FLUID TITRATION SYSTEM
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.
The present application claims priority benefit under 35 U.S.C. § 120 to, and is a continuation of U.S. patent application Ser. No. 13/287,060, filed on Nov. 1, 2011, entitled “Fluid Titration System,” which is a continuation of U.S. patent application Ser. No. 12/208,998, filed on Sep. 11, 2008, entitled “Fluid Titration System,” now U.S. Pat. No. 8,048,040, which claims priority benefit under 35 U.S.C. § 119(e) from U.S. Provisional Application No. 60/993,584, filed Sep. 13, 2007, entitled “Fluid Titration System;” the disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTIONPulse oximeters capable of reading through motion induced noise are disclosed in at least U.S. Pat. Nos. 6,770,028, 6,658,276, 6,650,917, 6,157,850, 6,002,952, 5,769,785, and 5,758,644; low noise pulse oximetry sensors are disclosed in at least U.S. Pat. Nos. 6,088,607 and 5,782,757; all of which are assigned to Masimo Corporation, Irvine, Calif. (“Masimo”) and are incorporated by reference herein.
Physiological monitors and corresponding multiple wavelength optical sensors are described in at least U.S. patent application Ser. No. 11/367,013, filed Mar. 1, 2006 and entitled Multiple Wavelength Sensor Emitters and U.S. patent application Ser. No. 11/366,208 [Ser. No. 11,367,033], filed Mar. 1, 2006 and entitled Noninvasive Multi-Parameter Patient Monitor, both assigned to Masimo Laboratories, Irvine, Calif. (Masimo Labs) and both incorporated by reference herein.
Further, physiological monitoring systems that include low noise optical sensors and pulse oximetry monitors, such as any of LNOP® adhesive or reusable sensors, SofTouch™ sensors, Hi-Fi Trauma™ or BIue™ sensors; and any of Radical®, SatShare™, Rad-9™, Rad-S™, Rad-5v™ or PPO+™ Masimo SET® pulse oximeters, are all available from Masimo. Physiological monitoring systems including multiple wavelength sensors and corresponding noninvasive blood parameter monitors, such as Rainbow™ adhesive and reusable sensors and RAD-57™ and Radical7™ monitors for measuring SpO2, pulse rate, perfusion index, signal quality, HbCO and HbMet among other parameters are also available from Masimo.
PI=AC/DC (1)
where “AC” 454 designates a peak amplitude 462 minus a valley amplitude 464 for a particular pulse and where “DC” 456 designates a peak amplitude 462 for a particular pulse. In an embodiment, an IR channel plethysmograph from a detector response to an IR wavelength LED is utilized to calculate PI. A plethysmograph variability index (PVI) is then calculated that is responsive to variations in perfusion index, as described below.
In an embodiment, PVI calculations utilize only PI values resulting from acceptable plethysmograph pulses. For example, a red channel plethysmograph responsive to a red wavelength LED is used to verify acceptable pulses in the IR channel. Physiological plethysmograph identification is disclosed in U.S. Pat. No. 7,044,918 titled Plethysmograph Pulse Recognition Processor, which is incorporated by reference herein. PVI values are calculated from a sorted and trimmed buffer representing a sliding time window of PI values. The sort orders the PI values from the minimum PI at one end of the buffer to the maximum PI at the other end of the buffer. A predetermined number of both maximum and minimum PIs are deleted from each end of the buffer and PVI is calculated as:
PVI=[(PIMAX−PIMIN)/PIMAX]×100 (2)
That is, PVI is the PI variation, expressed as a percentage of the difference between the maximum and minimum PIs remaining in the buffer. In an embodiment, a median PVI is calculated from PVIs stored in a second buffer. PVI is described in U.S. Provisional Patent App. No. 60/873,663 filed Dec. 9, 2006 titled Plethysmograph Variability Index, incorporated by reference herein. A PVI enabled physiological monitor advantageously provides a noninvasive numerical measure of hypovolemic conditions so as to titrate patient fluids.
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In an embodiment, the instrument manager 650 provides a control signal 659 responsive to control values 644 calculated by the fluid titration firmware 670. The control signal 659 communicates with a device interface 668 so as to generate a corresponding IV infusion device control 532. For example, the instrument manager 360 converts PVI measurements 344 to a control signal 644 and transmits the control signal via the control port 659 to a device interface 668.
In an embodiment, an input port 658 responds to a user input device 666, such as a keypad, network, computer or similar device that provides an external interface. Using this interface, a caregiver 3 (
The fluid titration process 670 may be DSP firmware that executes a closed-loop algorithm for controlling an IV infusion device 540 based upon PVI or other measured plethysmograph or perfusion variability parameter. In an embodiment, the fluid titration process 670 triggers a control output 644 so as to disable fluid flow from the IV infusion device 540 if PVI falls below a predetermined threshold or otherwise reflects that hypovolemia may no longer be indicated for a patient 2 (
A fluid titration system has been disclosed in detail in connection with various embodiments. These embodiments are disclosed by way of examples only and are not to limit the scope of the claims that follow. One of ordinary skill in art will appreciate many variations and modifications.
Claims
1-19. (canceled)
20. 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 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 and the nonpulsatile component being indicative of a blood volume in the tissue, the pulsatile component being responsive to variable absorption and the nonpulsatile component being responsive to static absorption;
- 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.
21. The method of claim 20, 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.
22. The method of claim 21, further comprising visually presenting the first infusion indication and the second infusion indication to the caregiver on a display.
23. The method of claim 21, 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.
24. The method of claim 21, further comprising audibly presenting the first infusion indication and the second infusion indication to the caregiver.
25. The method of claim 21, 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.
26. The method of claim 20, further comprising visually presenting the first infusion indication to the caregiver on a display as +, on, increase, or start.
27. The method of claim 20, wherein the first measure of variability is responsive to a dehydration condition of the patient.
28. The method of claim 20, wherein the first measure of variability is responsive to a hemorrhaging condition of the patient.
29. The method of claim 20, wherein the liquid solution comprises blood products.
30. The method of claim 20, wherein the liquid solution comprises nutrient fluids.
31. The method of claim 20, further comprising administering the liquid solution to the patient subsequent to said outputting the first infusion indication for presentation to the caregiver.
32. The method of claim 31, wherein said 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.
33. The method of claim 20, further comprising comparing the first measure of variability with a threshold to determine whether the first measure of variability indicates the need.
34. The method of claim 20, wherein said determining the first measure of variability comprises processing a respiration-induced cyclical variation in the signal.
35. The method of claim 20, wherein said 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.
36. The method of claim 20, wherein the first measure of variability comprises a measure of perfusion index variability of the signal.
37. The method of claim 20, further comprising irradiating, with one or more emitters of the optical sensor, the tissue with red and infrared wavelengths.
38. The method of claim 20, wherein the measurement site comprises a finger.
39. The method of claim 20, further comprising determining, with the one or more hardware processors, a parameter measurement from the signal, the parameter measurement comprising carboxyhemoglobin or methemoblobin.
Type: Application
Filed: Oct 26, 2017
Publication Date: Apr 19, 2018
Inventor: Massi Joe E. Kiani (Laguna Niguel, CA)
Application Number: 15/794,838