Automated blood analysis system

• US 4,109,505 A
• Filed: 04/07/1975
• Issued: 08/29/1978
• Est. Priority Date: 07/22/1974
• Status: Expired due to Term

• Current Assignee: Primary Children's Hospital
• Original Assignee: Primary Children's Hospital
• Inventors: Clark, Justin S., Veasy, Lloyd G.
• Primary Examiner(s): Swisher, S. Clement
• Application Number:
  US05/566,023
• Time in Patent Office: 1,240 Days
• Field of Search: 324/30 R, 73/1 R, 73/1 G, 204/195 B, 204/195 P
• US Class Current: 73/1.02
• CPC Class Codes: G01N 35/00594 Quality control, including calibration or testing of components of the analyser
• CPC Class Codes: G01N 35/00693 Calibration

Abstract

A system for automatically withdrawing blood from a patient and testing various parameters of the blood, such as oxygen saturation, hemoglobin, gas content (PO₂, PCO₂) and pH, includes a withdrawal unit which automatically withdraws a measured volume of blood, and returns all of it to the patient except a small measured quantity which is provided to an analysis unit that measures the gas content and pH. The withdrawal unit includes provision for continuously monitoring patients'"'"' blood pressure, irrigation from a standard I.V. source between blood withdrawals, or a constant low flush of saline, alternatively, as well as detection of any air in the blood, which results in shutting down the system and activating an air alarm. The withdrawal unit also has provision for automatically withdrawing a small sample of blood, measuring oxygen content, and returning all blood to the patient, all on a programmed basis. The analysis unit includes two-point gas and pH calibration and includes use of calibration fluid for washout. In each complete use cycle, blood from the withdrawal unit is washed into the analysis unit and blood in the analysis unit is moved and washed out using saline, water and calibration fluids. The withdrawal unit may be used alone to acquire blood samples, and the analysis unit may be fed by more than one withdrawal unit or by manually-acquired blood specimens.

Claims

1. An automated blood unit to provide a fool proof safety check against calibration drift comprising:

a blood gas tester;

a blood pH tester;

fluid source means providing a source of blood, a source of blood gas test calibration gases, and a source of blood pH test calibration buffer solution; and

means including pumps and valves and operable in response to a controlled program to calibrate said gas tester and said pH tester by applying calibration fluid thereto and sampling the readings thereof, immediately followed by filling said testers with blood and sampling the readings thereof, and then immediately applying said calibration fluids to said testers and taking an additional sampling thereof, whereby said testers are calibrated both immediately before and immediately after the testing of blood such that blood test results may be discarded if before and after calibration readings differ.

2. An automated blood unit comprising:

a blood gas tester employing an electric potential;

a blood pH tester, said pH tester providing a different test result in dependence upon a differing electrical potential in the blood therein;

means providing intercommunication of electrical potential between said pH tester and said gas tester;

a source of blood; and

operational means including pump means and valve means operable under a program of control for alternatively connecting said source of blood first to said pH tester and then to said gas tester, and for first sampling said pH tester with blood in said pH tester but not in said gas tester and then sampling said pH tester with blood in both said pH tester and said gas tester, whereby a difference between the first and second pH tests will indicate a possibility of an electrically responding failure in said gas detector.

3. The automated blood unit according to claim 2 wherein said gas tester comprises a membrane tester of the type having electrical potential applied to the non-blood side of the membranes therein, whereby a difference between the first and second pH tests will indicate a possibility of a membrane failure in said gas detector.

4. Automated blood apparatus for reducing measurment time by preconditioning at least one test site comprising:

a blood gas tester;

a source of blood;

a source of washout water;

a pressurized source of calibration gas for said blood gas tester;

means interconnecting said calibration gas source with said washout water source for providing a determinable concentration of said calibration gas in said washout water; and

operational means including pumps and valves operative under a program of control for first providing blood to said gas tester for testing the gas content thereof, and then providing washout water to said gas tester for washing the blood therefrom, while at the same time maintaining in said gas tester a certain concentration of said gas, and for thereafter applying calibration gas to said gas tester to enable the taking of a calibration reading therein, whereby the equilibration time required between applying the calibration gas to said gas tester and the time at which a sampling thereof can be made is reduced as a result of there being a determined concentration of said calibration gas established and maintained in said washout water.

5. Automated blood apparatus according to claim 4 wherein said calibration gas source comprises a pair of sources, one having a high concentration of said calibration gas therein and the other having a lower concentration of said calibration gas therein, said washout water being connected to said high concentration calibration gas and said gas tester being thereafter calibrated with said lower concentration calibration gas in response to operation of said operational means.

6. Automated blood apparatus comprising:

a fluid source;

a primary pump having a push stroke and a pull stroke;

a first fluid means valve actuated in conjunction with said primary pump and having two positions, said valve when in one position receiving fluid from the push stroke of said pump and dumping said fluid to waste;

a blood pH tester;

a blood gas tester;

second and third fluid valve means each operated between two positions in conjunction with one another, said second valve means connecting said fluid source with said gas tester when in a first of its positions, said third valve means connecting said gas tester with said first valve means when in a first of its positions, said first and second valve means, when in their second of said positions connecting said fluid source with said pH tester and connecting said pH tester with said first valve means, said first valve means when in a second of its positions connecting said third valve means with said pump, whereby a pull stroke of said pump draws fluids through said gas tester when said second and third valves are in said first position and draws fluid through said pH tester when said second and third valves are in said second position; and

means for simultaneously operating said pump and said first valve so as to draw fluid from said source through said first valve and into said pump and thereafter to expel fluid from said pump through said first valve to waste, and for alternatively operating said second and third valves between their two positions so that fluid is alternatively drawn through said gas tester or said pH tester and discharged to waste.

7. Automated blood apparatus according to claim 6 additionally comprising:

a source of calibration gas under pressure, said second valve means connecting said gas tester with waste when in a second of its positions and said third valve means connecting said gas tester with said source of calibration fluid when in its second position, whereby said calibration gas pushes fluid to waste through said gas tester at the time that said pump means is drawing fluid through said pH tester.

8. A method of monitoring blood comprising the steps of:

introducing calibration fluids under pressure into respective parts of a blood monitoring apparatus and displacing the calibration fluids respectively to diverse blood monitoring sites of the apparatus;

calibrating each monitoring site in conjunction with the calibration fluid present at said site;

retaining the calibration fluids as disposed in the apparatus following calibration;

introducing blood into the apparatus and displacing the blood to and from one or more of the monitoring sites using at least in part the calibration fluids to cause said displacement of the blood.

9. A method of circulating fluids in a blood examination system comprising at least one blood testing site to enhance blood clean out comprising the steps of:

displacing blood obtained from a patient in a one direction to the testing site;

testing the blood at the site;

displacing the blood by reverse flow two cleaning fluids by creating a wash solution/gas interface at the testing site and alternating displacing the wash solution and gas in generally opposite direction to and away from the site to scrub the site of any residual blood whereby accurate testing of sequential blood samples is achieved at the site.