Computerized system for blood chemistry monitoring

Abstract

An apparatus and computerized method of intravenously monitoring a patient's blood chemistry transmits real time measurements to an electronically controlled closed loop system that auto-regulates blood osmolality and glucose level with medications infused through a catheter designed for such purpose. The closed loop system utilizes a glucose algorithm and an osmolality algorithm implemented in hardware and software to control the flow of dextrose, insulin and hypertonic saline to a patient in an effort to achieve better patient outcomes in instances of trauma, surgery and medical illnesses.

1 . A computerized osmolality adjustment system for intravenously controlling a patient's blood osmolality on a real time basis, said system comprising:
 a catheter placed within the patient's venous system;   a conductivity sensor assembly attached to said catheter and in direct contact with the patient's bloodstream;   a pump connected to a fluid source for infusing said fluid into a patient's bloodstream through said catheter;   a computer processor in electronic communication with said conductivity sensor assembly to convert blood conductivity into an osmolality measurement, wherein the processor is also in electronic communication with said pump;   a fluid infusion control module stored in said processor for controlling the pumped fluid flow rate, wherein said fluid infusion control module comprises pump controlling commands to (i) determine where the patient's real time average osmolality lies along a continuum of osmolality values; (ii) track the rate at which the blood osmolality is changing over time; and (iii) iteratively adjust the pump output so that the fluid flow rate into the patient's body adjusts the average osmolality level closer to a known normal range.   
     
     
         2 . A computerized osmolality adjustment system according to  claim 1 , wherein said fluid is hypertonic saline. 
     
     
         3 . A computerized osmolality adjustment system according to  claim 1 , wherein said fluid infusion control module converts the conductivity measurement to an osmolality measurement using the formula
   Serum Osmolality=18.95 (mOsm/mSiemen)×measured conductivity (mSiemen).
   
     
     
         4 . A computerized osmolality adjustment system according to  claim 3 , wherein a user sets the known normal range for blood osmolality between OsmSl and OsmSh. 
     
     
         5 . A computerized osmolality adjustment system according to  claim 4 , wherein said fluid infusion control module calculates and stores an average blood osmolality level Ya over a specified time period. 
     
     
         6 . A computerized osmolality adjustment system according to  claim 2 , wherein said fluid infusion control module calculates and stores blood osmolality value Yt every 30 seconds and calculates the average osmolality level Ya over said specified time period equal to 10 minutes. 
     
     
         7 . A computerized osmolality adjustment system according to  claim 2 , wherein said pump controlling commands are divided into categories defined by osmolality value ranges along said osmolality value continuum. 
     
     
         8 . A computerized osmolality adjustment system according to  claim 7 , wherein said controller calculates the category for the current average osmolality measurement Ya. 
     
     
         9 . A computerized osmolality adjustment system, according to  claim 2 , wherein said pump controlling command category is selected from the group consisting of the following where Ya is the most recently calculated average blood osmolality, OsmSl is the lowest acceptable value for blood osmolality, and OsmSh is the highest acceptable value for blood osmolality:
 Category 1: Ya−OsmSl<−5 mOsm/Kg   Category 2: −5 Ya−OsmSl<0 mOsm/Kg   Category 3: 0≦Ya−OsmSl<(OsmSh−OsmSl)/3 mOsm/Kg   Category 4: (OsmSh−OsmSl)/3≦Ya−OsmSl<2(OsmSh−OsmSl)/3 mOsm/Kg   Category 5: 2(OsmSh−OsmSl)/3≦Ya−OsmSl<OsmSh−OsmSl mOsm/Kg   Category 6: OsmSh−OsmSl≦Ya−OsmSl<(OsmSh−OsmSl)+5 mOsm/Kg   Category 7: OsmSh−OsmSl)+5≦Ya−OsmSl mOsm/Kg   
     
     
         10 . A computerized osmolality adjustment system according to  claim 9 , wherein said controller compares said current osmolality measurement Ya to a prior average osmolality measurement Yb to determine the rate at which the osmolality level is changing. 
     
     
         11 . A computerized osmolality adjustment system according to  claim 9 , wherein said infused fluid is hypertonic saline and wherein said pump controlling commands adjust the flow rate of hypertonic saline by an adjustment factor defined by the category in which the current osmolality measurement fits and the rate at which the osmolality level is changing. 
     
     
         12 . A computerized osmolality adjustment system according to  claim 11 , wherein for each category, the next saline flow rate is adjusted for condition Ya−Yb, wherein said condition is selected from the group consisting of Ya−Yb<−2; 2>Ya−Yb≦−2; and Ya−Yb≧2. 
     
     
         13 . A computerized osmolality adjustment system according to  claim 12 , wherein said pump controlling commands adjust said next saline flow rate as a function of the previous saline flow rate within said specified time period. 
     
     
         14 . A computerized osmolality adjustment system according to  claim 13 , wherein said previous saline flow rate is selected from the group consisting of:
 (i) HTSfp=0 mL/hour;   (ii) 0 mL/hour<HTSfp≦(0.2*Wt*3/Z) mL/hour;   (iii) (0.2*Wt*3/Z) mL/hour<HTSfp≦(0.6*Wt*3/Z) mL/hour   (iv) (0.6*Wt*3/Z) mL/hour<HTSfp≦(1.0*Wt*3/Z) mL/hour;   (v) HTSfp>(1*Wt*3/Z) mL/hour;   
       wherein Z is the initial concentration of saline in percent weight/volume, and HTSfp is the past flow of saline into the patient and Wt is the patient's weight in kilograms. 
     
     
         15 . A computerized osmolality adjustment system according to  14 , wherein said fluid infusion control module operates continuously on a real time basis with updated conductivity measurements from said conductivity sensor on said catheter. 
     
     
         16 . A computerized method of adjusting a patient's blood osmolality on a real time basis by adjusting the saline flow to the patient, the method comprising:
 continuously measuring the patient's real time blood osmolality;   storing each real time blood osmolality value in a computer processor;   calculating via the computer processor the average blood osmolality, Ya, over a specified time period;   electronically assigning the average osmolality level to one of a series of osmolality control ranges;   calculating the rate at which the average blood osmolality level changes from one of said specified time periods to the next;   determining the saline flow adjustment factor necessary for an average osmolality level in an assigned control range changing at a calculated rate.   
     
     
         17 . A computerized method according to  claim 16 , further comprising the step of multiplying the current saline flow rate by respective adjustment factors. 
     
     
         18 . A computerized method according to  claim 17 , wherein the saline adjustment factor is selected from the group consisting of 0, 0.5, 0.6, 0.7, 0.8, 0.85, 0.86, 0.87, 0.9, 0.92, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.1, 1.15, 1.2, 1.24, 1.25, 1.3, 1.4 
     
     
         19 . A computerized method according to  claim 18 , further comprising the step of adjusting the saline flow rate to a flow rate greater than zero. 
     
     
         20 . A computerized method according to  claim 19 , further comprising the step of setting the values of the initial saline flow rate manually prior to the step of continuously measuring the patient's real time osmolality level.