Some Challenges of Postoperative Pain Treatment
Acta Universitatis Tamperensis, No 1580

By Pia Puolakka
Febuary 2011
Tampere University Press
Distributed by Coronet Books Inc.
ISBN: 9789514483165
104 pages
$84.50 Paper Original

Multimodal analgesia is recommended after surgery to reduce the consumption of opioids. The efficacy of nonsteroidal anti-inflammatory drugs (NSAID) has been demonstrated, but they have certain adverse effects on haemostasis of gastric mucosa and platelet function. These adverse effects could be avoided by replacing NSAIDs with cyclo-oxygenase (COX)-2 inhibitors. In any case, the renal adverse effects of COX-2 inhibitors are thought to be equal to those of NSAIDs, but this is only poorly documented.

High prevalence of persistent pain has been documented after various operations. Numbers from orthopaedic surgery have varied between ten and 60%. Pain is mostly the main indication for knee replacement surgery. The evaluation of the prevalence of persistent pain among these patients is important, even as an outcome of the surgery itself. Underlying risk factors should be known to be affected.

The aim of this thesis was to study the efficacy and safety of coxibs in perioperative use and the prevalence and risk factors of persistent pain after total knee replacement. The efficacy studies (I-II) were prospective, randomized, double-blinded and placebo controlled. All the patients were undergoing laparoscopic cholecystectomy. Parecoxib 40mg or 80mg was given intravenously at the end of the procedure (I). Etoricoxib 120mg was given alone or in combination with paracetamol 1000mg as a part of premedication (II). The primary endpoint was to compare opioid consumption between the groups. The total number of patients was 148. Renal adverse effects of parecoxib were studied in patients undergoing laparoscopic surgery as a physiological stressful model with sensitive markers (III). The patients (15) enrolled were undergoing laparoscopic hysterectomy and received parecoxib 80mg intravenously at the beginning of anaesthesia. This prospective study was also double-blinded and placebo controlled.

Persistent pain after total knee replacement was studied by a questionnaire sent to all patients operated on the period from September 2002 to February 2004. Multivariate logistic regression analysis was performed to test assumed risk factors. The type of operation (primary, bilateral or revision) was assumed to influence the prevalence of persistent pain.The total number of patients recruited was 855.

Opioid sparing effect was evident with etoricoxib, but adding paracetamol to etoricoxib or giving parecoxib at the end of surgery did not show any opioid sparing effect. In any case, the worst pain score on the ward was significantly lower in the parecoxib 80mg treated group than in the placebo group. Parecoxib 80mg was also well tolerated in Study III. The sensitive markers of both glomerular and tubular damage did not differ significantly between the groups. The response rate of the questionnaire was 65.7%. Prevalence of persistent pain after knee replacement surgery was 21.5% at rest and 29.8% during exercise. The risk factors for persistent pain were female gender, adjusted age, duration of pain (more than twelve months) prior to surgery and intensity of pain (more than mild) during the first postoperative week. The type of surgery did not influence the prevalence of persistent pain.

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