Bioreactance: A new tool for cardiac output and thoracic fluid content monitoring during hemodialysis

Outpatient hemodialysis therapy (HD) can be associated with hemodynamic compromise. Bioreactance^® has recently been shown to provide accurate, noninvasive, continuous, measurements of cardiac output (CO) and thoracic impedance (Zo) from which thoracic fluid content (TFC) can be derived assuming TFC=1000/Zo. This study was designed to evaluate the changes in TFC in comparison with the traditional indices of fluid removal (FR) and to understand the trends in CO changes in HD patients. Minute-by-minute changes in TFC and CO were prospectively collected using the bioreactance system (NICOM^®) in HD patients of a single unit. Changes in body weight (ΔW), hematocrit (ΔHct), and amount of FR were also measured. Twenty-five patients (age 77 ± 11 years) were included. The TFC decreased in all patients by an average of 5.4 ± 7.9 kΩ⁻¹, weight decreased by 1.48 ± 0.98 kg, and FR averaged 2.07 ± 1.93 L over a 3- to 4-hour HD session. There were good correlations between ΔTFC and ΔW (R=0.80, P<0.0001) and FR (R=0.85, P<0.0001). ΔHct (4.13 ± 3.42%) was poorly correlated with ΔTFC (R=0.35, P=0.12) and FR (R=0.40, P=0.07). The regression line between FR and TFC yielded FR=1.0024−0.1985TFC; thus, a 1 kΩ⁻¹ change of Zo correlates with an ∼200 mL change in total body water. The change in CO (−0.52 ± 0.49 L/min m²) during HD did not correlate with FR (R=0.15, P=NS). Changes in TFC represented the monitored variable most closely related to FR. CO remained fairly constant in this stable patient cohort. Further studies in high-risk patients are warranted to understand whether TFC and CO monitoring can improve HD session management.     

The effect of hemodialysis ultrafiltration on changes in whole blood viscosity

Increased whole blood viscosity (WBV) can be injurious to the vascular endothelium and increase the risk of atherothrombotic events. This study examined the effect of hemodialysis ultrafiltration (UF) on WBV, with a focus on high vs. low‐volume UF patients. In stable hemodialysis patients, blood was drawn for hematocrit (Hct) and WBV at the start, midpoint, and at the end of dialysis. For analysis, patients were divided into high UF (≥2700 mL) or low UF (<2700 mL) groups. A total of 59 patients completed the study. Mean Hct increased during dialysis in both groups. The intradialytic increase in Hct was significantly greater in the high vs. the low UF group (3.2% vs. 1.28%, P = 0.01), with a significantly higher end‐dialysis Hct in the high UF group (40.5% vs. 38%, P = 0.02). At the end of dialysis, both high shear rate WBV (P < 0.01) and low shear rate WBV (P < 0.01) were significantly higher in the high UF compared with the low UF group. There was an approximately two‐fold greater increase in high shear rate (P < 0.01) and low shear rate (P = 0.01) WBV during dialysis in high vs. low UF groups. The increase in high shear rate WBV during dialysis was significantly correlated with an increase in Hct (R² = 0.63, P < 0.01). We found that hemodialysis UF causes a surge in WBV. The surge was of greater magnitude in high than in low UF patients.     

Polycythemia due to obstructive sleep apnea in a patient on hemodialysis

Both anemia and sleep disordered breathing are common in patients with dialysis‐dependent stage 5 chronic kidney disease. Erythrocytosis resulting from obstructive sleep apnea (OSA) is rare in the general population and has never been described in the hemodialysis population. We present a case of asymptomatic isolated erythrocytosis and elevated serum erythropoietin level in an otherwise well and previously erythropoietin‐dependent chronic hemodialysis patient with chronic kidney disease secondary to ischemic nephropathy. There was no history or symptoms of cardio‐pulmonary or hepatic diseases nor any relevant family history. Screening work‐up for malignancies was negative. The clinical history was highly suggestive of OSA and severe OSA (respiratory disturbance index of 59) was confirmed by polysomnographic studies. Successful treatment of the OSA with continuous positive airway pressure resulted in permanent stabilization of the hemoglobin to levels below 13 g/dL without the need for repeated phlebotomies and in dramatic lowering of serum erythropoietin levels. To our knowledge, this is the first case of OSA mediated erythrocytosis in a dialysis patient documented in the literature.     

Bilateral quadriceps and triceps tendon rupture in a hemodialysis patient

This paper presented a 58‐year‐old hemodialysis patient who had bilateral quadriceps and triceps tendon rupture, whereby the role of rehabilitation in functional parameters has been highlighted.     

Acquired reactive perforating collagenosis and pseudoporphyric bullous dermatosis in a hemodialysis patient

Hemodialysis patients present with a broad spectrum of specific and nonspecific skin disorders, which rarely coexist. We report an exceptional case of a hemodialysis patient that developed acquired reactive perforating collagenosis and pseudoporphyric bullous dermatosis on the basis of common skin disorders which include hyperpigmentation, pruritus, xerosis cutis, and Linsday's nails. Interestingly, our patient presented with two unusual but distinctive cutaneous dermopathies on the background of other commonly seen skin alterations. The patient was successfully treated with allopurinol and N‐acetylcysteine. Avoidance of potentially triggering factors such as alcohol, sunlight exposure and certain medication was recommended. Thus, increasing clinical awareness, assiduous investigation and early treatment of skin disorders are required to improve the prognosis and quality of life in this patient population.     

Beneficial effects of nocturnal hemodialysis in a hemodynamically unstable patient with AL‐amyloidosis

We present a patient with primary systemic AL‐amyloidosis, who stabilized hemodynamically on nocturnal hemodialysis (NHD). The NHD allowed a significant reduction in ultrafiltration rates which likely underlies the procedural tolerability. It also provided an increase in urea clearance, better control of serum phosphorus levels without the use of any binders, and normalization of blood pressure despite the discontinuation of all antihypertensive agents. Given the autonomic derangements associated with AL‐amyloidosis pathophysiology and the clinical benefits of NHD on hemodynamic stability, the use of intensive hemodialysis may be considered for the management of patients with unstable hemodynamic profiles.     

Necrotizing fasciitis and infective endocarditis caused by Escherichia coli in a hemodialysis patient

Patients with uremia are often immunocompromised and uremia patients undergoing maintenance dialysis are often vulnerable to uncommon infections. We report a 40‐year‐old man who was undergoing maintenance hemodialysis and was initially diagnosed with monomicrobal necrotizing fasciitis of the lower limbs, based on blood and pus cultures that yielded Escherichia coli. His condition improved after surgical debridement and antibiotic therapy. However, he eventually died of intracranial hemorrhage related to septic emboli. Concurrent infective endocarditis was diagnosed based on an echocardiogram that indicated vegetation in the left ventricular region. Escherichia coli‐related necrotizing fasciitis and infective endocarditis is rarely seen in clinical practice. There should be a high index of suspicion for multiple infections when a hemodialysis patient presents with an uncommon infection.     

The source of net ultrafiltration during hemodialysis is mostly the extracellular space regardless of hydration status

Fluid shifts are common in patients undergoing chronic hemodialysis (HD) during the intradialytic periods, as several liters of fluid are removed during ultrafiltration (UF). Some patients have experienced frequent intradialytic hypotension (IDH). However, the characteristics of fluid shifts and which fluid space is affected remain controversial. Therefore, we designed this study to evaluate the fluid spaces most affected by UF and to determine whether hydration status influences the fluid shifts during HD. This was a prospective cohort study of 40 patients undergoing HD. We measured the patient's fluid spaces using a whole‐body bioimpedance apparatus to evaluate the changes in the fluid spaces before HD and 1–4 hours of HD and 30 minutes after HD. UF achieved during HD by the 40 patients (age, 60.0 ± 5.2 years; 50% men; 50% of patients with diabetes; body weight, 61.3 ± 10.5 kg) was 2.18 ± 0.78 L (measured fluid overload, 2.15 ± 1.24 L). 1) Mean relative reduction of total body water and extracellular water was reduced from the start to the end of HD. 2) However, mean relative reduction of intracellular water was not reduced from the start to the end of HD. 3) No significant differences in fluid shifts were observed according to hydration status. The source of net UF during HD is mostly the extracellular space regardless of hydration status. Thus, IDH may be related to differences in the interstitial fluid shift to the vascular space.     

The effect of hemodialysis session on postural strategies in older end‐stage renal disease patients

Patients suffering from end‐stage renal disease experience multiple disabilities, such as muscle wasting, weakness, higher postural sway, and fall rates compared with healthy population, which has a negative effect on physical functioning and autonomy. The vital treatment of hemodialysis is recognized to induce important post‐hemodialysis fatigue, hypotension, cramps, and headache due to the rapid fluid redistribution, among others. Nevertheless, even the well‐known negative effect of aforementioned consequences of hemodialysis treatment, its effect on physical function, especially postural balance, is unclear. Thus, this study hypothesized the adverse effect of hemodialysis treatment on postural sway in 12 end‐stage renal disease patients (mean age 63.3 ± 11 years) through the analysis of center‐of‐pressure (COP) trajectories recorded before and immediately after hemodialysis session. Evident postural alterations were observed at post‐hemodialysis balance assessment for COP position‐based (Fs < 7.7, P < 0.02) and COP velocity‐based variables (Fs > 2.33, P < 0.05), without changes in complexity of COP time series in anteroposterior and mediolateral directions. These results suggest that period after hemodialysis treatment is particularly unsafe, as evidenced by important disability in postural control, and highlight the importance of the medical support and falls‐related prevention strategies of these older frail patients after hemodialysis treatment.     

Impact of intradialytic exercise on arterial compliance and B-type natriuretic peptide levels in hemodialysis patients

Cardiovascular (CV) disease is the most common cause of mortality in end-stage kidney disease (ESKD), and arterial stiffness, measured by pulse wave velocity (PWV), is an independent predictor of all-cause and CV mortality. B-type natriuretic peptide (BNP) levels are high in patients with CV disease and ESKD, and increases in BNP may also be a marker of CV risk. Regular exercise has many benefits on quality of life and physical strength and may also improve CV risk, but few studies have addressed the impact of exercise on CV risk in ESKD. We performed a prospective cross-over trial in 19 hemodialysis (HD) patients to assess the impact of regular exercise on surrogate markers of CV risk-arterial compliance and BNP levels. Exercise involved the use of a bicycle ergometer for minimum 30 min at each HD session for 3 months, with a 1-month washout period. Group A (n=9) exercised for the first 3 months only, while group B (n=10) performed no intradialytic exercise initially and exercised for 3 months at cross-over (month 4). Pulse wave velocity was performed using a SphygmoCor device, with concurrent measurements of BNP and other serum markers, at the commencement of the study, at 3 months, and on completion. The mean PWV (A: 10.4+/-3.1 m/s, B: 9.8+/-3.8 at baseline) showed a trend toward improvement with exercise (A: 8.7+/-2.7, p=0.07), and no significant change without (B: 10.5+/-3.6, p=0.31). After cross-over, there was an increase in PWV in group A with cessation of exercise (9.75+/-2.4, p=0.01 vs. 3 months) and an improvement in group B with exercise (9.33+/-2.3, p=0.11 vs. 3 months). When comparing PWV after 3 months of exercise vs. 3 months of no exercise (paired t test), there was a significant difference in favor of exercise (9.04+/-0.59 vs. 10.16+/-0.74, p=0.008). The mean BNP levels following 3 months of exercise were also lower than those after 3 months of no exercise (504.4+/-101.2 vs. 809.4+/-196.1[N<100], p=0.047). There was an overall improvement in PWV, and to a lesser extent BNP levels, with 3 months of intradialytic exercise compared with no exercise, suggesting that regular exercise in ESKD may be associated with improvements in arterial compliance and a reduction in CV risk.     

An unusual case of an irretrievable hemodialysis catheter in a patient with end stage renal disease

Hemodialysis catheters are associated with higher risks of complications compared to arteriovenous fistulas and grafts. Some common complications of dialysis catheters include infection, thrombus formation, central venous stenosis, and mechanical dysfunction. Rarely, catheters can become firmly adhered to a vessel wall. Catheter adhesion is a serious complication that can impact the delivery of safe and effective dialysis to affected patients. Adherent catheters commonly present insidiously with no overt diagnostic signs and symptoms or antecedent catheter malfunction. Prognosis is variable, but can be potentially fatal depending on the severity of adhesion, and sequelae of complications. There are no standardized methods of therapy and treatment strategies are anecdotally reported by interventional radiology, vascular, and cardiothoracic surgery. We hereby describe a case of hemodialysis catheter that has become firmly embedded within the superior vena cava wall. We review the available literature on the epidemiology, risk factors, long‐term sequelae, and known management strategies of adherent catheters. The development of preventative measures will be of great importance given serious complications and limited treatment options. Clinical awareness and understanding of this rare condition is imperative to the prevention and management of adherent catheters.     

Effect of a single hemodialysis session on inflammatory markers

Inflammation is a common feature of end-stage renal disease. Although there is evidence for hemodialysis (HD)-induced inflammatory process, the effect of a dialysis session on changes in inflammatory markers is still unclear. Seventeen patients of end-stage renal disease on maintenance HD along with 20 age-matched and sex-matched healthy controls were recruited after informed consent. C-reactive protein (CRP) and lipoprotein-associated phospholipase A2 (LpPLA2) activity were measured in the study and control groups. Intradialytic in CRP and LpPLA2 were studied. Comparison of pre-HD vs. the control group and predialytic and postdialytic values was performed using the Mann-Whitney U test and Wilcoxon's test, respectively. Statistical evaluation of intradialytic changes in inflammatory markers was performed using Friedman's test. Hemodialysis patients had higher CRP levels compared with controls (P=0.001). Post-HD LpPLA2 activity (n=17) was higher (P=0.039) compared with the pre-HD activity. Intradialytic changes in inflammatory markers showed a significant increase (P=0.012) in LpPLA2 activity (n=7), while no change (P=0.133) was observed in CRP levels (n=17). Evidence on the pro-inflammatory state being initiated by dialysis is provided by increased LpPLA2 activity. This may add to the atherogenic mileu and cause endothelial dysfunction in this high-risk group. Drugs that inhibit the LpPLA2 pathway have been developed and may be effective in these patients.     

Survival pattern of hemodialysis patients in Kumasi, Ghana: A summary of forty patients initiated on hemodialysis at a new hemodialysis unit

To evaluate the survival pattern of hemodialysis patients at a dialysis unit in Kumasi, Ghana, through a retrospective (observational) study. Patients who were placed on hemodialysis at the dialysis unit at Komfo Anokye teaching hospital from October 25, 2006 to December 2007. The patients were followed from initiation of dialysis until December 31, 2007. The overall mortality was 14 (35.9%) on the incident population for the period and that for the first 90 days was 12 (32.4%) patients. Chronic glomerulonephritis was the underlying kidney disease in 35.9%. This was followed by hypertension (19.1%) and diabetes mellitus (15.4%), respectively. Cardiovascular diseases accounted for 42% of mortality. This was followed by septicemia (25%) from the access site and anemia (25%). Fifty percent of the patients were able to afford 20 sessions of hemodialysis before stopping. The most powerful predictors of survival were the duration of hemodialysis (P=0.05) and the number of hemodialysis sessions (P=0.02). Age at initiation of hemodialysis was not significant. First 90-day mortality of patients on hemodialysis is high in poor African countries. This is due partially to the late referral of patients and also the cost of the dialysis treatment. Efforts will have to be made to reduce the cost of the dialysis treatment. Reuse technology (of dialyzer, etc.) should be introduced to cut down the cost of hemodialysis. Peritoneal dialysis should also be introduced for highly motivated patients. Efforts should also be made to reduce the increasing incidence of kidney disease, and finally third-world countries should consider establishing kidney transplantation, that is cost effective.     

GMAW焊接熔池的流场及其对熔池形状的影响

采用数值分析方法研究了ＧＭＡＷ焊接熔滴状,射流过渡时焊接池的流场,分析了流场对熔池形状的影响。实验表明,焊缝尺寸的计算值和实测值吻合良好,建立的数值分析模型可精确地模拟ＧＭＡＷ焊接熔池的流场,这对控制焊接成形,提高焊接质量具有重要意义。