Tracking nociception under anesthesia using a multimodal metric

Abstract

Systems and methods for tracking sympathetic-driven arousal state (SDAS) including nociception under anesthesia is described herein. The method includes obtaining heart rate variability and electrodermal activity of a subject. Point process models are generated for the heart rate variability and the electrodermal activity. A multimodal approach is implemented to determine a state space framework based on these point process models. SDAS can be estimated using the state space framework. In some implementations, an anesthesiologist can modify the dosage of drugs administered to the subject based on this estimation.

1 . A method of administering anesthetic agents to a patient, the method comprising:
 measuring a variability in electrodermal activity of the patient;   measuring heart rate and heart rate variability of the patient while measuring the electrodermal activity;   determining a nociceptive state of the patient based on the variability in the electrodermal activity, the heart rate, and the heart rate variability; and   adjusting a dosage of an anesthetic agent administered to the patient based on the nociceptive state.   
     
     
         2 . (canceled) 
     
     
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         4 . (canceled) 
     
     
         5 . The method of  claim 1 , wherein measuring the heart rate variability comprises:
 obtaining electrocardiography (ECG) data from the patient;   obtaining pulse plethysmography data from the patient; and   estimating a point process model for the heart rate and the heart rate variability based on the ECG data and/or the pulse plethysmography data.   
     
     
         6 . The method of  claim 5 , wherein determining the nociceptive state comprises:
 estimating sympathetic and parasympathetic activity of the patient from the point process model of the heart rate and the heart rate variability.   
     
     
         7 . The method of  claim 5 , wherein estimating the point process model for the heart rate and the heart rate variability comprises:
 determining RR intervals between consecutive R wave peaks in the ECG data and/or the pulse plethysmography data, the RR intervals being time elapsed between the consecutive R wave peaks;   determining at least one distribution of the RR intervals; and   determining the heart rate and the heart rate variability from the at least one distribution of the RR intervals.   
     
     
         8 . (canceled) 
     
     
         9 . The method of  claim 7 , wherein determining the at least one distribution of the RR intervals comprises:
 modeling the RR intervals using an inverse Gaussian model.   
     
     
         10 . The method of  claim 1 , wherein adjusting the dosage comprises:
 changing the dosage of the anesthetic in response to determining a change in the nociceptive state of the patient.   
     
     
         11 . The method of  claim 1 , wherein measuring the variability in electrodermal activity comprises:
 obtaining the electrodermal activity of the patient; and   estimating a point process model of the electrodermal activity.   
     
     
         12 . The method of  claim 11 , wherein determining the nociceptive state comprises:
 estimating sympathetic activity of the patient from the point process model of the electrodermal activity.   
     
     
         13 . The method of  claim 11 , wherein estimating the point process model of the electrodermal activity comprises:
 classifying pulses extracted from the electrodermal activity in a phasic component of the electrodermal activity;   determining inter-pulse intervals between consecutive pulses;   determining at least one distribution for the inter-pulse intervals; and   determining an instantaneous mean pulse rate and an instantaneous pulse rate variability of the electrodermal activity from the at least one distribution.   
     
     
         14 . The method of  claim 13 , further comprising:
 determining the nociceptive state of the patient based at least in part on the instantaneous pulse rate variability of the electrodermal activity.   
     
     
         15 . The method of  claim 13 , wherein determining the at least one distribution comprises:
 modeling the inter-pulse intervals using an inverse Gaussian, generalized inverse Gaussian, lognormal, gamma and/or exponential distribution.   
     
     
         16 . The method of  claim 13 , wherein classifying the pulses in the phasic component comprises:
 removing a tonic component from the electrodermal activity.   
     
     
         17 . The method of  claim 1 , further comprising:
 removing at least one interference-related artifact from the electrodermal activity before determining the nociceptive state of the patient based on the electrodermal activity.   
     
     
         18 . A system for tracking a nociceptive state of a patient, the system comprising:
 a sensor to measure electrodermal activity of the patient;   a sensor to measure heart rate and heart rate variability of the patient;   a processor, operably coupled to the sensor, to determine the nociceptive state of the patient in real time based on the electrodermal activity, the heart rate, and the heart rate variability; and   a display, operably coupled to the processor, to display a real-time indication of the nociceptive state of the patient to a physician for adjusting a dosage of an anesthetic administered to the patient based on the nociceptive state.   
     
     
         19 . A method, comprising:
 obtaining electrodermal activity of a patient;   obtaining a variability in heart rate of the patient;   generating a point process model of the electrodermal activity;   generating a point process model of the variability in the heart rate; and   constructing a quantitative multi-dimensional measure of a nociceptive state of the patient based on the point process model of the electrodermal activity and the point process model of the variability in the heart rate.   
     
     
         20 . The method of  claim 19 , wherein the multi-dimensional measure includes an instantaneous mean heart rate, an instantaneous heart rate variability, an instantaneous mean pulse rate, and an instantaneous pulse rate variability. 
     
     
         21 . The method of  claim 20 , further comprising:
 administering an anesthetic agent to the patient based on the quantitative multi-dimensional measure of the nociceptive state.   
     
     
         22 . The method of  claim 21 , further comprising:
 in response to determining a decrease in the instantaneous mean heart rate and an increase in the instantaneous heart rate variability, determining a decrease in the quantitative multi-dimensional measure of the nociceptive state; and   in response to determining the decrease in the quantitative multi-dimensional measure of the nociceptive state, decreasing a dosage of the anesthetic agent.   
     
     
         23 . The method of  claim 21 , further comprising:
 in response to determining an increase in the instantaneous mean pulse rate and an increase in the instantaneous pulse rate variability, determining an increase in the quantitative multi-dimensional measure of the nociceptive state; and   in response to determining the increase in the quantitative multi-dimensional measure of the nociceptive state, increasing a dosage of the anesthetic agent.   
     
     
         24 . (canceled) 
     
     
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         26 . (canceled) 
     
     
         27 . (canceled) 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . (canceled) 
     
     
         32 . (canceled) 
     
     
         33 . (canceled) 
     
     
         34 . A method of administering an anesthetic agent to a patient, the method comprising:
 obtaining electrodermal activity of the patient;   extracting temporal information from the electrodermal activity;   extracting amplitude information from the electrodermal activity;   determining a nociceptive state of the patient based at least in part on the temporal information and the amplitude information of the electrodermal activity; and   adjusting a dosage of the anesthetic agent administered to the patient based on the nociceptive state.   
     
     
         35 . The method of  claim 34 , wherein extracting the amplitude information from the electrodermal activity comprises determining amplitude of pulses in the electrodermal activity. 
     
     
         36 . The method of  claim 35 , further comprising:
 determining an excess volume of sweat produced by the patient based at least in part on the amplitude of pulses.   
     
     
         37 . (canceled) 
     
     
         38 . The method of  claim 37 , wherein determining the nociceptive state from the amplitude information comprises determining the nociceptive state based at least in part on the excess volume of sweat produced. 
     
     
         39 . The method of  claim 34 , further comprising:
 generating at least one point process model for the temporal information and/or the amplitude information of the electrodermal activity.   
     
     
         40 . The method of  claim 39 , wherein determining the nociceptive state comprises:
 estimating sympathetic activity of the patient from the first point process model and the second point process model.   
     
     
         41 . (canceled) 
     
     
         42 . A method, comprising:
 obtaining electrodermal activity of a patient;   obtaining a variability in heart rate of the patient;   determining a measure of the variability in the heart rate of the patient;   constructing a state space framework model based on the electrodermal activity of the patient and the measure of the variability in the heart rate of the patient; and   estimating a sympathetic-driven arousal state based on the state space framework model.   
     
     
         43 . (canceled)