Long-term measurement of renal cortical and medullary tissue oxygenation and perfusion in unanesthetized sheep

The role of renal cortical and medullary hypoxia in the development of acute kidney injury is controversial, partly due to a lack of techniques for the long-term measurement of intrarenal oxygenation and perfusion in conscious animals. We have, therefore, developed a methodology to chronically implant combination probes to chronically measure renal cortical and medullary tissue perfusion and oxygen tension (tPo2) in conscious sheep and evaluated their responsiveness and reliability. A transit-time flow probe and a vascular occluder were surgically implanted on the left renal artery. At the same operation, dual fiber-optic probes, comprising a fluorescence optode to measure tPo2 and a laser-Doppler probe to assess tissue perfusion, were inserted into the renal cortex and medulla. In recovered conscious sheep ( n = 8) breathing room air, mean 24-h cortical and medullary tPo2 were similar (31.4 ± 0.6 and 29.7 ± 0.7 mmHg, respectively). In the renal cortex and medulla, a 20% reduction in renal blood flow (RBF) decreased perfusion (14.6 ± 8.6 and 41.2 ± 8.5%, respectively) and oxygenation (48.1 ± 8.5 and 72.4 ± 8.5%, respectively), with greater decreases during a 50% reduction in RBF. At autopsy, minimal fibrosis was observed around the probes. In summary, we have developed a technique to chronically implant fiber-optic probes in the renal cortex and medulla for recording tissue perfusion and oxygenation over many days. In normal resting conscious sheep, cortical and medullary tPo2 were similar. The responses to and recovery from renal artery occlusion, together with the consistent measurements over a 24-h period, demonstrate the responsiveness and stability of the probes.

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Assessment of changes in intrarenal blood flow in conscious rats using laser-Doppler flowmetry

AJP Renal Physiology ◽

10.1152/ajprenal.1993.264.6.f956 ◽

1993 ◽

Vol 264 (6) ◽

pp. F956-F962 ◽

Cited By ~ 7

Author(s):

S. Lu ◽

D. L. Mattson ◽

R. J. Roman ◽

C. G. Becker ◽

A. W. Cowley

Keyword(s):

Blood Flow ◽

Fiber Optic ◽

Recovery Period ◽

Laser Doppler ◽

Intravenous Bolus ◽

Ang Ii ◽

Doppler Flowmetry ◽

Conscious Rats ◽

Fiber Optic Probes

The present study was designed to develop, for the first time, a method that allows long-term repeated measurements of renal cortical blood flow (CBF) and medullary blood flow (MBF) in conscious unanesthetized rats. The use of fiber-optic probes (0.5 mm diam) for the chronic measurement of renal CBF and MBF was evaluated. Basal renal cortical and medullary laser-Doppler flow (LDF) signals and the responses to intravenous bolus injections of angiotensin II (ANG II, 12.5 ng) were determined every other day for 11 days in conscious Sprague-Dawley rats (n = 9). A recovery period of 5-7 days after surgery was required before stable signals were obtained from the implanted probes. Thereafter, the fiber-optic probes gave reproducible laser-Doppler measurements of CBF and MBF for 11 days. The CBF and MBF responses to intravenous bolus injections of ANG II (12.5 ng) were also constant during this period. Chronic implantation of the fiber-optic probes caused minimal tissue damage and did not significantly alter urine concentrating ability or renal function. These findings suggest that LDF technique with chronically implanted optical fibers provides a new tool for the continuous long-term monitoring of regional blood flow in the kidney of conscious rats.

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Rapid and Persistent Decrease in Brain Tissue Oxygenation in Ovine Gram-negative Sepsis

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00184.2021 ◽

2021 ◽

Author(s):

Nobuki Okazaki ◽

Yugeesh R Lankadeva ◽

Rachel M Peiris ◽

Ian E Birchall ◽

Clive N. May

Keyword(s):

Oxygen Tension ◽

Cerebral Perfusion ◽

Renal Cortex ◽

Renal Medulla ◽

Brain Perfusion ◽

Tissue Perfusion ◽

Brain Dysfunction ◽

Cerebral Tissue ◽

Brain Tissue Oxygenation ◽

Conscious Sheep

The changes in brain perfusion and oxygenation in critical illness, which are thought to contribute to brain dysfunction, are unclear due to the lack of methods to measure these variables. We have developed a technique to chronically measure cerebral tissue perfusion and oxygen tension in unanesthetised sheep. Using this technique, we have determined the changes in cerebral perfusion and PO2 during the development of ovine sepsis. In adult Merino ewes, fibre-optic probes were implanted in the brain, renal cortex and renal medulla to measure tissue perfusion, oxygen tension (PO2) and temperature and flow probes were implanted on the pulmonary and renal arteries. Conscious sheep were infused with live Escherichia coli for 24-hr, which induced hyperdynamic sepsis; mean arterial pressure decreased (85.2±5.6 to 71.5±8.7 mmHg), while cardiac output (4.12±0.70 to 6.15±1.26 L/min) and total peripheral conductance (48.9±8.5 to 86.8±11.5 mL/min/mmHg) increased (n=8, all P<0.001) and arterial PO2 decreased (104±8 to 83±10 mmHg; P<0.01). Cerebral perfusion tended to decrease acutely, although this did not reach significance, but there was a significant and sustained decrease in cerebral tissue PO2 (32.2±10.1 to 18.8±11.7 mmHg) after 3 h and to 22.8±5.2 mmHg after 24-hr of sepsis (P<0.02). Sepsis induced large reductions in both renal medullary perfusion and PO2 but had no effect in the renal cortex. In ovine sepsis, there is an early decrease in cerebral PO2 that is maintained for 24-hours despite minimal changes in cerebral perfusion. Cerebral hypoxia may be one of the factors causing sepsis-induced malaise and lethargy.

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WALANT–Epinephrine injection may lead to short term, reversible episodes of critical oxygen saturation in the fingertips

Archives of Orthopaedic and Trauma Surgery ◽

10.1007/s00402-020-03744-5 ◽

2021 ◽

Vol 141 (3) ◽

pp. 527-533

Author(s):

P. Moog ◽

M. Dozan ◽

J. Betzl ◽

I. Sukhova ◽

H. Kükrek ◽

...

Keyword(s):

Blood Flow ◽

Oxygen Saturation ◽

Substantial Reduction ◽

Tissue Perfusion ◽

Critical Levels ◽

Short Term ◽

Doppler Flowmetry ◽

Epinephrine Injection ◽

Venous Oxygen Saturation

Abstract Introduction Although the WALANT technique’s long-term safeness has been demonstrated in many studies, there are only few data investigating its short-term effects on tissue perfusion and oxygen levels. It was hypothesized that, temporarily, critical levels of tissue perfusion may occur. Methods Seventeen patients, who were scheduled for different procedures in WALANT technique, were injected with 5–7 ml of 1% Articain containing 1:200,000 epinephrine at the finger base. Capillary-venous oxygen saturation, hemoglobin volume in the capillaries, and relative blood flow in the fingertips were recorded once per second by white light spectrometry and laser Doppler flowmetry before, during and after injection for an average of 32 min. Results Clinically, no persistent tissue malperfusion was observed, and there were no postoperative complications. Capillary-venous oxygen saturation was reduced by ≥ 30% in seven patients. Critical levels of oxygen saturation were detected in four patients during 13 intervals, each lasting for 132.5 s on average. Oxygen saturation returned to noncritical values in all patients by the end of the observation period. Blood flow in the fingertips was reduced by more than 30% in nine patients, but no critical levels were observed, as with the hemoglobin. Three patients demonstrated a reactive increase in blood flow of more than 30% after injection. Conclusions Injection of tumescent local anesthesia containing epinephrine into finger base may temporarily cause a substantial reduction in blood flow and lead to critical levels of oxygen saturation in the fingertips. However, this was fully reversible within minutes and does not cause long-term complications.

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Renal artery revascularization using the inferior mesenteric artery as an inflow source with a long-term follow-up

Journal of Vascular Surgery Cases and Innovative Techniques ◽

10.1016/j.jvscit.2021.02.010 ◽

2021 ◽

Vol 7 (2) ◽

pp. 223-225

Author(s):

Khaled I. Alnahhal ◽

Tambi Jarmi ◽

Albert G. Hakaim ◽

Houssam Farres

Keyword(s):

Renal Artery ◽

Mesenteric Artery ◽

Inferior Mesenteric Artery ◽

Long Term Follow Up

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Clinical predictors of improved long-term blood pressure control after successful stenting of hypertensive patients with obstructive renal artery atherosclerosis

Catheterization and Cardiovascular Interventions ◽

10.1002/(sici)1522-726x(199906)47:2<167::aid-ccd7>3.0.co;2-r ◽

1999 ◽

Vol 47 (2) ◽

pp. 167-172 ◽

Cited By ~ 63

Author(s):

Krishna J. Rocha-Singh ◽

Gregory J. Mishkel ◽

Richard E. Katholi ◽

Robert A. Ligon ◽

Julie A. Armbruster ◽

...

Keyword(s):

Blood Pressure ◽

Renal Artery ◽

Blood Pressure Control ◽

Pressure Control ◽

Clinical Predictors ◽

Hypertensive Patients

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Packing Technique with or without Remodeling for Endovascular Coil Embolization of Renal Artery Aneurysms: Safety, Efficacy and Mid-Term Outcomes

Journal of Clinical Medicine ◽

10.3390/jcm10020326 ◽

2021 ◽

Vol 10 (2) ◽

pp. 326

Author(s):

Grégory Secco ◽

Olivier Chevallier ◽

Nicolas Falvo ◽

Kévin Guillen ◽

Pierre-Olivier Comby ◽

...

Keyword(s):

Renal Artery ◽

Success Rate ◽

Coil Embolization ◽

Preventive Treatment ◽

Parent Artery ◽

Technical Success ◽

Technical Success Rate ◽

Endovascular Coil Embolization ◽

Lower Morbidity

The endovascular treatment of renal artery aneurysms (RAAs) has lower morbidity and shorter stay lengths compared to surgical repair. Here, we describe coil packing with or without remodeling and assess outcomes and complications. We retrospectively identified the 19 consecutive preventive endovascular RAA coil embolizations done in 18 patients at our center in 2010–2020. Patient and aneurysm characteristics, technical success rate, complications, and recurrences were recorded. Mean patient age was 63 ± 13 years. The RAA was >1.5 cm in 11 cases, and in four cases, the aneurysm-to-parent artery size ratio was >2. Simple coiling was performed for 11 (57.9%) aneurysms, stent-assisted coiling for seven (36.8%) aneurysms, and balloon-assisted coiling for one (5.3%) aneurysm. Technical success rate was 100%. Complete definitive RAA exclusion was achieved with a single procedure for 17 (89.5%) aneurysms, whereas two (10.5%) aneurysms required a repeat procedure. Four minor complications occurred but resolved with no long-term consequences. No major complications occurred during the mean follow-up of 41.1 ± 29.7 months. Coil embolization by sac packing or remodeling proved very safe and effective. Together with the known lower morbidity and shorter stay length compared to open surgery, these data indicate that this endovascular procedure should become the preventive treatment of choice for RAAs.

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