MXPA97002508A - Method and apparatus for the monitoring and / or control of the neuromuscular block, in particular of the block produced by muscle relaxing drugs used during the anesthetic - Google Patents

Abstract

The present invention relates to the method comprising the nerve stimulation and the detection and measurement of the response, and is characterized in that the nerve stimulation is performed on the skin covering the muscles on which the response is detected; comprises means for the application of nerve stimulation, means for detecting the response and optionally means for monitoring the neuromuscular block, and is characterized in that said means are arranged in a same body, which is a sleeve of the type used for the measurement of blood pressure provided with means for detecting pressure or connected to said means, it is not necessary to stimulate any peripheral nerve and a more manageable and compact device is achieved

Description

METHOD AND APPARATUS PORA Lfl MONITORING AND / OR CONTROL OF THE NEUROMUSCULAR BLOCK. IN PARTICULAR OF THE BLOCKING PRODUCED BY MUSCLE RELAXING MASSAGES USED DURING THE ANESTHESIA.

The present invention relates to a device for the monitoring and / or control of neuromuscular blockade, especially the blockage produced by muscle relaxant drugs used during anesthesia. Mainly the new method and apparatus allow the quantification and control of neuromuscular block by means of transcutaneous stimulation directly on the muscle, stimulating the intramuscular nerve pathways and the neural part of the motor plate without having to stimulate a peripheral motor nerve. The invention also allows a controlled administration of the blocking drug during the induction of anesthesia as well as the control of the neuromuscular block during the operation and the control of recovery upon awakening from anesthesia.

BACKGROUND OF THE INVENTION It is known that the great advances of surgery have occurred from the application of muscle relaxants during anesthesia, which in addition to facilitating the work of the surgeon allows a less traumatic intubation and facilitates mechanical breathing. Also, muscle relaxation allows improvement of mechanical ventilation in patients intubated in the intensive care unit. It is also known that there are a variety of factors that influence the duration and effect of muscle relaxants depending, among others, on body weight, age, physical condition and possible pathologies of the patient to whom these types of drugs are administered. In the event that the dosage is insufficient, it could hinder intubation and subsequent surgery; In the case of overdosage, the patient upon awakening from anesthesia could have respiratory failure and the need to prolong artificial respiration, which would delay his departure from the operating room or his admission to a special care unit. Another danger of overdosing or poor reversal of the effects of muscle relaxants can be serious compilations such as aspiration of vomiting due to failure of reflexes or respiratory failure, complications that can lead to death of the patient. To avoid these complications, the state of the neuromuscular block is currently assessed by stimulating a peripheral motor nerve and measuring the degree of mobility of the muscle innervated by said nerve. There are various methods and devices designed to stimulate peripheral nerves by means of transcutaneous electrodes, for example the stimulators of Neuro Technology, Inc. Houston, Texas USA. The most important problem lies in the assessment or measurement and motorization of the neuromuscular blockade and the adequate administration of the muscle relaxant drug to maintain the desired level of blockade. The assessment of the blockage is currently carried out by the assessment of the electrical activity, the force or the movement of the muscle during its contraction. The methods used up to the present are: 1) The visual method. The movement of a muscle is visually assessed after stimulation of the motor nerve that innervates it. Its lack of accuracy and the difficulty of its quantification are evident, but the simplicity of the method makes it the one that is currently used most frequently. 2) The tactile method. Similar to the previous one, but in this case the assessment is made by the perception by the anesthesiologist's hand of the strength of the patient's contraction after the stimulus. As in the previous case, it is a subjective and low accuracy method that offers few guarantees of knowing the exact degree of neuromuscular block. 3) By means of electromyography. It consists in the recording of the muscular electrical activity evoked by the stimulation of the motor nerve that innervates said muscle. There are several devices and devices commercialized that monitor the neuromuscular blockade by said technique, which is described, for example, in the part of E.U.A. No. 4,291,705, among others. The main problem that involves this technique is its difficulty of application and the sophistication of the equipment so it has practically only been used in research, without being applied as a practical and daily technique. 4) By means of force transducers. In this case, the force that the thumb makes when the ulnar nerve is stimulated is recorded. There are also different devices marketed, such as the "Relaxograph" device from Biometer International ñ / S Denmark. As in the previous case, the main problem consists in the complication of the technique used that involves having to immobilize the arm in order to register correctly. Due to this reason and to the cost of the equipment, this device is impractical for everyday use. 5) By means of acceleration etria. This method is, after the visual method, the most widespread. It is based on the placement of a sensor of biaxial or triaxial accelerometry in the thumb, which stimulates the ulnar nerve causing its movement, which is perceived by the accelerometer. This is a fairly valid method but it still has the disadvantage that separate electrodes of the sensor must be placed to stimulate the peripheral nerve. On the other hand, the accelerometer is fragile and requires some immobilization of the arm. Other placements of the accelerometer have been described, for example on the face, in which case a motor branch of the facial nerve must be stimulated and the stimulation electrodes must go separately from the accelerometer, increasing the risk of any of the elements detaching from the accelerometer. the skin. As examples of monitors based on accelerometry, we can mention the "Accelograph" and "Tof-Guard" models, both from Biometer International A / S, Denmark and the one described in the American patent 4,817,528, which is also an example of a facial accelerometer. 6) By means of flexible sheet piezoelectric sensors. The phenomenon of piezoelectricity has been known for many years, as well as its application in the field of medicine, for example with the application of piezoelectric sensors that, by deformation, capture the plethysmographic wave transmitted to the skin. Based on this principle, the monitor of the American patent 5,131,401 requires, like the other methods, the stimulation of a peripheral motor nerve, mainly the ulnar nerve and has some cables for the stimulation electrodes and others for a sensor in the form of flexible piezoelectric sheets placed in the palm of the hand records the contraction of the muscles of the hand. Also, like the "Tof-Guard" model, it consists of an icroprocessor that allows a programmed stimulation and the visualization of the quantified response of the neuromuscular block by means of a program. The main drawback of these monitors except the last is that they require the stimulation of a peripheral motor nerve, specifically the ulnar nerve, and the placement of the sensor in the hand or thumb. They also require the use of two electrodes for the stimulus separated from the sensor element of the response, which increases the risk of detachment of the electrodes or the sensor. Due to this, the placement of the electrodes can be uncomfortable and some immobilization of the limb is necessary, being limited the placement in other positions. On the other hand, said type of apparatus may be more sensitive to certain interferences or involuntary movements of the patient. Regarding the control of neuromuscular blockade, there are several works based on far acoykinetic models and closed circuit models such as those described in different articles of medical journals: "Q? Antitative assessment of residual antidepolarizing block (Partí)" Ali HH et al., Br 3 Anaesthesia 1971 vol. 43 pp 473-477. "Monitoring of neuromuscular function" Ali HH and others., Anesthesiology 1976 vol. 45 pp 216-249. "A microcomputer based controller for neuromuscular block during surgery" Ritc ie G. et al., Ann Biomed Eng 1985 vol. 13 pp3-15. "Microcomputer based muscle relaxation monitor and controller for clinical use" Bradlow HS et al., Med Biol Eng Comput 1985, vol. 23 pp547-555. "Online parameter estimation and control of D-Tubocurarine-induced muscle relaxation." Rametti LB et al., Med Biol Eng Comput 1985 vol. 23 pp. 556-564. "Online control of Atracuriurn induced muscle relaxation" Bradlow HS et al., 3. Bio ed Eng. 1986 vol. 8 pp. 772-775. "Co puter-Controlled Muscle Paralysis with atracurium in the Sheep" D.G. Lampard and others. Anesthesia and Intensive Care, vol. 41 (1986) pp 316-320. "Clinical automatic control of neuromuscular blockade" Asbury fí3 et al., Anaesthesia 1986 vol. 41 pp. 316-320. "Infusion of vecuronium controlled by a closed-loop system" Br R Anaesth 1986 vol. 58 pp. 1100-1103. "Closed-Loop admistraistration of Atracurium" N.R. Webster et al., Aneethesia vol. 42 (1987) pp. 1085-1091. "A rnodel-based self-adjusting two-phase contoller for vecuronium-induced muscle relaxation during anesthesia" 3aklist RR. IEEE Transac Biomed Eng 1987 vol. 34 pp. 583-594"Closed-loop infusion of atracurium with four different anesthetic tec niquee" O'Hara DA et al., Anesthesiology 1991 vol. 74 pp. 258-263. These articles describe cases of muscular relaxation control by means of computers with pharmacokinetic models, through sensors of the previously mentioned or with closed circuit systems. In all cases there are correct approaches but they are still experimental and unsafe models, which due mainly to the need to stimulate a peripheral nerve, are impractical and complicated to use, whether by the type of transducer used or by the pharmacokinetic model, which requires large data entry or very sophisticated computers.

DESCRIPTION OF THE TNVFNCTON With the method and apparatus of the invention, the aforementioned drawbacks are solved. The method for the monitoring and / or control of the n-β-skeletal block, object of the invention, is characterized by the fact that nerve stimulation is performed on the skin covering the muscle (s) on which the detection of the response to said stimulation, that is, without the need to stimulate any periphenerve. Thanks to this method, it is not necessary to stimulate the periphenerve and the stimulation-detector device can be placed in the upper or lower extremity, depending on the type of surgery that is going to be performed, without having to limit the stimulation to the ulnar nerve. Optionally, the method of the invention further comprises the automatic control of the supply of the muscle relaxant drug from the detection of the muscular response. The invention also relates to an apparatus for the monitoring and / or control of neuromuscular blockade, comprising means for the application of nerve stimulation, means for detecting the response to stimulation and means for monitoring the neuromuscular block and it is characterized by the fact that the means for nerve restimulation and the means for detecting the response are arranged in the same body. Thanks to this arrangement in the same body, the following advantages are achieved: i) a single element is used to measure blood pressure and to measure neuromuscular block, achieving a more manageable and compact device. ii) the placement is easier. iii) the independent disconnection of any of the components is avoided. iv) simplifies monitoring in the operating room. According to another embodiment, the apparatus of the invention comprises means for the application of nerve stimulation, means for detecting the response to stimulation and means for monitoring the neuromuscular block, and is characterized in that it also comprises means for the supply of the drug that causes the neuromuscular block and control means that coordinate the generation of the stimulus, the registration of the activity, the process of the data, the calculation of the dose of drug and the control of the means for the supply of the drug depending on the calculated dose. The apparatus of the invention thus comprises three essential parts: i) means for nerve stimulation comprising the stimulator and the stimulation electrodes. ii) means for the detection of muscle response consisting of a sensor that can be of different types. iii) onitarization and control means that can be of different types according to the specific embodiment of the invention, and iv) optionally a closed circuit for the automatic dosage of drug. The apparatus of the second embodiment can also be characterized in that the means for applying the nerve stimulation and the means for detecting the response are arranged in the same body, whereby in this case the advantages are also obtained already described. Preferably, the apparatus is characterized in that the body is a sleeve of the type used for the measurement of arterial pressure provided with means for detecting the pressure or connected to said means, which sleeve incorporates means for the application of the nerve stimulation. This simplifies the electronics and maneuvers for sensor placement since the same blood pressure cuff and non-invasive blood pressure monitor transducer are used. This arrangement simplifies the measurement technique of neuromuscular block. Preferably, the means for applying the nerve stimulation comprise at least two electrodes. Also preferably, the means for applying the nerve stimulation and the means for detecting the pressure are attached to the monitoring means by means of a multiconductor tube comprising inside it an air duct for transmitting the pressure waves and therefore minus a pair of electrical conductors for the transmission of stimulation pulses. In a preferred embodiment said conductors are included in the wall of the multi-conductor tube. Due to the existence of a single tube that transmits the pressure wave, the wave of the contraction, and also include the cables that carry the stimulus, the use of the device is extremely simple. This solution is also very economical since it takes advantage of the cuff and the electronic circuits of the blood pressure monitor. Electronic installation is easier and less cumbersome. The method of the invention also represents a great advance with respect to all the previous ones even to the most modern ones (Tof-Gard and Pat. US No. 5,131,401), since it does not require the stimulation of a peripheral motor nerve for the registration of muscle activity The method of the invention is based on the stimulation of the intramuscular neural pathways and neural terminations of the muscular motor plate with the application of a current of stimulation in the skin directly on the muscle whose activity we want to know. Usually, the stimulus current does not exceed 50 mA and the application time should not be applied for more than 30 s so as not to stimulate the muscle fibers directly, which would give an erroneous reading of the neuromuscular block. The means of monitoring can be any of the monitors for blood pressure bloodless that exist in the market modified with the incorporation of a pulse generator for muscle stimulation, with the possibility of adjusting different parameters such as the intensity of the stimulus or the time between two readings and with the possibility of providing on screen the data corresponding to muscle relaxation. The monitors can also have LEDs or light and acoustic alarm signals for cases of loss of signal or contact of the electrodes (by impedance), disconnection of the sensor or some of its parts, blocking level excessively high or low with respect to the level fixed, as well as other common alarms in medical devices, such as current leakage, power failure, etc. The monitoring and control means comprise an isolated amplifier, with filters of 50-60Hz and high frequency to avoid the interferences of the electric scalpel, a stimulator circuit of the type commonly used for nerve stimulation, capable of generating currents of up to an intensity of 100mfi, a measuring circuit and driver of the current intensity of the stimulus, an air pump to inflate the cuff , and optionally an A / D converter, a memory bus and a microprocessor that by means of an EPROM memory program controls gives the functions of the device, coordinating the next cycle of closed circuit: stimulation, registration, data processing and signal processing according to standards of valuation of the neuromuscular block (TOF assessment).

BRIEF DESCRIPTION OF THE DRAWINGS In order to improve the understanding of what has been exposed, some drawings are attached in which, schematically and only by way of non-limiting example, the differences with conventional methods and a practical example of realization of the stimulus-registration device are described. as the neuromuscular blocking device controller. Figure 1 is a graph of muscular activity demonstrating the validation of the apparatus of the invention; Figure 2 is a schematic of a conventional placement of the electrodes and the sensor; Figure 3 is a perspective diagram of a pressure sleeve to which stimulus electrodes have been incorporated on its internal face, with detail on a larger scale of the multiconductor "tube"; Figure 4 shows an embodiment of the apparatus of the invention; and Figure 5 is a closed circuit flow diagram controlling the infusion of a muscle relaxant drug.

DESCRIPTION OF A PREFERRED EMBODIMENT Figure 2 shows a conventional positioning of the electrodes 1,2 and the sensor 3. In this case the electrodes 1,2 and the sensor 3. In this case the electrodes 1,2 are arranged in the arm and the sensor 3 is arranged in the Finger. The figure shows the two cables 4,5 corresponding to the electrodes and the cable 6 corresponding to the sensor. Figure 3 shows the stimulator-detector device of the apparatus of the invention. In the figure, the electrodes 7, 8 arranged in a pressure sleeve 9 can be seen. As the detail on a larger scale shows, the multiconductor tube 10 comprises an air conductor 11 and two electrical conductors 12 and 13. In the embodiment shown in FIGS. conductors 12 and 13 are included in the wall of the ulticonductor tube 10. Figure 1 shows a curve A with continuous line corresponding to the method of the invention with the pressure sleeve provided with the stimulation electrodes disposed on the muscle in the that the block is assessed, and a B curve with dashed line that corresponds to a conventional method, with the stimulation electrodes on the ulnar nerve and the sensor on the thumb. To demonstrate the validity of the method of the invention and ensure that with direct skin stimulation on the muscle mass in which it is desired to assess the neuromuscular block, there is no direct stimulation of the muscle fibers but the stimulation follows the intramuscular and intramuscular nerve pathways. Neural endings of the muscular motor plate, the following test has been performed: Sensors have been placed on the thumb and stimulation electrodes on the ulnar nerve following the guidelines of the previous conventional methods. The curve B has been obtained. In the same patient and simultaneously the pressure sleeve with the electrodes has been placed on its internal face following the guidelines of the method of the invention. Curve A has been obtained. Comparing the evolution of both curves during the application of muscle relaxant drugs to anesthetized patients, results have been obtained that validate the method of the invention since the curves A and B demonstrate an analogous behavior for the same method. of application of drugs. Figure 4 shows the various components of the apparatus of the invention. Firstly, the stimulator-detector device 14 detailed in FIG. 3, which includes the stimulation electrodes 7,8 and the pressure cuff 9. This can be made in different sizes depending on the measurement of the extremity on which it is wanted applies, being able to exist realizations for adults or pediatrics. The device can be reusable or reusable, and comprises the two electrodes 7,8, also disposable or reusable, which are coupled to the sleeve and have a stimulus surface variable between 0.05 cma to 5 cma each. The electrodes 7,8 are placed on the inner side of the blood pressure cuff 9, which with the wave of muscle contraction transmitted to the skin generates a pressure wave proportional to the muscle contraction that is transmitted through the tube to the skin. pressure transducer disposed inside a blood pressure monitor 15 of conventional type. The stimulation electrodes 78 can be located in different ways on the inner face of the cuff 9. The further apart they are, the greater the number of stimulated nerve endings will be and the greater the response will be. The cycle followed for the measurement is as follows: 1) Inflate the sleeve slightly to ensure good contact of the electrodes with the skin. (from 10 to 300 mHg). 2) Generation and application through cutaneous electrodes, of a series of four stimuli <; 50mA and < of 30ms duration at a frequency of 2Hz called "TOF" ("Train Of Four", standard accepted in all valuation methods of neuromuscular block). 3) Record the pressure generated inside the cuff by the wave that is transmitted to the surface of the skin by contractions of the muscle. 4) Digitalization and signal processing, graphic representation through an LCD or electroluminescent screen. Figure 4 shows an embodiment of an apparatus of the invention. In said figure can be seen the stimulator-detector device 14 represented in figure 3 and? N blood pressure monitor 15 of conventional type. In the lower right part of the dial of the monitor 15 the connections 16, 17 and 18 corresponding respectively to the multiconductor tube 10, to the information on oxygen saturation and to the electrocardiogram can be seen. In the upper right part you can see a pair of control buttons, one of which 19 serves to adjust the time between two readings and the other 20 to adjust the intensity of the stimulus. On the left screen there are two curves, the surface corresponding to the electrocardiogram and the lower one to the pulse signal or plethysmogram. The bars at the bottom of the screen represent the responses over time to muscle stimulation. On the screen may also appear data such as muscle activity (Muse: 30%), heart rate (HR: 60), blood pressure ( PA: 120/70) and oxygen saturation (98% Sat). The conventional monitor 15 is provided with a pulse generator for muscle stimulation through conductors 12, 13 (figure 3) and electrodes 7,8. Figure 5 shows a flow diagram of a closed circuit. The electric stimulator 21 stimulates the muscle 22. The sensor 23 provides the muscle response or the control means 24. By means of a program it controls the acquisition of data, the A / D conversion and the analysis of the data, the signals being provided to drive the supply or infusion system of the muscle relaxant 25. In this way, the infusion would be carried out automatically.

Claims (9)

NQVEPRP PE ñ INVENTION CLAIMS

1. Apparatus for the monitoring and / or control of neuromuscular blockade, especially the blockage produced by muscle relaxant drugs during anesthesia, comprising means (7, 8) for the application of nerve stimulation, means (9) for the detection of the response to the stimulation and means (15) for monitoring the neuromuscular block, characterized in that the means (7, 8) for the nerve stimulation and the means (9) for the detection of the response are arranged in a same body (14).

2. Apparatus for the monitoring and / or control of neuromuscular blockade, in particular of the block produced by muscle relaxant drugs during anesthesia, comprising means (7, 8) for the application of nerve stimulation, means (9) for the detection of the response to stimulation and means (15) for the monitoring of the neuromuscular block, characterized in that it also comprises means for the supply of the drug that causes the neuromuscular block and control means that coordinate the generation of the stimulus, the record of the activity, the process of the data, the calculation of the dose of drug and the control of the means for the supply of the drug according to the calculated dose. Apparatus according to claim 2, characterized in that the means (7, S) for the application of the nerve stimulation and the means (9) for the detection of the response are arranged in the same body (14). Apparatus according to claim 1 or 3, characterized in that the body (14) is a sleeve of the type used for the measurement of blood pressure provided with means (9) for detecting the pressure or connected to said means, whose sleeve incorporates means (7, 8) for the application of nerve stimulation. Apparatus according to claim 1 or 3, characterized in that the means for applying the nerve stimulation comprise at least two electrodes (7, 8). Apparatus according to claim 4, characterized in that the means (7, 8) for the application of the nerve stimulation and the means for detecting the pressure are connected to the means (15) for monitoring by means of a tube multiconductor (10) comprising inside it an air duct (11) for transmitting the pressure waves and at least one pair of electrical conductors (12, 13) for transmitting the stimulation pulses. Apparatus according to claim 6, characterized in that the electrical conductors (12, 13) for the transmission of the stimulation pulses are included in the wall of the multi-conductor tube (10). Apparatus according to claim 1 or 3, characterized in that the means for the application of the nerve stimulation comprises a pressure sleeve having at least one electrode placed to couple the skin when the sleeve is applied. Apparatus according to claim 8, characterized in that the means for monitoring the neuromuscular block comprises means for measuring the pressure changes in said sleeve.