a portable neuromuscular stimulator is disclosed . in the following detailed description , numerous specific details are set forth to provide a full understanding of the present invention . it will be obvious , however , to those ordinarily skilled in the art that the present invention may be practiced without some of these specific details . in other instances , well - known structures and techniques have not been shown in detail so as to avoid unnecessarily obscure the present invention . reference is made to fig2 ( a )-( d ), where an external design of an exemplary stimulator device 20 with a disposable bi - polar pad 25 in accordance with the present invention is illustrated . referring to fig2 ( a )-( d ), the stimulator device 20 , which may have an exemplary dimension of 53 mm × 30 mm × 10 mm , has three control buttons : on / off 210 , trigger 215 and level 220 . a lithium battery , for example , a 3v cr2025 battery , which is placed into a battery receptacle on the side of the device , is used to power this stimulator device 20 . to help the anesthesiologist monitor the operation of the device , an lcd display 205 is positioned on the stimulator device . on the back side of the device 20 , electrode terminals 230 a , 235 a , such as the female button - type clip receptacle , are positioned to provide electric contact to a one - piece electrode pad 25 . upon the user &# 39 ; s pressing of the trigger button 215 , the device 20 can generate either 4 pulses at 2 hz (“ p1 mode ”), or a continuous pulse at 50 hz (“ p2 mode ”). also , the intensity level of the pulse can be adjusted for each mode . for example , as shown in table 2 ( e ), for p1 , the intensity level may increment through 11 levels ( amplitude in ma , peak - to - peak ), e . g . 0 , 20 , 30 , 40 , 50 , 55 , 60 , 65 , 70 , 75 and 80 . the intensity level for p2 may step through 0 , 20 , 25 , 30 , 35 , 40 , 45 , 50 , 55 , 60 and 65 . however , the intensity levels , or the increments , can be easily modified by those skilled in the art when implementing the stimulator device in accordance with the present invention based on their own operating requirements . by having a visual display of the mode and intensity level on the lcd 205 , the anesthesiologist can be assured that the same , consistent stimulation be applied to the patient for accurate monitoring , even if the device is powered off or removed from the patient briefly . referring to fig2 ( c )-( d ), a flexible , single - piece , bi - polar electrode pad 25 is shown in a simplified cross - sectional view . at the top layer of the pad 25 , two protruded male electrode terminals 230 b , 235 b , allow the stimulator device 20 to be removably attached to the electrode pad 25 through its female receptacle 230 a , 235 a . this kind of male - female , push - button metal clipper is quite common to those skilled in the field . the electrode terminals 230 b , 235 b , are electrically connected to the gel pads 250 through a plastic insulator layer 245 . the gel pads 250 can be adhesively attached to a patient &# 39 ; s skin after the peel - away cover 246 is removed . as shown in fig2 ( d ), the electrode pad 25 can be easily applied to the patient &# 39 ; s skin 27 to provide a consistent and complete contact surface , thanks to the flexible shape of the electrode pad 25 , which can accommodate the anatomical shape of the patient , e . g . on the forearm or on the temporal facial area . once the pad 25 is placed on the patient , the stimulator device 20 can be easily attached to the pad 25 by engaging the terminals 230 a , 235 a on the stimulator device 20 to the terminals 230 b , 235 b on the electrode pad 25 . more importantly , the electrode pad 25 can remain on the patient &# 39 ; s skin throughout the procedure , even if the stimulator device 20 may be removed from time to time . all the doctor has to do is simply re - engaging the stimulator device 20 back onto the electrode pad 25 . preferably , the electrode pad 25 is disposable so as to prevent cross contamination to the patients . as described in the background of the invention , the conventional technique of applying stimulation is either through direct skin contact by two metal electrodes from the stimulator box ( as exemplified in fig1 ), or through using wires to connect two separate ekg pads on the patient . in contrast , the stimulator device 20 and the disposable flexible electrode pad 25 of the present invention provide a consistent and uniform contact to the patient , through the single bi - polar electrode pad 25 . such contact can be made with or without the use of extension wires between the stimulator device and the patient , although it is preferable to attach the stimulator device 20 directly on the electrode pad 25 itself . additionally , multiple levels of intensity and different modes of pulses , i . e . tof and tetanus , are provided by the stimulator device 20 of the present invention . the adjustable intensity levels allow the output of the stimulator device 20 to be tested before the patient is under general anesthesia to find the optimal comfort level of stimulation , so that any unnecessary high voltage pulses can be avoided during anesthesia . the level and mode of stimulation displayed on the lcd 205 allow the attending doctors to accurately monitor and record the event for delivering better anesthesia care to the patients . reference is now to fig3 , where an exemplary functional block diagram of the stimulator device in accordance with the present invention is illustrated . a control circuit 300 and memory 303 receive the user &# 39 ; s input with respect to the mode and intensity of stimulation and convert it into instructions for the pulse generator 305 . the pulse generator circuit 305 then generates either the tetanus pulses or tof pulses at the specified intensity level . the mode and intensity data are also displayed on the lcd 310 of the stimulator device . the power supply 320 , e . g . the 3v lithium battery , provides power to the components on board . it should be noted that a pulse generator circuit is readily available as an integrated circuit chip (“ ic ”), possibly with the control circuit also implemented on the circuit board . currently , an 8 - bit microcontroller from holtek semiconductor , inc ., of hsinchu , taiwan , republic of china , with part no . ht 49c30 , is used to provide the pulses and drive the lcd , based on the user input . of course , those skilled in the art may find other microcontrollers or microprocessors just as suitable for their application in accordance with the teaching of the present invention . reference is to fig4 ( a )-( c ), where an exemplary process flow of the stimulator device 20 in accordance with the present invention is illustrated . as shown in fig4 ( a ), from “ start ,” the stimulator device continuously checks if the “ mode ” button is pressed , so that it can be out of the “ battery save ” mode . when the “ mode ” button is pressed , the “ p1 ” mode is first activated with the lcd displaying “ p1 ” accordingly . it stays in the “ p1 ” mode until the “ mode ” button is pressed again . when the “ mode ” button is pressed again , the “ p2 ” mode is activated with the lcd displaying “ p2 ” accordingly . if the “ mode ” button is pressed for an extended duration , e . g . more than 3 seconds , the stimulator device goes into its “ battery save ” mode . fig4 ( b ) further illustrates the process flow of the stimulator device in p1 mode . when the “ intensity ” button is pressed successively , the intensity level can be incremented from level 0 to level 10 , with the lcd displaying the intensity levels . then , pressing the “ start ” button will activate the 2 hz tof output of the stimulator device . if the “ intensity ” button is not pressed , then the default level 0 is activated . as a safety precaution , the stimulator device preferably always starts at the lowest level in order to avoid overpowering the patient . fig4 ( c ) illustrates the same process flow for the case of 50 hz tetanus output in p2 mode . although the invention is described herein with reference to the preferred embodiment , one skilled in the art will readily appreciate that other applications may be substituted for those set forth herein without departing from the scope of the present invention . accordingly , the invention should only be limited by the claims included below .
a portable neuromuscular stimulator is disclosed . the neuromuscular stimulator for use with a patient during general anesthesia comprises a housing , a pair of electrode terminals disposed on the outside of the housing , a pulse generator within the housing , wherein the pulse generator is disposed to controllably generate one of tof and tetanus stimulations to the electrode terminals , and the pulse generator having an intensity controller to controllably vary the level of intensity of the stimulations . the stimulator also has a liquid crystal display on the outside of the housing , with the lcd being disposed to display a mode of operation and a level of intensity representative of the stimulation being applied to the electrode terminals from said pulse generator .