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Abstract
Background and aims Intrathecal morphine (ITM) is effective in treating post-operative pain in major surgery (1). the optimal dose for upper gastrointestinal (GI) surgery remains unknown and beyond a ceiling level, side effects may increase with no additional analgesic benefit. We aimed to evaluate local practice of ITM use in upper GI surgery.
Methods Retrospective data was collected over a 12-month period; cases were identified from theatre controlled-drug registers. All patients undergoing upper GI surgery with complete data sets were included. a Pearson correlation coefficient (R) was calculated for ITM doses and total perioperative opioid consumption (inclusive) and ITM doses and postoperative opioid consumption only. Morphine equivalents were calculated using paindata.org.
Formal ethics approval was not required as the project was service evaluation, as per NHS Health Research Authority (2).
Results 52 cases were included in the analysis; 45 open and 7 laparoscopic. Mean ITM dose 440 mcg (range 300–800 mcg); mean ITM dose/kg 5.69 (range 3.3–10.08). No correlation was found between ITM dose or ITM dose/kg and total perioperative morphine equivalent use, R=0.1811 and R=0.1577, or total postoperative morphine equivalent use, R=0.0542 and R=0.0738. Respiratory depression was reported in 3 cases; these were not dose related.
Post-op morphine (IV equivalent) dose vs intrathecal morphine dose
Total peri-op morphine (IV equivalent) dose vs intrathecal morphine dose
Conclusions There appears to be no correlation between increasing ITM dose, or ITM dose/kg, and reduced perioperative opioid use in patients undergoing upper GI surgery, and no difference in side-effect profiles. With no beneficial reduction in perioperative opioid use demonstrated with higher ITM doses, we suggest use of a standardised dose of ITM in the ERAS pathway for upper GI surgery.