Konstantinos Leivaditis

Vascular access for hemodialysis: postoperative evaluation and function monitoring

SummaryVascular access (VA) survival is a crucial issue associated with morbidity and mortality of patients undergoing maintenance hemodialysis. The development of stenosis is the major factor that leads to VA failure. Strategies for early detection of lesions within a VA system before serious complications arise are therefore crucial. The implementation of a VA surveillance program could lead to timely detection of VA dysfunction and referral for correction, reduction in central venous catheter use and decrease in hospitalization and VA-related cost. Suggested methods for arteriovenous fistulae and grafts surveillance include blood flow measurement, static pressure evaluation and duplex ultrasonography. Physical examination is an accepted method in contrast to nonstandardized dynamic pressure measurement for grafts. Access recirculation (not urea based) and dynamic pressure measurements are accepted methods for fistulae. Decreasing URR or Kt/V (otherwise unexplained) and increased (negative) arterial pressure in the dialysis machine are methods of limited sensitivity and specificity for both fistulae and grafts. Measurement of access blood flow has been proposed as the gold standard for the screening of all types of VA. Access flow can be measured by various techniques which are direct or indirect. Several studies about VA surveillance programs have demonstrated conflicting results. Larger, randomized controlled trials need to be carried out in order to clarify whether surveillance programs are necessary and which is the best surveillance strategy for each type of VA.

Adaptation of Renal Function in Heart Failure

Congestive heart failure is the only major cardiovascular disease with an increasing incidence and prevalence in industrialized countries. Despite considerable progress in the clinical management of heart failure during the last 20 years, the prognosis is still worse than in many common types of cancer. The kidney is the main organ affected when cardiac function is compromised. In addition, the kidney significantly contributes to the development of the clinical syndrome of heart failure. Specific hemodynamic and neurohormonal abnormalities define the pathophysiology, clinical presentation, and prognosis of this disorder. In this setting, the kidney plays a dual role: the activation of the renin-angiotensin-aldosterone system and the regulation of sodium and water excretion. The kidney is generally intact in heart failure, but extrarenal stimuli alter its function to a point where mechanisms that are initially homeostatic become maladaptive. In this review article, the mechanisms involved in renal adaptation to heart failure are presented.

Animal models in peritoneal dialysis

Peritoneal dialysis (PD) has been extensively used over the past years as a method of kidney replacement therapy for patients with end stage renal disease (ESRD). In an attempt to better understand the properties of the peritoneal membrane and the mechanisms involved in major complications associated with PD, such as inflammation, peritonitis and peritoneal injury, both in vivo and ex vivo animal models have been used. The aim of the present review is to briefly describe the animal models that have been used, and comment on the main problems encountered while working with these models. Moreover, the differences characterizing these animal models, as well as, the differences with humans are highlighted. Finally, it is suggested that the use of standardized protocols is a necessity in order to take full advantage of animal models, extrapolate their results in humans, overcome the problems related to PD and help promote its use.

The kidney in space

Renal adaptation in space has been studied during various space missions since the early 70s. Technical and financial disadvantages of performing experiments under real microgravity conditions have warranted the conductance of relative studies under simulated weightlessness on earth. Arriving in microgravity leads to a redistribution of body fluids to the upper part of the body and an exaggerated extravasation very early in-flight. Plasma volume as well as skin evaporation and oral hydration are reduced, while total body water seems to remain stable. Urinary sodium is diminished and a substantial amount of sodium is retained outside the intravascular space. Glomerular filtration rate shows a transient mild increase. Urinary albumin excretion is reduced although initial studies had demonstrated the opposite. Examination of renal histopathology after exposure to simulated microgravity in rats revealed glomerular atrophy, interstitial edema, and degeneration of renal tubular cells. Acute urinary retention which has been reported during spaceflights can lead to certain medical complications that could compromise an entire mission. Kidney stone formation is another important potential hazard for any manned spaceflight. Increased kidney stone formation in space is attributed to several factors including reduced fluid intake, hypercalciuria, and the presence of nanobacteria. Nutritional and pharmacological interventions are currently recommended as preventive measures against renal stone formation in space travelers.

Calciphylaxis: Current Management and Emerging Therapies

Calciphylaxis or calcific uremic arteriolopathy is a relatively uncommon condition with poor prognosis. Although it is predominantly observed in patients with end stage renal disease, a few cases of patients without kidney failure have been reported. Calciphylaxis is characterized by calcification of the arteriolar intima media and eventually by vascular thrombosis, tissue ischemia and painful skin necrosis. Septicemia is the main cause of death. According to published literature concerning the pathology of calciphylaxis, prevention and treatment are principally based on interventions in calcium and phosphorus metabolism. Although novel therapies have emerged, due to the rarity of this condition, there is no sufficient data in favor of a certain treatment.

Intraocular pressure changes during hemodialysis.

The response of intraocular pressure (IOP) to hemodialysis procedure has been a subject of research throughout many decades. Several studies that evaluated the impact of hemodialysis (HD) on IOP have reported conflicting results and have drawn varied conclusions. Some studies have described an IOP elevation during HD, a finding they attributed to the osmotic disequilibrium between serum and aqueous humor induced by the HD procedure, especially when the facility of the outflow system is already compromised. On the other hand, several studies have reported a significant IOP decrease during HD. The majority of these studies supported the notion that the increase in plasma colloid pressure induced by fluid removal during the HD session is the underlying cause of decreased IOP. Finally, recent investigations did not establish a significant change in IOP measurements during HD. They have therefore suggested that improved dialysis techniques, such as high-flux HD, or hemofiltration and better urea control, maintain better osmolar balance and prevent a marked IOP elevation. Nevertheless, specific preventive measures are still necessary in HD patients with ocular pathologies (e.g., glaucoma) whose vision may be adversely influenced by significant IOP fluctuation.

Late onset of clinically apparent central vein stenosis due to previous central venous catheter in a patient with inherited thrombophilia.

We describe a case of a patient with a functional kidney transplant who was admitted to our department with clinically evident central vein stenosis (CVS) 7 years after the removal of a central venous catheter (CVC) from the right internal jugular vein. The catheter was used as a hemodialysis access for a 2‐month period. In the interval before his last admission, the patient suffered two episodes of deep vein thrombosis. Investigation revealed heterozygosity for factor V Leiden, the most common inherited thrombophilia encountered in 5% of Caucasians, and anticoagulation treatment was started. Magnetic resonance angiography showed stenosis just after the convergence of the right subclavian vein with the internal jugular vein to the innominate vein. Transluminal angioplasty restored venous patency and right upper arm edema resolved. Coexistence of CVS, accompanied by hemodynamic changes and endothelial dysfunction, with thrombophilia fulfill all the elements of the Virchows triad. Therefore, the patient was at great risk for central vein thrombosis, from which he was possibly protected by the early administration of anticoagulant treatment. This case indicates that CVS can be asymptomatic for several years after CVC removal and also raises the question if thrombophilia workup and investigation for CVS may be beneficial in every patient with CVC placement in order to avoid any harmful outcomes.

Intermittent Intraperitoneal Dose of Teicoplanin in Peritoneal Dialysis–Related Peritonitis

The patient was initially given empiric intraperitoneal antibiotics. When fungal hyphae were reported, his treatment was changed to oral fluconazole 200 mg daily. The Tenckhoff catheter removed, and hemodialysis was commenced. The initial cultures later grew Paecilomyces lilacinus. Results of minimal inhibitory concentration testing showed resistance to fluconazole 128 mg/L, amphotericin B 16 mg/L, and itraconazole >16 mg/L, and sensitivity to voriconazole 0.5 mg/L. The isolate was also sensitive to terbinafine, but the minimal inhibitory concentration not determined. Treatment was changed to oral voriconazole 300 mg twice daily. The patient improved slowly and was discharged 33 days later. After 2 weeks, the patient’s abdominal pain and fever relapsed, and computed tomography showed enhancing intraperitoneal collections. Aspirated fluid had profuse fungal hyphae and P. lilacinus was again isolated from cultures. Oral terbinafine 250 mg on alternate days was commenced, and the voriconazole was continued. The patient’s pain improved, but the intraperitoneal collections remained static on repeat computed tomography. Repeat percutaneous drainage showed a reduction in the amount of fungal hyphae, and cultures now remained sterile. The patient continued on hemodialysis and completed 12 months of oral therapy with voriconazole and terbinafine, complicated by poor appetite and altered taste. At 3 months after treatment end, the patient remains free of clinical relapse, with no recurrence of pain and a normalized level of C-reactive protein (1.6 mg/L).

Sternal instability in a hemodialysis patient with secondary hyperparathyroidism

A 77‐year‐old man, 11 years under chronic hemodialysis treatment for chronic renal failure of unknown origin, presented with anterior chest pain, dyspnea with paradoxical breathing, and sternal instability after a simple fall from a standing height. Patient underwent three‐vessel coronary artery bypass grafting 31 months ago. Computed tomography with three‐dimensional volume rendering showed sternal nonunion with a great gap between the two halves of the sternum and at least one fracture in the left half of the sternum. A successful surgical repair followed. Patient suffered from severe secondary hyperparathyroidism for many years. Despite treatment with sevelamer, paricalcitol and cinacalcet, intact parathyroid hormone was 1682 pg/mL. During the last 5 years, serum intact parathyroid hormone remained steadily above 1000 pg/mL. Patient refused parathyroidectomy in the past. We assume that long‐lasting severe hyperparathyroidism contributed to this rare and life‐threatening complication of median sternotomy in our patient, due to the detrimental effect of hyperparathyroidism on bone metabolism and its association with increased incidence of bone fractures and defect in bone fracture healing.

Automated Peritoneal Dialysis: An alternative to Continuous Ambulatory or a First Choice Treatment?

Abstract The use of the various forms of Automated Peritoneal Dialysis (APD) has considerably increased in the past few years. This increase is driven by improved cycler design, apparent lifestyle advantages, and the increased ability to achieve adequacy and ultrafiltration targets. It is therefore reasonable to raise the question whether APD is superior to Continuous Ambulatory Peritoneal Dialysis (CAPD). APD is considered the most suitable Peritoneal Dialysis (PD) modality for high transporters as well as for assisted PD. It has also been associated with improved compliance, lower intraperitoneal pressure and possibly lower incidence of peritonitis. On the other hand, there are concerns regarding increased cost, a more rapid decline in residual renal function, inadequate sodium removal and disturbed sleep. Besides its beneficial results in high transporters, other medical advantages of APD still remain unclear. Individual patient’s choice remains the most important indication for applying APD, which should be made available to all patients starting PD.