CA2307151A1 - Needle oxygen measurement device - Google Patents
Needle oxygen measurement device Download PDFInfo
- Publication number
- CA2307151A1 CA2307151A1 CA 2307151 CA2307151A CA2307151A1 CA 2307151 A1 CA2307151 A1 CA 2307151A1 CA 2307151 CA2307151 CA 2307151 CA 2307151 A CA2307151 A CA 2307151A CA 2307151 A1 CA2307151 A1 CA 2307151A1
- Authority
- CA
- Canada
- Prior art keywords
- sensor
- tissue
- measurement device
- oxygen
- measurements
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/14542—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue for measuring blood gases
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1468—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means
- A61B5/1473—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means invasive, e.g. introduced into the body by a catheter
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
- A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
- A61B5/6848—Needles
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Biomedical Technology (AREA)
- Medical Informatics (AREA)
- Veterinary Medicine (AREA)
- Public Health (AREA)
- Biophysics (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- General Health & Medical Sciences (AREA)
- Heart & Thoracic Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
Description
A method is described which improves measurement of tissue oxygenation made by oxygen sensors that are mechanically driven through tissue.
One method of measuring the oxygenation status of tissue is to insert an oxygen sensor, generally housed in a needle, into the tissue of interest. The sensor is then driven through tissue by a motorized drive and makes sequential oxygen measurements along its path (U.S. patent 4 582 064). One problem we have identified with this method is that when the sensor impinges tissue that is fibrous in nature, the oxygen measurements may be erroneous. The reason, we believe, is that proteinaceous fibres adjacent to the oxygen sensor impede the diffusion of oxygen to the sensor. As a consequence the oxygen tension readings appear lower than they really are. The ability to identify false readings is of particular importance in oncology, where this device is often used to determine the oxygenation status of solid tumours in which low oxygen tension measurements indicate poor prognosis for many conventional treatments.
We have developed and tested a device that measures the force exerted by the motorized drive in advancing the sensor through tissue. The force required to move the sensor forward increases in proportion to the resistance offered by the tissue. We have found that erroneous oxygen measurements as outlined above can be detected from the increase in force required to move the sensor through the tissue.
The force exerted by the motorized drive can be measured using several techniques including; measurement of the electrical energy consumed by the motor in advancing the sensor forward a fixed distance or measurement of the pressure exerted on the sensor base by the motor drive via a pressure transducer. In our case, we determine the average force required to move the sensor each step through the tissue by measuring the time integral of the electrical current which passes through the motorized drive with each step.
(Force can then be calculated from F=v(* idt)/*x, where v is the voltage across the motor, (* idt) is the time integral of the electrical current during the movement of the sensor and *x is the distance over which the sensor is moved). The force required to move the sensor forward each step is then recorded along with the measured oxygen tension.
Assessment of tumour oxygenation using an Eppendorf p02 histograph is becoming recognized as predictive of response to radiation therapy and other cancer treatment modalities. Tumours with high p02, as measured by the histograph, are more likely to respond favourably to treatment than tumours with poor oxygenation status.
Using tissue substitutes, we have found that low p02 values can be registered when significant resistance to the forward motion of the needle oxygen sensor is encountered.
The measured p02 values in this situation do not correspond to the actual oxygen tension.
Patterns of p02 values seen under these modelling conditions are identical with patterns that can occur during clinical measurements, suggesting that at least some values measured during clinical examination are erroneous.
As a consequence of this phenomenon some tumours will appear to be poorly oxygenated because of the fibrosis within the tumour mass, and not because of compromised tumour oxygenation. This has clear relevance to the accuracy of the Eppendorf p02 histograph as a predictor of tumour response. We have developed a method which can be used to identify the p02 measurements that are caused by elevated back pressure against the needle. Using this technique it should be possible to filter the clinical p02 measurements and obtain a more accurate assessment of tumour oxygenation.
Eppendorf p02 histographs are used clinically (in an experimental setting) to measure tumour p02.
Several clinical trials now show that p02, as measured using an Eppendorf p02 histograph, correlate with outcome to radiation therapy, surgery, combined modality treatments.
This is useful because 1) it aids treatment selection and 2) it permits clinical trials of novel agents to be examined in tumours that are well or poorly oxygenated.
We have shown that back-pressure causes erroneously low values to be registered which decreases the accuracy of device.
We have developed a means of quantifying the back-pressure and back-pressure measurements to identify erroneous p02 measurements. This would permit these values to be filtered out of the data set giving a more accurate estimate of tumour p02.
Z
One method of measuring the oxygenation status of tissue is to insert an oxygen sensor, generally housed in a needle, into the tissue of interest. The sensor is then driven through tissue by a motorized drive and makes sequential oxygen measurements along its path (U.S. patent 4 582 064). One problem we have identified with this method is that when the sensor impinges tissue that is fibrous in nature, the oxygen measurements may be erroneous. The reason, we believe, is that proteinaceous fibres adjacent to the oxygen sensor impede the diffusion of oxygen to the sensor. As a consequence the oxygen tension readings appear lower than they really are. The ability to identify false readings is of particular importance in oncology, where this device is often used to determine the oxygenation status of solid tumours in which low oxygen tension measurements indicate poor prognosis for many conventional treatments.
We have developed and tested a device that measures the force exerted by the motorized drive in advancing the sensor through tissue. The force required to move the sensor forward increases in proportion to the resistance offered by the tissue. We have found that erroneous oxygen measurements as outlined above can be detected from the increase in force required to move the sensor through the tissue.
The force exerted by the motorized drive can be measured using several techniques including; measurement of the electrical energy consumed by the motor in advancing the sensor forward a fixed distance or measurement of the pressure exerted on the sensor base by the motor drive via a pressure transducer. In our case, we determine the average force required to move the sensor each step through the tissue by measuring the time integral of the electrical current which passes through the motorized drive with each step.
(Force can then be calculated from F=v(* idt)/*x, where v is the voltage across the motor, (* idt) is the time integral of the electrical current during the movement of the sensor and *x is the distance over which the sensor is moved). The force required to move the sensor forward each step is then recorded along with the measured oxygen tension.
Assessment of tumour oxygenation using an Eppendorf p02 histograph is becoming recognized as predictive of response to radiation therapy and other cancer treatment modalities. Tumours with high p02, as measured by the histograph, are more likely to respond favourably to treatment than tumours with poor oxygenation status.
Using tissue substitutes, we have found that low p02 values can be registered when significant resistance to the forward motion of the needle oxygen sensor is encountered.
The measured p02 values in this situation do not correspond to the actual oxygen tension.
Patterns of p02 values seen under these modelling conditions are identical with patterns that can occur during clinical measurements, suggesting that at least some values measured during clinical examination are erroneous.
As a consequence of this phenomenon some tumours will appear to be poorly oxygenated because of the fibrosis within the tumour mass, and not because of compromised tumour oxygenation. This has clear relevance to the accuracy of the Eppendorf p02 histograph as a predictor of tumour response. We have developed a method which can be used to identify the p02 measurements that are caused by elevated back pressure against the needle. Using this technique it should be possible to filter the clinical p02 measurements and obtain a more accurate assessment of tumour oxygenation.
Eppendorf p02 histographs are used clinically (in an experimental setting) to measure tumour p02.
Several clinical trials now show that p02, as measured using an Eppendorf p02 histograph, correlate with outcome to radiation therapy, surgery, combined modality treatments.
This is useful because 1) it aids treatment selection and 2) it permits clinical trials of novel agents to be examined in tumours that are well or poorly oxygenated.
We have shown that back-pressure causes erroneously low values to be registered which decreases the accuracy of device.
We have developed a means of quantifying the back-pressure and back-pressure measurements to identify erroneous p02 measurements. This would permit these values to be filtered out of the data set giving a more accurate estimate of tumour p02.
Z
Claims
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2307151 CA2307151A1 (en) | 2000-04-28 | 2000-04-28 | Needle oxygen measurement device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2307151 CA2307151A1 (en) | 2000-04-28 | 2000-04-28 | Needle oxygen measurement device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2307151A1 true CA2307151A1 (en) | 2001-10-28 |
Family
ID=4166031
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2307151 Abandoned CA2307151A1 (en) | 2000-04-28 | 2000-04-28 | Needle oxygen measurement device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2307151A1 (en) |
-
2000
- 2000-04-28 CA CA 2307151 patent/CA2307151A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20021128 |