Non-occlusive mesenteric ischemia in chronically dialyzed patients: a disease with multiple risk factors

Preoperative risk factors for 90-day postoperative mortality outcome in patients with non-occlusive mesenteric ischemia

PURPOSE

The mortality rate for non-occlusive mesenteric ischemia remains high even after patients survive the acute postoperative period with tremendous treatment efforts, including emergency surgery, which is challenging. The aim of this study was to explore the preoperative risk factors for 90-day postoperative mortality in patients with non-occlusive mesenteric ischemia.

METHODS

This single-center, retrospective cohort study included patients diagnosed with non-occlusive mesenteric ischemia who underwent emergency surgery between August 2014 and January 2023. All patients were divided into survival-to-discharge and mortality outcome groups at the 90-day postoperative follow-up. Preoperative factors, including comorbidities, preoperative status of vital signs and consciousness, blood gas analysis, blood test results, and computed tomography, were compared between the two groups.

RESULTS

Twenty patients were eligible, and 90-day mortality was observed in 10 patients (50%). The mortality outcome group had significantly lower HCO3- (20.9 vs. 14.6, p = 0.006) and higher lactate (4.4 vs. 9.4, p = 0.023) levels than did the survival outcome group. The median postoperative time to death was 19 [2-69] days, and five patients (50%) died after postoperative day 30, mainly because hemodialysis was discontinued because of hemodynamic instability in patients requiring hemodialysis.

CONCLUSION

Low preoperative HCO3- and high lactate levels may be preoperative risk factors for 90-day postoperative mortality in patients with non-occlusive mesenteric ischemia. However, patients on hemodialysis die from discontinuing hemodialysis even after surviving the acute postoperative phase. Therefore, indications for emergency surgery in patients with risk factors for postoperative mortality should be carefully determined.

Early endovascular approaches for treating acute mesenteric arterial occlusive disease in hemodialysis patients

BACKGROUND

Among hemodialysis patients, acute superior mesenteric artery (SMA) thrombosis a condition with a high mortality rate. Very few larger case series have been reported.

METHOD

We reviewed eight hemodialysis patients with diabetes mellitus and SMA thrombosis managed with endovascular therapy in our institution. Demographic, clinical, and radiological data were described. The patency of the SMA was assessed by computed tomography angiography (CTA) at one month after the endovascular procedure. At the last visit, clinical symptoms and check of mortality were recorded.

RESULTS

Multidetector CTA scan revealed severe stenosis of SMA in 6 patients and SMA occlusion in the other two patients. The severe stenosis of SMA were verified by angiography. Balloon angioplasty without stenting was performed to obtain satisfactory patency of SMA. Seven of eight patients achieved resolution of abdominal pain after the endovascular procedure. One patient died of suspected intestinal necrosis after 6 days of balloon angioplasty. All seven surviving patients did not experience a recurrence of symptoms with a median follow-up of 2 years. No significant residual stenotic or occlusive lesions were noted in follow-up CTA at one month after the endovascular procedure.

CONCLUSION

SMA thrombosis should be systematically suspected in hemodialysis patients experiencing abdominal pain. Prompt diagnosis of SMA thrombosis as soon as possible and early endovascular therapy are required to obtain a favorable prognosis in the hemodialysis patient with SMA thrombosis.

Construction of an Early Alert System for Intradialytic Hypotension before Initiating Hemodialysis Based on Machine Learning

Introduction

Intradialytic hypotension (IDH) is prevalent and associated with high hospitalization and mortality rates. The purpose of this study was to explore the risk factors for IDH and use artificial intelligence to establish an early alert system before hemodialysis sessions to identify patients at high risk of IDH.

Materials and Methods

We obtained data on 314,534 hemodialysis sessions conducted at Sichuan Provincial People's Hospital from the renal disease treatment information system. IDH was defined as a systolic blood pressure drop ≥20 mm Hg, a mean arterial pressure drop ≥10 mm Hg during dialysis, or the occurrence of clinical hypotensive events requiring nursing intervention. After pre-processing, the data were randomly divided into training (80%) and testing (20%) sets. Four interpolation methods, three feature selection methods, and 18 machine learning algorithms were used to construct predictive models. The area under the receiver operating characteristic curve (AUC) was the main indicator for evaluating the performance of the models, while Shapley Additive ExPlanation was used to explain the contribution of each variable to the best predictive model.

Results

A total of 3,906 patients and 314,534 dialysis sessions were included, of which 142,237 cases showed IDH (incidence rate, 45.2%). Nineteen parameters were identified through artificial intelligence feature screening. They included age, pre-dialysis weight, dry weight, pre-dialysis blood pressure, heart rate, prescribed ultrafiltration, blood cell counts (neutrophil, lymphocyte, monocyte, eosinophil, lymphocyte, and platelet counts), hematocrit, serum calcium, creatinine, urea, glucose, and uric acid. Random forest, gradient boosting, and logistic regression were the three best models, and the AUCs were 0.812 (95% confidence interval [CI], 0.811-0.813), 0.748 (95% CI, 0.747-0.749), and 0.743 (95% CI, 0.742-0.744), respectively.

Conclusion

Our dialysis software-based artificial intelligence alert system can be used to predict IDH occurrence, enabling the initiation of relevant interventions.

Intradialytic hypotension prediction using covariance matrix-driven whale optimizer with orthogonal structure-assisted extreme learning machine

Intradialytic hypotension (IDH) is an adverse event occurred during hemodialysis (HD) sessions with high morbidity and mortality. The key to preventing IDH is predicting its pre-dialysis and administering a proper ultrafiltration prescription. For this purpose, this paper builds a prediction model (bCOWOA-KELM) to predict IDH using indices of blood routine tests. In the study, the orthogonal learning mechanism is applied to the first half of the WOA to improve the search speed and accuracy. The covariance matrix is applied to the second half of the WOA to enhance the ability to get out of local optimum and convergence accuracy. Combining the above two improvement methods, this paper proposes a novel improvement variant (COWOA) for the first time. More, the core of bCOWOA-KELM is that the binary COWOA is utilized to improve the performance of the KELM. In order to verify the comprehensive performance of the study, the paper sets four types of comparison experiments for COWOA based on 30 benchmark functions and a series of prediction experiments for bCOWOA-KELM based on six public datasets and the HD dataset. Finally, the results of the experiments are analyzed separately in this paper. The results of the comparison experiments prove fully that the COWOA is superior to other famous methods. More importantly, the bCOWOA performs better than its peers in feature selection and its accuracy is 92.41%. In addition, bCOWOA improves the accuracy by 0.32% over the second-ranked bSCA and by 3.63% over the worst-ranked bGWO. Therefore, the proposed model can be used for IDH prediction with future applications.

Identifying survival protective factors for chronic dialysis patients with surgically confirmed acute mesenteric ischemia

BACKGROUND

Mesenteric ischemia is significantly more common in end-stage kidney disease patients undergoing chronic dialysis than in the general population and is associated with high morbidity and mortality. However, reports on prognostic factors in this population are limited.

AIM

To elucidate the in-hospital outcomes of acute mesenteric ischemia in chronic dialysis patients and to analyze protective factors for survival.

METHODS

The case data of 426 chronic dialysis patients who were hospitalized in a tertiary medical center for acute mesenteric ischemia over a 14-year period were retrospectively reviewed. Of these cases, 103 were surgically confirmed, and the patients were enrolled in this study. A Cox regression analysis was used to evaluate the protective factors for survival.

RESULTS

The in-hospital mortality rate among the 103 enrolled patients was 46.6%. Univariate analysis was performed to compare factors in survivors and nonsurvivors, with better in-hospital outcomes associated with a surgery delay (defined as the time from onset of signs and symptoms to operation) < 4.5 d, no shock, a higher potassium level on day 1 of hospitalization, no resection of the colon, and a total bowel resection length < 110 cm. After 1 wk of hospitalization, patients with lower white blood cell count and neutrophil counts, higher lymphocyte counts, and lower C-reactive protein levels had better in-hospital outcomes. Following multivariate adjustment, a higher potassium level on day 1 of hospitalization (HR 1.71, 95%CI 1.19 to 2.46; P = 0.004), a lower neutrophil count (HR 0.91, 95%CI 0.84 to 0.99; P = 0.037) at 1 wk after admission, resection not involving the colon (HR 2.70, 95%CI 1.05 to 7.14; P = 0.039), and a total bowel resection length < 110 cm (HR 4.55, 95%CI 1.43 to 14.29; P = 0.010) were significantly associated with survival.

CONCLUSION

A surgery delay < 4.5 d, no shock, no resection of the colon, and a total bowel resection length < 110 cm predicted better outcomes in chronic dialysis patients with acute mesenteric ischemia.

Hepatic portal vein gas detected by point of care ultrasound

Introduction

Portal venous gas is a rare finding in adults and is typically associated with underlying intestinal ischemia. Portal venous gas can be detected by a bedside point of care ultrasound (POCUS) examination in adult patients in critical care units (CCU). Findings include echogenic bubbles flowing centrifugally throughout the portal venous system.

Case presentation

We present the case of a 73-year-old female with advanced ischemic cardiomyopathy and cardiorenal syndrome who was managed in the CCU. She developed vague abdominal pain and respiratory depression requiring intubation and dialysis during her course of treatment in the CCU. Her findings were consistent with portal venous gas upon POCUS, prompting computed tomography of her abdomen and surgical consultation. She was ultimately found to have nonobstructive mesenteric ischemia.

Clinical discussion

PVG is an ominous radiological sign and reflects intestinal ischemia in up to 72% of cases. Acute mesenteric ischemia of the small bowel could be due to occlusive or nonocclusive obstruction of the arterial blood supply or obstruction of venous outflow. Nonocclusive obstruction accounts for 5% to 15% of patients with acute mesenteric ischemia.

Conclusion

With the increasing use of POCUS, critical care physicians should be aware of findings consistent with portal venous gas as a bedside tool for directing the treating physician toward an ominous diagnosis in patients with shock.

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Portal vein gas detected by point-of-care ultrasound in situations of unidentified shock indicates a high likelihood of underlying intestinal ischemia.

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Point-of-care ultrasound plays an important role in detecting the sources of surgical emergencies.

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Nonobstructive mesenteric ischemia can present with nonspecific symptoms in critically ill patients, leading to a delay in diagnosis.

An update review of intradialytic hypotension: concept, risk factors, clinical implications and management

Intradialytic hypotension (IDH) is a frequent and serious complication of chronic haemodialysis, linked to adverse long-term outcomes including increased cardiovascular and all-cause mortality. IDH is the end result of the interaction between ultrafiltration rate (UFR), cardiac output and arteriolar tone. Thus excessive ultrafiltration may decrease the cardiac output, especially when compensatory mechanisms (heart rate, myocardial contractility, vascular tone and splanchnic flow shifts) fail to be optimally recruited. The repeated disruption of end-organ perfusion in IDH may lead to various adverse clinical outcomes affecting the heart, central nervous system, kidney and gastrointestinal system. Potential interventions to decrease the incidence or severity of IDH include optimization of the dialysis prescription (cool dialysate, UFR, sodium profiling and high-flux haemofiltration), interventions during the dialysis session (midodrine, mannitol, food intake, intradialytic exercise and intermittent pneumatic compression of the lower limbs) and interventions in the interdialysis period (lower interdialytic weight gain and blood pressure–lowering drugs). However, the evidence base for many of these interventions is thin and optimal prevention and management of IDH awaits further clinical investigation. Developing a consensus definition of IDH will facilitate clinical research. We review the most recent findings on risk factors, pathophysiology and management of IDH and, based on this, we call for a new consensus definition of IDH based on clinical outcomes and define a roadmap for IDH research.

Nonocclusive Mesenteric Ischemia: A Lethal Complication in Peritoneal Dialysis Patients

Nonocclusive mesenteric ischemia (NOMI) is a relatively uncommon disorder, seen primarily in elderly patients with cardiac disease, and is characterized by progressive intestinal ischemia leading to infarction, sepsis, and death. It is suspected of being the underlying cause in at least 20% – 30% of acute mesenteric ischemia patients.

End-stage renal disease patients are among the highest risk populations for developing this lethal complication; however, NOMI is not unique to hemodialysis and can occur in peritoneal dialysis patients as well. Unfortunately, the presentation of NOMI is very similar to that of peritonitis. The key to correct diagnosis is a high index of suspicion in predisposed patients. The high mortality rate is a clear reflection of failure to recognize the syndrome at an earlier, treatable stage.

We present our case experience and an extensive review of the literature regarding this dreadful complication that may be reversible if considered early as a possible etiology and the appropriate diagnostic maneuvers undertaken.

The Relationship between Intradialytic Hypotension and Hospitalized Mesenteric Ischemia: A Case-Control Study

BACKGROUND AND OBJECTIVES

Mesenteric ischemia is a rare but devastating condition caused by insufficient blood supply to meet the demands of intestinal metabolism. In patients with ESKD, it can be difficult to diagnose and has a >70% mortality rate. Patients on hemodialysis have a high prevalence of predisposing conditions for mesenteric ischemia, but the contribution of intradialytic hypotension, a potential modifiable risk factor, has not been well described.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used data from the US Renal Data System to identify 626 patients on hemodialysis with a hospitalized mesenteric ischemia event (cases). We selected 2428 controls in up to a 1:4 ratio matched by age, sex, black race, incident dialysis year, diabetes mellitus, coronary artery disease, and peripheral artery disease. We used six different definitions of intradialytic hypotension on the basis of prior studies, and categorized patients as having had intradialytic hypotension if ≥30% of hemodialysis sessions in the 30 days before the event met the specified definition.

RESULTS

The proportion of patients with intradialytic hypotension varied depending on its definition: from 19% to 92% of cases and 11% to 94% of controls. Cases had a higher adjusted odds (1.82; 95% confidence interval, 1.47 to 2.26) of having had intradialytic hypotension in the preceding 30 days than controls when using nadir-based intradialytic hypotension definitions such as nadir systolic BP <90 mm Hg. To examine a potential dose-response association of intradialytic hypotension with hospitalized mesenteric ischemia, we categorized patients by the proportion of hemodialysis sessions having intradialytic hypotension, defined using the Nadir90 definition (0%, 1%-9%, 10%-29%, 30%-49%, and ≥50%), and found a direct association of proportion of intradialytic hypotension with hospitalized mesenteric ischemia (P-trend<0.001).

CONCLUSIONS

Patients with hospitalized mesenteric ischemia had significantly higher odds of having had intradialytic hypotension in the preceding 30 days than controls, as defined by nadir-based definitions.

Occurrence and severity of non-occlusive mesenteric ischemia (NOMI) after cardiovascular surgery correlate with preoperatively assessed FGF-23 levels

Purpose

To evaluate the value of preoperatively assessed fibroblast growth factor 23 (FGF-23) levels and to correlate FGF-23 with angiographic findings in non-occlusive mesenteric (NOMI) ischemia using a standardized scoring system.

Materials and methods

Between 2/2011 and 3/2012 a total of 865 patients (median age: 67 years) underwent cardiovascular surgery during this ethics committee approved, prospective study. 65 of these patients had clinical suspicion of NOMI and consequently underwent catheter angiography of the superior mesenteric artery. Images were assessed using a standardized reporting system (Homburg-NOMI-Score). These data were correlated to following preoperative parameters of kidney function: cystatin C, creatinine, FGF-23 and estimated glomerular filtration rate (eGFR), and outcome data (death, acute renal failure) using linear and logistic regressions, as well as nonparametric tests.

Results

Significant correlations were found between FGF-23 and the angiographic appearance of NOMI (p = 0.03). Linear regression analysis showed no significant correlation to the severity of NOMI with creatinine (p = 0.273), cystatin C (p = 0.484), cystatin C eGFR (p = 0.914) and creatinine eGFR (p = 0.380). Logistic regression revealed a significant correlation between death and the Homburg-NOMI-Score (p<0.001), but not between development of NOMI and acute renal failure (p = 0.122). The ROC Analysis yielded an area under the curve of 0.695 (95% CI: 0.627–0.763) with a sensitivity of 0.672 and specificity of 0.658.

Conclusions

FGF-23 significantly correlates with the severity of NOMI, which is in contrast to other renal function parameters. The applied scoring system allows to predict mortality in NOMI patients.

Usefulness of intraoperative observation using a fluorescence imaging instrument for patients with nonocclusive mesenteric ischemia

The authors evaluated the usefulness of intraoperative photodynamic eye (PDE) observation in patients with nonocclusive mesenteric ischemia (NOMI). Between February 2012 and July 2013, 6 patients who had undergone emergency surgery for NOMI were enrolled. Intraoperative PDE observation was performed to decide the adequate length of bowel resection including all skipped dark spots, which could not be detected as ongoing mucosal ischemic changes under visible light observation. All ongoing mucosal ischemic changes were easily detected as dark spots using PDE observation in all 6 patients. The mean length of adequate ileal resection (92 ± 48 cm) was significantly longer than that of ischemic ileum (85 ± 50 cm) (mean ± SD) (P = 0.043). After resection of an adequate length of bowel, all the patients had a good course until discharge without incidents due to residual bowel ischemia, except for 1patient who died. PDE observation is useful for deciding the adequate length of bowel to resect, including ongoing mucosal ischemic changes that cannot be detected under visible light observation. In patients with NOMI, resection of an adequate length of bowel is necessary to prevent postoperative incidents due to residual bowel ischemia.

Cooling dialysate during in-center hemodialysis: Beneficial and deleterious effects

The use of cooled dialysate temperatures first came about in the early 1980s as a way to curb the incidence of intradialytic hypotension (IDH). IDH was then, and it remains today, the most common complication affecting chronic hemodialysis patients. It decreases quality of life on dialysis and is an independent risk factor for mortality. Cooling dialysate was first employed as a technique to incite peripheral vasoconstriction on dialysis and in turn reduce the incidence of intradialytic hypotension. Although it has become a common practice amongst in-center hemodialysis units, cooled dialysate results in up to 70% of patients feeling cold while on dialysis and some even experience shivering. Over the years, various studies have been performed to evaluate the safety and efficacy of cooled dialysate in comparison to a standard, more thermoneutral dialysate temperature of 37 °C. Although these studies are limited by small sample size, they are promising in many aspects. They demonstrated that cooled dialysis is safe and equally efficacious as thermoneutral dialysis. Although patients report feeling cold on dialysis, they also report increased energy and an improvement in their overall health following cooled dialysis. They established that cooling dialysate temperatures improves hemodynamic tolerability during and after hemodialysis, even in patients prone to IDH, and does so without adversely affecting dialysis adequacy. Cooled dialysis also reduces the incidence of IDH and has a protective effect over major organs including the heart and brain. Finally, it is an inexpensive measure that decreases economic burden by reducing necessary nursing intervention for issues that arise on hemodialysis such as IDH. Before cooled dialysate becomes standard of care for patients on chronic hemodialysis, larger studies with longer follow-up periods will need to take place to confirm the encouraging outcomes mentioned here.

Improvements in Pneumatosis Cystoides Intestinalis and Hepatic Portal Venous Gas with Conservative Therapy in a Patient on Maintenance Dialysis

A 77-year-old man on maintenance dialysis developed hypotension, nausea and abdominal pain one hour after beginning to undergo hemodialysis. Abdominal computed tomography (CT) showed gas shadows in the intrahepatic portal vein and the small intestinal wall, but no signs indicating intestinal necrosis. Three days later, the gas shadows on abdominal CT disappeared by conservative therapy. In cases with both pneumatosis cystoides intestinalis and hepatic portal venous gas, intestinal necrosis should therefore be suspected and surgical therapy should also be considered, particularly in hemodialysis patients with a risk of intestinal ischemia. However, conservative therapy may be an option in cases with no intestinal necrosis.

Refractory Abdominal Pain in a Hemodialysis Patient

Nonocclusive mesenteric ischemia (NOMI) is a rare disorder. Failure of an early diagnosis may cause progressive intestinal ischemia, leading to abdominal pain, sepsis, and death. Patients with end-stage renal disease are among the highest risk populations for developing this lethal complication. The key to a correct diagnosis at an early stage is a high index of suspicion in predisposed patients. In our case, we present a 62-year-old female undergoing maintenance hemodialysis for 8 years; she complained of abdominal pain after hemodialysis in the last 3 months; NOMI was suspected after a CT angiography. She partially recovered after multiple clinical interventions such as decreased ultrafiltration, an increased dose of low molecular-weight heparin and the use of vasoactive drugs. In conclusion, NOMI can be reversible if it is diagnosed as early as possible and after the necessary diagnostic measurements are initiated.

Elevated endothelin-1 level is a risk factor for nonocclusive mesenteric ischemia

OBJECTIVE

Nonocclusive mesenteric ischemia may occur after cardiac surgery, commonly in conjunction with the use of cardiopulmonary bypass. Some evidence suggests that endothelin-1 serum levels are increased in patients with mesenteric ischemia, but the association of endothelin-1 and nonocclusive mesenteric ischemia has not been studied. The objective was to investigate whether elevated levels of endothelin-1 could be found in patients exhibiting nonocclusive mesenteric ischemia.

METHODS

In an observational cohort study, nonocclusive mesenteric ischemia developed in 78 of 865 patients undergoing elective cardiac surgery. Control patients were identified from the cohort through 1:1 propensity score matching. Preoperative and postoperative endothelin-1 serum levels were determined by means of enzyme-linked immunosorbent assay. Odds ratios (with 95% confidence interval) were calculated by logistic regression analyses to determine the risk of endothelin-1 for the development of nonocclusive mesenteric ischemia.

RESULTS

Patients with nonocclusive mesenteric ischemia had higher preoperative (11.3 vs 9.3 pg/mL; P = .001) and postoperative (15.7 vs 11.1 pg/mL, P < .001) levels of endothelin-1 than the controls. The probability of developing nonocclusive mesenteric ischemia increased with each picogram/milliliter endothelin-1 level preoperatively (odds ratio, 1.29; 95% confidence interval, 1.12-1.49) and each picogram/milliliter postoperatively (odds ratio, 2.04; 95% confidence interval, 1.54-2.72). Receiver operating characteristic analyses showed that elevated endothelin-1 serum levels had a high accuracy to predict nonocclusive mesenteric ischemia (optimal cutoff value of 14.5 pg/mL, area under the curve of 0.77, sensitivity 51%, and specificity 94%).

CONCLUSIONS

Endothelin-1 seems to predispose patients undergoing cardiac surgery to develop nonocclusive mesenteric ischemia. In addition, it may be a useful marker to identify patients at risk for nonocclusive mesenteric ischemia after cardiac surgery.

The very old on hemodialysis: 8 years' experience in a single unit

BACKGROUND

Elderly patients constitute a significant proportion of chronically dialyzed patients. This study evaluated mortality rates and predictors of mortality among very old patients receiving chronic hemodialysis (HDx).

METHODS

A single-center retrospective analysis was carried out on patients >84 years of age who started chronic dialysis between 2004 and 2012. Univariate and multivariate analyses determined which parameters predicted survival.

RESULTS

Twenty-nine hemodialyzed patients (19 males) were studied. Mean age was 88 ± 3 years. Median survival time was 38 months (range 4-96). One-year and 2-year survival probability was 80 and 65%, respectively. The most common cause of death was complicated peripheral vascular disease. Multivariate analysis revealed the following: for each 1 g/dl decrease in serum albumin level, the hazard ratio for patient death was 2.63 (p = 0.017), and for each weekly HDx treatment time decrease of 1 h, the hazard ratio for patient death was 1.40 (p = 0.006).

CONCLUSION

Very elderly patients can be hemodialyzed with cautious optimism.

A scoring-system for angiographic findings in nonocclusive mesenteric ischemia (NOMI): correlation with clinical risk factors and its predictive value

PURPOSE

This study was designed to evaluate the clinical value of a standardized angiographic scoring system in patients with nonocclusive mesenteric ischemia (NOMI).

METHODS

Sixty-three consecutive patients (mean age: 73 ± 8 years) with suspect of NOMI after cardiac or major thoracic vessel surgery underwent catheter angiography of the superior mesenteric artery. Images were assessed by two experienced radiologists on consensus basis using a scoring system consisting of five categories, namely vessel morphology, reflux of contrast medium into the aorta, contrasting and distension of the intestine, as well as the time to portal vein filling. These were correlated to previously published risk factors of NOMI and outcome data.

RESULTS

The most significant correlation was found between the vessel morphology and death (p < 0.001) as well as reflux of contrast medium into the aorta and death (p = 0.005). Significant correlation was found between delayed portal vein filling and preoperative statin administration (p = 0.011), previous stroke (p = 0.033), and renal insufficiency (p = 0.043). Reflux of contrast medium correlated significantly with serum lactate >10 mmol/L (p = 0.046). The overall angiographic score correlated with death (p = 0.017) and renal insufficiency (p = 0.02). The ROC-analysis revealed that a score of ≥3.5 allows for identifying patients with increased perioperative mortality with a sensitivity of 85.7 % and a specificity of 49 %. With the use of a simplified score (vessel morphology, reflux of contrast medium into the aorta, and time to portal vein filling), specificity was increased to 71.4 %.

CONCLUSIONS

The applied scoring system allows standardized interpretation of angiographic findings in NOMI patients. Beyond that the score seems to correlate well with risk factors of NOMI and outcome.

Volume estimation in dialysis patients: the concordance of brain-type natriuretic peptide measurements and bioimpedance values

Correct estimation of the dialysis patients' hydration status remains an important clinical challenge. Bioimpedance measurements have been validated by various physiological tests, and the use of brain-type natriuretic peptide (BNP) has been validated by inferior vena cava diameter measurements. This is an observational cohort study that evaluated the correspondence between bioimpedance-measured overhydration percentage (OH%) and BNP. We measured predialysis OH% by bioimpedance apparatus (Body Composition Monitor) and BNP by microparticle enzyme-linked immunoassay in 41 prevalent stable hemodialysis patients, 19 (46%) women, aged 58.9 ± 14.5 years. The cohort's average BNP was 2694 ± 3278 pg/mL and 10 (24.4%) of these 41 patients had BNP < 500 pg/mL (average 260.7 ± 108.5). The OH% was 8.5 ± 7.0% among those with a BNP < 500 pg/mL, while the rest of the population had an OH% of 21.4 ± 8.0%, corresponding to excess volumes of 1.6 ± 1.3 and 4.4 ± 3.8 L, respectively. The OH% vs. BNP relationship was best described by the exponential regression of y = 216.4e(0.097x) , predicting a BNP of 216.4 pg/mL at 0% overhydration status (r 0.61). Receiver-operating curves revealed an area under the curve of 0.885 for BNP when the OH% was set ≥15% of overhydration and an area under the curve of 0.918 for OH% when the BNP was set ≥500 pg/mL for being abnormal. We conclude that in our cohort there was a high degree of correspondence between these two tests with an exponential relationship between the measurements.

Detection of patients at high risk for non-occlusive mesenteric ischemia in hemodialysis

BACKGROUND

Nonocclusive mesenteric ischemia (NOMI) is an emerging condition in hemodialysis (HD) patients not widely studied.

MATERIALS AND METHODS

A retrospective study was conducted between 2003 and 2011. NOMI cases were recorded, and demographic, clinical, biochemical, and HD parameters were collected. This group was compared with a control group (n = 93). Risk factors, prognosis, and survival were analyzed.

RESULTS

There were 57 episodes of NOMI (incidence, 2.29 episodes per 100 patients/y). Cecum was the most frequently affected segment. Nineteen patients (33%) underwent surgery. Twenty-six patients (59%) did not survive the acute episode. Cecal damage was the only protective factor associated with mortality (relative risk [RR], 0.712; P = 0.044). The incidence of NOMI was related to erythropoietin resistance index, diabetes mellitus, and longer time on HD compared with control group (RR, 6.92, P = 0.009; RR, 9.98, P = 0.005; and RR, 1.017, P < 0.001, respectively). Mortality in survival NOMI patients was higher at 4-y follow-up compared with that in the control group (log-rank, 15.5; P < 0.0001).

CONCLUSIONS

NOMI is associated with erythropoietin resistance index, diabetes mellitus, and longer time on HD. Hypotension must be avoided in these high-risk patients to prevent NOMI.

Lower gastrointestinal bleeding in chronic hemodialysis patients

Gastrointestinal (GI) bleeding is more common in patients with chronic kidney disease and is associated with higher mortality than in the general population. Blood losses in this patient population can be quite severe at times and it is important to differentiate anemia of chronic diseases from anemia due to GI bleeding. We review the literature on common causes of lower gastrointestinal bleeding (LGI) in chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. We suggest an approach to diagnosis and management of this problem.

[Mesenteric ischemia following a left radical nephrectomy]

The nephrectomy of a dialyzed renal insufficient patient is a frequent operation. Nevertheless, the vascular complication risks are increased for these patients. We report the case of a patient who had presented a mesenteric ischemia after a left nephrectomy. The cause of this ischemia was plurifactorial with, on one hand, a splanchnic hypoperfusion due to post-procedure hypovolemia caused by an important depletion during the dialysis as well as the use of vasoactive amines and, on the other hand, the peripheral mesenteric microvascularisation occlusion due to a kayexalate crystal deposit.

Gastrointestinal disorders and renal failure: exploring the connection

Gastrointestinal complications are known to commonly occur in patients with renal failure. Uremia and dialysis have long been speculated to increase the risk of lesions in the gastrointestinal tract and accessory organs. In addition, gastrointestinal procedures such as gastrointestinal bypass surgery and the administration of colonoscopy preparations can lead to the development of renal complications. Results from studies that have attempted to define the association between renal dysfunction and gastrointestinal complications are, however, conflicting and limited by small and varied sample populations. No clear management guidelines currently exist for many of the gastrointestinal problems that accompany renal failure. This Review examines the existing data on gastrointestinal complications in patients with chronic kidney disease and end-stage renal disease and aims to outline the etiology and management of common gastrointestinal disorders in such patients.

Baroreflex sensitivity and sympatho-vagal balance during intradialytic hypotensive episodes

OBJECTIVES

The role of the baroreflex function in the pathogenesis of hemodialysis-associated hypotension is controversial. Complex demodulation technique (CDM), providing continuous assessment of the amplitude of cardiovascular oscillation over time, is particularly suitable to assess dynamic changes in autonomic nervous system and baroreceptor sensitivity (BRS) during dialysis. In the present study, CDM was used to determine the effects of dialysis treatment on BRS and to characterize BRS changes during acute intradialytic hypotension.

METHODS

Continuous beat-to-beat blood pressure and interbeat intervals (IBIs) were monitored in 93 chronic patients without (n = 70) and with (n = 26) hypotension during 96 dialysis sessions. The amplitudes of SBP and DBP, IBIs, and BRS change in the low-frequency (around center frequency of 0.09 Hz) and high-frequency (around center frequency of 0.30 Hz) ranges were followed during the whole dialysis session.

RESULTS

Hemodialysis treatment was associated with increased low-frequency BRS, especially in sessions without hypotension. Hypotensive episodes were associated with significant increases in both low-frequency BRS and high-frequency BRS, mainly in patients with severe hypotension. The magnitude of the increase in baroreflex indices was proportional to the decrease in blood pressure. Low-frequency IBI/high-frequency IBI ratio, a marker of sympatho-vagal balance, did not significantly change during hypotension.

CONCLUSION

Our study shows that the baroreflex mechanism is preserved and adequately activated during intradialytic hypotension. Other factors, such as ischemic heart disease, left ventricular dysfunction, and inadequate arteriolar tone, rather than failure of baroreflex function, are more likely to be responsible for dialysis-induced hypotension.

Fulminant nonocclusive mesenteric ischemia just after hip arthroplasty

Nonocclusive mesenteric ischemia (NOMI) is not a rare clinical entity in intensive medicine, and it can be a consequence of several clinical or surgical situations. This pathology results from reduced intestinal microvascular blood supply associated with an acute inflammatory process, culminating with bowel necrosis. This is a case on a female patient who developed immediate postsurgical NOMI following hip arthroplasty and died. Since diagnosis of this potentially fatal condition remains a dilemma, NOMI should always be considered an eventual postoperative complication in high-risk surgical patients such as elderly individuals with previous history of nicotine abuse, congestive heart failure, and essential hypertension. The present paper highlights the importance of early diagnosis and prompt adequate treatment of NOMI in subjects with diminished cardiac output and severe abdominal pain.

Acute non-occlusive mesenteric ischemia of the small bowel in a patient started on hemodialysis: a case report

BACKGROUND

Non-occlusive mesenteric ischemia is not uncommon in chronic hemodialysis patients and is the major cause of an acute abdomen in this population. Intensive ultrafiltration and intradialytic hypotension are usually the precipitation factors. A definite diagnosis is usually late and associated with high mortality. We present a rare case of a patient who developed abdominal symptoms during his first week on HD without having obvious hypotensive episodes.

CASE PRESENTATION

A 76-year-old man was admitted with pulmonary edema and renal failure developed abdominal symptoms during his first week on hemodialysis without having obvious hypotensive episodes. Abdominal diagnostic procedures were all unrevealing. Mesenteric ischemia was diagnosed during laparoscopy done on the basis of physical findings and clinical suspicion. Ischemic small bowel of the distal ileum was resected and histopathology examination of the small bowel demonstrated transmural ischemic necrosis with hemorrhages and non-occluded mesenteric artery. Patient maid a steady recovery, and was discharged on the 11th post-operative day.

CONCLUSION

Mesenteric ischemia should be systematically suspected in dialysis patients experiencing even mild and nonspecific abdominal symptoms with or without hemodialysis-induced hypotensive episodes. Identification of patients at risk and prevention of intradialytic hypotension may help to reduce the incidence of this potentially fatal complication in hemodialysis patients.

Amplification of atherosclerotic calcification and Mönckeberg's sclerosis: a spectrum of the same disease process

Autopsy studies have shown the near universal presence of fatty streaks and fibroatheromas in the general population from which chronic kidney disease (CKD) patients arise. The vast majority of CKD patients have multiple conventional cardiovascular risk factors. Atherosclerosis, once present, can predominantly manifest as medial calcification, which has been previously termed Mönckeberg's sclerosis. This term has also been used in rare cases to describe vascular calcinosis not related to CKD. This clarification is critical to advance the field in terms of pathological diagnosis and treatment of CKD bone and mineral disorder. Factors that appear to promote the osteoblastic transformation of vascular smooth muscle cells and enhance deposition of calcium hydroxyapatite crystals include phosphorus activation of the Pit-1 receptor, bone morphogenic proteins 2 and 4, leptin, endogenous 1,25 dihydroxy vitamin D, vascular calcification activating factor, and measures of oxidative stress. These entities work to accelerate the atherosclerotic process in CKD patients and may be future targets for diagnosis and treatment. Although conventional atherosclerotic risk factors should be optimally managed, it should be noted that trials of hydroxymethylglutaryl-CoA reductase inhibitors have failed to attenuate the rate of progressive vascular calcification as measured by computed tomography scans.

Accelerated atherosclerotic calcification and Monckeberg's sclerosis: a continuum of advanced vascular pathology in chronic kidney disease

Autopsy studies have demonstrated the near universal presence of fatty streaks and fibroatheromas in the general population from which patients with chronic kidney disease (CKD) arise. The vast majority of patients with CKD have multiple conventional cardiovascular risk factors. Vascular atherosclerotic calcification develops in most patients as they transition from the general population to significant CKD as part of cholesterol crystallization within atherosclerotic lesions. Once present, however, atherosclerotic medial calcification can become prominent and has been previously identified as Mönckeberg's sclerosis. A unifying concept supported by the preponderance of pathologic evidence contends that Mönckeberg's sclerosis is a manifestation of accelerated atherosclerosis in patients with CKD. The term has also been used in rare cases to describe vascular calcinosis not related to CKD. This clarification is critical to advance the field in terms of pathologic diagnosis and treatment of CKD bone and mineral disorder. Factors that seem to promote the osteoblastic transformation of vascular smooth muscle cells and enhance deposition of calcium hydroxyapatite crystals include phosphorus activation of the Pit-1 receptor, bone morphogenic proteins 2 and 4, leptin, endogenous 1,25 dihydroxyvitamin D, vascular calcification activating factor, and measures of oxidative stress. These entities work to accelerate the atherosclerotic process in patients with CKD and may be future targets for diagnosis and treatment because randomized trials with hydroxymethylglutaryl-CoA reductase inhibitors have failed to attenuate the rate of progressive vascular calcification.

Can we predict the development of ischemic colitis among patients with lower abdominal pain?

PURPOSE

This study was performed to find clinical risk factors for developing ischemic colitis in patients experiencing lower abdominal discomfort with or without bloody diarrhea.

METHODS

A total of 467 patients who underwent sigmoidoscopy or colonoscopy because of lower abdominal discomforts with or without blood in stool were consecutively enrolled; 147 patients were diagnosed endoscopically and histologically as having ischemic colitis. The control group was composed of the remaining 320 patients with nonspecific endoscopic/histologic findings. Clinical variables were compared between the ischemic colitis group and the control group.

RESULTS

After excluding 67 patients in the ischemic colitis group, we compared the remaining 80 patients to the control group, using various clinical parameters. According to the logistic regression analysis, six factors were significantly related to ischemic colitis: older than aged 60 years (adjusted odds ratio, 5.7; 95 percent confidence interval: 2.6-11.7), hemodialysis (5; 1.2-21.6), hypertension (4.9; 2.3-10.5), hypoalbuminemia (3.5; 1.8-6.7), diabetes mellitus (3.4; 1.3-8.8), and constipation-inducing medications (2.8; 1.1-7.1). Through our analysis, we were able to predict the development of ischemic colitis for the patients with 0, 1, 2, 3, or 4+ risk factors: 8, 21, 55, 79, and 100 percent, respectively.

CONCLUSIONS

Old age, hemodialysis, hypertension, diabetes mellitus, hypoalbuminemia, and constipation-inducing medications are clinically important risk factors for ischemic colitis in patients experiencing lower abdominal discomfort with or without bloody stool. By considering these factors, we were able to predict with high accuracy the development of ischemic colitis.