Measurement and control of pain
Last reviewed: 23.04.2024
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The simplest and most common method is to record the intensity of pain using rank scales. There is a numerical rank scale (CHRS) consisting of a series of numbers from 1 to 5 or up to 10. The patient should choose a number that reflects the intensity of the pain experienced. The Verbal Ranking Scale (BPP) contains a set of pain descriptors that reflect the degree of pain increase, successively numbering from less severe to greater: no (0), mild pain (1), moderate pain (2), severe pain (3), very severe pain (4), unbearable (unbearable) pain (5). Visual analog scale (VASH) is a straight line with a length of 100 mm with or without millimeter divisions applied on it. The starting point of the line means no pain, the final line is unbearable pain. From the patient it is required to note the pain level of the point on the proposed straight line. For patients who have difficulty in abstracting and presenting pain in the form of a digit or a point on a straight line, one can use a facial (mimic pain scale).
The simplicity and high sensitivity of the methods of rank-based scaling make them very useful, and sometimes indispensable in clinical practice, but they also have a number of disadvantages. The mathematical analysis of the results is based on the unlikely assumption that each rank is equal to the psychological unit of measurement. The pain is assessed unambiguously - in intensity, as a simple sensation, which differs only quantitatively, whereas it has qualitative differences. Analogous, numerical and verbal scales give a single, generalized assessment that reflects the almost completely unexplored process of integrating multidimensional pain experience.
For the multidimensional assessment of pain, R.Melzack and WSTorgerson (1971) proposed a questionnaire called the McGill Pain Questionnaire. A method of multidimensional semantic descriptive pain is also known, based on the expanded McGillian questionnaire (Melzack R ... 1975). The extended questionnaire contains 78 words-descriptors of pain, introduced into 20 subclasses (subchal) according to the principle of semantic meaning and forming three main classes (scales): sensory, affective and evaluative. The results of the survey can serve as a criterion for the mental state of patients. Numerous studies have tested the adequacy of the method for assessing pain, anesthesia and diagnosis, now it has become the standard method of examination abroad.
A similar work has been done in our country. VV Kuzmenko, VA Fokin, ER Mutis and co-authors (1986), based on the McGillian questionnaire, developed the original Russian questionnaire and proposed a methodology for analyzing its results. In this questionnaire, each subclass consists of words that are similar in meaning to their meaning, but differ in the intensity of the pain they transmit. Subclasses form three main classes (scales): sensory, affective and evaluative (evaluation). Descriptors of the sensor scale (1-13 subclasses) characterize pain in terms of mechanical or thermal effects, changes in spatial or temporal parameters. The affective scale (14-19 subclasses) reflects the emotional side of pain in terms of tension, fear, anger or vegetative manifestations. The evaluation scale (20 subclass) consists of five words expressing a subjective assessment of the pain intensity of the patient, and is a variant of the verbal rank scale. When completing the questionnaire, the patient chooses words corresponding to his feelings at the moment, in any of the 20 subclasses (not necessarily in each, but only one word in the subclass). Each selected word has a numerical value corresponding to the ordinal number of the word in the subclass. Counting is reduced to the definition of two indicators: the index of the number of selected descriptors (IHVD), which is the number (sum) of selected words, and the rank index of pain (RIB), which is the sum of ordinal descriptors in subclasses. Both indicators are calculated for the sensory and effective scales separately and together (total index).
McGill's pain questionnaire
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What words can you describe your pain? (touchscreen) |
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What feelings causes pain, what impact does the psyche have? (affective scale)
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How do you assess your pain? (scoring scale)
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According to the definition of the international association for the study of pain, "pain threshold (PB) is a minimal pain sensation that can be realized." An informative characteristic is also the level of pain tolerance (pain tolerance threshold - PPB), defined as "the highest level of pain that can be sustained". The name of the method of quantitative study of pain sensitivity is formed from the name of the algogenic stimulus used in it: mechanical-algometry, thermo-algometry, electro-algometry.
Most often, the pressure is used as a mechanical action, and then the method is called a strain gage (dolorimetry). At tensoalgonomy, the PB is expressed in units of pressure force per unit area (kg / cm 2 ). Depending on the localization, removable attachments are used for measurements: in the region of the head and distal limbs with a diameter of 1.5 mm, and in the region of massive skeletal muscles - 5 mm. Tenzoalgometry is carried out by a gradual or stepwise increase in pressure on the test area of the body. Painful sensation occurs at the time when the pressure force reaches values sufficient to excite Ab-mechanoreceptors and C-polymodal nociceptors.
The definition of PB and PPB can provide important clinical information. A decrease in PB indicates the presence of allodynia, and a decrease in PPB is a sign of hyperesthesia (hyperalgesia). Peripheral sensitization of nociceptors is accompanied by both allodynia and hyperalgesia, and central sensitization is manifested primarily by hyperalgesia without concomitant allodynia.
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