Hemoglobin Oxygen Saturation Levels Research Articles

Evaluating the effects of hypoxic storage on platelet function and health using a novel storage system.

Thousands of units of whole blood (WB) and blood components are transfused daily to treat trauma patients. Improved methods for blood storage are critical to support trauma-related care. The Hemanext ONE® system offers a unique method for hypoxic storage of WB, with successfully demonstrated storage of clinically viable RBCs. This work evaluated the system for the storage of WB, focusing on platelet health and function. WB was collected from healthy donors and processed through the Hemanext ONE® system. Hemoglobin oxygen saturation (HbSO2) levels of WB were depleted to 10%, 20%, or 30% of total HbSO2 and then stored in PVC bags sealed in oxygen-impermeable bags (except for normoxic control) with samples collected on days 1, 7, and 14 post-processing. Flow cytometry assessed the activation and apoptosis of platelets. Clot dynamics were assessed based on aggregometry and thromboelastography assays, as well as thrombin generation using a calibrated-automated thrombogram method. Hypoxic storage conditions were maintained throughout the storage period. Hypoxia triggered increased lactate production, but pH changes were negligible compared to normoxic control. Storage at 10% HbSO2 had a significant impact on platelet function, resulting in increased activation and reduced clot formation and aggregation. These effects were less significant at 20% and 30% HbSO2. This study indicates that platelets are sensitive to hypoxic storage and suffer significant metabolic and functional deterioration when stored at or below 10% HbSO2.

Validation of a new 3D quantitative BOLD based cerebral oxygen extraction mapping

Quantitative BOLD (qBOLD) MRI allows evaluation of oxidative metabolism of the brain based purely on an endogenous contrast mechanism. The method quantifies deoxygenated blood volume (DBV) and hemoglobin oxygen saturation level of venous blood (Yv), yielding oxygen extraction fraction (OEF), and along with a separate measurement of cerebral blood flow, cerebral metabolic rate of oxygen (CMRO2) maps. Here, we evaluated our recently reported 3D qBOLD method that rectifies a number of deficiencies in prior qBOLD approaches in terms of repeat reproducibility and sensitivity to hypercapnia on the metabolic parameters, and in comparison to dual-gas calibrated BOLD (cBOLD) MRI for determining resting-state oxygen metabolism. Results suggested no significant difference between test-retest qBOLD scans in either DBV and OEF. Exposure to hypercapnia yielded group averages of 38 and 28% for OEF and 151 and 146 µmol/min/100 g for CMRO2 in gray matter at baseline and hypercapnia, respectively. The decrease of OEF during hypercapnia was significant (p ≪ 0.01), whereas CMRO2 did not change significantly (p = 0.25). Finally, baseline OEF (37 vs. 39%) and CMRO2 (153 vs. 145 µmol/min/100 g) in gray matter using qBOLD and dual-gas cBOLD were found to be in good agreement with literature values, and were not significantly different from each other (p > 0.1).

Panoramic volumetric clinical handheld photoacoustic and ultrasound imaging

Photoacoustic (PA) imaging has gained much attention, providing structural and functional information in combination with clinical ultrasound (US) imaging systems. 2D PA and US imaging is easily implemented, but its heavy dependence on operator skills makes 3D imaging preferable. In this study, we propose a panoramic volumetric clinical PA and US imaging system equipping a handheld imaging scanner weighing 600 g and measuring 70 × 62 × 110 mm3. Multiple PA/US scans were performed to cover a large field-of-view (FOV), and the acquired PA/US volumes were mosaic-stitched after manually correcting the positions and rotations in a total of 6 degrees of freedom. PA and US maximum amplitude projection images were visualized online, while spectral unmixed data was quantified offline. The performance of the system was tested via tissue-mimicking phantom experiments. The system’s potential was confirmed in vivo by panoramically imaging vascular networks in human arms and necks, with FOVs of 331 × 38 and 129 × 120 mm2, respectively. Further, we quantified hemoglobin oxygen saturation levels in the radial artery, brachial artery, carotid artery, and jugular vein. We hope that this system can be applied for various clinical fields such as cardiovascular imaging, dermatology, vascular surgery, internal medicine, and oncology.

Comparison of the vitality tests used in the dental clinical practice and histological analysis of the dental pulp.

In dentistry, indirect diagnostic methods such as electrical sensibility testing and pulse oximetry are used to assess the status of the pulp. Our study aimed to determine the correlation between hemoglobin oxygen saturation and vascular volume density (Vvasc). We also wanted to examine an electrical sensibility test and the volume density of myelinated nerve fibers (Vnerv). Twenty-six intact permanent premolars were included in the study. For histological analysis, the pulp tissue was stained with hematoxylin-eosin and immunohistochemically for von Willebrand factor and S100 to detect blood vessels and myelinated nerve fibers, respectively. The stereological analysis was used to determine the Vvasc and Vnerv. Statistical analysis was done using the Pearson correlation test and Welch’s ANOVA test. Histological analysis showed that the pulp tissue was strongly vascularized and innervated. A significant positive correlation was found between Vvasc and hemoglobin oxygen saturation levels (p = 0.030). A significant negative correlation was found between Vnerv and the lowest electrical voltage that patient felt (p = 0.033). According to the maturity of the dental apex, teeth were divided into a group with open (n = 6, OA group) and closed apex (n = 20, CA group). We found that pulps in the CA group had higher Vnerv than the OA group (p = 0.037). In contrast, there were no significant differences in Vvasc of the pulp tissue (p = 0.059), oxygen saturation (p = 0.907), or electrical voltage (p = 0.113) between both groups. We can conclude that the measurement of pulse oximetry and electrical sensibility test reflects the morphology of healthy pulp tissue independently of the maturity of the dental apex.

Whole-brain 3D mapping of oxygen metabolism using constrained quantitative BOLD

Quantitative BOLD (qBOLD) MRI permits noninvasive evaluation of hemodynamic and metabolic states of the brain by quantifying parametric maps of deoxygenated blood volume (DBV) and hemoglobin oxygen saturation level of venous blood (Yv), and along with a measurement of cerebral blood flow (CBF), the cerebral metabolic rate of oxygen (CMRO2). The method, thus should have potential to provide important information on many neurological disorders as well as normal cerebral physiology. One major challenge in qBOLD is to separate deoxyhemoglobin's contribution to R2′ from other sources modulating the voxel signal, for instance, R2, R2′ from non-heme iron (R′2,nh), and macroscopic magnetic field variations. Further, even with successful separation of the several confounders, it is still challenging to extract DBV and Yv from the heme-originated R2′ because of limited sensitivity of the qBOLD model. These issues, which have not been fully addressed in currently practiced qBOLD methods, have so far precluded 3D whole-brain implementation of qBOLD. Thus, the purpose of this work was to develop a new 3D MRI oximetry technique that enables robust qBOLD parameter mapping across the entire brain. To achieve this goal, we employed a rapid, R2′-sensitive, steady-state 3D pulse sequence (termed ‘AUSFIDE’) for data acquisition, and implemented a prior-constrained qBOLD processing pipeline that exploits a plurality of preliminary parameters obtained via AUSFIDE, along with additionally measured cerebral venous blood volume. Numerical simulations and in vivo studies at 3 T were performed to evaluate the performance of the proposed, constrained qBOLD mapping in comparison to the parent qBOLD method. Measured parameters (Yv, DBV, R′2,nh, nonblood magnetic susceptibility) in ten healthy subjects demonstrate the expected contrast across brain territories, while yielding group-averages of 64.0 ± 2.3 % and 62.2 ± 3.1 % for Yv and 2.8 ± 0.5 % and 1.8 ± 0.4 % for DBV in cortical gray and white matter, respectively. Given the Yv measurements, additionally quantified CBF in seven of the ten study subjects enabled whole-brain 3D CMRO2 mapping, yielding group averages of 134.2 ± 21.1 and 79.4 ± 12.6 μmol/100 g/min for cortical gray and white matter, in good agreement with literature values. The results suggest feasibility of the proposed method as a practical and reliable means for measuring neurometabolic parameters over an extended brain coverage.

Multiparametric Photoacoustic Analysis of Human Thyroid Cancers In Vivo.

Thyroid cancer is one of the most common cancers, with a global increase in incidence rate for both genders. Ultrasound-guided fine-needle aspiration is the current gold standard to diagnose thyroid cancers, but the results are inaccurate, leading to repeated biopsies and unnecessary surgeries. To reduce the number of unnecessary biopsies, we explored the use of multiparametric photoacoustic (PA) analysis in combination with the American Thyroid Association (ATA) Guideline (ATAP). In this study, we performed in vivo multispectral PA imaging on thyroid nodules from 52 patients, comprising 23 papillary thyroid cancer (PTC) and 29 benign cases. From the multispectral PA data, we calculated hemoglobin oxygen saturation level in the nodule area, then classified the PTC and benign nodules with multiparametric analysis. Statistical analyses showed that this multiparametric analysis of multispectral PA responses could classify PTC nodules. Combining the photoacoustically indicated probability of PTC and the ATAP led to a new scoring method that achieved a sensitivity of 83% and a specificity of 93%. This study is the first multiparametric analysis of multispectral PA data of thyroid nodules with statistical significance. As a proof of concept, the results show that the proposed new ATAP scoring can help physicians examine thyroid nodules for fine-needle aspiration biopsy, thus reducing unnecessary biopsies. SIGNIFICANCE: This report highlights a novel photoacoustic scoring method for risk stratification of thyroid nodules, where malignancy of the nodules can be diagnosed with 83% sensitivity and 93% specificity.

Association between Hb A1c and Severity of COVID-19 Patients

This study aimed to examine the relationship between Hb A1c levels and the clinical course of coronavirus-19 (COVID-19) patients. Sixty-six COVID-19(+) patients with high Hb A1c and 46 with average Hb A1c and 30 COVID-19(–) patients with average Hb A1c were included. Hb A1c levels and parameters examined in COVID-19(+) patients were compared between groups, and correlation analysis was performed between these parameters and Hb A1c levels. The effect of Hb A1c levels on intensive care unit (ICU) admission and mortality rate in COVID-19 patients was analyzed with the χ2 test. It was observed that hemoglobin (Hb) and arterial oxygen saturation (SaO2) levels of the COVID-19 (+) groups was lower than the COVID-19 (–) group, while ferritin, D-dimer, procalcitonin (PCT), and C-reactive protein (CRP) levels were higher. The COVID-19 (+) group with high Hb A1c had higher lactate dehydrogenase (LDH), PCT and D-dimer levels than the other two groups, while Hb, partial arterial oxygen pressure (PaO2) levels were lower. The Hb A1c levels of the COVID-19 (+) groups were positively correlated with absolute neutrophil count (ANC), LDH, PCT and (K+) levels, while negatively correlated with Hb and PaO2 levels. Hb A1c was found to be associated with the inflammation process, coagulation disorders and low PaO2 in COVID-19 patients. The COVID-19 patients with high Hb A1c levels had a higher mortality rate than other COVID-19 patients. Using Hb A1c measurements with other prognostic markers would contribute to the patient’s risk of death assessment.

Toward Wearable Healthcare: A Miniaturized 3D Imager With Coherent Frequency-Domain Photoacoustics.

Medical monitoring is undergoing a translation from the hospital-based system to the personalized home-based system. With the aim of wearable application of photoacoustic technique, we propose a miniaturized photoacoustic 3D imager for superficial medical imaging. By employing the compact continuous-wave laser diode based optical irradiation and an ultrathin 2D matrix array based photoacoustic detection in the coherent frequency domain, a wearable imaging probe with a size of about 80 × 25 × 24mm3 and a weight of 21 g is developed. At the backend, an FPGA controlled Howland current source drives the laser diodes to excite linear frequency modulated optical irradiation. Recorded by a portable multichannel data acquisition system, the generated photoacoustic responses are firstly compressed with the coherent frequency domain photoacoustic method and then extrapolated in the wavenumber-frequency domain for fast image reconstruction. With three-wavelength (450nm, 638nm, and 808nm) laser irradiation, photoacoustic imaging can be operated multispectrally, endowing the developed imager with functional imaging capability in 3D space. With the imager worn on the human forearm, hemoglobin oxygen saturation level in superficial arm vasculature can be long-term monitored with high stability. When the imager is applied for imaging in a relatively large area (e.g., early melanoma detection in the human breast), flexible scanning in a handheld manner can be performed. This work opens the application potential of photoacoustic technique in a broad range of areas, including personalized healthcare, home health monitoring, and long-term physiologic monitoring.

THE USE OF KETAMINE-XYLAZINE OR BUTORPHANOL-AZAPERONE-MEDETOMIDINE TO IMMOBILIZE AMERICAN BLACK BEARS ( URSUS AMERICANUS).

Wildlife anesthetic protocols must offer rapid inductions and recoveries, be physiologically safe, and be minimally regulated. With this in mind, we evaluated differences in induction and recovery times and physiological parameters in 33 American black bears ( Ursus americanus) anesthetized with ketamine-xylazine (KX) or immobilized with a commercial drug combination of butorphanol, azaperone, and medetomidine (BAM). Dose was based on mass estimated from field observations. Bears were housed at Appalachian Bear Rescue, Townsend, Tennessee, US, or free-ranging within the Great Smoky Mountains National Park (Tennessee and North Carolina, US) and chemically immobilized for management purposes. From 11 April to 29 June 2016, we immobilized bears with injection via pole syringe or disposable dart projected from an air-powered dart rifle. Once immobilized, we measured each bear's temperature, respiration (breaths/min), heart rate (beats/min), hemoglobin oxygen saturation (via pulse oximetry), arterial blood gases, and mass (kg). We found no differences in the induction parameters, partial pressures of CO2, and rectal temperatures. The BAM-treated bears had lower heart and respiratory rates that led to lower hemoglobin oxygen saturation levels (from blood gas analysis, SaO2). The SaO2 after treatment with BAM (91.1±0.8%) was lower than with KX (93.4±0.9%). After handling, we reversed KX-treated bears with a x̄=0.2±0.02 mg/kg yohimbine and BAM-treated bears with x̄=1.5±0.1 mg/kg atipamezole and 0.8±0.1 mg/kg naltrexone. We found no differences in the recovery times to increased respiration and to the bear assuming a head-up position. The BAM-treated bears stood and recovered quicker than did KX-treated animals. Based on our observations, BAM appears to offer safe, predictable immobilizations with fewer drawbacks and faster recovery times than KX-treated bears.

Tissue Oxygenation within Diabetic Wounds can be Monitored Using Difluoroboron β– Diketonate Polylactide Nanoparticles

OBJECTIVERoughly 6.5 million diabetic patients in the United States suffer from chronic wounds that exhibit impaired healing response1. These wounds often do not respond to standard treatment due to insufficient oxygenation in the wound bed2. Given the heterogeneity of oxygen levels in wounds and the importance of oxygen in tissue repair, it is compelling to develop a reliable way to non‐invasively monitor oxygen levels within chronic wounds over time. Previously, we demonstrated the ability of topically‐delivered BF2nbm(I)PLA boron dye nanoparticles (BNPs) that phosphoresce differentially at varying oxygen levels, to provide a spatial map of oxygen levels throughout the wound bed of a murine full‐thickness cutaneous wound3. The objective of this work is to validate the ability of BNP imaging to detect impaired tissue oxygenation during wound healing in diabetic individuals compared to healthy individuals.METHODSWe have developed a novel model of wound healing in the murine ear which allows measurements of oxygen levels in both tissue and blood vessels using BNP imaging and photoacoustic microscopy (PAM), respectively. PAM non‐invasively measures structural and hemodynamic changes, including vessel diameter, hemoglobin concentration, blood flow speed, and hemoglobin oxygen saturation levels in individual blood vessels down to the capillary level during microvascular remodeling within wound beds4. In this ear wound model, the epidermis and a portion of the dermis, including the center feeder arteriole and its main branches, are excised from the center of the ear lobe. The wound is covered with Tegaderm bandage to prevent drying, and the mouse is fitted with an Elizabethan collar to prevent it from removing the bandage. At regular intervals until the wound heals, BNPs are topically applied to the wound and excited by UV light for two minutes during which the fluorescence (F) and phosphorescence (P) emission signals are recorded using a camera. A custom Matlab program calculates the ratio of F:P emission intensities at each pixel in the wound bed image, which provides a relative mapping of oxygen levels throughout the wound. Following BNP imaging, PAM imaging is performed in order to calculate the percent sO2 in each blood vessel in/around the wound bed. BNP and PAM measurements are compared to one another for wounds in both healthy and diabetic mice.RESULTSDiabetic db/db mice exhibit muted wound oxygenation increases over time compared to non‐diabetic control mice. BNP fluorescence:phosphorescence emission ratios from wound beds emulate sO2 trends generated via PAM, confirming the ability of BNPs to assess tissue oxygenation over time in both diabetic and healthy wounds.CONCLUSIONSBNPs can be used to monitor tissue oxygenation over time in diabetic and healthy wounds. Given their low cost and potential for clinical monitoring of these wounds in humans, BNPs warrant further study for non‐invasively monitoring wound healing over time.Support or Funding InformationUVA School of Medicine Pinn Scholars ProgramThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

History of Asthma is Associated with Albuminuria within an International Pediatric Cohort of Sickle Cell Disease Patients: A Casire Group Analysis

Background: Renal disease is a common end organ complication of sickle cell disease(SCD). Risk factors of sickle cell nephropathy include age, genotype, and anemia. We have investigated and discovered Lower Hemoglobin Oxygen Saturation levels associated with microalbuminuria. To further investigate this, we investigated a patient's history of asthma as a risk factor of renal disease. Asthma has been linked to increased mortality in adult and children with SCD from the National Cooperative SCD Study Group. In our ongoing International CASIRE Renal Cohort study, we investigated the clinical history of asthma and laboratory correlates of albuminuria and proteinuria as measured by Urine Protein/Creatinine and Urine Albumin/Creatinine .Methods: 538pediatric and adult SCD (3-59 y/o) patients were recruited at baseline from 6 Centers (USA: Univ of Michigan, Case Medical Center/Rainbow Babies, Albert Einstein-Montefiore Medical Center, Univ of Connecticut; Italy: Univ. of Padova, Univ of Naples;). Clinical history and laboratory studies, including Pain crisis patterns, SBP, DBP, BMI, CBC, Serum Crt, Urine ph, Urine SG were collected. For this report, we concentrated on patient’s comorbidities and sickle cell medical history, specifically pain crisis patterns, acute chest history and asthma. Urine Microalbumin/Crt(UMA) (mg/gm) was obtained in 172 patients and we categorized patients into No Albuminuria: (No UMA)<30mg/gm and Albuminuria(UMAlbum): Microalbuminuria(MicroUMA) 30-299mg/gm and Macroalbuminuria (MacroUMA)>300mg/gm.334 subjects answered the question of medical history of asthma and of those 172 had Urine Microalbumin (UMA) levels. 75% of SCD-Asthma group (N=56) and 78% of SCD-NoAsthma group (N=204) had severe SCD (SS or SBeta Zero). Children (<18y/o) comprised 58% of the SCD-Asthma group (N=43) and 62% of the SCD-NoAsthma group (N=161). Mean age was 16 y/o in both SCD-Asthma and SCD-NoAsthma Groups.Results: No Albuminuria (NoUMAlbum) was reported in 80% (138/172) while Albuminuria(UMAlbum) was recorded in 20% (34/172) of the Cohort. Severe SCD pts represented 91% (n=33) of the Albuminuria pts. Adult UMA levels were higher (mean=61) than Peds UMA levels (mean=22) (p=0.025). Patients with History of Asthma had higher mean UMA levels ( 94 vs 21, p=0.005). Further, a history of asthma was associated with higher mean UMA levels (122 vs 23, p=0.003) within the Severe Genotype group (p=0.002), within all Pediatric SCD patients ( 60 vs 17, p=0.002), and within Severe Pediatric SCD patients ( 68 vs 19, p=0.004) (One Way Anova). Within the Medical history, BMI in the underweight range and a history of priapism were associated with elevated UMA levels.Conclusions: Age and Severe Genotype was associated with Albuminuria. A history of asthma was strongly associated with renal disease in Pediatric SCD patients in addition to a very strong association within Pediatric Severe Genotype patients. Optimal control of asthma could possibly mitigate the risk of kidney disease with SCD patients. A more in-dept analysis of patient's history of asthma would provide stronger evidence of these findings. DisclosuresAsare:Intramural University of Ghana Research fund: Research Funding; Vanderbilt University Medical Center Gift Funds: Research Funding. Piccone:Novartis: Other: Speaker. Rivers:Acetylon: Research Funding.

Assessment of Microcirculatory Hemoglobin Levels in Normal and Diabetic Subjects using Diffuse Reflectance Spectroscopy in the Visible Region — a Pilot Study

Light-based diagnostic techniques provide a minimally invasive way for selective biomarker estimation when tissues transform from a normal to a malignant state. Spectroscopic techniques based on diffuse reflectance characterize the changes in tissue hemoglobin/oxygenation levels during the tissue transformation process. Recent clinical investigations have shown that changes in tissue oxygenation and microcirculation are observed in diabetic subjects in the initial and progressive stages. In this pilot study, we discuss the potential of diffuse reflectance spectroscopy (DRS) in the visible (Vis) range to differentiate the skin microcirculatory hemoglobin levels between normal and advanced diabetic subjects with and without neuropathy. Average concentration of hemoglobin as well as hemoglobin oxygen saturation within the probed tissue volume is estimated for a total of four different sites in the foot sole. The results indicate a statistically significant decrease in average total hemoglobin and increase in hemoglobin oxygen saturation levels for diabetic foot compared with a normal foot. The present study demonstrates the ability of reflectance spectroscopy in the Vis range to determine and differentiate the changes in tissue hemoglobin and hemoglobin oxygen saturation levels in normal and diabetic subjects.

Breast Tissue Composition and Its Dependence on Demographic Risk Factors for Breast Cancer: Non-Invasive Assessment by Time Domain Diffuse Optical Spectroscopy

BackgroundBreast tissue composition is recognized as a strong and independent risk factor for breast cancer. It is a heritable feature, but is also significantly affected by several other elements (e.g., age, menopause). Nowadays it is quantified by mammographic density, thus requiring the use of ionizing radiation. Optical techniques are absolutely non-invasive and have already proved effective in the investigation of biological tissues, as they are sensitive to tissue composition and structure.MethodsTime domain diffuse optical spectroscopy was performed at 7 wavelengths (635-1060 nm) on 200 subjects to derive their breast tissue composition (in terms of water, lipid and collagen content), blood parameters (total hemoglobin content and oxygen saturation level), and information on the microscopic structure (scattering amplitude and power). The dependence of all optically-derived parameters on age, menopausal status, body mass index, and use of oral contraceptives, and the correlation with mammographic density were investigated.ResultsYounger age, premenopausal status, lower body mass index values, and use of oral contraceptives all correspond to significantly higher water, collagen and total hemoglobin content, and lower lipid content (always p < 0.05 and often p < 10-4), while oxygen saturation level and scattering parameters show significant dependence only on some conditions. Even when age-adjusted groups of subjects are compared, several optically derived parameters (and in particular always collagen and total hemoglobin content) remain significantly different.ConclusionsTime domain diffuse optical spectroscopy can probe non-invasively breast tissue composition and physiologic blood parameters, and provide information on tissue structure. The measurement is suitable for in vivo studies and monitoring of changes in breast tissue (e.g., with age, lifestyle, chemotherapy, etc.) and to gain insight into related processes, like the origin of cancer risk associated with breast density.

Monte Carlo Investigation of Optical Coherence Tomography Retinal Oximetry.

Optical coherence tomography (OCT) oximetry explores the possibility to measure retinal hemoglobin oxygen saturation level (sO2). We investigated the accuracy of OCT retinal oximetry using Monte Carlo simulation in a commonly used four-layer retinal model. After we determined the appropriate number of simulated photon packets, we studied the effects of blood vessel diameter, signal sampling position, physiological sO2 level, and the blood packing factor on the accuracy of sO2 estimation in OCT retinal oximetry. The simulation results showed that a packing factor between 0.2 and 0.4 yields a reasonably accurate estimation of sO2 within a 5% error tolerance, which is independent of vessel diameter and sampling position, when visible-light illumination is used in OCT. We further explored the optimal optical spectral range for OCT retinal oximetry. The simulation results suggest that visible spectral range around 560nm is better suited than near-infrared spectral range around 800nm for OCT oximetry to warrant accurate measurements.

Abstract 177: Testing of a Novel Pelvic Hemostasis Belt to Control Lethal Pelvic Arterial Hemorrhage

Objectives: Hemorrhage is the leading cause of death for both battlefield and injuries civilian. Hemorrhage caused by pelvic vascular injuries is of particular concern since it is challenging to manage or control prior to surgical intervention. Recently, there has been renewed interest in developing pre-surgical endovascular interventions to control such hemorrhage. However, other short-term techniques may be needed as a conduit to such endovascular approaches. Attempts at external tamponade of these complex injuries as a bridge to definitive surgical care of such injuries is not new. We tested a prototype device called the Pelvic Hemostasis Belt (PHB) for its ability to reduce or stop blood flow in a lethal model of pelvic arterial injury. Methods: Twelve male swine, 43(5.6) kg were utilized in this study. Animals were anesthetized, instrumented then randomized into two groups, Military Anti Shock Trousers group (MAST) and Pelvic Hemostasis Belt group (PHB). Through laparotomy, a stainless-steel monofilament suture was placed through the right iliac artery, the abdomen was closed and the suture was exteriorized. Hemorrhage was produced by pulling the suture through the iliac artery. In both groups, the hemostasis devices (MAST or BHP) were applied over the pelvis and lower abdomen for 60 minutes followed by release and monitoring for 30 minutes or until the animal expired. An infusion of 500 mL of hetastarch was started immediately after initiation of hemorrhage. Results: All animals in the PHB group and only two from the MAST group survived for 60 minutes. Average survival time for the rest of the MAST group was 44(17.9) minutes. The log-rank (Mantel-Cox) survival analysis demonstrated a significant difference in survival time between PHB and MAST group (p = 0.018). Significant differences were noted between the two groups in mean arterial pressure, lactate and central venous hemoglobin oxygen saturation levels. Conclusion: The PHB was successful in improving survival for 60 minutes after a lethal vascular injury. The Pelvic Hemostasis Belt might be helpful to bridge endovascular methods of hemorrhage control.

Photoacoustic imaging of vascular hemodynamics: validation with blood oxygenation level-dependent MR imaging.

To noninvasively assess vascular hemodynamics with photoacoustic imaging (PAI) and blood oxygenation level-dependent (BOLD) magnetic resonance (MR) imaging in phantoms and in an animal model. In vivo studies were performed with institutional animal care and use committee approval. In vitro experiments were performed by using a tissue-mimicking phantom in multiple oxygenation conditions (n = 6) to compare PAI measurements and BOLD MR imaging measurements. PAI and T2-weighted spin-echo-based BOLD MR imaging were performed to assess tumor response to carbogen (95% O2, 5% CO2) in mice with head and neck tumors before (n = 11) and after (n = 9) treatment with a vascular disrupting agent (VDA). Two-tailed Pearson correlation analysis was performed to determine the correlation between the parameters measured with PAI and BOLD MR imaging in vitro. Two-tailed paired t tests were used to compare change in tumor hemoglobin oxygen saturation (sO2) levels and BOLD signal in response to carbogen. Changes in PAI and BOLD signal intensity before and after VDA treatment were analyzed for significance by using analysis of variance with repeated measures. Phantom measurements yielded good correlation between photoacoustically derived sO2 levels and BOLD signal intensity (r = 0.937, P = .005) and partial pressure of oxygen (r = 0.981, P = .005). In vivo hemodynamic response to carbogen was characterized by a significant increase in tumor sO2 levels (P = .003) and BOLD signal (P = .001). When compared with pretreatment estimates, treatment with VDA resulted in a significant reduction in the tumor hemodynamic response to carbogen at PAI (P = .030). Carbogen-based functional imaging with PAI and BOLD MR imaging enables monitoring of early changes in tumor hemodynamics after vascular targeted therapy.

Polymorphisms in the glutathione pathway modulate cystic fibrosis severity: a cross-sectional study.

BackgroundCystic fibrosis (CF) clinically manifests with various levels of severity, which are thought to be modulated by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR), modifier genes, and the environment. This study verified whether polymorphisms in modifier genes associated with glutathione (GSH) metabolism influence CF severity.MethodsA cross-sectional study of 180 CF patients was carried out from 2011 to 2012. We analyzed CFTR mutations, polymorphisms (GSTM1 and GSTT1 deletions, GSTP1 + 313A > G, GCLC-129C > T, and GCLC-3506A > G) in modifier genes and CF clinical severity as assessed by 28 clinical and laboratory variables.ResultsSignificant associations were found between modifier gene polymorphisms and particular phenotypes or genotype changes. These included GCLC-129C > T with a higher frequency of the Pseudomonas aeruginosa mucoid to CC genotype (p = 0.044), and GCLC-3506A > G with a higher frequency of the no-mucoid P. aeruginosa (NMPA) to AA genotype (p = 0.012). The GSTT1 deletion was associated with a higher frequency of the NMPA to homozygous deletion (p = 0.008), GSTP1 + 313A > G with a minor risk of osteoporosis (p = 0.036), and patient age ≤ 154 months (p = 0.044) with the AA genotype. The Bhalla score was associated with GCLC-3506A > G (p = 0.044) and GSTM1/GSTT1 deletion polymorphisms (p = 0.02), while transcutaneous hemoglobin oxygen saturation levels were associated with GSTT1 deletions (p = 0.048).ConclusionCF severity is associated with polymorphisms in GSH pathways and CFTR mutations.

Accuracy of retinal oximetry: a Monte Carlo investigation

Retinal hemoglobin oxygen saturation (sO2) level is believed to be associated with the pathophysiology of several leading blinding diseases. Methods to properly measure retinal sO2 have been investigated for decades; however, the accuracy of retinal oximetry is still considered to be limited. The Monte Carlo simulation of photon transport in retina to examine how the accuracy of retinal oximetry is affected by local parameters is discussed. Fundus photography was simulated in a multilayer retinal model, in which a single vessel segment with 0.7 sO2 was embedded, at six optical wavelengths. Then, 200 million photons were traced in each simulation to ensure statistically stable results. The optical reflectance and energy deposit were recorded to measure sO2 using both the reflection method (existing retinal oximetry) and a new absorption method, photoacoustic ophthalmoscopy (PAOM). By varying the vessel diameter and melanin concentration in the retinal pigment epithelium, the relative error of sO2 measurement in the reflection method increased with increasing vessel diameter and melanin concentration; in comparison, the sO2 measurement was insensitive to these two parameters in PAOM. The results suggest that PAOM potentially can be a more accurate tool in quantifying retinal sO2.

Dual-wavelength photothermal optical coherence tomography for imaging microvasculature blood oxygen saturation

A swept-source dual-wavelength photothermal (DWP) optical coherence tomography (OCT) system is demonstrated for quantitative imaging of microvasculature oxygen saturation. DWP-OCT is capable of recording three-dimensional images of tissue and depth-resolved phase variation in response to photothermal excitation. A 1,064-nm OCT probe and 770-nm and 800-nm photothermal excitation beams are combined in a single-mode optical fiber to measure microvasculature hemoglobin oxygen saturation (SO(2)) levels in phantom blood vessels with a range of blood flow speeds (0 to 17 mm/s). A 50-μm-diameter blood vessel phantom is imaged, and SO(2) levels are measured using DWP-OCT and compared with values provided by a commercial oximeter at various blood oxygen concentrations. The influences of blood flow speed and mechanisms of SNR phase degradation on the accuracy of SO(2) measurement are identified and investigated.

828 SPECTROSCOPIC TISSUE ANALYSIS OF RENAL ISCHEMIA AND RECOVERY DURING PARTIAL NEPHRECTOMY: WHAT IS THE QUANTITATIVE BENEFIT OF SEGMENTAL RENAL ARTERY VS MAIN RENAL ARTERY CLAMPING?

You have accessJournal of UrologyTechnology & Instruments: Laparoscopy: Malignant & Benign Disease1 Apr 2013828 SPECTROSCOPIC TISSUE ANALYSIS OF RENAL ISCHEMIA AND RECOVERY DURING PARTIAL NEPHRECTOMY: WHAT IS THE QUANTITATIVE BENEFIT OF SEGMENTAL RENAL ARTERY VS MAIN RENAL ARTERY CLAMPING? Philip Dorsey, Quincy Brown, Janet Colli, Kate Elfer, Theodore Saitz, Ross McCaslin, Liang Wang, and Benjamin Lee Philip DorseyPhilip Dorsey New Orleans, LA More articles by this author , Quincy BrownQuincy Brown New Orleans, LA More articles by this author , Janet ColliJanet Colli New Orleans, LA More articles by this author , Kate ElferKate Elfer New Orleans, LA More articles by this author , Theodore SaitzTheodore Saitz New Orleans, LA More articles by this author , Ross McCaslinRoss McCaslin New Orleans, LA More articles by this author , Liang WangLiang Wang New Orleans, LA More articles by this author , and Benjamin LeeBenjamin Lee New Orleans, LA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.395AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Spectroscopic tissue analysis has been used to monitor changes in tissue vascular hemoglobin oxygen saturation during periods of tissue ischemia. Our goals were to utilize spectroscopic tissue analysis to quantify renal ischemia during hilar clamping and to compare tissue vascular hemoglobin oxygen saturation levels while clamping the main renal artery versus clamping segmental renal arteries using a laparoscopic porcine model. METHODS Institutional Animal Care and Use Committee approval was obtained. Spectroscopic renal ischemia was measured before, during and after laparoscopic hilar clamping of 8 Yorkshire swine renal units. Spectroscopic renal measurements (n=257) were obtained at baseline (prior to selective renal hilar clamping), every 30 seconds during warm ischemia (5 min trials) and for 10 minutes after unclamping. Times to 10% of max hemoglobin saturation after clamping were recorded as ischemic times, while times to 90% of max hemoglobin saturation after unclamping were recorded as reperfusion times. Trials clamping the main renal artery were compared to clamping a segmental renal artery. RESULTS When the main renal artery was clamped, the drop in tissue ischemia occurred faster than compared to segmental artery clamping (22.3 vs 45.5 sec). In addition, during segmental artery clamping, tissue spectrometry levels remained higher when the probe was placed in regions not perfused by the clamped segmental artery. Upon reperfusion, mean renal spectrometry saturation levels returned to baseline slower when the main renal artery was clamped compared to when only a segmental renal artery was clamped (53.8 vs 45.5 sec). CONCLUSIONS Tissue spectrometry demonstrated a reproducible measurement of the drop in tissue oxygen saturation during periods of renal ischemia in a porcine model. Spectrometric tissue analysis during main renal arterial clamping demonstrated more significant drops in tissue oxygen saturation and slower recovery of tissue ischemia when compared to clamping a segmental renal artery alone. Further studies correlating tissue spectrometry to renal function recovery following hilar clamping are underway. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e339-e340 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Philip Dorsey New Orleans, LA More articles by this author Quincy Brown New Orleans, LA More articles by this author Janet Colli New Orleans, LA More articles by this author Kate Elfer New Orleans, LA More articles by this author Theodore Saitz New Orleans, LA More articles by this author Ross McCaslin New Orleans, LA More articles by this author Liang Wang New Orleans, LA More articles by this author Benjamin Lee New Orleans, LA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...