BACKGROUND:
Chronic pain and opioid consumption may trigger diffuse hyperalgesia, but their relative contributions to pain vulnerability remain unclear.
OBJECTIVES:
To assess preoperative opioid-induced hyperalgesia and its postoperative clinical consequences in patients with chronic pain scheduled for orthopaedic surgery.
DESIGN:
A prospective observational... + Leer más
BACKGROUND:
Chronic pain and opioid consumption may trigger diffuse hyperalgesia, but their relative contributions to pain vulnerability remain unclear.
OBJECTIVES:
To assess preoperative opioid-induced hyperalgesia and its postoperative clinical consequences in patients with chronic pain scheduled for orthopaedic surgery.
DESIGN:
A prospective observational study.
SETTINGS:
Raymond Poincare teaching hospital.
PATIENTS:
Adults with or without long-term opioid treatment, scheduled for orthopaedic surgery.
PRIMARY OUTCOME MEASURE:
Preoperative hyperalgesia was assessed with eight quantitative sensory tests, in a pain-free zone.
SECONDARY OUTCOME MEASURES:
Postoperative morphine consumption and pain intensity were evaluated using a numerical rating scale (NRS) in the recovery room and during the first 72 h.
RESULTS:
We analysed results from 68 patients (28 opioid-treated patients and 40 controls). Mean daily opioid consumption was 42 ± 25 mg of morphine equivalent. The opioid-treated group displayed significantly higher levels of preoperative hyperalgesia in three tests: heat tolerance threshold (47.1°C vs. 48.4°C; P = 0.045), duration of tolerance to a 47°C stimulus (40.2 vs. 51.1 s; P = 0.03) and mechanical temporal summation [1.79 vs. 1.02 (ΔNRS10-1); P = 0.036]. Patients in the opioid-treated group consumed more morphine (19.1 vs. 9.38 mg; P = 0.001), had a higher pain intensity (7.6 vs. 5.5; P = 0.001) in the recovery room and a higher cumulative morphine dose at 72 h (39.8 vs. 25.6 mg; P = 0.02).
CONCLUSION:
Chronic pain patients treated with low doses of opioid had hyperalgesia before surgery. These results highlight the need to personalise the management of patients treated with opioids before surgery
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