The effect of uremia on platelet contractile force, clot elastic modulus and bleeding time in hemodialysis patients

The in-vitro influence of urea concentration on thromboelastrography in patients with and without end stage renal disease

BACKGROUND

End stage renal disease (ESRD) is associated with platelet dysfunction but also thromboembolic complications. The specific role of increased blood urea nitrogen (BUN) on coagulation is unclear. We aimed to characterize thromboelastography (TEG) parameters from males and females with ESRD and normal kidney function and evaluate if exogenous urea in vitro reproduced those TEG differences.

METHODS

We collected blood samples from 20 living kidney donors and 20 kidney recipients. TEG was performed without and with two increasing urea concentrations in vitro. TEG parameters were compared between recipients and donors.

RESULTS

Blood from kidney recipients showed baseline increased maximum amplitude (MA) and shortened time to maximum amplitude (TMA) compared to donors. These differences were not confirmed in females. In all patients, BUN was inversely correlated with TMA (r = -0.342; p = 0.031). In males, BUN and creatinine concentrations showed a direct correlation with MA (0.583; p = 0.007) and an inverse correlation with TMA (r = -0.520; p = 0.019). Urea in vitro decreased R-time (p = 0.005) and increased LY30 (p = 0.009) in donors but not recipients.

CONCLUSIONS

ESRD is associated with increased MA and decreased TMA on TEG. No change in MA was observed with increasing urea concentrations in vitro. Gender-specific variability in TEG parameters were observed.

Metabolic dysfunction-associated fatty liver disease (MAFLD) and advanced liver fibrosis among hemodialysis patients in a multiethnic urban population in Malaysia

BACKGROUND

Metabolic-dysfunction-associated fatty liver disease (MAFLD) and end stage kidney disease (ESKD) are complications of the metabolic syndrome. Our aim is to study the prevalence of MAFLD and advanced liver fibrosis and the associated factors among hemodialysis patients in a multiracial urban population in Malaysia.

METHODS

A cross-sectional study of hemodialysis patients from 10 hemodialysis centers was used. FibroTouch examination was performed on all patients. Fatty liver was diagnosed based on ultrasound attenuation parameter ≥248 dB/m while advanced liver fibrosis was diagnosed based on liver stiffness measurement ≥10 kPa.

RESULTS

This study included 447 hemodialysis patients (median age 59 [50-67], male 55%, Chinese 61%, Malay 20%, Indian 18%). Dialysis vintage was 49 (22-93) months. The prevalence of MAFLD was 43.4%. Independent factors associated with MAFLD were elevated waist circumference (aOR = 10.1, 95% CI = 5.3-19.4, p < 0.001), normal platelet count (aOR = 3.1, 95% CI = 1.3-7.3, p < 0.05), low HDL cholesterol (aOR = 2.3, 95% CI = 1.3-4.2, p < 0.01), elevated fasting blood sugar (aOR = 2.3, 95% CI = 1.3-3.8, p < 0.01), elevated hsCRP (aOR = 2.2, 95% CI = 1.2-4.0, p < 0.01), and advanced liver fibrosis (aOR = 3.0, 95% CI = 1.6-5.6, p < 0.001). The prevalence of advanced liver fibrosis was 25.5%. Independent factors associated with advanced liver fibrosis were male gender (aOR = 1.8, 95% CI = 1.0-3.0, p < 0.05), elevated waist circumference (aOR = 2.0, 95% CI = 1.0-4.0, p < 0.05), low platelet count (aOR = 5.4, 95% CI = 2.7-11.0, p < 0.001), elevated GGT (aOR = 5.0, 95% CI = 2.9-8.8, p < 0.001), and MAFLD (aOR = 3.2, 95% CI = 1.7-5.9, p < 0.001).

CONCLUSION

A high prevalence of MAFLD and advanced liver fibrosis was observed among hemodialysis patients. Nephrologists should consider a more proactive approach in diagnosing MAFLD and/or advanced liver fibrosis in hemodialysis patients.

Complications related to dental extractions in patients with chronic kidney failure undergoing hemodialysis: a pilot study

OBJECTIVE

To clinically assess socket healing after tooth extraction and the occurrence of intra- and postoperative complications in patients with chronic kidney failure (CKF) receiving hemodialysis (HD) by comparing them with a control group.

STUDY DESIGN

This prospective study involved 48 patients with CKF receiving HD (study group [SG]) and 29 participants without CKF (control group [CG]) undergoing tooth extractions. No prophylactic antibiotic was administered to the participants. One calibrated dentist evaluated all individuals at 3, 7, 21, and 60 days after the tooth extractions and assessed hemostasis time, occurrence of local or distant infection, epithelialization, and deposition of alveolar bone.

RESULTS

In the SG, 87 teeth were extracted through 65 interventions, and in the CG, 76 teeth were extracted through 36 interventions. Bleeding beyond 30 minutes was observed in 12 interventions (18.5%) in SG participants and was controlled with local hemostatic agents. Neither group had individuals presenting with postoperative infectious complications at the surgical site or at a distance. After 21 days, we observed delayed epithelialization in 29.9% (26 of 87) of the individuals in the SG compared with 3.9% (3 of 37) of those in the CG (P < .001). After 60 days, all the sockets were epithelialized and showing radiographic signs of alveolar bone neoformation.

CONCLUSIONS

Individuals with CKF receiving hemodialysis tend to heal well after dental extractions. They did not have an increased risk of infectious complications after simple tooth extractions, but they showed prolonged bleeding events more often than control subjects. Additional research studies using larger sample sizes of patients with CKF receiving hemodialysis are needed to confirm our findings.

Evaluation of platelet function in cats with and without kidney disease: a pilot study

OBJECTIVES

The aims of this study were to determine if stable chronic kidney disease (CKD) cats and uremic crisis cats have altered platelet function, and to determine the prevalence of positive fecal occult blood in CKD cats.

METHODS

Platelet function in normal cats, clinically stable International Renal Interest Society (IRIS) stage 2-4 CKD cats and CKD cats experiencing a uremic crisis were evaluated using impedance aggregometry. Area under the curve (AUC) at 6 mins was calculated for saline, adenosine diphosphate (AUCADP) and arachidonic acid (AUCASPI). The AUC in addition to hematocrit, platelet count and mean platelet volume (MPV) were compared between groups using the Kruskal-Wallis test followed by Dunn's post-hoc analysis. Guaiac fecal occult blood tests were performed on fecal samples and results were compared between groups using a χ2 for trend test.

RESULTS

AUCADP (P = 0.04) and AUCASPI (P = 0.05) were significantly higher in uremic crisis cats compared with normal cats at 6 mins. Hematocrit was significantly higher in normal cats when compared with IRIS stage 3 and 4 (P = 0.002) and uremic crisis (P = 0.0008) cats, with no difference among groups for platelet count or MPV. The proportion of cats with positive fecal occult blood samples was significantly different between groups (P = 0.0017); 50% uremic crisis cats, 33% IRIS stage 3 and 4 cats, and 10% IRIS stage 2 cats were positive, while no normal cats were positive. The proportion of cats with platelet clumping was significantly different between groups (P = 0.03).

CONCLUSIONS AND RELEVANCE

Platelet hyper-reactivity may be occurring in CKD cats experiencing a uremic crisis. The etiology of positive fecal occult blood samples in CKD cats is unclear and did not appear to be related to decreased platelet function as measured in this study and requires further investigation.

A case-control study indicates that coagulation imbalance is associated with arteriosclerosis and markers of endothelial dysfunction in kidney failure

Endothelial dysfunction, one of many causes of arterial changes in end-stage kidney disease (kidney failure), is a likely link between early vascular aging and the risk of thrombosis or bleeding in this condition. To evaluate this, we compared links between arterial stiffness and endothelial/coagulation factors in 55 patients receiving hemodialysis therapy and 57 age-/sex-matched control individuals. Arterial stiffness was assessed from carotid-femoral pulse wave velocity, and coagulation status from the endogenous thrombin generating potential. Markers of endothelial dysfunction (von Willebrand factor, tissue factor pathway inhibitor), neutrophil extracellular traps and tissue factor-positive extracellular vesicles were higher in patients with kidney failure. Prothrombin fragments 1 and 2, and D-dimer markers of in vivo coagulation activation were also higher. However, in vitro in the presence of platelets, endogenous thrombin generating potential was lower and its downregulation by activated protein C impaired. Antiplatelet drugs did not affect these parameters. In multiple regression analysis, prothrombin fragments 1 and 2, D-dimer, factor VIII and monocyte-derived tissue factor-positive extracellular vesicles correlated with higher carotid-femoral pulse wave velocity. In patients with kidney failure, in vivo hypercoagulability occurred with reduced thrombin generation in platelet-rich plasma, likely explaining the opposing thrombotic and bleeding tendencies in patients with kidney failure. Importantly, arteriosclerosis is more closely related to a prothrombotic state. Thus, coagulation changes plus arterial stiffness highlight a major therapeutic challenge for anticoagulant and antiplatelet drug use.

Using controlled attenuation parameter combined with ultrasound to survey non-alcoholic fatty liver disease in hemodialysis patients: A prospective cohort study

BACKGROUND AND AIMS

Controlled attenuation parameter (CAP) is a non-invasive method for measuring hepatic steatosis (HS). Non-alcoholic fatty liver disease (NAFLD) is closely related to cardiovascular diseases (CVDs). CVDs are the leading cause of morbidity and mortality in hemodialysis patients. The aim of this study was to investigate the prevalence of NAFLD in hemodialysis patients.

METHOD

We prospectively enrolled patients undergoing chronic hemodialysis, as well as patients with normal renal function who served as controls. The control group patients were referred by an endocrinologist to be tested for NAFLD; most of these patients had diabetes, hypertension, or dyslipidemia. We excluded those with excess alcohol intake, use of drugs known to induce HS, chronic viral hepatitis, or CAP failure. CAP ≥ 238 dB/m was used as a cutoff suggesting HS. An increased liver kidney contrast, as defined by ultrasound, was used to make the diagnosis of HS.

RESULTS

Three hundred and forty-three hemodialysis patients and 252 control group patients were enrolled. Among the hemodialysis patients, 192 (56.0%) had CAP- or ultrasound-identified HS compared with 91 (26.5%) who only had ultrasound-identified HS (P<0.001). Among the control group patients, 212 (84.1%) had CAP- or ultrasound-identified HS compared with 180 (71.4%) who only had ultrasound-identified HS (P<0.001).

CONCLUSIONS

The prevalence of NAFLD in the hemodialysis patients was 56%. The number of diagnoses of NAFLD made by using CAP combined with ultrasound was more than 2 times the number made with ultrasound alone in the hemodialysis patients. Therefore, we suggest the use of CAP combined with ultrasound to screen for NAFLD in hemodialysis patients.

Platelet aggregometry cannot identify uremic platelet dysfunction in heart failure patients prior to cardiac surgery

BACKGROUND

Patients with heart failure often have concomitant renal disease which can result in uremic platelet dysfunction. Determining whether uremia has affected platelets by platelet aggregometry can be challenging in these patients since they are often on antiplatelet medications. This study was undertaken to determine if platelet aggregation studies could identify heart failure patients at risk for uremic bleeding prior to cardiac surgery.

METHODS

Platelet aggregation studies from three groups were studied and compared: 17 heart failure patients with mild to moderate renal impairment, 17 heart failure patients without renal abnormalities and 17 healthy volunteers.

RESULTS

Platelet aggregation was severely impaired in both heart failure groups with and without renal abnormalities compared to healthy controls, and there were no significant differences in platelet aggregation in response to any of the agonists. There was a pan-decrease in platelet aggregation to all agonists in all heart failure patients.

CONCLUSION

Platelet aggregometry does not appear to be useful in measuring platelet dysfunction in heart failure patients with mild to moderate renal impairment.

Roll, adhere, spread and contract: structural mechanics of platelet function

Platelets are involved in life-sustaining processes such as hemostasis, wound healing, atherothrombosis and angiogenesis. Mechanical trauma to blood vessels causes platelet activation resulting in their adherence and clot formation at the damaged site, culminating in clot retraction and tissue repair. Two of the major players underlying this process are the cytoskeleton, i.e., actin and microtubules, and the membrane integrin receptors. Rare congenital bleeding disorders such as Glanzmann thrombasthenia and Bernard-Soulier syndrome are associated with genetic alterations of platelet surface receptors, also affecting the platelet cytoskeletal structure. In this review, we summarize the current knowledge about platelet structure and adhesion, and delve into the mechanical aspects of platelet function. Platelets lack a nucleus, and can thus provide a minimal model of a biological cell. New biophysical tools may help to scrutinize platelets anew and to extend the existing knowledge on cell biology.

Differences in coagulation between hemodialysis and peritoneal dialysis

BACKGROUND

End-stage renal disease patients have significant cardiovascular morbidity and mortality, but little is known about differences in coagulation profiles between patients on hemodialysis (HD) and on peritoneal dialysis (PD). Given their long-term exposure to glucose-based dialysate, patients on PD can experience metabolic derangements. Theoretically, that exposure should create a more prothrombotic environment than occurs in HD patients. The objective of the present study was to quantify potential differences in baseline coagulation between PD and HD patients. ♢

METHODS

Our single-center cross-sectional study at a large academic health science center enrolled 50 age-, race-, and sex-matched subjects (10 control subjects, 20 HD patients, and 20 PD patients). Measurements included platelet function, platelet receptor distribution, and coagulation dynamics by thromboelastography and Hemodyne hemostasis assay (Hemodyne, Richmond, VA, USA). ♢

RESULTS

Compared with healthy control subjects, patients on both forms of dialysis showed prothrombotic coagulation protein profiles. The tissue-factor pathway was markedly elevated in both groups, but PD was associated with significantly greater concentrations of tissue factor (p = 0.0056) and tissue-factor pathway inhibitor (p = 0.0138). Similarly, compared with patients receiving HD, patients on PD had greater concentrations of fibrinogen (p = 0.0325), which corresponded with platelet hyperfunction as measured by platelet contractile force and clot elastic modulus (p = 0.003 and 0.017 respectively, compared with values in HD patients). Platelet receptor distribution was similar between the groups. ♢

CONCLUSIONS

Compared with patients on HD, patients on PD appear to have a more prothrombotic profile. The clinical relevance of these findings needs to be studied in a prospective manner.

Whole blood platelet aggregation and release reaction testing in uremic patients

Background. Platelet function analysis utilizing platelet-rich plasma and optical density based aggregometry fails to identify patients at risk for uremia associated complications. Methods. We employed whole blood platelet aggregation analysis based on impedance as well as determination of ATP release from platelet granules detected by a chemiluminescence method. Ten chronic kidney disease (CKD) stage 4 or 5 predialysis patients underwent platelet evaluation. Our study aims to evaluate this platform in this patient population to determine if abnormalities could be detected. Results. Analysis revealed normal aggregation and ATP release to collagen, ADP, and high-dose ristocetin. ATP release had a low response to arachidonic acid (0.37 ± 0.26 nmoles, reference range: 0.6–1.4 nmoles). Platelet aggregation to low-dose ristocetin revealed an exaggerated response (20.9 ± 18.7 ohms, reference range: 0–5 ohms). Conclusions. Whole blood platelet analysis detected platelet dysfunction which may be associated with bleeding and thrombotic risks in uremia. Diminished ATP release to arachidonic acid (an aspirin-like defect) in uremic patients may result in platelet associated bleeding. An increased aggregation response to low-dose ristocetin (a type IIb von Willebrand disease-like defect) is associated with thrombus formation. This platelet hyperreactivity may be associated with a thrombotic diathesis as seen in some uremic patients.

Skin bleeding time for the evaluation of uremic platelet dysfunction and effect of dialysis

INTRODUCTION

In patients with chronic kidney disease (CKD) predisposition to bleeding is frequently seen due to disturbances in platelet adhesion and aggregation. Various tests have been utilized to evaluate the disturbance of hemostasis in end-stage renal disease patients. In this trial; we evaluated skin bleeding time in patients admitted to our hospital with uremic symptoms and having hemodialysis (HD) for the first time. We also examined the effects of HD and uremia on this test and investigated its effectiveness in predicting the hemorrhagic complications before implementation of invasive procedures in uremic patients.

MATERIAL-METHOD

Twenty nine patients (13 men,16 women; mean age 59.7 ± 18.1) with CKD who presented with symptoms of uremia and treated with HD for the first time were enrolled in this trial. The skin bleeding time were measured before initiation of first hemodialysis and after the second hemodialysis session.

RESULTS

The skin bleeding time after the second dialysis was significantly shorter when compared to pre-dialysis values (p < 0.05). Correlation analysis between the skin bleeding time and urea, creatinine, hemoglobin, platelet, and bicarbonate showed no correlation.

CONCLUSIONS

Skin bleeding time could reveal the uremic platelet dysfunction and beneficial effect of dialysis in the patients who presented with uremic symptoms and treated with HD for the first time. We suggest that skin bleeding time may be an appropriate test for the evaluation of hemostasis disturbance in uremic patients and prediction of the bleeding risk before invasive procedures.

Mechanobiology of platelets: techniques to study the role of fluid flow and platelet retraction forces at the micro- and nano-scale

Coagulation involves a complex set of events that are important in maintaining hemostasis. Biochemical interactions are classically known to regulate the hemostatic process, but recent evidence has revealed that mechanical interactions between platelets and their surroundings can also play a substantial role. Investigations into platelet mechanobiology have been challenging however, due to the small dimensions of platelets and their glycoprotein receptors. Platelet researchers have recently turned to microfabricated devices to control these physical, nanometer-scale interactions with a higher degree of precision. These approaches have enabled exciting, new insights into the molecular and biomechanical factors that affect platelets in clot formation. In this review, we highlight the new tools used to understand platelet mechanobiology and the roles of adhesion, shear flow, and retraction forces in clot formation.

Hematological issues in critically ill patients with cancer

Patients with solid and hematologic malignancies presenting with major bleeding or thrombotic complications, potentially life-ending events in a cancer patient's clinical course, usually require admission to an intensive care unit (ICU), making their diagnosis and management even more important for the intensivist. Given the significant advances in the diagnosis and treatment of almost all types of cancers in recent years, the intensivist is likely to encounter an ever-increasing number of cancer patients in the ICU setting with these complications. Abnormal hemostasis can occur as a consequence of both the pathology and treatment of cancer. Because cancer can have multiple effects on hemostatic equilibrium, treatment of these complications can be more complex than in the general population. This article reviews the physiology of coagulation and fibrinolysis, with special attention to those aspects that are most frequently altered in the setting of malignancy. The pathophysiology of bleeding and thrombotic complications specific to critically ill cancer patients are then detailed, and the diagnostic and therapeutic strategies are discussed. Special emphasis is placed on new cancer medications that have an effect on hemostasis, and on novel clotting and anticoagulant agents that are available to the intensivist for the management of these patients.

Therapeutic management in patients with renal failure who experience an acute coronary syndrome

BACKGROUND AND OBJECTIVES

Prior reports have suggested that patients with impaired renal function receive less aggressive care after an acute coronary syndrome (ACS). The aim of this study was to determine whether this held true in a contemporary cohort, after thorough adjustment for cotreatments/comorbidities.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients who were admitted for an ACS in eight participating hospitals were stratified into three groups according to estimated creatinine clearance (CrC): less than 45 ml/min, 45 to 60 ml/min, and reference >60 ml/min.

RESULTS

During hospitalization, uses of reperfusion therapy in tertiary care centers [difference between CrC < or =45 ml/min and reference group (Delta): 4%, 95% confidence interval (CI): (-13%, 21%)] and systemic anticoagulation [Delta: 0%, CI (-5%, 5%)] were similar in the three groups. Coronary angiography was performed less often in patients with lower CrC [Delta: -16%, CI: (-31%, -1%)]. At discharge, nearly all patients received either an antiplatelet agent or warfarin regardless of CrC [Delta: -1%, CI: (-3%, 1%)]. Discharge use of angiotensin converting enzyme (ACE) inhibitors or angiotensin-receptor blockers was comparable [Delta: 7%, CI: (-1%, 15%)]. beta-blockers [Delta: -9%, CI: (-17%, -1%)] and lipid-lowering drugs (LLDs) [Delta: -7%, CI: (-13%, -1%)] were used less frequently in patients with lower CrC. In multivariate analyses, decreased CrC predicted lower coronary angiography and LLD use, but not lower beta-blocker use at discharge.

CONCLUSIONS

These results suggest that in patients with ACS, the extent of undertreatment due to chronic kidney disease is less than reported previously, which is partially explained by more complete adjustment for cotreatments/comorbidities.

Percutaneous liver biopsy is safe in chronic hepatitis C patients with end-stage renal disease

BACKGROUND & AIMS

Liver biopsy is useful for staging fibrosis in chronic hepatitis C (CHC) patients with end-stage renal disease (ESRD) to determine renal transplant eligibility and to make CHC treatment decisions. There is concern about an increased risk associated with percutaneous liver biopsy (PCNB) in ESRD patients. We compared the safety of PCNB in CHC patients with and without ESRD.

METHODS

We reviewed PCNBs performed between 1996 and 2004 for technique, histology, and complications in 78 ESRD patients with CHC and in 241 control patients with CHC and no renal failure, randomly matched for age, sex, and race. Platelet counts, prothrombin, and partial thromboplastin times, but not bleeding times, were checked before biopsy. Deamino-8-D-arginine vasopressin was not given before the biopsy.

RESULTS

The mean age of the patients was 50 years; 72% were male, 97% were African American, and 3% were Caucasian. The control group had a significantly higher proportion of patients with advanced fibrosis (P < .04). Only 1 patient with ESRD (1.3%) developed a moderate complication. Five controls (2.1%) developed complications, 3 of which were severe.

CONCLUSIONS

Severe complications after PCNB are uncommon, and patients with ESRD and CHC are at no increased risk. Testing for bleeding time and the routine use of deamino-8-D-arginine vasopressin are not necessary before PCNB in patients with ESRD.