A dolorimeter is an instrument used to measure pain threshold and pain tolerance. Dolorimetry has been defined as "the measurement of pain sensitivity or pain intensity". Several types of dolorimeter have been developed. Dolorimeters apply steady pressure, heat, or electrical stimulation to some area, or move a joint or other body part and determine what level of heat or pressure or electric current or amount of movement produces a sensation of pain. Sometimes the pressure is applied using a blunt object, or by locally increasing the air pressure on some area of the body, and sometimes by pressing a sharp instrument against the body.
In 1940, James D. Hardy, Harold G. Wolff and Helen Goodell of Cornell University introduced the first dolorimeter as a method for evaluating the effectiveness of analgesic medications. They did their work at New York Hospital. They focused the light of a 100 watt projection lamp with a lens on an area of skin that had been blackened. They found that most people expressed a pain sensation when the skin temperature reached 113 °F (45 °C). They also found that after the skin temperature reached 152 °F (67 °C), the pain sensations did not intensify even if the heat was increased. They developed a pain scale, called the "Hardy-Wolff-Goodell" scale, with 10 gradations, or 10 levels. They assigned the name of "dols" to these levels. Unfortunately, other researchers were not able to reproduce the results of Hardy, Wolff and Goodell, and the device and the approach were abandoned. Harvard Medical School Professor and Massachusetts General Hospital Anaesthetist Henry K. Beecher (1957) expressed skepticism about this method of measuring pain.
A dolorimeter known as the Sonic Palpometer was developed at the University of Victoria in British Columbia, Canada. Patents have been applied for worldwide. The Sonic Palpometer uses ultrasound and computer technology to automate the physician's technique of palpation to determine sensitivity of some part of the patient's body.
The related pressure controlled palpometer (PCP) uses a pressure-sensitive piece of plastic film to determine how much pressure is being applied in palpation. This technique appears to be more reliable than unaided palpation.
Algorimeter and other methods
Techniques using lasers
A laser-based dolorimeter called a Dolorimeter Analgesia meter is marketed by IITC Life Sciences.
Techniques using heat lamps
- Björnström's algesimeter measures sensitivity of the skin to pain.
- Boas' algesimeter measures sensitivity over the epigastrium
- The AlgiScan, used for measuring the analgesia level in patients during anesthesia, quantifies within seconds the reflex papillary dilatation[clarification needed] through an integrated nociceptive stimulator[clarification needed].
Other terms for similar instruments include algesiometer, algesichronometer (which also takes time into consideration), analgesia meter, algometer, algonometer, prick-algesimeter, pressure-algometer.
Dolorimetry for animals
Dolorimetry in animals involves application of pain to various body parts. It is occasionally used as a diagnostic tool, and routinely used in basic pain research and in the testing of analgetics.
- Tail-withdrawal tests
- Tail-pinch tests
- Tail flick test
- Stedman's Medical Dictionary 2004 Houghton Mifflin Company
- Pain Sensations and Reactions, J. D. Hardy, H. G. Wolff, H. Goodell, Williams and Wilkins, Baltimore, 1952.
- The Problem of Pain, Time magazine, July 30, 1956.
- Thermally Induced Pain, the Dol Scale, and the Psychophysical Power Law, Eleanor R. Adair, Joseph C. Stevens, Lawrence E. Marks, The American Journal of Psychology, Vol. 81, No. 2 (Jun., 1968), pp. 147-164 doi:10.2307/1421259
- Displacing the Dolorimeter: The Fate of a Pain Measuring Instrument in the Era of Therapeutic Reform, U. S. 1940s-50s Archived 2006-10-16 at the Wayback Machine., Noémi Tousignant, University of Alabama at Birmingham, Department of Anesthesiology.
- The Measurement of Pain: Prototype for the Quantitative Study of Subjective Responses, Henry K. Beecher, Pharmacological Reviews. 9:59-209
- Ouch!, Time, Monday, Jan. 01, 1945.
- GLUZEK, L. J. B. "Dolorimetry in medical practice: the quantitative measure of deep sensibility and of pain". Med. rec., N. Y., 1944, 157, 292-294.
- University of Victoria Palpometer site
- L Bendtsen, R Jensen, NK Jensen, J Olesen (1995), Pressure-controlled palpation: a new technique which increases the reliability of manual palpation, Cephalalgia 15 (3), 205–210. doi:10.1046/j.1468-2982.1995.015003205.x
- Comparative psychophysical characteristics of cutaneous CO2 laser and contact heat stimulation, Peter Svensson, Barry Rosenberg, Ahmad Beydoun, Thomas J. Morrow and Kenneth L. Casey, Somatosensory & Motor Research, Taylor & Francis , Volume 14, Number 2 / April 1, 1997, Pages 113 - 118, doi:10.1080/08990229771114