Brain Tissue and Sagittal Sinus pO2 Measurements Using the Lifetimes of Oxygen-Quenched Luminescence of a Ruthenium Compound

Nwaigwe, Casmiar; Roche, Marcie A.; Grinberg, Oleg Y.; Dunn, Jeff F.

doi:10.1007/978-1-4615-0075-9_10

Cited by 8 publications

(5 citation statements)

References 12 publications

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“…Simultaneous recordings are necessary to assess the effect of both parameters on oxygen diffusion in tissue. Our data confirm that PO 2 and blood flow are highly correlated 25 . Furthermore, by directly observing EATs we confirmed that oxygen is highly modulated between individual RBCs in the CNS vasculature.…”

Section: Discussionsupporting

confidence: 85%

Simultaneous two-photon imaging of oxygen and blood flow in deep cerebral vessels

Lecoq

Parpaleix

Roussakis

et al. 2011

Nat Med

236

268

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Uncovering principles that regulate energy metabolism in the brain requires mapping of partial pressure of oxygen (PO2) and blood flow with high spatial and temporal resolution. Using two-photon phosphorescence lifetime microscopy (2PLM) and the oxygen probe PtP-C343, we show that PO2 can be accurately measured in the brain at depths up to 300 μm with micron-scale resolution. In addition, 2PLM allowed simultaneous measurements of blood flow and of PO2 in capillaries with less than one-second temporal resolution. Using this approach, we detected erythrocyte-associated transients (EATs) in oxygen in the rat olfactory bulb and showed the existence of diffusion-based arterio-venous shunts. Sensory stimulation evoked functional hyperemia, accompanied by an increase in PO2 in capillaries and by a biphasic PO2 response in the neuropil, consisting of an ‘initial dip’ and a rebound. 2PLM of PO2 opens new avenues for studies of brain metabolism and blood flow regulation.

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Section: Discussionsupporting

confidence: 85%

Simultaneous two-photon imaging of oxygen and blood flow in deep cerebral vessels

Lecoq

Parpaleix

Roussakis

et al. 2011

Nat Med

236

268

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“…In particular, the fluorescence calibration is dependent on the rate of quenching of fluorescence, and so the calibration remains stable over the lifetime of the sensor. Previously, we compared the manufacture’s pre-calibration with an in-house calibration of a ruthinum based sensor and, although the values differed by a small amount, the results were consistent and very precise below approximately 40mmHg (Nwaigwe et al, 2003). Another advantage of fluorescent probes is that the sensitivity improves as PO 2 declines.…”

Section: Discussionmentioning

confidence: 80%

“…The calibration was found to have significant temperature variation (Nwaigwe et al, 2003). The current version using the platinum based material showed little variation in PO 2 over an 8°C range of temperature.…”

Section: Discussionmentioning

confidence: 99%

A method for measuring brain partial pressure of oxygen in unanesthetized unrestrained subjects: The effect of acute and chronic hypoxia on brain tissue PO2

Ortíz-Prado

Natah

Srinivasan

et al. 2010

Journal of Neuroscience Methods

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The level of tissue oxygenation provides information related to the balance between oxygen delivery, oxygen utilization, tissue reactivity and morphology during physiological conditions. Tissue partial pressure of oxygen (PtO 2 ) is influenced by the use of anesthesia or restraint. These factors may impact the absolute level of PtO 2 . In this study we present a novel fibre optic method to measure brain PtO 2 . This method can be used in unanesthetized, unrestrained animals, provides absolute values for PO 2 , has a stable calibration, does not consume oxygen and is MRI compatible. Brain PtO 2 was studied during acute hypoxia, as well as before and after 28 days of high altitude acclimatization. A sensor was chronically implanted in the frontal cortex of 8 Wistar rats. It is comprised of a fiber optic probe with a tip containing material that fluoresces with an oxygen dependent lifetime. Brain PtO 2 declines by 80% and 76% pre-and post-acclimatization respectively, when the fraction of inspired oxygen declines from 0.21 to 0.08. In addition, a linear relationship between brain PtO 2 and inspired O 2 levels was demonstrated r 2 =0.98 and r 2 =0.99 (pre-and post-acclimatization). Hypoxia acclimatization resulted in an increase in the overall brain PtO 2 by approximately 35%. This paper demonstrates the use of a novel chronically implanted fibre optic based sensor for measuring absolute PtO 2 . It shows a very strong linear relationship in awake animals between inspired O 2 and tissue O 2 , and shows that there is a proportional increase in PtO 2 over a range of inspired values after exposure to chronic hypoxia.

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“…The technique has been validated and provides robust data on the microcirculation. [18][19][20][21][22][23] Factors affecting the measurements 24 include temperature, external pressure, stress, ambient light and movement artefact. It is important to be aware of these variables so that appropriate precautions can be taken during measurements.…”

Section: Discussionmentioning

confidence: 99%

Measurement of blood flow in the rotator cuff using laser Doppler flowmetry

Levy

Relwani

Zaman

et al. 2008

The Journal of Bone and Joint Surgery. British volume

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The aim of this study was to define the microcirculation of the normal rotator cuff during arthroscopic surgery and investigate whether it is altered in diseased cuff tissue. Blood flow was measured intra-operatively by laser Doppler flowmetry. We investigated six different zones of each rotator cuff during the arthroscopic examination of 56 consecutive patients undergoing investigation for impingement, cuff tears or instability; there were 336 measurements overall. The mean laser Doppler flowmetry flux was significantly higher at the edges of the tear in torn cuffs (43.1, 95% confidence interval (CI) 37.8 to 48.4) compared with normal cuffs (32.8, 95% CI 27.4 to 38.1; p = 0.0089). It was significantly lower across all anatomical locations in cuffs with impingement (25.4, 95% CI 22.4 to 28.5) compared with normal cuffs (p = 0.0196), and significantly lower in cuffs with impingement compared with torn cuffs (p < 0.0001). Laser Doppler flowmetry analysis of the rotator cuff blood supply indicated a significant difference between the vascularity of the normal and the pathological rotator cuff. We were unable to demonstrate a functional hypoperfusion area or so-called 'critical zone' in the normal cuff. The measured flux decreases with advancing impingement, but there is a substantial increase at the edges of rotator cuff tears. This might reflect an attempt at repair.

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Brain Tissue and Sagittal Sinus pO2 Measurements Using the Lifetimes of Oxygen-Quenched Luminescence of a Ruthenium Compound

Cited by 8 publications

References 12 publications

Simultaneous two-photon imaging of oxygen and blood flow in deep cerebral vessels

Simultaneous two-photon imaging of oxygen and blood flow in deep cerebral vessels

A method for measuring brain partial pressure of oxygen in unanesthetized unrestrained subjects: The effect of acute and chronic hypoxia on brain tissue PO2

Measurement of blood flow in the rotator cuff using laser Doppler flowmetry

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