Patient-controlled analgesia with morphine plus lysine acetyl salicylate

Using a patient-controlled analgesia (PCA) delivery system, we evaluated th e clinical advantages and disadvantages of morphine PCA compared with morph ine plus lysine acetyl salicylate (LAS), a soluble aspirin. After major ort hopedic surgery, 50 adult patients were enrolled in a prospective, randomiz ed, and double-blinded study. When a patient in the recovery room complaine d of pain, an initial dose of morphine or the morphine/LAS mixture was titr ated to achieve analgesia of visual analog score less than or equal to 3 in 30 min. An equivalent volume PCA dose of either morphine 1 mg/mL or morphi ne 0.5 mg + LAS 90 mg/mL was used with a lockout interval of 10 min. Pain s core, patient satisfaction, vital signs, and adverse effects were observed for 48 h. Adequate analgesia (visual analog scale score less than or equal to 3) was achieved with either drug. Morphine consumption in the morphine/L AS group was significantly less than in morphine group (13.9 vs 18.4 mg in 24 h and 24.3 vs 32.4 mg in 48 h). Significantly more sedation was evident with the morphine group (P < 0.05). We conclude that injectable LAS can be used as an effective and safe adjuvant to morphine for PCA. This combinatio n reduces dose requirements of morphine and hence some of its adverse effec ts. Implications: Injectable aspirin could be used as an effective and safe adjuvant to morphine for patient-controlled analgesia. This combination re duces the dose requirement of morphine and therefore some of the morphine-r elated untoward effects.