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Prediction of post-operative pain by an electrical pain stimulus

Authors

  • P. R. Nielsen,

    Corresponding author
    1. 1Department of Anaesthesia, Centre of Head and Orthopaedics, Rigshospitalet, University of Copenhagen, 2Clinical Unit of Health Promotion/WHO Collaborating Centre for Evidence-Based Health Promotion in Hospitals, Bispebjerg Hospital, University of Copenhagen, 3Department of Gynaecology and Obstetrics and 4Section for Surgical Pathophysiology, Juliane Marie Centre, Rigshospitalet, University of Copenhagen, Denmark
      Per Rotbøll Nielsen
      Department of Anaesthesia
      Centre of Head and Orthopaedics
      Rigshospitalet
      University of Copenhagen
      Blegdamsvej 9
      DK-2100 Copenhagen
      Denmark
      e-mail: per.rotboell.nielsen@rh.regionh.dk
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  • 1,2 L. Nørgaard,

    1. 1Department of Anaesthesia, Centre of Head and Orthopaedics, Rigshospitalet, University of Copenhagen, 2Clinical Unit of Health Promotion/WHO Collaborating Centre for Evidence-Based Health Promotion in Hospitals, Bispebjerg Hospital, University of Copenhagen, 3Department of Gynaecology and Obstetrics and 4Section for Surgical Pathophysiology, Juliane Marie Centre, Rigshospitalet, University of Copenhagen, Denmark
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  • 3 L. S. Rasmussen,

    1. 1Department of Anaesthesia, Centre of Head and Orthopaedics, Rigshospitalet, University of Copenhagen, 2Clinical Unit of Health Promotion/WHO Collaborating Centre for Evidence-Based Health Promotion in Hospitals, Bispebjerg Hospital, University of Copenhagen, 3Department of Gynaecology and Obstetrics and 4Section for Surgical Pathophysiology, Juliane Marie Centre, Rigshospitalet, University of Copenhagen, Denmark
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  • and 1 H. Kehlet 4

    1. 1Department of Anaesthesia, Centre of Head and Orthopaedics, Rigshospitalet, University of Copenhagen, 2Clinical Unit of Health Promotion/WHO Collaborating Centre for Evidence-Based Health Promotion in Hospitals, Bispebjerg Hospital, University of Copenhagen, 3Department of Gynaecology and Obstetrics and 4Section for Surgical Pathophysiology, Juliane Marie Centre, Rigshospitalet, University of Copenhagen, Denmark
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Per Rotbøll Nielsen
Department of Anaesthesia
Centre of Head and Orthopaedics
Rigshospitalet
University of Copenhagen
Blegdamsvej 9
DK-2100 Copenhagen
Denmark
e-mail: per.rotboell.nielsen@rh.regionh.dk

Abstract

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.

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