Systems and methods for testing pump flow rates

• US 5,608,650 A
• Filed: 08/19/1994
• Issued: 03/04/1997
• Est. Priority Date: 08/19/1994
• Status: Expired due to Fees

• Current Assignee: Mediq/Prn Life Support Services LLC (Baxter International Inc.)
• Original Assignee: Spectrel Partners, L.L.C.
• Inventors: Pierce, Richard, Figler, Alan A., DiGianfilippo, Aleandro, McClendon, Robert R.
• Primary Examiner(s): Cosimano, Edward R.
• Application Number:
  US08/294,480
• Time in Patent Office: 928 Days
• Field of Search: 327/551, 327/552, 364/509, 364/510, 364/572, 364/724.01
• US Class Current: 702/114
• CPC Class Codes: A61M 2209/02 Equipment for testing the apparatus
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: F04B 2205/09 Flow through the pump
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations

Abstract

The system and methods obtain a set of multiple data samples and derive an average of the data samples in the set (SET_AVE). The systems and methods derive a standard deviation for the data samples in the set (SET_STD). The systems and methods compare each of the data samples to SET_STD and either reject the data sample, if the absolute difference between the data sample is greater than or equal to k * SET_STD, where k is a selected value greater than zero, or retain the data sample, if the absolute difference between the data sample is less than k * SET_STD. The systems and methods repeat the foregoing steps until the absolute difference between every data sample remaining in the set is less than k * SET_STD. The systems and methods then derive a filtered average for the set FSET_AVG, where FSET_AVE is the SET_AVG for the data set in which the absolute difference between every data sample remaining in the set is less than k * SET_STD. The systems and methods find application in the calculation of pump flow rates, particularly using gravimetric calculation techniques.

Claims

1. A testing device for deriving a filtered average of a data set of multiple samples, comprising

a sampling component to obtain a data sample,

a controller for operating the sampling component to obtain a set of multiple data samples,

a processing element to (i) derive an average of the data samples in the set obtained by the sampling component (SET_AVE), (ii) derive a standard deviation for the data samples in the set(SET_STD), (iii) compare each of the data samples to SET_STD and either reject the data sample if the absolute difference between the data sample is greater than or equal to k * SET_STD, where k is a selected value greater than zero, or retain the data sample if the absolute difference between the data sample is less than k * SET_STD, the processing element being conditioned to repeat (i), (ii), and (iii) until the absolute difference between every data sample remaining in the set is less than k * SET_STD, and (iv) derive a filtered average for the set FSET_AVG, where FSET_AVE is the SET_AVG for the data set in which the absolute difference between every data sample remaining in the set is less than k * SET_STD, and

an element to output FSET_AVG.

2. A method for calculating an average liquid flow rate gravimetrically comprising the steps of

(a) conveying liquid having a known specific gravity into a receptacle,

(b) sampling the weight of the receptacle and the liquid it contains over a selected time interval to obtain a set of data samples,

(c) deriving an average of the data samples in the set (SET_AVE),

(d) deriving a standard deviation for the data samples in the set(SET_STD),

(e) comparing each of the data samples to SET_STD and

rejecting the data sample if the absolute difference between the data sample is greater than or equal to k * SET_STD, where k is a selected value greater than zero, or

retaining the data sample if the absolute difference between the data sample is less than k * SET_STD,

(f) repeating steps (c), (d), and (e) until the absolute difference between every data sample remaining in the set is less than k * SET_STD, and

(f) deriving the average flow rate (RATE_AVG) as follows:

##EQU3## where FSET_AVG is SET_AVG for the data set in which the absolute difference between every data sample remaining in the set is less than k, SET_STD,

SGRAVITY is the known specific gravity of the liquid conveyed into the receptacle, and

TIME is the interval of time during which the data samples were collected.

3. A method calculating an overall average of flow rate gravimetrically over a predetermined interval comprising the steps of

(a) conveying liquid having a known specific gravity into a receptacle,

(b) sampling the weight of the receptacle and the liquid it contains over a selected first time interval to obtain a set of data samples,

(c) deriving an average of the data samples in the set (SET_AVE),

(d) deriving a standard deviation for the data samples in the set(SET_STD),

(e) comparing each of the data samples to SET_STD and

rejecting the data sample if the absolute difference between the data sample is greater than or equal to k * SET_STD, where k is a selected value greater than zero, or

retaining the data sample if the absolute difference between the data sample is less than k * SET_STD,

(f) repeating steps (c), (d), and (e) until the absolute difference between every data sample remaining in the set is less than k * SET_STD,

(g) deriving a first average flow rate (RATE1_AVG) as follows:

##EQU4## where FSET1_AVG is SET_AVG for the data set in which the absolute difference between every data sample remaining in the set is less than k * SET_STD,

SGRAVITY is the known specific gravity of the liquid conveyed into the receptacle, and

TIME1 is the first interval of time during which the first set of data samples was collected,

(h) repeating steps (b) to (g) to collect a second set of data samples during a selected second time interval to derive a second average flow rate (RATE2_AVG) as follows;

##EQU5## where FSET2_AVG is SET_AVE for the second data set in which the absolute difference between every data sample remaining in the second set is less than k * SET_STD,

SGRAVITY is the known specific gravity of the liquid conveyed into the receptacle, and

TIME2 is the second interval of time during which the second set of data samples was collected, and

(I) deriving an overall average flow rate ORATE_AVG as follows;

##EQU6##

4. A method according to claim 3 and further including the step (i) of comparing ORATE_AVE to a specified flow rate value and generating an output based upon the comparison.

5. A pump testing apparatus comprising

a housing having an interior,

a first component in the housing interior adapted to be coupled in liquid flow communication with an external intravenous pump to test liquid flow rate and pressure of liquid conveyed by the pump, the first component including a receptacle for receiving liquid from the pump, and a load cell weighing the receptacle and the liquid it receives to measure liquid flow rate gravimetrically,

a controller in the housing interior for operating the first component to (a) collect liquid having a known specific gravity into a receptacle, (b) sample the weight of the receptacle and the liquid it contains over a selected time interval to obtain a set of data samples, (c) derive an average of the data samples in the set (SET_AVE), (d) derive a standard deviation for the data samples in the set(SET_STD), (e)compare each of the data samples to SET_STD and rejecting the data sample if the absolute difference between the data sample is greater than or equal to k * SET_STD, where k is a selected value greater than zero, or retaining the data sample if the absolute difference between the data sample is less than k * SET_STD, (f) repeating steps (c), (d), and (e) until the absolute difference between every data sample remaining in the set is less than k * SET_STD, and (f) deriving the average flow rate (RATE_AVG) as follows:

##EQU7## where FSET_AVG is SET_AVG for the data set in which the absolute difference between every data sample remaining in the set is less than k * SET_STD,

SGRAVITY is the known specific gravity of the liquid conveyed into the receptacle, and

TIME is the interval of time during which the data samples were collected.