Effects of preoperative intrathecal morphine on postoperative intravenous morphine dosage: a systematic review protocol

Review question/objective: The purpose of this systematic review is to describe the effect of preoperative intrathecal morphine (ITM) on postoperative intravenous (IV) morphine dosage during the first postoperative day. This systematic review will compare the postoperative IV morphine dosage of patients receiving ITM plus morphine morphine-based patient-controlled analgesia (PCA), to patients receiving PCA morphine without ITM. This will establish the magnitude of the postoperative morphine sparing effect of ITM. This review aims to answer the following specific question: In adult abdominal and thoracic surgery patients undergoing general anesthesia (GA), what is the effect of ITM plus PCA morphine, compared to PCA morphine alone, on total IV morphine dosage (in milligrams) during the first 24 hours after surgery?