US-12622603-B2 - Method and system for monitoring depth of muscle relaxation of a patient

US12622603B2US 12622603 B2US12622603 B2US 12622603B2US-12622603-B2

Abstract

A method of monitoring depth of muscle relaxation of a patient includes applying a series of stimulations to a nerve of a patient and measuring muscle responses thereto. A maximal stimulus current, a supramaximal stimulus current, and/or a submaximal stimulus current are determined based on the muscle responses, wherein the maximal stimulus current is a current at which a maximal muscle response is produced from stimulating the nerve, the supramaximal stimulus current is greater than or equal to the maximal stimulus current, and the submaximal stimulus current is less than the maximal stimulus current. A first set of stimulations are applied to the nerve of the patient. Either the supramaximal stimulus current or the submaximal stimulus current are then selected for a subsequent series of stimulations based on the measured muscle responses to the first series of stimulations, and the subsequent series of stimulations are performed accordingly to monitor the patient's depth of muscle relation.

Inventors

Mika Olli Kristian Sarkela
Mari Johanna Partio

Assignees

GE Precision Healthcare LLC

Dates

Publication Date: 20260512
Application Date: 20240411

Claims (11)

1 . A method of monitoring depth of muscle relaxation of a patient, the method comprising: prior to administration of a neuromuscular blocking agent to the patient: applying a series of stimulations via a stimulator to the nerve of the patient at varying stimulus currents to measure via a sensor device muscle responses to the series of stimulations to determine least one of a maximal stimulus current, a supramaximal stimulus current, and a submaximal stimulus current for the patient, wherein the maximal stimulus current is a current at which a maximal muscle response is produced from stimulating a nerve of the patient, the supramaximal stimulus current is greater than or equal to the maximal stimulus current, and the submaximal stimulus current is less than the maximal stimulus current; after administration of the neuromuscular blocking agent to the patient: periodically applying via the stimulator a train-of-four (TOF) stimulation to the nerve of the patient at the supramaximal stimulus current and measuring TOF response to the TOF stimulations to the nerve of the patient at the supramaximal stimulus current; upon identifying that the measured TOF response to the TOF stimulations is at least equal a supramax response threshold: periodically applying via the stimulator a TOF stimulation to the nerve of the patient at the submaximal stimulus current and measuring a submax TOF response to monitor the patient's depth of muscle relaxation; and storing a submaximal stimulation mode indicator in a non-transitory storage medium associated with a sensor device.
2 . The method of claim 1 , further identifying that the submax TOF response is less than a submax response threshold, and then reapplying the TOF stimulation to the nerve of the patient at the supramaximal stimulus current and measuring a new TOF response thereto; and comparing the new TOF response to the supramax response threshold to confirm or reject recurarization.
3 . The method of claim 2 , further comprising generating a recurarization alarm upon identifying that the submax TOF response is less than the submax response threshold and/or upon confirming recurarization, generating a recurarization alarm.
4 . The method of claim 1 , further comprising transmitting the stored submaximal stimulation mode indicator and a stimulus current indicator of the at least one of the maximal stimulus current, the supramaximal stimulus current, and the submaximal stimulus current to a patient monitor configured to monitor the patient.
5 . The method of claim 1 , wherein the supramaximal stimulus current is at least 10% greater than the maximal stimulus current for the patient, and wherein the submaximal stimulus current is at least 10% less than the maximal stimulus current.
6 . A system for monitoring depth of muscle relation of a patient, the system comprising: a stimulator configured to apply a series of stimulations to a nerve of the patient; a sensor device configured to measure muscle responses of the patient to the series of stimulations; a non-transitory storage medium storing a stimulation mode indicator that indicates a stimulation mode for the stimulator and/or a stimulus current indicator of at least one of a maximal stimulus current, a supramaximal stimulus current, and a submaximal stimulus current for the patient, wherein the maximal stimulus current is a current at which a maximal muscle response is produced from stimulating the nerve, the supramaximal stimulus current is greater than or equal to the maximal stimulus current, and the submaximal stimulus current is less than the maximal stimulus current; a controller configured to: control the stimulator to apply the series of stimulations to the nerve of the patient at varying stimulus currents and the sensor device to measure muscle responses to the series of stimulations to determine at least one of the maximal stimulus current, the supramaximal stimulus current, and a submaximal stimulus current for the patient; control the stimulator to periodically apply a train-of-four (TOF) stimulation to the nerve of the patient at the supramaximal stimulus current and measure a TOF response to the TOF stimulations to the nerve of the patient at the supramaximal stimulus current; compare the measured TOF response to a supramax response threshold; upon identifying that the measured TOF response to the TOF stimulations is at least equal to the supramax response threshold: periodically apply a TOF stimulation to the nerve of the patient at the submaximal stimulus current and measure a submax TOF responses to monitor the depth of muscle relaxation of the patient; and store a submaximal stimulation mode indicator in the non-transitory storage medium.
7 . The system of claim 6 , wherein the controller is integrated into a connector connecting the sensor device to a patient monitor, and wherein the controller is configured to receive the stimulation mode indicator and/or the stimulus current indicator stored in the non-transitory storage medium upon connection of the sensor device to the patient monitor.
8 . The system of claim 6 , wherein the controller is integrated into a connector connecting the sensor device to a patient monitor, and further comprising: a wireless transceiver in the connector; wherein the controller is further configured to wirelessly connect to a patient monitor configured to monitor the patient.
9 . The system of claim 6 , wherein the non-transitory storage medium is integrated into the sensor device, and wherein the controller is configured to receive the stimulation mode indicator and/or a stimulus current indicator stored in the non-transitory storage medium upon connection of the sensor device to the patient monitor.
10 . The system of claim 6 , wherein the controller is further configured to: identify that the submax TOF response is less than a submax response threshold, and then reapply the TOF stimulation to the nerve of the patient at the supramaximal stimulus current and measuring a new TOF response thereto; and compare the new TOF response to the supramax response threshold to confirm or reject recurarization.
11 . The system of claim 10 , wherein the controller is further configured to generate a recurarization alarm upon identifying that the submax TOF response is less than the submax response threshold and/or upon confirming recurarization.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This Application is a divisional of U.S. patent application Ser. No. 16/569,261, filed Sep. 12, 2019, which application is herein incorporated by reference in its entirety. BACKGROUND The present disclosure generally relates to medical patient monitoring, and more particularly to systems and methods for monitoring neuromuscular transmission to gauge depth of muscle relaxation of a patient to which a neuromuscular blocking agent has been administered. Neuromuscular transmission (NMT) is the transfer of an impulse between a nerve and a muscle in the neuromuscular junction. NMT may be blocked in a patient undergoing a surgical procedure, for example, by neuromuscular blocking agents/drugs, which may cause transient muscle paralysis and prevent the patient from moving and breathing spontaneously. Muscle relaxation is used during general anesthesia to enable endotracheal intubation and to provide the surgeon with optimal working conditions. At the end of a surgical procedure, the level of NMT is used to determine when the patient can be extubated. The level of neuromuscular block may be monitored to ensure appropriate block is provided for the given procedure and/or to determine when the patient can be safely extubated. SUMMARY This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. One embodiment of a method of monitoring depth of muscle relaxation of a patient includes applying a series of stimulations to a nerve of a patient and measuring muscle responses thereto. At least one of a maximal stimulus current, a supramaximal stimulus current, and a submaximal stimulus current for the patient are determined based on the muscle responses, wherein the maximal stimulus current is a current at which a maximal muscle response is produced from stimulating the nerve, the supramaximal stimulus current is greater than or equal to the maximal stimulus current, and the submaximal stimulus current is less than the maximal stimulus current. A first set of stimulations, such as a series of supramaximal stimulations, are applied to the nerve of the patient and muscle responses to the first set of stimulations are measured. Either the supramaximal stimulus current or the submaximal stimulus current are then selected for a subsequent series of stimulations based on the measured muscle responses to the first set of stimulations, and the subsequent series of stimulations are performed at the selected stimulus current and the muscle responses of the patient are measured to monitor the patient's depth of muscle relation. One embodiment of a method of monitoring depth of muscle relaxation of a patient includes, prior to administration of a neuromuscular blocking agent to the patient, determining at least one of a maximal stimulus current, a supramaximal stimulus current, and a submaximal stimulus current for the patient. In one embodiment, the at least one of the current values is stored in a storage medium associated with a sensor device. The maximal stimulus current is a lowest current at which a maximal muscle response is produced from a stimulation to a nerve of the patient, the supramaximal stimulus current is greater than or equal to the maximal stimulus current, and the submaximal stimulus current is less than the maximal stimulus current. After administration of the neuromuscular blocking agent to the patient, periodically applying a train-of-four (TOF) stimulation to the nerve of the patient at the supramaximal stimulus current and measuring TOF response to the supramaximal stimulations. In one embodiment, a supramaximal stimulation mode indicator is stored in a storage medium associated with a sensor device indicating that the supramaximal stimulation is being used to monitor the patient. Upon identifying that the measured TOF response is at least equal a supramax response threshold, periodically applying a TOF stimulation to the nerve of the patient at the submaximal stimulus current and measuring a submax TOF response to monitor the patient's depth of muscle relaxation. A submaximal stimulation mode indicator is stored in a storage medium associated with a sensor device indicating that the submaximal stimulation is being used to monitor the patient. One embodiment of a system for monitoring depth of muscle relation of a patient includes a stimulator configured to apply a series of stimulations to a nerve of the patient and a sensor device configured to measure muscle responses of the patient to the series of stimulations. A storage medium and controller are also included. The storage medium is configured to store a stimulation mode indicator that indicates a stimulation mode for the stimulator and/or a stimulus current indicator