Fluid titration system

Abstract

A fluid titration system has an optical sensor, a physiological monitor, a titration controller and an infusion device. The optical sensor transmits multiple wavelengths of light into a tissue site of a person and detects the optical radiation after attenuation by pulsatile blood flowing within the tissue site. The physiological monitor receives a resulting sensor signal and derives a plethysmograph that corresponds to the pulsatile blood flow. The monitor also calculates a plethysmograph variability measure that is responsive to changes in perfusion at the tissue site. A titration controller generates a fluid control output according to the variability measure. The infusion device administers a liquid solution via an intravenous (IV) connection to the person according to the fluid control output so as to regulate at least one of a fluid flow start, rate and stop.

1 . A method of managing a blood volume of a patient, the method comprising:
 noninvasively detecting, with a detector of an optical sensor, light attenuated by a tissue of the patient at a measurement site;   outputting, with the optical sensor, a signal responsive to the light;   determining, with one or more hardware processors, a first measure of variability from at least a ratio of a pulsatile component to a nonpulsatile component of the signal, the pulsatile component being responsive to variable absorption in a blood volume in the tissue and the nonpulsatile component being responsive to static absorption in the blood volume in the tissue;   determining, with the one or more hardware processors, that the first measure of variability indicates a need for the patient to receive a liquid solution; and   in response to determining that the first measure of variability indicates the need, outputting a first infusion indication for presentation to a caregiver, the first infusion indication indicating to administer the liquid solution to the patient.   
     
     
         2 . The method of  claim 1 , further comprising:
 determining, with the one or more hardware processors, a second measure of variability from at least the ratio of the pulsatile component to the nonpulsatile component of the signal at a first time, the first time being different from a second time at which the first measure of variability is determined;   determining, with the one or more hardware processors, that the second measure of variability does not indicate the need; and   in response to determining that the second measure of variability does not indicate the need, outputting a second infusion indication for presentation to the caregiver, the second infusion indication indicating not to administer the liquid solution to the patient.   
     
     
         3 . The method of  claim 2 , further comprising visually presenting the first infusion indication and the second infusion indication to the caregiver on a display. 
     
     
         4 . The method of  claim 2 , further comprising:
 visually presenting the first infusion indication to the caregiver on a display as +, on, increase, or start; and   visually presenting the second infusion indication to the caregiver on the display as −, off, decrease, or stop.   
     
     
         5 . The method of  claim 2 , further comprising audibly presenting the first infusion indication and the second infusion indication to the caregiver. 
     
     
         6 . The method of  claim 2 , further comprising:
 comparing the first measure of variability with a threshold to determine whether the first measure of variability indicates the need; and   comparing the second measure of variability with the threshold to determine whether the second measure of variability indicates the need.   
     
     
         7 . The method of  claim 1 , further comprising determining the ratio of the pulsatile component to the nonpulsatile component from a sliding time window of values determined from the signal. 
     
     
         8 . The method of  claim 1 , wherein the first measure of variability is responsive to a dehydration condition of the patient or a hemorrhaging condition of the patient. 
     
     
         9 . The method of  claim 1 , further comprising visually presenting the first infusion indication to the caregiver on a display as +, on, increase, or start. 
     
     
         10 . The method of  claim 1 , further comprising administering the liquid solution to the patient subsequent to the outputting the first infusion indication for presentation to the caregiver. 
     
     
         11 . The method of  claim 10 , wherein the administering the liquid solution to the patient is performed using an infusion device separate from a patient monitor comprising the one or more hardware processors. 
     
     
         12 . The method of  claim 1 , further comprising comparing the first measure of variability with a threshold to determine whether the first measure of variability indicates the need. 
     
     
         13 . The method of  claim 1 , wherein the determining the first measure of variability comprises processing a respiration-induced cyclical variation in the signal. 
     
     
         14 . The method of  claim 1 , wherein the determining the first measure of variability comprises determining the first measure of variability from at least a change in the ratio of the pulsatile component to the nonpulsatile component. 
     
     
         15 . The method of  claim 1 , wherein the first measure of variability comprises a measure of perfusion index variability of the signal. 
     
     
         16 . The method of  claim 1 , further comprising irradiating, with one or more emitters of the optical sensor, the tissue with red and infrared wavelengths. 
     
     
         17 . The method of  claim 1 , further comprising determining, with the one or more hardware processors, a parameter measurement from the signal, the parameter measurement comprising carboxyhemoglobin or methemoglobin. 
     
     
         18 . The method of  claim 1 , wherein the liquid solution comprises blood products or nutrient fluids. 
     
     
         19 . The method of  claim 1 , wherein the measurement site comprises a finger. 
     
     
         20 . Non-transitory physical computer storage comprising computer-executable instructions stored thereon that, when executed by one or more hardware processors, are configured to implement a process comprising:
 receiving a signal generated by a detector of an optical sensor, the signal being responsive to light attenuated by a tissue of a patient at a measurement site;   determining a first measure of variability from at least a ratio of a pulsatile component to a nonpulsatile component of the signal, the pulsatile component being responsive to variable absorption in a blood volume of the tissue and the nonpulsatile component being responsive to static absorption in the blood volume of the tissue;   determining that the first measure of variability indicates a need for the patient to receive a liquid solution; and   in response to determining that the first measure of variability indicates the need, outputting a first infusion indication for presentation to a caregiver, the first infusion indication indicating to administer the liquid solution to the patient.