Acta Anaesthesiol Stand 1990: 34: 673-676
Pressure pain thresholds in volunteers and herniorrhaphy patients J. B. DAHL,J. ROSENBERG, F. MOLKEJENSEN and H. KEHLET Departments of Anaesthesiology and Surgical Gastroenterology, Hvidovre University Hospital, University of Copenhagen, Copenhagen, Denmark
Pressure algometry is a method to estimate pressure pain sensitivity in tissues. The aim of the present study was to evaluate the reproducibility of pressure pain thresholds (PPT) in the abdominal integument and to evaluate the use of pressure algometry as a measure of wound tenderness following surgery. PPT was determined in 20 healthy volunteers on two separate examinations, and in 14 patients at the incisional site before and following inguinal herniotomy. In volunteers, PPT was higher for men than for women, and no difference was observed between the first and second day of examination. I n surgical patients a significant decrease in PPT was observed following operation. Morphine 0.07 mg/kg caused a slight but significant increase in PPT. Pressure algometry may be useful to study nociceptive mechanisms and the dynamics of wound pain in surgical patients. Received 28 April, accepted for publication 7 August 1990
KT words: Algometry; nociception; pain; postoperative pain; pressure pain threshold.
A major problem in clinical pain research and -treatment is the lack of objective methods to quantitate pain. Pressure algometry (dolometry) is a semi-quantitative (combined subjective and objective) method to estimate pressure pain sensitivity in tissues. Pressure algometry has been used for evaluation of sensitivity to pain and to assess pain perception in subcutaneous and underlying tissues, but mainly in musculoskeletal dysfunction and chronic pain ( 1 4 ) . The aim of the present study was to evaluate the reproducibility of pressure pain thresholds (PPT) in the abdominal integument and to evaluate the use of pressure algometry as a measure of wound tenderness following surgery. PATIENTS AND METHODS PPT was determined with a hand-held electronic pressure algometer (Somedic@,Stockholm, Sweden). The stimulation probe has a circular tip of 6 mm (0.28 cm') and is connected to a pressure transducer built into the gun-shaped handle. The signal from the pressure transducer is amplified in a main unit, and the applied pressure is shown in kPa on a digital display. A display consisting of horizontal light bars indicates whether the applied pressure is above or beneath a preset rate (10 kPa/s in the present study). When the PPT is reached, the subject activates a push-button, which freezes the digital display. The PPT was defined as the minimal pressure (force) which induces pain. The patients were instructed to activate the push button when the sensation changed from one of pressure alone to one of mixed pressure and pain. Volunteers Twenty healthy volunteers, ten males and ten females, age 32 1.3 years, height 177f 1.9 cm, weight 71 f 2 . 6 kg, (meanfs.e.mean),
were examined on 2 separate days with at least 48 h interval. PPT was determined at the following four locations: the TI, dermatome 8 cm lateral to the umbilicus on both sides of the midline and the T,, dermatome corresponding to the middle of a line drawn between the superior, anterior iliac spine and umbilicus on both sides. PPT was determined randomly at the four locations, with five determinations at each location. Surgical patients PPT was determined in 14 male surgical patients, age 56 f 4 years, height 178 f 2 cm, weight 77 ~t3 kg (mean s.e.mean), scheduled for inguinal herniotomy: 1) on the day before operation, 2) following operation in epidural or spinal anaesthesia at the moment when the patient first requested analgesics and 3) 15 min after the first request for analgesics and administration of intravenous morphine 0.07 mg/ kg. PPT was determined 0.5 cm cranial to the middle of the surgical incision (without dressing) and on the same location at the contralatera1 side of the abdomen. PPT was determined randomly at the two locations, with three determinations at each location. All PPT are given in kPa. If more than two groups of paired data were analyzed, the Friedman two-way analysis of variance was used. When comparing two groups of paired data, the Wilcoxon rank-sum test was used, and for unpaired data the Mann-Whitney U-test used. Correlations between paired data were calculated by means of a leastsquares regression analysis and P0.05 between males and females in right and left Tlo. No significant differences between the different locations in males or females (P>0.05).
Patients
1
loo
* p
Pressure pain thresholds in volunteers and herniorrhaphy patients J. B. DAHL,J. ROSENBERG, F. MOLKEJENSEN and H. KEHLET Departments of Anaesthesiology and Surgical Gastroenterology, Hvidovre University Hospital, University of Copenhagen, Copenhagen, Denmark
Pressure algometry is a method to estimate pressure pain sensitivity in tissues. The aim of the present study was to evaluate the reproducibility of pressure pain thresholds (PPT) in the abdominal integument and to evaluate the use of pressure algometry as a measure of wound tenderness following surgery. PPT was determined in 20 healthy volunteers on two separate examinations, and in 14 patients at the incisional site before and following inguinal herniotomy. In volunteers, PPT was higher for men than for women, and no difference was observed between the first and second day of examination. I n surgical patients a significant decrease in PPT was observed following operation. Morphine 0.07 mg/kg caused a slight but significant increase in PPT. Pressure algometry may be useful to study nociceptive mechanisms and the dynamics of wound pain in surgical patients. Received 28 April, accepted for publication 7 August 1990
KT words: Algometry; nociception; pain; postoperative pain; pressure pain threshold.
A major problem in clinical pain research and -treatment is the lack of objective methods to quantitate pain. Pressure algometry (dolometry) is a semi-quantitative (combined subjective and objective) method to estimate pressure pain sensitivity in tissues. Pressure algometry has been used for evaluation of sensitivity to pain and to assess pain perception in subcutaneous and underlying tissues, but mainly in musculoskeletal dysfunction and chronic pain ( 1 4 ) . The aim of the present study was to evaluate the reproducibility of pressure pain thresholds (PPT) in the abdominal integument and to evaluate the use of pressure algometry as a measure of wound tenderness following surgery. PATIENTS AND METHODS PPT was determined with a hand-held electronic pressure algometer (Somedic@,Stockholm, Sweden). The stimulation probe has a circular tip of 6 mm (0.28 cm') and is connected to a pressure transducer built into the gun-shaped handle. The signal from the pressure transducer is amplified in a main unit, and the applied pressure is shown in kPa on a digital display. A display consisting of horizontal light bars indicates whether the applied pressure is above or beneath a preset rate (10 kPa/s in the present study). When the PPT is reached, the subject activates a push-button, which freezes the digital display. The PPT was defined as the minimal pressure (force) which induces pain. The patients were instructed to activate the push button when the sensation changed from one of pressure alone to one of mixed pressure and pain. Volunteers Twenty healthy volunteers, ten males and ten females, age 32 1.3 years, height 177f 1.9 cm, weight 71 f 2 . 6 kg, (meanfs.e.mean),
were examined on 2 separate days with at least 48 h interval. PPT was determined at the following four locations: the TI, dermatome 8 cm lateral to the umbilicus on both sides of the midline and the T,, dermatome corresponding to the middle of a line drawn between the superior, anterior iliac spine and umbilicus on both sides. PPT was determined randomly at the four locations, with five determinations at each location. Surgical patients PPT was determined in 14 male surgical patients, age 56 f 4 years, height 178 f 2 cm, weight 77 ~t3 kg (mean s.e.mean), scheduled for inguinal herniotomy: 1) on the day before operation, 2) following operation in epidural or spinal anaesthesia at the moment when the patient first requested analgesics and 3) 15 min after the first request for analgesics and administration of intravenous morphine 0.07 mg/ kg. PPT was determined 0.5 cm cranial to the middle of the surgical incision (without dressing) and on the same location at the contralatera1 side of the abdomen. PPT was determined randomly at the two locations, with three determinations at each location. All PPT are given in kPa. If more than two groups of paired data were analyzed, the Friedman two-way analysis of variance was used. When comparing two groups of paired data, the Wilcoxon rank-sum test was used, and for unpaired data the Mann-Whitney U-test used. Correlations between paired data were calculated by means of a leastsquares regression analysis and P0.05 between males and females in right and left Tlo. No significant differences between the different locations in males or females (P>0.05).
Patients
1
loo
* p
