Associations of cerebral oxygenation with hemoglobin levels evaluated by near-infrared spectroscopy in hemodialysis patients

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 of cerebral oxygen saturation in dialysis patients: a comparison of three principals of near infrared spectroscopy

PURPOSE

It has been reported that cerebral oxygen saturation (rSO2) measured by near infrared spectroscopy is low in dialysis patients. We compared the rSO2 values of dialysis patients before living donor kidney transplantation and their donors as controls by using three spectroscopes that utilize different principals, the INVOS 5100C (spatially resolved spectroscopy), FORE-SIGHT ELITE (modified Beer-Lambert law) and tNIRS-1 (time-resolved spectroscopy).

METHODS

Before induction of anesthesia, the sensors of one of the three spectroscopes were placed on the forehead and rSO2 values were recorded followed by the same measurement using the other two spectroscopes. The primary objective was to compare the rSO2 values of the dialysis patients and controls using the three spectroscopes by the unpaired t test. Then we compared the rSO2 values among the spectroscopes in both dialysis patients and controls by one-way ANOVA. Finally, we examined the relations between the rSO2 values and the physiological values by using the Pearson correlation coefficient.

RESULTS

Fifteen pairs of dialysis patients and controls were studied. With the INVOS 5100 C, the values of the dialysis patients (59.7 ± 9.7% (mean ± standard deviation) were 13% lower than those of the controls (73.3 ± 6.9%) (P < 0.01). With the tNIRS-1, the values were 57.8 ± 4.8% in the dialysis patients and 63.3 ± 3.5% in the controls (P < 0.01). Almost no differences were observed with the FORE-SIGHT ELITE (71.6 ± 4.9% [dialysis patients] vs. 70.8 ± 4.3% [Controls]) (P = 0.62). Among the spectroscopes, the values were significantly different in both dialysis patients and controls. For the INVOS 5100C and tNIRS-1, correlation coefficients between rSO2 values and blood Hb and serum Alb were more than 0.5.

CONCLUSIONS

The rSO2 values for comparisons between the dialysis patients and the controls were different according to differences of the principles of the near infrared spectroscopes. In the INVOS 5100C and tNIRS-1, rSO2 values may be related to blood Hb and serum Alb.

Effects of percutaneous transluminal angioplasty and associated factors in access hand oxygenation in patients undergoing hemodialysis

In hemodialysis (HD) patients with arteriovenous fistula (AVF), changes in systemic or peripheral tissue circulation occur non-physiologically via the presence of AVF; however, associations between blood flow and tissue oxygenation in the brain and access hand are uncertain. In this study, 85 HD patients with AVF were included and evaluated for changes in flow volume (FV) and regional oxygen saturation (rSO₂) in the brain and hands with AVF before and after percutaneous transluminal angioplasty (PTA). Furthermore, we evaluated the factors that determine access hand rSO₂ without stenosis after PTA. Brachial arterial FV increased after PTA (p < 0.001), and carotid FV decreased (p = 0.008). Access hand rSO₂ significantly decreased after PTA (p < 0.001), but cerebral rSO₂ did not significantly change (p = 0.317). In multivariable linear regression analysis of factors associated with access hand rSO₂, serum creatinine (standardized coefficient: 0.296) and hemoglobin (standardized coefficient: 0.249) were extracted as independent factors for access hand rSO₂. In conclusion, a decrease in access hand oxygenation and maintenance of cerebral oxygenation were observed throughout PTA. To maintain access hand oxygenation, it is important to adequately manage Hb level and maintain muscle mass, in addition to having an AVF with appropriate blood flow.

Associations among preoperative transthoracic echocardiography variables and cerebral near-infrared spectroscopy values at baseline before anesthesia in patients undergoing cardiac surgery: a retrospective observational study

Cerebral tissue oximetry with near-infrared spectroscopy (NIRS) is used to monitor cerebral oxygenation during cardiac surgery. To date, reduced baseline cerebral NIRS values have been attributed to reduced cerebral blood flow primarily based on a significant positive correlation between left ventricular ejection fraction (LVEF) and baseline rSO₂ measured with the INVOS 5100C oximeter. Reportedly, however, rSO₂, but not StO₂ measured with the FORESIGHT Elite oximeter, correlated with LVEF. We, thus, investigated associations among baseline NIRS values measured with three different oximeters before anesthesia for cardiac surgery and preoperative transthoracic echocardiography (TTE) variables, including LVEF, to examine whether there are inter-device differences in associations among baseline NIRS values and TTE variables. Using Spearman's correlation coefficient, we retrospectively investigated associations among 15 preoperative TTE variables, including LVEF, and baseline NIRS values, including rSO₂, StO₂, and TOI with the NIRO-200NX oximeter in 1346, 515, and 301 patients, respectively. Only rSO₂ (p < 0.00001), but not TOI or StO₂ (p > 0.05), positively correlated with LVEF. On the other hand, baseline rSO₂, TOI, and StO₂ consistently, negatively correlated with the left atrial diameter index (LADI), early diastolic transmitral flow velocity (E), E-to-early diastolic mitral annular velocity ratio (E/e'), estimated right ventricular systolic pressure (eRVP), and inferior vena cava diameter index (IVCDI) (p < 0.0005 to p < 0.00001). Because all of these five TTE variables could be positively associated with right as well as left ventricular filling pressure, our results indicated that reduced baseline NIRS values were consistently associated not with reduced LVEF but with TTE findings indicative of elevated biventricular filling pressure. Our data suggest that regional venous congestion greatly contributes to reduced baseline NIRS values in patients undergoing cardiac surgery.

Cerebral oxygenation changes in response to post-hemodialysis standing

Few reports have examined the association between changes in cerebral oxygenation and clinical factors, including blood pressure (BP), upon standing after hemodialysis (HD). This study aimed to clarify the factors affecting the changes in cerebral regional oxygen saturation (rSO₂) upon standing after HD and monitor the differences in cerebral rSO₂ changes that occur upon standing after HD in patients with and without diabetes mellitus (DM). Changes in mean BP and cerebral rSO₂ were tracked in 43 HD patients during 120 s of standing after HD using an INVOS 5100c oxygen saturation monitor. The post-HD cerebral rSO₂ at rest was 55.8 ± 10.2%, while that at 120 s of standing decreased to 51.9 ± 9.6%; therefore, the percentage change in cerebral rSO₂ at 120 s of standing was - 6.8 ± 6.4%, which was significantly lower than before HD (p < 0.001). This change was significantly correlated with the presence of DM, HD duration, mean BP at 120 s of standing, and percentage change in mean BP at 120 s of standing. A multivariable linear regression analysis showed that percentage change in cerebral rSO₂ at 120 s of standing was independently associated with the percentage change in mean BP at 120 s of standing (standardized coefficient: 0.432; p = 0.004). Furthermore, there were significant decreases in percentage changes in cerebral rSO₂ throughout the standing period in HD patients with versus without DM. Therefore, cerebral oxygenation deterioration upon standing after HD should receive attention, particularly in HD patients with DM.

Cerebral oxygenation and body mass index association with cognitive function in chronic kidney disease patients without dialysis: a longitudinal study

In chronic kidney disease (CKD) patients, the prevalence of cognitive impairment increases with CKD progression; however, longitudinal changes in cognitive performance remain controversial. Few reports have examined the association of cerebral oxygenation with cognitive function in longitudinal studies. In this study, 68 CKD patients were included. Cerebral regional oxygen saturation (rSO₂) was monitored. Cognitive function was evaluated using mini-mental state examination (MMSE) score. Clinical assessments were performed at study initiation and 1 year later. MMSE score was higher at second measurement than at study initiation (p = 0.022). Multivariable linear regression analysis showed that changes in MMSE were independently associated with changes in body mass index (BMI, standardized coefficient: 0.260) and cerebral rSO₂ (standardized coefficient: 0.345). This was based on clinical factors with p < 0.05 (changes in BMI, cerebral rSO₂, and serum albumin level) and the following confounding factors: changes in estimated glomerular filtration rate, hemoglobin level, proteinuria, salt and energy intake, age, presence of diabetes mellitus, history of comorbid cerebrovascular disease, and use of renin–angiotensin system blocker. Further studies with a larger sample size and longer observational period are needed to clarify whether maintaining BMI and cerebral oxygenation improve or prevent the deterioration of cognitive function.

Cerebral oxygen saturation as outcome predictor after transfemoral transcatheter aortic valve implantation

Background

Cerebral oxygen saturation (ScO₂) can be measured non-invasively by near-infrared spectroscopy (NIRS) and correlates with cerebral perfusion. We investigated cerebral saturation during transfemoral transcatheter aortic valve implantation (TAVI) and its impact on outcome.

Methods and results

Cerebral oxygenation was measured continuously by NIRS in 173 analgo-sedated patients during transfemoral TAVI (female 47%, mean age 81 years) with self-expanding (39%) and balloon-expanding valves (61%). We investigated the periprocedural dynamics of cerebral oxygenation. Mean ScO₂ at baseline without oxygen supply was 60%. During rapid ventricular pacing, ScO₂ dropped significantly (before 64% vs. after 55%, p < 0.001). ScO₂ at baseline correlated positively with baseline left-ventricular ejection fraction (0.230, p < 0.006) and hemoglobin (0.327, p < 0.001), and inversely with EuroSCORE-II ( − 0.285, p < 0.001) and length of in-hospital stay ( − 0.229, p < 0.01). Patients with ScO2 < 56% despite oxygen supply at baseline had impaired 1 year survival (log-rank test p < 0.01) and prolonged in-hospital stay (p = 0.03). Furthermore, baseline ScO₂ was found to be a predictor for 1 year survival independent of age and sex (multivariable adjusted Cox regression, p = 0.020, hazard ratio (HR 0.94, 95% CI 0.90–0.99) and independent of overall perioperative risk estimated by EuroSCORE-II and hemoglobin (p = 0.03, HR 0.95, 95% CI 0.91–0.99).

Conclusions

Low baseline ScO₂ not responding to oxygen supply might act as a surrogate for impaired cardiopulmonary function and is associated with worse 1 year survival and prolonged in-hospital stay after transfemoral TAVI. ScO₂ monitoring is an easy to implement diagnostic tool to screen patients at risk with a potential preserved recovery and worse outcome after TAVI.

Graphical abstract

Clinical factors affecting cerebral oxygenation in patients undergoing peritoneal dialysis

BACKGROUND

Although cerebral regional oxygen saturation (rSO₂) is significantly lower in hemodialysis (HD) patients than that in healthy controls, investigations on cerebral oxygenation in peritoneal dialysis (PD) patients are limited. We aimed to confirm the cerebral oxygenation status and identify the factors affecting cerebral rSO₂ in PD patients.

METHODS

Thirty-six PD patients (21 men and 15 women; mean age, 62.8 ± 12.7 years) were recruited. In addition, 27 healthy volunteers (17 men and 10 women; mean age, 43.5 ± 18.8 years) were recruited as a control group. Cerebral rSO₂ was monitored at the forehead using an INVOS 5100c oxygen saturation monitor.

RESULTS

Cerebral rSO₂ was significantly lower in PD patients than that in healthy controls (57.0 ± 7.3% vs 68.9 ± 8.6%, p < 0.001); moreover, cerebral rSO₂ was significantly correlated with natural logarithm (Ln)-PD duration (r = -0.389, p = 0.019) and serum albumin concentration (r = 0.370, p = 0.026) in a simple linear regression analysis. Multivariable linear regression analysis was performed using variables that showed a significant correlation and p < 0.20 (serum creatinine, serum sodium, Ln-C-reactive protein, and dosage of erythropoiesis-stimulating agent) with the cerebral rSO₂. Cerebral rSO₂ was independently associated with Ln-PD duration (standardized coefficient: -0.339) and serum albumin concentration (standardized coefficient: 0.316).

CONCLUSIONS

Cerebral rSO₂ was significantly affected by the PD duration and serum albumin concentration. Further prospective studies are needed to clarify whether preventing a decrease in serum albumin concentration leads to the maintenance of cerebral oxygenation in patients undergoing PD.

Association between Cerebral Oxygenation, as Evaluated with Near-Infrared Spectroscopy, and Cognitive Function in Patients Undergoing Hemodialysis

INTRODUCTION

The prevalence of cognitive impairment in patients undergoing hemodialysis (HD) is higher than that in healthy controls. To date, studies on the association between cognitive function and cerebral oxygenation in these patients are limited. Therefore, in this study, we aimed to cross-sectionally investigate the association between cognitive assessment scores and clinical factors, including cerebral oxygenation, in patients undergoing HD.

METHODS

In this observational study, 193 HD patients were included. Cerebral regional oxygen saturation (rSO2) was monitored using an INVOS 5,100c oxygen saturation monitor. Poor cognition was defined as a Mini-Mental State Examination (MMSE) score ≤23. We analyzed the association between MMSE score and clinical factors, including cerebral rSO2.

RESULTS

MMSE score in HD patients included in this study was 26.8 ± 3.3. There were 164 patients (85%) with MMSE score ≥24 and 29 patients (15%) with an MMSE score ≤23. In the patients with MMSE score ≥24, cerebral rSO2 (53.8% ± 8.3%) was significantly higher than that in patients with MMSE score ≤23 (49.5% ± 9.8%; p = 0.013). Multivariable linear regression analysis was performed using the following confounding factors: age, mean blood pressure, cerebral rSO2, HD duration, ultrafiltration rate, hemoglobin, serum Cr, serum calcium, serum phosphate, total cholesterol, high-density lipoprotein cholesterol levels, serum albumin, presence of diabetes mellitus or chronic glomerulonephritis, history of comorbid cardiovascular or cerebrovascular disease, and use of renin-angiotensin-aldosterone system inhibitors or vitamin D analogs. MMSE score was independently and significantly associated with age (standardized coefficient: -0.244) and cerebral rSO2 (standardized coefficient: 0.180).

CONCLUSIONS

MMSE score was independently associated with age (negative effect) and cerebral rSO2 (positive effect) in this cross-sectional study. Further prospective studies are needed to clarify whether maintaining cerebral oxygenation prevents the deterioration of cognitive function in patients undergoing HD.

Difference in Cerebral and Hepatic Oxygenation in Response to Ultrafiltration in a Hemodialysis Patient With Congestive Heart Failure

Near-infrared spectroscopy has been used to measure regional oxygen saturation (rSO₂), and intradialytic tissue rSO₂ measurements have been playing an important role in evaluating changes in tissue oxygenation in various clinical settings of hemodialysis (HD) therapy.However, few reports have described changes in hepatic oxygenation associated with body fluid management in overhydrated HD patients. We herein report an HD patient with congestive heart failure (CHF) that had improved systemic and tissue oxygenation, including in the brain and liver, during HD with ultrafiltration. A 73-year-old man undergoing HD was admitted to our hospital with CHF. After admission, HD with ultrafiltration was performed to adequately manage his body fluid excess. Because of deterioration of systemic oxygenation on admission, we monitored his percutaneous arterial oxygen saturation (SpO₂) using a pulse oximeter and regional oxygen saturation (rSO₂) in the brain and liver using an INVOS 5100c oxygen saturation monitor during HD. At HD initiation, his cerebral and hepatic rSO₂ levels were relatively low, at 43.2% and 34.1%, respectively, in addition to the SpO₂ of 88%. During HD with ultrafiltration, systemic oxygenation evaluated by SpO₂ and tissue oxygenation by cerebral and hepatic rSO₂ improved. Interestingly, the hepatic rSO₂ ratio, defined as the ratio of rSO₂ values at t (min) during HD and the initial rSO₂ value before HD, increased larger than the cerebral rSO₂ ratio during HD. After the adjustment of body fluid condition under the maintained SpO₂ values, we confirmed the hepatic and cerebral SO₂ ratio again during HD, and these two values changed nearly in the same manner. Throughout our experience, in this case, we confirmed a remarkable increase in hepatic rSO₂ ratio relative to cerebral rSO₂ ratio under a CHF status during HD, and these differences disappeared after the adjustment of the body fluid status.