A 38-year-old woman with a BMI of 32 kg/m² undergoes open abdominal hysterectomy under general anesthesia. Postoperatively, she is prescribed intravenous patient-controlled analgesia (IV-PCA) with morphine. The PCA settings are: demand dose 2 mg, lockout interval 10 minutes, 4-hour limit 30 mg, and background infusion 1 mg/hour. On postoperative day 2, the patient reports inadequate pain control despite pressing the demand button frequently. Nursing notes indicate she has been pressing the button 8–10 times per hour but receiving medication only once per 10-minute lockout period. Her respiratory rate is 16/min, SpO₂ is 96% on room air, and she is alert and oriented. Which modification to the PCA regimen is most appropriate?