LV14819B - Method and device for monitoring regional anaesthesia and invasive pain therapy - Google Patents

Description

DESCRIPTION OF THE INVENTION

Technical field

The invention is intended for use in anesthesiology, in particular for monitoring the effectiveness of regional anesthesia (RA) and for monitoring pain therapy (ST).

State of the art

By definition, pain is a conscious sensory perception and one of the hallmarks of human brain activity, a complex multi-level afferent reflex that determines his or her behavior (1). When treating pain or protecting a patient from potential pain, the physician guides the pain level. Another definition provided by the IASP (International Association for the Study of Pain) “Pain is an unpleasant sensation and emotion associated with, or perceived as, a real or potential tissue injury. These are always subjective feelings. ” However, in cases where the patient is in 'narcosis', medication sleep or cognitive problems (due to mental or somatic condition), no information on subjective pain level is available. Therefore, there is a need, indirectly, to objectify the patient's response to painful stimuli or therapeutic effects to relieve pre-existing (e.g., chronic) pain, or potential, such as regional anesthesia prior to surgery. Quantitative technologies must be used for objectification purposes.

One of the major tasks of regional anesthesia (RA) is to provide pain relief for the patient. There is currently no direct, ideal method for detecting the presence or degree of RA in an unconscious patient. Loss of sensitivity has traditionally been determined by needle punctures, pinching the skin, touching a piece of ice, or other mechanical action on the skin [2,3]. These clinical detection methods are undoubtedly simple but subjective and based on the patient-doctor contact. Unfortunately, this contact tends to be difficult for a number of objective reasons, such as patient stress, the presence and severity of the injury, unusual circumstances, age-related mental features, and co-morbidity. As a result, it is very often simply impossible for the patient to physically obtain an adequate response to their senses, and moreover, the response obtained in this way can be not only inaccurate and unclear, but also a false positive. This, in turn, can lead to a situation where the patient is not actually anesthetized prior to surgery, but the possibility of switching to another type of anesthesia under the existing situation is not feasible.

A significant component of pain physiology is the sympathetic nervous system. The ability to quantify the body's sympathetic responses will protect the patient from potential pain (RA) and, on the other hand, evaluate the therapeutic effect from manipulation (ablative interference, blockade).

The technology available to measure pain directly does not yet allow to measure pain, but many factors help to judge pain levels indirectly. After administration of a local anesthetic (LA), sensory, motor, and sympathetic blocks may be expected with adequate anesthesia. If it is not possible to measure the sensory block directly, one can try to evaluate the sympathetic effect and then indirectly judge the expected sensory effect. The sympathetic effect is associated with marked peripheral vasodilation, increased peripheral blood flow and elevated skin temperature. Temperature routine monitoring is very effective but limited to a very small area of skin to be measured. As a state-of-the-art method for estimating a larger area, a thermography camera that allows indirect RA visual monitoring by detecting temperature differences between different skin areas and their changes over time should be noted [4-6]. Unfortunately, this method is very expensive and not available in all clinics.

Several non-invasive methods and devices for detecting RA are known, such as a device and method for monitoring successful spinal anesthesia [7], which involves the insertion of at least one electronic temperature sensor on the skin surface within at least one dermatome. The device signals optically and / or acoustically when the temperature measurement results change by 2-3 ° C, indicating a positive anesthetic result.

There is a known method for evaluating the evolution of an adequate block of RA [8], which uses a patient's pulse index, which is measured every minute, starting with 5 minutes, simultaneously on the operated and healthy limbs. The median coefficient on a blocked and healthy limb is evaluated and anesthesia is considered successful if the difference between the coefficients exceeds three times.

The combination of ultrasound imaging with pulse oximetry for RA and peripheral block validation is very popular [9].

Other known methods of determining anesthesia are based on the measurement of electrodermal activity. Changes in skin conductance were controlled after the onset of a sympathetic block associated with successful RA [10,11].

Other devices, such as PAINVISION PS-210 (Osachi Itd; 2003) for quantitative perceptual monitoring using common anesthetic standard observation parameters (electrocardiography, TA, etc.) and adjustable electrical stimuli, have also been developed.

There is a known technique and device for monitoring RA using the principle of non-contact photoplethysmography (PPG) [12], photoplethysmography is a non-invasive optical method for measuring blood volume pulsations. The method is based on the ability of optical radiation to penetrate the tissue to a depth of several millimeters. Radiation is absorbed into soft tissues and blood. As a result of cardiac and respiratory function, as well as vasomotor activity, blood volume changes periodically, and the intensity of radiation diffused into the subcutaneous tissue is modulated at the expense of these processes. Changes in blood volume can be recorded using a video camera that detects radiation reflected from the skin tissue. The method can be used to monitor the blood flow (perfusion) of skin tissue.

OBJECT, NATURE, DESCRIPTION OF THE DRAWINGS AND DETAILED DESCRIPTION OF THE INVENTION

The object of the invention is to improve contactless monitoring for an objective evaluation of the effectiveness of regional and / or pain therapy.

Nowadays, white led LED operating lamps with a built-in video camera for documenting surgical operations - such as the one described on the website [13] - are increasingly being introduced in the operating room. The camcorder is usually located in the center of the lamp and is always oriented towards the most illuminated (anesthetized) area of the body to be operated on. The proposed technique involves the simultaneous use of such a combined lamp as a light source and a photo receiver for monitoring the microcirculation of the skin during surgery, to ensure the momentum of RA and ST exposure and continuous monitoring of exposure during the procedure. In this case, only a signal processing module is required, which includes a processor and a computer program for image processing. New features can be added to the program compared to [12], such as RGB monitoring of skin color changes caused by RA.

A smartphone or other mobile device that integrates a light source, a camcorder, a processor, and a display into a common enclosure can also be used as a RA monitoring device. In monitoring, information can be transmitted in real time over a mobile network and stored on a data server. In this case, in addition to the existing equipment, you only need a fixed device holder and a computer program (eg smartphone application).

The following figures illustrate the invention:

Fig. 1 a flow chart of a non-contact RA monitoring device is shown, which contains:

- a stabilized operating lamp or other light source suitable for irradiating the surface of the skin to be anesthetized, such as white light or narrow-band visible light or infrared light source 1, such as light emitting diodes (LEDs);

- a triple-color (RGB) or black-and-white image sensor integrated into the lamp, such as a video camera, capable of recording video signals from the skin surface;

- an assay unit (processor) 3, which calculates the PPG signal amplitude for each heartbeat cycle and calculates the median value and standard deviation of the signal amplitude over a given time interval, for recording RA exposure, and for lamp control;

- an output device, such as a graphic display showing the graph of the PPG amplitude, or a light or sound indicator indicating the occurrence of RA.

The assay unit may be functionally linked or not related to the light source.

Fig. 2 shows the graph of the amplitude changes of the recorded PPG signal and the time of onset of RA, which is determined by the signal standard deviation.

In the proposed method, a non-contact RA exposure detector uses an operating lamp with a built-in video camera already in the operating room to document the progress of the operation. The lamp emits visible or near infrared radiation, which is reflected from the anesthetized skin and is recorded by a built-in camcorder or other light sensitive RGB color or monochrome sensor. The amplitude of the PPG signal from each video cycle is calculated from the video signal. The median signal amplitude value and standard deviation over a selected time interval are then calculated. The time at which the PPG amplitude within two standard deviations (SN ₂ ) exceeds the baseline measurement PPG amplitude within two standard deviations (SNi) is considered statistically significant (Fig. 2). As soon as a statistically significant onset of anesthesia occurs, measurement can be discontinued and surgical manipulation may be initiated without undue delay.

With the proposed method and appropriate equipment, the process of regional anesthesia is easy to detect and, from the user's point of view, uncomplicated. The detection process is objective, independent of the patient's mental and physical condition. There are no limitations associated with the subjective opinion of the patient or doctor. There are no limitations associated with the time limit or the high cost of the hardware used, given its widespread availability and ease of access (in virtually any workplace, the operating room). There are no restrictions associated with long and costly staff training on PC and camcorder use.

References

1. www.sapes.lv/?p=6089&lang=1240

2. Boscheinen-Morrin J., Conolly W. Bruce. The Hand: The Fundamental of Therapy. Third 10 edition, I, pp. 6-7 (2002)

3. Chan A. W., MacFarlane I. A., Bowsher D., Campbell J. A. Weighted needle pinprick sensory thresholds: a simple exercise of sensory function in diabetic peripheral neuropathy. J. Neurol. Neurosurg. Psychiatry, 55, p. 56-59 (1992).

4. Jansen T., Asghar S., Kristensen P. L., Skjonnemand M., Nergaard P., Lange K. H. W. 15 Infrared thermography after selective ultrasound-guided peripheral blocks in the upper limbs. NYSORA World Anesthesia Congress, Dubai, UAE, Congress Abstracts CD (2010)

5. J. Klaessens, M. Landman, R. De Roode, H. J. Noordmans, R. M. Verdaasdonk. Objective methods for achieving an early prediction of the effectiveness of regional block anesthesia using thermography and hyper-spectral imaging. Proc. SPIE v.7895, 78950Q (2011)

6. J. Klaessens, H. J. Noordmans, M. Nelisse, R. Verdaasdonk. Development of an LEDmultispectral imaging system for non-contact tissue perfusion and oxygenation imaging, first results of clinical intervention studies. SPIE vol. 7174, (2013, in press)

7. A. Penn, U.Grossmann. Device and method for monitoring the success of spinal anesthesia. 25 Patent Application WO2010075997 (6/8/2010)

8. S. Nedzvetsky, A. Tarasov, N. Vaganov. Method of evaluation of adequacy of block in conduction anesthesia. Patent RU2357660 (Jun 10, 2009)

9. R Nagarajan, et.al. Integrated ultrasound imaging device with pulse oximeter waveform display for application of regional anesthesia. Patent Application WO2010076808 (June 8, 2010)

10. Ledowski T, Preuss J, Ford A, Paech MJ, McTeman C, Kapila R, Schug SA. New parameters of skin conductance compared with bispectral index monitoring to assess emergence from total intravenous anesthesia. Br.J.Anaesth., 99: 547-551 (2007).

11. H Matsumura, Evaluation of pain intensity measurement during wound removal 5 dressing material using 'the PainVision ™ system' for quantitative analysis of perception and pain sensation in healthy subjects. Int Wound J.; 9 (4): 451-5. doi: 10.1111 / j.1742481Χ.2011.00911.x. (2012)

12. A.Miscuks, R.Erts, U.Rubins, J.Spigulis, M.Mihelsons. Method and device for determining the effect of peripheral regional anesthesia using non-contact photopetysmography.

Patent LV14444 B (2/20/2012)

13. http://www.skytron.us/camera_intro.htm; http://www.brandon-medical.com/; http://www.brennanco.ie/brennanco/Main/MedicalEng_OperatingLights_New.htm

Claims (6)

Claims 1. A method of non-contact monitoring of the effect of a regional anesthetic, characterized in that the monitoring is performed with a built-in lamp or other related trichromatic (RGB) or black-and-white image sensor installed for recording a video signal from the skin surface. calculated photoplethysmographic signal (PPG) amplitude for each heart rate cycle and median signal amplitude value and standard deviation over a defined time interval to determine the moment of regional anesthesia The method of claim 1, further comprising analyzing the patient's skin discoloration for the ratio of RGB signal amplitudes. Device for carrying out the method according to claims 1 and 2, comprising a stabilized operation lamp or a white light or narrow-band visible light or infrared source (1) with a tris-color (RGB) or black-and-white image sensor (2). ) for recording a video signal from the skin surface and an analysis unit consisting of a processor (3) for image video analysis of the image sensor and calculation and comparison of the amplitude of the photoplethysmographic signal (PPG) for monitoring anesthesia effects; . The device according to claim 3, wherein the radiation source (1) is made of light emitting diodes (LEDs). The device according to claims 3 and 4, further comprising an output device (4) for displaying a time graph or numerical value of the signal amplitude and for visual or acoustic indication of the anesthetic effect. The device according to any one of claims 3 to 5, wherein a smartphone or other mobile device is used for illumination and signal registration and processing.