THE DEVELOPMENT OF THE RAPID METHOD OF DIAGNOSIS OF HUMAN REACTION TO PAIN

Mokryk O. Y., Zaplatynsky V. O.

CONTENTS

Scentific article

Introduction. The research of the human reactions to pain is a complex process. This problem is not solved completely yet. Nowadays, subjective methods of evaluating pain are being mainly used in the clinic. By na-ture these methods are verbal-symbolic: visual analogue, visual rank and verbal rank scales and others. However, the patients may diversely assess their feelings that arise with the appearance of pain. It largely depends on their emotional condition. People having stress that is often accompanied by depression, anxiety, fear, oppression can’t adequately assess pain: some may underestimate its influence, others tend exaggerating. This reality complicates the assessment of pain intensity, that’s why much attention is paid to the development of the objective methods of its diagnosis, in particular, to those that consider sensory, motional, autonomic, and psycho-emotional components of pain. Pupillometry (diagnosis of pupil diameter) is an informative method for studying human autonomic responses. It is known that increased activity of the sympathetic innervation causes dilated pupils, while narrowing them testi-fies about the increasing of parasympathetic tone. Psycho-emotional tension, fear, painful irritants cause mydriasis (Parrot–Robertson-symptom). We have chosen pupillary reflex (the most accessible object «open» for the direct noninvasive research of the central nervous system [CNS]) as the object of study. The reaction of pupils to painful aggravator is an unconditioned reflex that is not controlled by the cortex and therefore by the consciousness. At the same time, this reaction is a unique and sensitive indicator of a wide range of physiological processes dependent on the condition of sympathetic-parasympathetic balance. The advantage of pupillometry, in contradistinction to the majority of traditional methods, is in the implementation of the objective and quantitative assessment of the func-tional condition of the autonomic nervous system (ANS). Moreover, there is also a wide range of preferences while administering pupillometry as the screening method of investigation of psychophysiological status. No doubt, the realization of this mode of research using adequate approaches to the quantitative evaluation of the functional condition of the ANS by registering eye dynamic parameters is actual, because it is aimed at the solution of the important task of clinical medicine – estimation of the individual peculiarities of the condition of the regulatory processes of human body in the circs of painful stress. Considering the above, we set the goalto work out the objective rapid method of diagnosis of human reaction to pain by registering pupillary reflex via computer software. Materials and methods of research. 30 volunteers participated in the experiment. The reactions of the autonom-ic nervous system (ANS) to painful stress were explored in those people. The stress was modeled with the help of Trousseau’s test modified by A. V. Beletsky (2005). Pneumatic cuff was put on the shoulder, the pressure in the cuff was being increased and maintained 50% more, than systolic blood pressure, during 5 minutes. While the incentive of pain was being brought in, the patients were evaluating their feels by numeric rating scale of pain. Simultane-ously, we were observing the dynamics of enlargement of the pupil by calculating its diameter, velocity and duration of this process. We have used portable electronic microscope Sigeta Gam – 01 (Taiwan) to get video stream with the image of the eye in a real-time. The device was connected to the laptop through USB. Video series fixed by the microscope consist of the sequence of frames with the effigy of the eye. The frames arrive with the frequency of 2°Cadres per second that allows to measure diameter of the pupil every 500ms (0,5s). The pupil stands out among the other parts of the human eye on the images of the video stream that helps to gauge its diameter. In particular, the pupil differs substantially from the iris in brightness, namely the gradient value on the circumference (the border of the pupil) is greater than the gradient value of the iris. This peculiarity allowed to search the pupil as the dark circle on the effigy. We have applied the binarization of the frame to dissever the black (the pupil) and the light (the iris) parts of the eye. In order to improve the accuracy of the identification of the pupil we have worked out the algorithm of the searching of the gyre on the basis of Thales’ theorem. This theorem affirms that the hypotenuse of a right triangle inscribed in a circle is the diameter of the circle and the midpoint of the hypotenuse is the center of the circle. The algorithm consists of the following steps: The binarization of the image (to separate the secondary objects from the main one on the effigy). The search of the basic dots by masks (namely, the allotment of the points that are potentially the edges of the gyre in the sundry quarters). The determination of circle’s center and diameter. We have made the decision to choose object oriented programming language – C # to create versatile software. The convenient user interface was elaborated by programming environment – Microsoft Visual Studio 2012. Results of the research. Computer software tool that graphically records the duration and the intensity of the amplitude’s growth of the pupillogram (mydriasis) under the influence of external factors has been worked out by means of mathematical processing of the video images of the pupil. This software tool was used to develop the modes of pupillometry. The developed rapid method of diagnosis of autonomic human response to pain stressor has successfully undergone approbation in the dental clinic that gave us a lot of beneficial information. Conclusion. The developed rapid method of the objective evaluation of the nociceptive human response can be widely applied to diagnose pain.

human reaction to pain, pupillary reflex, pupilloalgometry, computer software

«Bulletin of problems biology and medicine» Issue 2 part 2 (108), 2014 year, 013-017 pages, index UDK 612. 821. 2:612. 67+616. 893-053. 8