Effect of Electrode Dimensions on Tissue pO2 Measurement in vivo

Nature ◽  
1964 ◽  
Vol 201 (4925) ◽  
pp. 1227-1228 ◽  
Author(s):  
DANA JAMIESON ◽  
H. A. S. VAN DEN BRENK
Keyword(s):  
Tissue Po2 ◽  
Po2 Measurement

Performance evaluation of recessed microcathodes: criteria for tissue PO2 measurement

1985 ◽  
Vol 58 (4) ◽  
pp. 1400-1405 ◽  
Author(s):  
D. W. Crawford ◽  
M. A. Cole
Keyword(s):  
Performance Evaluation ◽  
Diameter Ratio ◽  
Radial Diffusion ◽  
In Vivo Studies ◽  
External Diameter ◽  
O2 Consumption ◽  
Tissue Po2 ◽  
Po2 Measurement

Measurement of local tissue PO2 using recessed microcathodes has again been criticized. Therefore, we reexamined electrode performance. Sharply beveled electrodes (3 micron external diameter) were fabricated with several tip recess lengths (4–10 micron), and some recesses were filled with hydrated polymer. In vitro, 2-mm agar (3%) sheets were equilibrated with solution of known PO2 (continuously flowing). Electrode currents at 100-micron intervals through the agar and of convected superfusion solution were compared. At the longest recess lumen length-to-diameter ratio of 10, minimum response midagar (1 mm) averaged 98%. Performance improved with the use of recess polymer and increased recess length. For in vivo studies, microcathodes (ratio approximately 10) were fluid calibrated, and PO2 was measured at 10–20 micron through canine femoral artery walls. PO2 distribution fit a model for radial diffusion with medial O2 consumption. After local cyanide application to the femoral wall, PO2 fit a model for radial diffusion without tissue O2 consumption. Carefully designed microcathodes and experiments measure accurate tissue PO2.

Intraoperative Microdialysis and Tissue-pO2 Measurement in Human Glioma

1998 ◽  
pp. 241-243 ◽  
Author(s):  
S. Baunach ◽  
Jürgen Meixensberger ◽  
M. Gerlach ◽  
J. Lan ◽  
K. Roosen
Keyword(s):  
Human Glioma ◽  
Tissue Po2 ◽  
Po2 Measurement

In vivo visualization of oxygen transport in microvascular network

1994 ◽  
Vol 267 (5) ◽  
pp. H2068-H2078 ◽  
Author(s):  
T. Itoh ◽  
K. Yaegashi ◽  
T. Kosaka ◽  
T. Kinoshita ◽  
T. Morimoto
Keyword(s):  
Oxygen Transport ◽  
Time Lag ◽  
Epifluorescence Microscopy ◽  
Oxygen Quenching ◽  
Microvascular Network ◽  
Membrane Technique ◽  
Po2 Measurement ◽  
Micropositioning System

Oxygen transport from the blood to the tissues is a diffusive process driven by the gradient of oxygen tension (PO2). We developed an oxygen-quenching fluorescent membrane that allowed visualization of the PO2 distribution near the microvessels as optical patterns on the membrane by epifluorescence microscopy. This membrane was highly gas permeable to allow PO2 measurement and was transparent enough to also permit observation of the microcirculation. In combination with a newly devised gastight chamber and a micropositioning system, this membrane technique made it possible to visualize the PO2 distribution in the rat mesenteric microvascular network under well-defined conditions. Our preliminary findings indicate that the oxygen distribution in the microvascular network is heterogeneous and suggest that there is considerable release of oxygen from the arterioles. The time lag of the system for tracking rapid PO2 changes in vitro was shown to be negligible, indicating that dynamic PO2 changes occurring in vivo can also be assessed. This technique should provide a novel tool for the study of oxygen transport and metabolism under normal and abnormal conditions.

Tissue oxygen tension in rabbits measured with a galvanic electrode

1976 ◽  
Vol 41 (2) ◽  
pp. 245-250 ◽  
Author(s):  
M. E. Towell ◽  
I. Lysak ◽  
E. C. Layne ◽  
S. P. Bessman
Keyword(s):  
Oxygen Tension ◽  
Peritoneal Cavity ◽  
Tissue Oxygen Tension ◽  
Tissue Oxygen ◽  
Reliable Measure ◽  
Air Breathing ◽  
Wide Range ◽  
Tissue Po2 ◽  
Range Of Values

A galvanic electrode which generates current in response to oxygen was used to measure tissue PO2 in 10 rabbits. Sixteen electrodes were calibratedin vitro at PO2 = 0 mmHg and PO2 = 100 mmHg before implantation into muscleand peritoneal cavity. Electrode calibration was checked after removal 7–20days later; mean +/- SE reading at PO2 = 0 was 1.5 +/- 1.83 mmHg and at PO2 = 100 was 98.1 +/- 6.49 mmHg. Continuous recordings of tissue PO2 showed little fluctuation in unanesthetized rabbits resting quietly. Tissue PO2 was lower than arterial or venous PO2 during air breathing but frequently exceeded venous PO2 during O2 breathing. Highly significant correlations(P less than 0.001) were found between blood and tissue PO2 over a wide range of values obtained during air breathing and during 10%, 50%, and 100% O2breathing. Thus, the galvanic electrode provided a reliable measure of tissue PO2 and maintained its stability in vivo for periods as long as 20 days.

scholarly journals In vivo imaging with a water immersion objective affects brain temperature, blood flow and oxygenation

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Morgane Roche ◽  
Emmanuelle Chaigneau ◽  
Ravi L Rungta ◽  
Davide Boido ◽  
Bruno Weber ◽  
...  
Keyword(s):  
Blood Flow ◽  
Brain Temperature ◽  
Water Immersion ◽  
Phosphorescence Lifetime ◽  
Cranial Window ◽  
Hemoglobin Saturation ◽  
Tissue Po2 ◽  
Physiological Values ◽  
Water Immersion Objective

Previously, we reported the first oxygen partial pressure (Po2) measurements in the brain of awake mice, by performing two-photon phosphorescence lifetime microscopy at micrometer resolution (Lyons et al., 2016). However, this study disregarded that imaging through a cranial window lowers brain temperature, an effect capable of affecting cerebral blood flow, the properties of the oxygen sensors and thus Po2 measurements. Here, we show that in awake mice chronically implanted with a glass window over a craniotomy or a thinned-skull surface, the postsurgical decrease of brain temperature recovers within a few days. However, upon imaging with a water immersion objective at room temperature, brain temperature decreases by ~2–3°C, causing drops in resting capillary blood flow, capillary Po2, hemoglobin saturation, and tissue Po2. These adverse effects are corrected by heating the immersion objective or avoided by imaging through a dry air objective, thereby revealing the physiological values of brain oxygenation.

Brain Ischemia Detected by Tissue-PO2 Measurement and the Lactate-Oxygen Index in Head Injury

1998 ◽  
pp. 170-171 ◽  
Author(s):  
Matthias Holzschuh ◽  
C. Metz ◽  
C. Woertgen ◽  
R. D. Rothörl ◽  
A. Brawanski
Keyword(s):  
Head Injury ◽  
Brain Ischemia ◽  
Oxygen Index ◽  
Tissue Po2 ◽  
Po2 Measurement

pO2 Measurement in an Experimental Model of Patellar Tendon Autograft Pro-Anterior Cruciate Ligament

1998 ◽  
Vol 21 (3) ◽  
pp. 174-178 ◽  
Author(s):  
M. Rocca ◽  
G. Giavaresi ◽  
N. Nicoli Aldini ◽  
M. Fini ◽  
M. Marcacci ◽  
...  
Keyword(s):  
Anterior Cruciate Ligament ◽  
Patellar Tendon ◽  
Microvessel Density ◽  
Cruciate Ligament ◽  
Microvessel Count ◽  
Experimental Tool ◽  
Anterior Cruciate ◽  
Tendon Autograft ◽  
Po2 Measurement

Thirty-four sheep were submitted to surgery substituting the native ACL with the central third of the patellar tendon, ten enter this study. The purpose was to find a possible relationship between tissue pO2 and healing processes considering also the biomechanical and histomorphological aspects of the grafts. Four of them were sacrificed under general anaesthesia after 6 months, and six after 1 year in order to perform tissue pO2 measurement and an analysis of microvessel density on specimens of the normal ACL and the graft. Our data showed higher pO2 values of the autografts after 6 months. After 1 year the data was comparable to those of native ACL. This was confirmed by a microvessel count of the histological specimens and the data was in relationship to biomechanical and histomorphological analysis. Tissue pO2 can be observed and recorded in “in vivo” ACL, and patellar tendon used as graft, with no injury to their integrity. The monitoring system might be considered as an experimental tool for indirect controls of the anterior cruciate substitutes.

Reduction of cytochrome-c oxidase copper precedes failing cerebral O2 utilization in fluorocarbon-perfused cats

1996 ◽  
Vol 271 (2) ◽  
pp. H579-H587 ◽  
Author(s):  
R. Stingele ◽  
B. Wagner ◽  
M. V. Kameneva ◽  
M. A. Williams ◽  
D. A. Wilson ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Redox State ◽  
Near Infrared ◽  
Hypoxic Conditions ◽  
Sagittal Sinus ◽  
Tissue Po2 ◽  
Relationship Of ◽  
The Relationship

We determined the relationship of the low-potential copper (CuA) redox state of cytochrome-c oxidase to the brain tissue PO2 (PtiO2) and global cerebral O2 consumption (CMRO2) in vivo. The redox state of cytochrome-c oxidase copper was monitored in perfluorocarbon-exchanged cats under normoxic and graded hypoxic conditions with use of near-infrared spectroscopy. Continuous spectra ranging from 730 to 960 nm were acquired, and the change in copper redox state was assessed by the absorption changes at 830 nm. PtiO2 was measured with O2-sensitive electrodes implanted into the cortex, and CMRO2 was determined by sampling arterial and superior sagittal sinus perfusate and by measuring blood flow with radiolabeled microspheres. As PtiO2 decreased with hypoxia, the CuA of cytochrome-c oxidase became progressively reduced, whereas the CMRO2 was unchanged during the initial stages of hypoxia. Only with severe hypoxia, did CMRO2 and the amplitude of somatosensory evoked potentials decrease. We conclude that the CuA site of cytochrome-c oxidase is involved in a regulatory adjustment that helps maintain CMRO2 constant.

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