Prediction of post-operative pain by an electrical pain stimulus
Version of Record online: 5 APR 2007
2007 Acta Anaesthesiol Scand
Acta Anaesthesiologica Scandinavica
Volume 51, Issue 5, pages 582–586, May 2007
How to Cite
Nielsen, P. R., Nørgaard, L., Rasmussen, L. S. and Kehlet, H. (2007), Prediction of post-operative pain by an electrical pain stimulus. Acta Anaesthesiologica Scandinavica, 51: 582–586. doi: 10.1111/j.1399-6576.2007.01271.x
- Issue online: 5 APR 2007
- Version of Record online: 5 APR 2007
- Accepted for publication 6 January 2007
- Caesarean section;
- pre-caesarean section;
- pain threshold;
- electrical pain threshold;
- pre-operative pain;
- post-operative pain;
- visual analogue scale
Background: Treatment of post-operative pain is still a significant problem. Recently, interest has focused on pre-operative identification of patients who may experience severe post-operative pain in order to offer a more aggressive analgesic treatment. The nociceptive stimulation methods have included heat injury and pressure algometry. A simple method, Pain Matcher® (PM), using electrical stimulation, is validated for pain assessment, but has not been evaluated as a tool for prediction of post-operative pain. Our aim was to assess the predictive value of pre-caesarean section pain threshold on intensity of post-caesarean section pain using the PM.
Patients and methods: Thirty-nine healthy women scheduled for elective caesarean section were studied. The anaesthetic/analgesic procedures included spinal anaesthesia, paracetamol, diclofenac, controlled-release (CR) oxycodone and morphine on request. Pre-operatively, the sensory and pain thresholds were measured using the PM. Post-operatively, a midwife, blinded for pre-caesarean pain threshold assessments, assessed the pain at rest and during mobilization every 12 h for 2 days. Consumption of analgesics was also recorded.
Results: Pre-operative pain threshold correlated significantly with post-caesarean pain score (VAS) at rest and mobilization: [Spearman’s rho =–0.65 (–0.30 to –0.75), P < 0.01] and [Spearman’s rho =–0.52 (–0.23 to –0.72), P < 0.01], respectively. There was no significant correlation between pre-operative PM assessment of sensory threshold and post-operative pain.
Conclusion: Electrical pain threshold before caesarean section seems to predict the intensity of post-operative pain. This method may be used as a screening tool to identify patients at high risk of post-operative pain.