Neuromuscular monitoring using phonomyography

1. A system using phonomyography for monitoring relaxation of a given muscle of a living subject, comprising:

means for applying muscle-activating stimulation signals to the living subject's body via at least one electrode to stimulate the given muscle of the living subject;

means for sensing pressure waveform signals produced by the given muscle of the living subject in response to the applied stimulation signals;

means for processing the sensed pressure waveform signals to produce data indicative of a level of relaxation of the given muscle of the living subject; and

means for displaying the data indicative of the level of relaxation of the given muscle of the living subject from the processing means.

2. A system using phonomyography for monitoring relaxation of a given muscle of a living subject, comprising:

at least one neurostimulator to apply muscle-activating stimulation signals to the living subject's body via at least one electrode to stimulate the given muscle of the living subject;

at least one pressure waveform sensor to detect pressure waveform signals produced by the given muscle of the living subject in response to the applied stimulation signals;

a processor of the detected pressure waveform signals to produce data indicative of a level of relaxation of the given muscle of the living subject; and

a display of the data indicative of the level of relaxation of the given muscle of the living subject from the processor.

3. The system of claim 2 , wherein the data displayed through the display is selected from the group consisting of: raw pressure waveform signals detected through said at least one pressure waveform sensor, amplitudes of the pressure waveform signals, and ratios of said amplitudes.

4. The system of claim 2 , further comprising an amplifier for amplifying the pressure waveform signals detected by said at least one pressure waveform sensor.

5. The system of claim 2 , comprising a controller connected to said at least one neurostimulator and to said at least one pressure waveform sensor, said controller incorporating the processor and display.

6. The system of claim 5 , wherein the controller includes a laptop computer.

7. The system of claim 5 , wherein said controller includes a pocket computer.

8. The system of claim 2 , wherein said at least one neurostimulator includes a plurality of neurostimulators respectively associated to different muscles of the living subject.

9. The system of claim 2 , wherein said at least one pressure waveform sensor includes a plurality of pressure waveform sensors respectively associated to different muscles of the living subject.

10. The system of claim 2 , wherein said at least one pressure waveform sensor has a detection frequency bandwidth ranging from about 2 Hz to about 10 Hz.

11. The system of claim 10 , wherein said at least one pressure waveform sensor comprises at least one microphone.

12. The system of claim 2 , wherein the muscle-activating stimulation signals comprises single stimulation signals.

13. A neuromuscular monitoring system using phonomyography, comprising:

at least one neurostimulator to apply muscle-activating stimulation signals to a patients body via at least one electrode;

at least one pressure waveform sensor to detect pressure waveform signals produced by a patient's muscle in response to the applied stimulation signals; and

a controller connected to said at least one neurostimulator and to said at least one pressure waveform sensor, said controller including a processor of the detected pressure waveform signals and a display of data, from the processor, related to the detected pressure waveform signals;

wherein the controller is so configured as to:

before the administration of a relaxant to the patient:

apply a predetermined muscle-activating stimulation signal to the patient's body through said at least one neurostimulator and via said at least one electrode;

sample the pressure waveform signal detected by said at least one pressure waveform sensor in response to the applied predetermined stimulation signal; and

measure a reference amplitude (A ref ) of the sampled signal; and

after a relaxant has been administered to the patient:

apply the predetermined muscle-activating stimulation signal through said at least one neurostimulator and via said at least one electrode;

sample the pressure waveform signal detected by said at least one pressure waveform sensor in response to the applied predetermined stimulation signal;

measure an amplitude (A) of the response signal;

calculate a ratio A/A ref ; and

display the calculated ratio.

14. A neuromuscular monitoring system using phonomyography, comprising:

at least one neurostimulator to apply muscle-activating stimulation signals to a patient's body via at least one electrode;

at least one pressure waveform sensor to detect pressure waveform signals produced by a patient's muscle in response to the applied stimulation signals: and

a processor of the detected pressure waveform signals and a display of data, from the processor, related to the detected pressure waveform signals;

wherein the muscle-activating stimulation signals comprise train-of-four twitches.

15. A neuromuscular monitoring system using phonomyography, comprising:

at least one neurostimulator to apply muscle-activating stimulation signals to a patient's body via at least one electrode;

at least one pressure waveform sensor to detect pressure waveform signals produced by a patient's muscle in response to the applied stimulation signals; and

a controller connected to said at least one neurostimulator and to said at least one pressure waveform sensor, said controller including a processor of the detected pressure waveform signals and a display of data, from the processor, related to the detected pressure waveform signals;

wherein the muscle-activating stimulation signals comprise train-of-four twitches, and wherein the controller is so configured as to:

measure a peak-to-peak amplitude of a pressure waveform signal detected by said at least one pressure waveform sensor in response to a first pulse of the train-of-four (T 1 );

measure a peak-to-peak amplitude of a pressure waveform signal detected by said at least one pressure waveform sensor in response a fourth pulse of the train-of-four (T 4 );

calculate a ratio T 4 /T 1 ; and

display the calculated ratio.

16. A neuromuscular monitoring method using phonomyography, comprising:

providing at least one pressure waveform sensor;

positioning said at least one pressure waveform sensor at a predetermined position of a patient's body;

providing at least one electrode;

positioning said at least one electrode at a predetermined position of the patient's body;

applying a muscle-activating stimulation signal to the patient's body via said at least one electrode;

sampling a pressure waveform signal detected by said at least one pressure waveform sensor in response to the applied muscle-activating stimulation signal;

measuring a reference amplitude (A ref ) of the sampled signal;

after a relaxant has been administered:

applying a subsequent muscle-activating stimulation signal to the patient's body via said at least one electrode;

sampling a subsequent pressure waveform signal detected by said at least one pressure waveform sensor in response to the subsequent muscle-activating stimulation signal;

measuring an amplitude (A) of the subsequent pressure waveform signal;

calculating a ratio A/A ref ; and

displaying the calculated ratio.

17. The neuromuscular monitoring method of claim 16 , wherein applying a muscle-activating stimulation signal comprises applying a single pulse stimulation signal.

18. The neuromuscular monitoring method of claim 16 , wherein measuring an amplitude comprises measuring a peak-to-peak amplitude.

19. A method using phonomyography for monitoring relaxation of a muscle of a living subject, comprising:

providing at least one pressure waveform sensor;

positioning said at least one pressure waveform sensor at a first predetermined position of the living subject's body;

providing at least one electrode;

positioning the at least one electrode at a predetermined second position of the living subject's body;

applying muscle-activating stimulation signals to the living subject's body via said at least one electrode to stimulate the given muscle of the living subject;

sampling pressure waveform signals detected by said at least one pressure waveform sensor and produced by the given muscle of the living subject in response to the applied muscle-activating stimulation signals;

processing the sampled detected pressure waveform signals to produce data indicative of a level of relaxation of the given muscle of the living subject; and

displaying the data indicative of the level of relaxation of the given muscle of the living subject from the act of processing.

20. The method of claim 19 , wherein:

processing the sampled detected pressure waveform signals comprises measuring amplitudes of the detected pressure waveform signals; and

displaying data comprises displaying the detected pressure waveform signals and the measured amplitudes.

21. A neuromuscular monitoring method using phonomyography, comprising:

providing at least one pressure waveform sensor;

positioning said at least one pressure waveform sensor at a predetermined position of a patient's body;

providing at least one electrode;

positioning the at least one electrode at a predetermined position of the patient's body;

applying muscle-activating stimulation signals to the patient's body via said at least one electrode;

sampling pressure waveform signals detected by said at least one pressure waveform sensor in response to the applied muscle-activating stimulation signals;

processing the detected pressure waveform signals; and

displaying data, from the act of processing, related to the detected pressure waveform signals;

wherein applying muscle-activating stimulation signals comprises applying train-of-four twitches.

22. A neuromuscular monitoring method using phonomyography, comprising:

providing at least one pressure waveform sensor;

positioning said at least one pressure waveform sensor at a predetermined position of a patient's body;

providing, at least one electrode;

positioning the at least one electrode at a predetermined position of the patient's body;

applying muscle-activating stimulation signals to the patient's body via said at least one electrode;

sampling pressure waveform signals detected by said at least one pressure waveform sensor in response to the applied muscle-activating stimulation signals;

processing the sampled detected pressure waveform signals; and

displaying data, from the act of processing, related to the detected pressure waveform signals;

wherein:

processing the sampled detected pressure waveform signals comprises measuring amplitudes of the detected pressure waveform signals; and

displaying data comprises displaying the detected pressure waveform signals and the measured amplitudes; and

wherein applying muscle-activating stimulation signals comprises applying train-of-four twitches, and wherein measuring amplitudes of the detected pressure waveform signals comprises:

measuring a peak-to-peak amplitude of the pressure waveform signal detected by said at least one pressure waveform sensor in response to a first pulse of each train-of-four (T 1 );

measuring a peak-to-peak amplitude of the pressure waveform signal detected by said at least one pressure waveform sensor in response to a fourth pulse of the same train-of-four (T 4 ); and

calculating a ratio T 4 /T 1 .

23. The neuromuscular monitoring method of claim 22 , wherein displaying the measured amplitudes comprises displaying the T 4 /T 1 calculated ratio.