title: Pain is difficult to measure.
authors: C W
authors: CW
authors: Birch
authors: A J
authors: AJ
authors: McLintic
mesh_terms: D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use*; D010147:Pain Measurement / Q000379:methods*; D020250:Postoperative Nausea and Vomiting / Q000517:prevention & control; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine