Hepatic Oxygenation Changes and Symptomatic Intradialytic Hypotension.

INTRODUCTION: Clinical studies on differences among changes in cerebral and hepatic oxygenation during hemodialysis (HD) in patients with and without intradialytic hypotension (IDH) are limited. We investigated changes in intradialytic cerebral and hepatic oxygenation before systolic blood pressure (SBP) reached the nadir during HD and compared these differences between patients with and without symptomatic IDH. METHODS: We analyzed data from 109 patients with (n = 23) and without (n = 86) symptomatic IDH who were treated with HD. Cerebral and hepatic regional oxygen saturation (rSO2), as a marker of tissue oxygenation and circulation, was monitored during HD using an INVOS 5100c oxygen saturation monitor. Changes in cerebral or hepatic rSO2 when SBP reached the nadir during HD were compared between the groups of patients. RESULTS: The cerebral rSO2 before HD in patients with and without symptomatic IDH was 49.7 ± 11.2% and 51.3 ± 9.1% (p = 0.491). %Changes in cerebral rSO2 did not significantly differ between the two groups from 60 min before the SBP nadir during HD. Hepatic rSO2 before HD in patients with and without symptomatic IDH was 58.5 ± 15.4% and 57.8 ± 15.9% (p = 0.869). The %changes in hepatic rSO2 were significantly lower in patients with symptomatic IDH than in those without throughout the observational period (p < 0.001). We calculated the area under the receiver operating characteristic curve (AUC) and estimated cutoff values for changes in hepatic rSO2 as a symptomatic IDH predictor. The predictive ability at 5 and 40 min before symptomatic IDH onset was excellent, with AUCs and cutoff values of 0.847 and 0.841, and -10.9% and -5.0%, respectively. CONCLUSIONS: Hepatic oxygenation significantly decreased more in patients with symptomatic IDH before its onset, than in those without symptomatic IDH, whereas changes in cerebral oxygenation did not differ. Evaluating changes in hepatic oxygenation during HD might help to predict symptomatic IDH.

Use of a radiofrequency identification system for precise sublobar resection of small lung cancers.

BACKGROUND: The incidence of sublobar resection is increasing because of the rise in the detection of small lung cancers. However, local recurrence needs to be addressed, and several methods are needed for the resection with secure margins of non-visible and non-palpable tumors. METHODS: We retrospectively reviewed the use of a radiofrequency identification (RFID) system in sublobar resection of adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) at our institute. RESULTS: From June 2020 to June 2022, 39 patients underwent sublobar resection for AIS or MIA. The median age was 69 years (interquartile range, 64-76). Among the 39 patients, 24 were diagnosed with AIS and 15 with MIA. Segmentectomy, subsegmentectomy, and wedge resection were performed in nine, six, and 24 patients, respectively. The median size of the target tumor was 9.0 mm (8.1-12.9) and the median distance between the tag and the tumor was 2.9 mm (0-7.5). The median pathological surgical margin was 15.0 mm (10-17.5). Complete resection of all lesions was performed with a secure surgical margin. The median follow-up duration was 6 months, during which no local recurrence was detected in any of the patients. CONCLUSIONS: The RFID marking system accurately informed the surgeons of the tumor location and helped them to perform precise sublobar resection.

Resident CD34-positive cells contribute to peri-endothelial cells and vascular morphogenesis in salivary gland after irradiation.

Salivary gland (SG) hypofunction is a common post-radiotherapy complication. Besides the parenchymal damage after irradiation (IR), there are also effects on mesenchymal stem cells (MSCs) which were shown to contribute to regeneration and repair of damaged tissues by differentiating into stromal cell types or releasing vesicles and soluble factors supporting the healing processes. However, there are no adequate reports about their roles during SG damage and regeneration so far. Using an irradiated SG mouse model, we performed certain immunostainings on tissue sections of submandibular glands at different time points after IR. Immunostaining for CD31 revealed that already one day after IR, vascular impairment was induced at the level of capillaries. In addition, the expression of CD44-a marker of acinar cells-diminished gradually after IR and, by 20 weeks, almost disappeared. In contrast, the number of CD34-positive cells significantly increased 4 weeks after IR and some of the CD34-positive cells were found to reside within the adventitia of arteries and veins. Laser confocal microscopic analyses revealed an accumulation of CD34-positive cells within the area of damaged capillaries where they were in close contact to the CD31-positive endothelial cells. At 4 weeks after IR, a fraction of the CD34-positive cells underwent differentiation into α-SMA-positive cells, which suggests that they may contribute to regeneration of smooth muscle cells and/or pericytes covering the small vessels from the outside. In conclusion, SG-resident CD34-positive cells represent a population of progenitors that could contribute to new vessel formation and/or remodeling of the pre-existing vessels after IR and thus, might be an important player during SG tissue healing.

Changes in tissue oxygenation in response to sudden intradialytic hypotension.

A 76-year-old woman on hemodialysis (HD) for diabetic nephropathy was admitted to our hospital with occasional intradialytic hypotension (IDH). We continuously monitored the regional oxygen saturation (rSO2) in the brain, liver, and lower limb muscle during HD. The time course of changes in rSO2 ratios in each region was evaluated throughout HD. The rSO2 ratio was defined as the ratio of rSO2 value at t (min) during HD to the rSO2 value before HD. During the early phase of HD, blood pressure (BP) gradually decreased and both hepatic and lower limb muscle rSO2 ratios decreased with changes in BP, whereas the cerebral rSO2 ratio was relatively maintained. At around 90 min after HD initiation, the BP decreased to 71/46 mmHg (mean BP, 54 mmHg) and the previously maintained cerebral rSO2 ratio also suddenly decreased. Soon after the onset of IDH, ultrafiltration was stopped, normal saline was infused, and intravenous noradrenaline infusion was started. After the BP recovered, cerebral and hepatic rSO2 ratios improved, but the lower limb muscle rSO2 ratio remained low. After restarting ultrafiltration, improvement in the lower limb muscle rSO2 ratio was delayed, although cerebral and hepatic oxygenation were maintained. This observation aids in our understanding of the effect of IDH on regional tissue oxygenation.

Association between carnitine deficiency and the erythropoietin resistance index in patients undergoing peritoneal dialysis: a cross-sectional observational study.

Carnitine deficiency contributes to developing various pathological conditions, such as cardiac dysfunction, muscle weakness, and erythropoietin-resistant anemia in patients undergoing hemodialysis. However, a conclusion has not been reached concerning the prevalence and the effect of carnitine deficiency in patients undergoing peritoneal dialysis (PD). In this study, the prevalence of carnitine deficiency and the clinical factors associated with carnitine deficiency were investigated in 60 patients undergoing PD. The median age of the patients was 62.5 years (52.5-72.5 years), the proportion of male sex was 44/60 (73.3%), and the median PD period was 24 months (12-45 months). Carnitine deficiency (acyl carnitine/free carnitine ratio >0.4) was detected in 56/60 (93%) patients. Multiple regression analysis showed that the erythropoietin resistance index was independently associated with carnitine deficiency (ß = 0.283, p = 0.04). These results suggest that carnitine plays pivotal roles in hematogenesis in patients undergoing PD.

Successful treatment of cholesterol crystal embolism with anti-proprotein convertase subtilisin/kexin type 9 (PCSK9) antibody: a case report.

Background: We report a unique case of renal cholesterol crystal embolism (CCE) induced by carotid artery stenting that was successfully treated with evolocumab, a fully human monoclonal antibody against proprotein convertase subtilisin kexin type 9 (PCSK9).Case presentation: A 77-year-old man with hypertension, hyperlipidemia, and chronic kidney disease was referred to our department for decreased estimated glomerular filtration rate (eGFR)-from 32.0 to 13.9 mL/min/1.73 m2-5 weeks after carotid artery stenting. Further examination revealed livedo reticularis in the bilateral toes and eosinophilia (723/µL). Skin biopsy from livedo reticularis tissue in the bilateral toes showed cholesterol clefts in the small arteries. The patient was therefore diagnosed with CCE. After 25 weeks' administration of evolocumab at a dose of 140 mg subcutaneously administered every 2 weeks, his eGFR had improved from 10.7 to 18.1 mL/min/1.73 m2.Conclusion: Evolocumab may have a beneficial effect on renal involvement in patients with CCE.

Differences in cerebral and hepatic oxygenation in response to intradialytic blood transfusion in patients undergoing hemodialysis.

Hemodialysis (HD) patients frequently experience severe anemia, requiring intradialytic blood transfusion. Severe anemia leads to deterioration of systemic tissue oxygenation. However, few reports have examined the effect of intradialytic blood transfusion on tissue oxygenation changes. This study aimed to (i) monitor the differences in tissue oxygenation in the brain and liver during intradialytic blood transfusion, and (ii) elucidate the clinical factors affecting cerebral and hepatic oxygenation. Thirty-eight HD patients with severe anemia requiring intradialytic blood transfusion were included (27 men, 11 women; mean age, 70.2 ± 1.6 years). Cerebral and hepatic regional oxygen saturation (rSO2) values were monitored using near-infrared spectroscopy (INVOS 5100c oxygen saturation monitor). Cerebral and hepatic rSO2 were significantly higher after than before blood transfusion (p < 0.001, both). Furthermore, hepatic rSO2 was significantly higher than cerebral rSO2 after transfusion (p = 0.004). In multivariable linear regression analysis, cerebral rSO2 changes were independently associated with the natural logarithm of hemoglobin (Hb) ratio (Hb after/before transfusion) (standardized coefficient: 0.367, p = 0.023), whereas hepatic rSO2 changes were independently associated with the natural logarithm of [Hb ratio/colloid osmotic pressure ratio (colloid osmotic pressure after/before transfusion)] (standardized coefficient: 0.378, p = 0.019). In conclusion, throughout intradialytic blood transfusion, brain and liver tissue oxygenation improved. Hepatic rSO2 was significantly higher than cerebral rSO2 at the end of HD. Furthermore, cerebral oxygenation changes were associated with only transfusion-induced Hb increase, whereas hepatic oxygenation changes were associated with both transfusion-induced Hb increase (positive changes) and ultrafiltration-induced colloid osmotic pressure increase (negative changes).

Differences in tissue oxygenation and changes in total hemoglobin signal strength in the brain, liver, and lower-limb muscle during hemodialysis.

Near-infrared spectroscopy has been used to measure regional saturation of oxygen (rSO2) based on the total hemoglobin (t-Hb) signal strength. To date, few studies have investigated the changes of systemic oxygenation and t-Hb signal strength during hemodialysis (HD). This study aimed to (1) monitor rSO2 and t-Hb signal strength in the brain, liver, and lower-limb muscle during HD and (2) clarify the differences in rSO2 and t-Hb signal strength in each compartment. Fifty-three patients receiving 4-h HD were included and divided into three groups according to the compartments in which tissue oxygenation was measured as follows: brain (n = 44), liver (n = 42), and lower-limb muscle (n = 40). The rSO2 and t-Hb signal strength was monitored using an INVOS 5100c (Covidien Japan, Tokyo, Japan). The rSO2 levels were significantly lower in the brain than in the liver from HD initiation to the end (HD initiation: rSO2 in the brain and liver, 46.5 ± 1.3 and 52.4 ± 1.7%, respectively, p = 0.031). Furthermore, compared to the t-Hb signal strength ratio [value at t (min) during HD/initial value before HD] in the brain during HD, there were significant increases in the liver and lower-limb muscle, respectively. In conclusion, deterioration of cerebral oxygenation was remarkable compared to the hepatic oxygenation in HD patients. Our results, which revealed significant differences among the t-Hb signal strength ratios in the brain, liver, and lower-limb muscle during HD, might reflect the non-uniform body-fluid reduction within systemic tissues induced by ultrafiltration.

Preoperative detection of pleural adhesions by respiratory dynamic computed tomography.

BACKGROUND: Video-assisted thoracic surgery (VATS) plays an important role in thoracic surgery because it is less invasive. However, the existence of severe pleural adhesions may make VATS difficult and complicated. The aim of this study was to assess the utility of inspiration and expiration computed tomography (respiratory dynamic CT (RD-CT)) in evaluation of pleural adhesions preoperatively. METHODS: RD-CT was performed on 107 patients undergoing thoracotomies (both VATS and open). We assessed synchronous motion during respiration on RD-CT. Comparing the results of RD-CT and intraoperative findings, we assessed the utility of preoperative evaluation. RESULTS: A negative correlation between sliding score and adhesion grade was revealed. Sliding score in adhesion negative patients was significantly higher than that in adhesion positive patients (P < 0.0001). The sensitivity of RD-CT was 63.6%, specificity was 74.1%, and accuracy was 72%. Among 62 patients with a CT-Respiration Ratio of less than 0.65, the sensitivity of RD-CT was 77.8%, specificity was 86.8%, and accuracy was 85.5%. CONCLUSIONS: RD-CT may be clinically useful for detecting the presence of pleural adhesions. It can be adopted as one of the criteria for deciding the surgical approach.

Rib resection using a pneumatic high-speed power drill system for lung cancer with chest wall invasion: our clinical experience.

Rib resection for chest wall tumors, including lung cancer with chest wall invasion, is usually performed through open thoracotomy. Resection of part of the external rib cage requires an elongated or additional incision depending on the location and extension of the tumor, eventually becoming more invasive to patients. We recently introduced a technique of rib resection using a pneumatic high-speed power drill system known as "air tome". This novel technique is easy to perform through a small incision or even via video-assisted thoracoscopic surgery (VATS) in selected patients. We present our clinical experience and discuss the usefulness of this technique for rib resection in patients with lung cancer and chest wall invasion.

[A case of rapidly progressive glomerulonephritis exhibiting granulomatosis with polyangiitis (GPA) and extremely high level of PR3-ANCA with improvement of renal dysfunction after plasma exchange therapy].

A 68-year-old Japanese man was diagnosed with left otitis media with effusion and left uveitis more than 5 months before admission. He was urgently admitted to our hospital for progressive deterioration of his renal function [serum creatinine(Cr) 7.59 mg/dL] with proteinuria and urinary red blood cell casts, inflammation, and anemia. Additionally, his serum proteinase 3 antinuclear antibody (PR3-ANCA) level, determined by using the chemiluminescence enzyme immunoassay method, had increased to more than 3,500 U/mL. Hemodialysis (HD) was initiated on the third day after admission and renal biopsy was performed on the eighth day. The histological findings showed necrotic cellar crescents, hence, he was diagnosed as granulomatosis with polyangiitis on the basis of the clinical criteria. Methylprednisolone pulse therapy was administered from the 11th day. Thereafter, the administration of oral prednisolone (PSL) was started, and plasma exchange was initiated for the purpose of RP3-ANCA removal. In his clinical course, PSL was tapered as soon as possible because of the development of steroid psychosis, and we started intravenous cyclophosphamide on the 25th day instead of tapering the PSL. Subsequently, his renal function improved even without HD, and he was discharged on the 49th day. Although his PR3-ANCA level was still high after discharge, the administration of azathioprine led to a decrease in the PR-3 ANCA levels. About 2 years after discharge, the PR3-ANCA level decreased to 10.0 U/mL, and there has been no sign of GPA recurrence.

Growth Factor-Bearing Polymer Brushes--Versatile Bioactive Substrates Influencing Cell Response.

In this study we present the development of responsive nanoscale substrates exhibiting cell-guiding properties based on incorporated bioactive signaling cues. The investigative approach considered the effect of two different surface-bound growth factors (GFs) on cell behavior and response: hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF). Two surface biofunctionalization strategies were explored in order to conceive versatile, bioactive thin polymer brush films. Polymer brushes made of tethered poly(acrylic)acid (PAA) polymer layers with a high grafting density of polymer chains were biofunctionalized with GFs either by physisorption or chemisorption. Both GFs showed high binding efficiencies to PAA brushes based on their initial loading concentrations. The GF release kinetics can be distinguished depending on the applied biofunctionalization method. Specifically, a high initial burst followed by a constant slow release was observed in the case of both physisorbed HGF and bFGF. In contrast, the release kinetics of chemisorbed GFs were quite different. Remarkably, chemisorbed HGF remained bound to the brush surface for over 1 week, whereas 50% of chemisorbed bFGF was released slowly. Furthermore, the effect of these GF-biofunctionalized PAA brushes on different cells was investigated. A human hepatoma cell line (HepG2) was used to analyze the bioactivity of HGF-modified PAA brushes by measuring cell growth inhibition and scattering effects. Additionally, the differentiation of mouse embryonic stem cells (mESCs) toward endoderm was studied on bFGF-modified PAA brush surfaces. Finally, the results illustrate that PAA brushes, particularly those biofunctionalized with chemisorbed GFs, produce an expected measurable effect on both cell types. Therefore, PAA polymer brushes biofunctionalized with GFs can be used as bioactive cell culture substrates with tuned efficiency.

Effect of skin-transmitted vibration enhancement on vibrotactile perception.

Vibration on skin elicited by the mechanical interaction of touch between the skin and an object propagates to skin far from the point of contact. This paper investigates the effect of skin-transmitted vibration on vibrotactile perception. To enhance the transmission of high-frequency vibration on the skin, stiff tape was attached to the skin so that the tape covered the bottom surface of the index finger from the periphery of the distal interphalangeal joint to the metacarpophalangeal joint. Two psychophysical experiments with high-frequency vibrotactile stimuli of 250 Hz were conducted. In the psychophysical experiments, discrimination and detection thresholds were estimated and compared between conditions of the presence or the absence of the tape (normal bare finger). A method of limits was applied for the detection threshold estimation, and the discrimination task using a reference stimulus and six test stimuli with different amplitudes was applied for the discrimination threshold estimation. The stimulation was given to bare fingertips of participants. Result showed that the detection threshold was enhanced by attaching the tape, and the discrimination threshold enhancement by attaching the tape was confirmed for participants who have relatively large discrimination threshold under normal bare finger. Then, skin-transmitted vibration was measured with an accelerometer with the psychophysical experiments. Result showed that the skin-transmitted vibration when the tape was attached to the skin was larger than that when normal bare skin. There is a correlation between the increase in skin-transmitted vibration and the enhancement of the discrimination threshold.

Renoprotective effects of thiazides combined with loop diuretics in patients with type 2 diabetic kidney disease.

BACKGROUND/AIMS: Type 2 diabetic kidney disease (DKD) is frequently accompanied by uncontrollable hypertension due to the sodium sensitivity inherent in DKD and to diuretic-resistant edema. In general, diuretics are effective in treating this condition, but thiazide diuretics are thought to be innocuous in advanced chronic kidney disease (CKD). We examined the renoprotective effects of combination therapy with thiazides and loop diuretics in type 2 DKD patients with CKD stage G4 or G5. METHODS: This study included 11 patients with type 2 DKD and an estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m(2) who were suffering from severe edema even with loop diuretics. Each patient received additional hydrochlorothiazide (HCTZ) therapy, which was continued for more than 12 months. We examined clinical parameters including blood pressure (BP), proteinuria, and eGFR before and after the addition of HCTZ. RESULTS: Patients received a 13.6 ± 3.8 mg/day dose of HCTZ in addition to loop diuretics (azosemide: 120 mg/day in 6 cases, 60 mg/day in 3 cases and furosemide: 80 mg/day in 1 case, 120 mg/day in 1 case). Side effects of HCTZ were not observed in all patients. After the addition of HCTZ therapy, systolic and diastolic blood pressures (S-BP, D-BP) as well as proteinuria significantly decreased (S-BP: at 6 months, p < 0.05 and 12 months, p < 0.01 vs. 0 month, D-BP: at 12 months, p < 0.05 vs. 0 month, proteinuria: at 6 months, p < 0.05 and 12 months, p < 0.01 vs. 0 month). The annual decline in eGFR was not significantly different before and after HCTZ therapy (-7.7 ± 8.5 and -8.4 ± 4.8 mL/min/1.73 m(2)/year, respectively). CONCLUSION: Our findings suggest that the combination of HCTZ and loop diuretics improves BP levels, and decreases proteinuria even in advanced stage type 2 DKD patients with severe edema. The addition of HCTZ therapy was not found to negatively affect the change in eGFR in the present study.

Evaluation of cerebral oxygenation in patients undergoing long-term hemodialysis.

BACKGROUND/AIMS: Patients undergoing hemodialysis (HD) have higher occurrence rates of cerebral diseases, including uremic encephalopathy, cognitive impairment, dementia, and cerebrovascular disease, than the general population. During HD, ultrafiltration is performed to maintain an adequate fluid condition and is associated with subsequent blood volume (BV) reduction. We aimed to (1) monitor changes in cerebral oxygenation and BV reduction during HD, and (2) clarify the mechanism that influences cerebral oxygenation in HD patients. METHODS: Eighteen HD patients and 12 healthy controls were recruited. Regional saturation of oxygen (rSO2) was continuously monitored in the frontal cortex using INVOS 5100C before, during, and after HD, and in healthy controls. Relative change in BV (%ΔBV) was simultaneously monitored during HD using a BV monitor. RESULTS: Before HD, patients had significantly lower rSO2 values than controls (56.1 ± 1.4 vs. 70.4 ± 2.5%, p < 0.001). Although %ΔBV significantly decreased from 20 min to the end of HD (20 min: -3.3 ± 0.3%, p < 0.05; end of HD: -12.0 ± 1.0%, p < 0.01), changes in rSO2 values during HD were not significant. No relationship existed between rSO2 values and blood pressure levels, hemoglobin levels, oxygen pressure, HCO3(- ), oxygen saturation, and arterial O2 content before and after HD. Furthermore, changes in rSO2 were not correlated with changes in these parameters. CONCLUSION: rSO2 values before HD were significantly lower in HD patients than in healthy controls. rSO2 values were maintained during HD and were not influenced by BV reduction.

Heparinization of a biomimetic bone matrix: integration of heparin during matrix synthesis versus adsorptive post surface modification.

This study intended to evaluate a contemporary concept of scaffolding in bone tissue engineering in order to mimic functions of the extracellular matrix. The investigated approach considered the effect of the glycosaminoglycan heparin on structural and biological properties of a synthetic biomimetic bone graft material consisting of mineralized collagen. Two strategies for heparin functionalization were explored in order to receive a three-component bone substitute material. Heparin was either incorporated during matrix synthesis by mixing with collagen prior to simultaneous fibril reassembly and mineralization (in situ) or added to the matrix after fabrication (a posteriori). Both methods resulted in an incorporation of comparable amounts of heparin, though its distribution in the matrix varied as indicated by TOF-SIMS analyses, and a similar modulation of their protein binding properties. Differential scanning calorimetry revealed that the thermal stability and thereby the degree of crosslinking of the heparinized matrices was increased. However, in contrast to the a posteriori modification, the in situ integration of heparin led to considerable changes of morphology and composition of the matrix: a more open network of collagen fibers yielding a more porous surface and a reduced mineral content were observed. Cell culture experiments with human mesenchymal stem cells (hMSC) revealed a strong influence of the mode of heparin functionalization on cellular processes, as demonstrated for proliferation and osteogenic differentiation of hMSC. Our results indicate that not only heparin per se but also the way of its incorporation into a collagenous matrix determines the cell response. In conclusion, the a posteriori modification was beneficial to support adhesion, proliferation and differentiation of hMSC.

Factors related to post-thoracotomy pain following robotic-assisted thoracic surgery.

BACKGROUND: Robotic-assisted thoracic surgery (RATS) is a minimally invasive procedure; however, some patients experience persistent postoperative pain. This study aimed to investigate factors related to postoperative pain following RATS. METHODS: The data of 145 patients with lung cancer, who underwent RATS with a four-port (one in the sixth intercostal space [ICS] and three in the eighth ICS) lobectomy or segmentectomy between May 2019 and December 2022, were retrospectively analyzed. Factors associated with analgesic use for at least 2 months following postoperative pain (PTP group) were analyzed. RESULTS: Patients who underwent preoperative pain control for any condition or chest wall resection were excluded. Among the 138 patients, 45 (32.6%) received analgesics for at least 2 months after surgery. Patient height and transverse length of the thorax correlated with PTP in the univariate analysis (non-PTP vs. PTP; height, 166 vs. 160 cm; p < .001; transverse length of the thorax, 270 vs. 260 mm, p = .016). In the multivariate analysis, height was correlated with PTP (p = .009; odds ratio, 0.907; 95% confidence interval, 0.843-0.976). Height correlated with the transverse length of the thorax (r = .407), anteroposterior length of the thorax (r = .294), and width of the eighth ICS in the middle axillary line (r = .210) using Pearson's correlation coefficients. When utilizing a 165-cm cutoff value for height to predict PTP using receiver operating characteristic curve analysis, the area under the curve was 0.69 (95% confidence interval, 0.601-0.779). CONCLUSION: Short stature is associated with a high risk of postoperative pain following RATS.

Effects to cerebral oxygenation by arteriovenous fistula creation in patients with chronic kidney disease.

BACKGROUND: Vascular access, including arteriovenous fistula (AVF), is essential in patients undergoing hemodialysis (HD). However, the presence of AVF is non-physiological in humans and could pose a burden to the systemic circulation or tissue microcirculation, potentially affecting tissue oxygenation, including in the brain. Recently, near-infrared spectroscopy has been used to measure regional oxygen saturation (rSO2) as a marker of cerebral oxygenation in various settings, including in patients undergoing HD. Thus far, no studies have reported changes in cerebral rSO2 before and after AVF creation. This study aimed to monitor the differences in cerebral oxygenation before and after AVF creation and to clarify the clinical factors affecting the changes in cerebral rSO2. METHODS: Forty-eight patients (34 men, 14 women) with chronic kidney disease (CKD) who were not undergoing dialysis and newly created AVF were recruited. Cerebral rSO2 values before and after AVF creation were evaluated using near-infrared spectroscopy (INVOS 5100c). RESULTS: Cerebral rSO2 values were significantly changed from 60.3% ± 7.5% to 58.4% ± 6.8% before and after AVF creation in all patients (p < 0.001). Cerebral rSO2 were also lower in patients with diabetes mellitus (DM) than in those without DM (57.5 ± 7.1 vs 63.7 ± 6.5, p = 0.003) before surgery; however, no differences of changes in cerebral rSO2 were observed between the two groups after AVF creation. Additionally, multivariate regression analysis identified changes in HR (standardized coefficient: 0.436) as independent factors associated with changes in cerebral rSO2. CONCLUSION: Surgically created AVF was associated with the deterioration of cerebral rSO2 in patients with CKD not undergoing dialysis. Notably, AVF could cause cerebral hypoxia, and thus further studies are needed to clarify the clinical factors influencing changes in cerebral oxygenation after AVF creation.

Differences between Hepatic and Cerebral Regional Tissue Oxygen Saturation at the Onset of Intradialytic Hypotension.

BACKGROUND: Intradialytic hypotension (IDH) is a critical pathological condition associated with all-cause mortality in patients undergoing hemodialysis (HD). However, few studies have investigated IDH-related changes in hepatic and cerebral regional tissue oxygen saturation (rSO2). This study investigated IDH-induced changes in hepatic and cerebral rSO2. METHODS: Hepatic and cerebral rSO2 during HD were measured using an INVOS 5100C oxygen saturation monitor, and their percentage (%) changes during the development of IDH were analyzed. Ninety-one patients undergoing HD were investigated, including twenty with IDH. RESULTS: In patients with IDH, % changes in hepatic and cerebral rSO2 decreased at the onset of IDH. Additionally, the % change in hepatic rSO2 was significantly larger than that in cerebral rSO2 (p < 0.001). In patients without IDH, no significant differences were found between the % changes in hepatic and cerebral rSO2 at the time of the lowest systolic blood pressure during HD. Multivariable linear regression analysis showed that the difference between the % changes in cerebral and hepatic rSO2 was significantly associated with the development of IDH (p < 0.001) and the ultrafiltration rate (p = 0.010). CONCLUSIONS: Hepatic and cerebral rSO2 significantly decreased during the development of IDH, and hepatic rSO2 was more significantly decreased than cerebral rSO2 at the onset of IDH.