Method of surgical fluid analysis

• US 5,956,130 A
• Filed: 07/09/1997
• Issued: 09/21/1999
• Est. Priority Date: 05/03/1994
• Status: Expired due to Fees

• Current Assignee: Thierry G. Vancaillie
• Original Assignee: Aquintel, Inc.
• Inventors: Newton, David W., Vancaillie, Thierry G., Mitchiner, Robert K.
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): Smith, Zandra V.
• Application Number:
  US08/890,364
• Time in Patent Office: 804 Days
• Field of Search: 356/39, 356/40, 356/41, 356/435, 356/436, 600/310, 600/322
• US Class Current: 356/39
• CPC Class Codes: A61B 5/02042 Determining blood loss or bleeding, e.g. during a surgical procedure
• CPC Class Codes: A61M 1/77 Suction-irrigation systems aspiration tips supplying fluids A61M1/85; specific for negative pressure wound therapy A61M1/92; combined with tracheal tubes A61M16/0463
• CPC Class Codes: A61M 1/777 Determination of loss or gain of body fluids due to suction-irrigation, e.g. during surgery
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 2205/3393 by weighing the reservoir
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/502 User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2205/8206 battery-operated
• CPC Class Codes: A61M 2209/082 Mounting brackets, arm supports for equipment
• CPC Class Codes: A61M 2209/084 Supporting bases, stands for equipment
• CPC Class Codes: A61M 3/0204 Physical characteristics of the irrigation fluid, e.g. conductivity or turbidity
• CPC Class Codes: A61M 3/0212 after use
• CPC Class Codes: A61M 3/022 Volume; Flow rate
• CPC Class Codes: A61M 3/0233 characterised by liquid supply means, e.g. from pressurised reservoirs
• CPC Class Codes: A61M 3/0283 with at least two inner passageways, a first one for irrigating and a second for evacuating suction-irrigation systems A61M1/77; aspiration tips with fluid supply means A61M1/85; for negative pressure wound therapy A61M1/92
• CPC Class Codes: A61M 3/0287 with an external liquid collector
• CPC Class Codes: A61M 5/16895 by monitoring weight change, e.g. of infusion container
• CPC Class Codes: G01G 17/04 for weighing fluids, e.g. gases, pastes
• CPC Class Codes: G01G 19/00 Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups electric measuring arrangements involving comparison with a reference value G01R17/00

Abstract

A monitor to provide substantially real-time estimates of fluid absorption rate and tissue loss rate in a patient during a surgical procedure. The monitor estimates fluid source flow rates and waste fluid flow rates based on weight changes per unit time or direct reading fluid flow rate meters. Tissue loss flow rates are estimated based on tissue concentration measurable in waste irrigation fluid using an optical comparator, and are used to correct waste fluid flow rates. Correct waste fluid flow rates are used in turn to obtain estimated fluid absorption rates.

Claims

1. A method of estimating fat concentration in a waste fluid sample, the method comprising:

inducing cytolysis in the waste fluid sample producing a cytolytic fluid;

variably scattering at a least a portion of light from a light source;

intercepting the variably scattered light at two comparison chambers where one comparison chamber receives and transmits the cytolytic fluid and a second comparison chamber receives and transmits a reference standard fluid;

detecting output light emanating from the two comparision chambers;

comparing light absorption characteristics of the cytolytic fluid with light absorption characteristics of the reference standard fluid; and

looking up in a table a fat concentration of a reference standard fluid having light absorption characteristics substantially similar to the cytolytic fluid.

2. A method of estimating hemoglobin concentration in a waste fluid sample, the method comprising:

processing erythrocytes in the waste fluid sample including subjecting the erythrocytes to cytolysis producing a cytolytic fluid;

converting free hemoglobin in the cytolytic fluid to another colored compound;

after converting the free hemoglobin, comparing light absorption characteristics of the cytolytic fluid with light absorption characteristics of a reference standard; and

looking up in a table a hemoglobin concentration of a reference standard having light absorption characteristics substantially similar to the cytolytic fluid.

3. The method of claim 2 where the step of converting includes chemically converting the free hemoglobin.

4. The method of claim 2 where the step of converting includes mixing the waste fluid sample with Drabkin'"'"'s solution.

5. The method of claim 2 where the step of processing includes diluting the waste fluid sample with distilled water.

6. The method of claim 2 where the step of processing includes subjecting erythrocytes in the waste fluid sample to osmotic cytolysis.

7. The method of claim 2 where the step of processing includes subjecting erythrocytes in the waste fluid sample to complement-induced cytolysis.

8. A method of estimating hemoglobin concentration in a waste fluid sample, the method comprising:

inducing cytolysis of red blood cells in the waste fluid sample producing a cytolytic fluid;

converting free hemoglobin in the cytolytic fluid to another colored compound; and

after converting the free hemoglobin, comparing light absorption characteristics of the cytolytic fluid with light absorption characteristics of a reference standard at substantially a same wavelength.

9. The method of claim 8 where the step of inducing includes subjecting erythrocytes in the waste fluid sample to osmotic cytolysis.

10. The method of claim 8 where the step of inducing includes subjecting erythrocytes in the waste fluid sample to complement-induced cytolysis.