Art: 714382-00D
Rev. Date: 02/20/06
20-5
DETERMINATION OF CELL CONCENTRATION
CPB
Each time a cartridge containing a hematocrit sensor is used, the operator has
the option of selecting, in addition to the sample type, the CPB compensation
algorithm for samples with abnormally low protein levels. The CPB option
is specifically intended for use when samples are collected from patients on
cardiopulmonary bypass. However, the facility may validate its use for other
patient populations known to have protein levels significantly lower than the
normal adult population.
The CPB algorithm infers the total protein level by assuming the pump priming
solution dilutes the hematocrit and total protein equally. Modeling the pre-
pump hematocrit as 43 %PCV and the pre-pump total protein as 7.0 g/dL, the
following graph indicates the inferred total protein and resultant correction.
It is known that direct methods read up to 7% higher than indirect methods
in measuring the concentration of electrolytes. This is because there is an
excluded volume occupied by plasma protein and lipids that is not considered
in indirect measurements. Typically, however, the elevation of results is less
than the full 7% because some of the analyte is bound to protein and other
ions, and is not assayed by direct methods. For each analyte this discrepancy
is characterized, and the result of the direct measurement is adjusted so that
normal ranges are in agreement with indirect reference methods at normal
levels of total protein and lipids.
Hematocrit
In whole blood, plasma conducts electricity while the cellular constituents, red
and white blood cells and platelets, do not. For a sample of a given electrolyte
concentration, as the number of cells per unit volume of plasma increases, the
conductivity of the sample decreases. The total cell concentration in whole
blood can, therefore, be determined from:
1) the known electrolyte concentration of the calibrant,
2) the measured electrolyte concentration of the sample,
3) the measured conductivity of the calibrant and
4) the measured conductivity of the sample.
These measured quantities are determined using a combination of
potentiometric and conductometric sensors.
Direct measurement of hematocrit by the conductometric technique gives a
result related to the non-conducting excluded volume fraction of the sample
fluid. Red blood cell volume is the predominant component of the non-
conducting volume, but proteins, lipids, and white blood cells also contribute.
Elevated hematocrit readings are expected at abnormally elevated levels of
these components. Decreased hematocrit readings are expected at abnormally
low levels of protein, such as found in hemodiluted samples taken from
patients on cardiopulmonary bypass.
Osmotic imbalance causes a discrepancy between direct (conductometric,
spun) and indirect (Coulter) measurements because of variation in the mean
cell volume.
Summary of Contents for i-STAT 1
Page 1: ...i STAT 1 System Manual Rev Date 20 Jan 12 Art 714336 00L ...
Page 18: ...1 8 Art 714363 00U Rev Date 02 Aug 12 ...
Page 44: ......
Page 90: ......
Page 106: ...9 12 Art 714371 00E Rev Date 06 Aug 12 ...
Page 162: ......
Page 166: ...Art 730292 00A Rev Date 20 Feb 12 4 ...
Page 176: ...10 10 Art 714372 00L Rev Date 30 Jul 12 ...
Page 182: ...11 6 Art 714373 00F Rev Date 17 Jan 11 ...
Page 184: ...12 2 Art 714374 00J Rev Date 25 Aug 11 ...
Page 185: ...Art 714374 00J Rev Date 25 Aug 11 12 3 ...
Page 186: ...12 4 Art 714374 00J Rev Date 25 Aug 11 ...
Page 187: ...Art 714374 00J Rev Date 25 Aug 11 12 5 ...
Page 192: ......
Page 194: ......
Page 214: ...14 20 Art 714376 00M Rev Date 31 Jan 12 ...
Page 216: ...14 22 Art 714376 00M Rev Date 31 Jan 12 ...
Page 218: ...14 24 Art 714376 00M Rev Date 31 Jan 12 ...
Page 220: ...14 26 Art 714376 00M Rev Date 31 Jan 12 ...
Page 222: ...14 28 Art 714376 00M Rev Date 31 Jan 12 ...
Page 224: ...14 30 Art 714376 00M Rev Date 31 Jan 12 ...
Page 226: ......
Page 236: ......
Page 252: ...17 4 Art 714379 00F Rev Date 18 Jul 12 ...
Page 254: ......
Page 294: ...Art 725768 00E Rev Date 04 Jan 12 20 ...
Page 336: ...22 2 Art 714384 00D Rev Date 07 18 06 ...
Page 342: ...22 8 Art 714384 00D Rev Date 07 18 06 ...
Page 348: ...22 14 Art 714384 00D Rev Date 07 18 06 ...
Page 352: ...22 18 Art 714384 00D Rev Date 07 18 06 ...
Page 364: ...22 30 Art 714384 00D Rev Date 07 18 06 ...
Page 384: ...22 50 Art 714384 00D Rev Date 07 18 06 ...
Page 404: ...22 70 Art 714384 00D Rev Date 07 18 06 ...
Page 488: ...Kaolin ACT 4 Art 715878 00M Rev Date 31 Jan 12 ...
Page 536: ......
Page 556: ...Art 714261 00E Rev Date 10 Jan 11 8 ...
Page 560: ...Art 716240 00D Rev Date 03 Mar 10 4 ...
Page 572: ...Art 715617 00D Rev Date 06 11 08 ...
Page 578: ...Art 714547 00F Rev Date 06 11 08 ...
Page 590: ...Art 720735 00B Rev Date 06 11 08 ...
Page 592: ...Art 721106 00B Rev Date 06 11 08 ...
Page 598: ...Art 722831 00A Rev Date 19 Feb 09 ...
Page 610: ...Art 720654 00B Rev Date 06 11 08 ...
Page 614: ...Art 721317 00D Rev Date 13 Aug 12 4 ...
Page 616: ...Art 725703 00A Rev Date 08 Mar 10 2 ...
Page 618: ...Art 721296 00A Rev Date 07 16 08 ...
Page 620: ...REV DATE 16 Oct 12 ART 714446 00L ...
Page 627: ...PROCEDURE MANUAL FOR THE i STAT SYSTEM 6 REV DATE 16 Oct 12 ART 714446 00L ...
Page 628: ...PROCEDURE MANUAL FOR THE i STAT SYSTEM 7 REV DATE 16 Oct 12 ART 714446 00L ...
Page 629: ...PROCEDURE MANUAL FOR THE i STAT SYSTEM 8 REV DATE 16 Oct 12 ART 714446 00L ...
Page 630: ...PROCEDURE MANUAL FOR THE i STAT SYSTEM 9 REV DATE 16 Oct 12 ART 714446 00L ...
Page 658: ......