A Prospective Randomized Dose-Finding Study of Intrathecal Opioids for Postoperative Analgesia After Minimally...

Area of Science:

• Anesthesiology
• Pharmacology
• Colorectal Surgery

Background:

• Postoperative pain management is crucial for patient recovery after minimally invasive colorectal surgery.
• Intrathecal analgesia offers targeted pain relief, but optimal dosing for specific agents like morphine and hydromorphone requires precise determination.
• Minimally invasive techniques in colorectal surgery necessitate effective and safe postoperative pain control strategies.

Purpose of the Study:

• To determine the optimal dose of intrathecal morphine and hydromorphone for postoperative analgesia in patients undergoing minimally invasive colorectal surgery.
• To establish the dose effective in 90% of patients (ED90) for achieving specific pain and opioid requirement targets.
• To compare the efficacy and safety profiles of intrathecal morphine versus hydromorphone in this patient population.

Main Methods:

• A double-blinded clinical dosing trial randomized 80 patients to receive either intrathecal morphine or hydromorphone.
• Dosing employed a sequential up-down method with a biased-coin design to adjust subsequent doses based on patient outcomes.
• The primary outcome measured was the ED90, defined by pain scores ≤4 and postoperative opioid use ≤15 oral morphine equivalents at 12 hours.

Main Results:

• The ED90 for both intrathecal morphine and hydromorphone could not be determined within the studied dose ranges.
• The ED50 was determined to be 100 mcg for morphine and 75 mcg for hydromorphone.
• While both agents provided similar pain relief, increased hydromorphone dosage correlated with a higher incidence of moderate to severe pruritus (P=.009).

Conclusions:

• An ED90 for intrathecal dosing of morphine and hydromorphone in minimally invasive colorectal surgery patients could not be established.
• The ED50 for intrathecal morphine and hydromorphone was successfully determined, providing valuable dosing information.
• No serious adverse events were reported, indicating a generally safe profile for the tested intrathecal agents in this context.