3. Inject levobupivacaine slowly
4. Consider using hyperbaric technique by positioning the patient with the fractured hip inferior to ameliorate hypotension 1
5. Always provide supplemental oxygen during the procedure 1

Adjuncts to Consider

• Intrathecal opioid: Consider adding fentanyl (10-25 μg) to prolong postoperative analgesia
  • Fentanyl is preferred over morphine or diamorphine due to lower risk of respiratory depression and cognitive dysfunction in elderly patients 1
• Peripheral nerve block: Consider femoral nerve or fascia iliaca block as an adjunct to extend the period of postoperative non-opioid analgesia 1
• Avoid: Sedation should be used cautiously in the very elderly as it may increase the risk of postoperative confusion 1

Monitoring Requirements

• Continuous presence of the anesthetist
• Pulse oximetry, capnography, ECG, and non-invasive blood pressure monitoring
• Core temperature monitoring
• Consider invasive blood pressure monitoring for patients with limited left ventricular function or valvular heart disease 1

Common Pitfalls and Caveats

• Hypotension: The most common adverse event with levobupivacaine (reported in up to 31% of patients) 3

  • Have vasopressors readily available
  • Consider pre-loading with crystalloid fluids
  • Monitor blood pressure frequently

• Dosage individualization: While standard dosing guidelines are provided, be aware that the ideal dose may vary based on the patient's age, height, weight, and comorbidities

• Cognitive effects: Prolonged recovery time from motor block can cause cognitive alterations in elderly patients 4, so using the minimal effective dose is crucial

• Positioning: Proper positioning during administration can affect the spread of anesthetic and impact hemodynamic stability

By following these recommendations, you can provide effective anesthesia for hip arthroplasty while minimizing the risk of complications in elderly patients.