Nicholas Dombros

Blood Pressure and Serum Potassium Levels in Hypertensive Patients Receiving or Not Receiving Antihypertensive Treatment

Objective. Serum potassium has a fundamental role in blood pressure (BP) regulation, and there is evidence highlighting the importance of potassium homeostasis in hypertension. The aim of this study was to determine the relationship between serum potassium levels and office BP in untreated essential hypertensives and the effect of antihypertensive medication on serum potassium levels. Setting and Participants. In a retrospective analysis, we collected data for consecutive patients first visiting our Hypertension Clinic from 1999–2004. From this population, we first selected patients who were not taking any antihypertensive medication. Patients who had conditions that could affect potassium metabolism, such as history of arrhythmias treated with digitalis, diabetes mellitus under insulin treatment, and hypo- and hyperthyroidism, were excluded from the study. From the remaining patients, those who had impaired renal function (serum creatinine ≥1.6 mg/dL for men and ≥1.4 mg/dl for women) and patients with secondary forms of hypertension were also excluded. The final population consisted of 817 subjects. Multivariate linear regression analysis was applied, and models were created associating serum potassium with systolic BP, diastolic BP, mean BP, or pulse pressure. The population for the second part of the study consisted of patients first visiting our Hypertension Clinic who were on one antihypertensive agent. This second group included 757 patients, 218 of whom were on β-blockers, 42 on diuretics, 187 on angiotensin-converting enzyme (ACE) inhibitors, 287 on calcium channel blockers (CCBs), and 28 on angiotensin receptor blockers (ARBs). Results. After adjusting for age, gender, and body mass index, significant negative correlations were found between serum potassium levels and systolic BP (R = −0.093, p = 0.007), diastolic BP (R = −0.078, p = 0.03), mean BP (R = −0.122, p = 0.002), and pulse pressure (R = −0.071, p = 0.044). The levels of potassium were found to be significantly lower among patients receiving diuretics than those receiving one of the other four drug categories of antihypertensive (p < 0.05 for β-blockers, ACE inhibitors, and CCBs; p < 0.001 for ARBs). In addition, hypokalemia was found to be significantly more prevalent in the group using diuretics than the other groups. Conclusions. The observed reverse relation between serum potassium and BP supports a close pathophysiological connection between serum potassium and essential hypertension. Moreover, diuretic therapy is a significant cause of hypokalemia and requires systematic monitoring.

Peritoneal dialysis glossary 2009

A number of attempts to create a commonly accepted terminology regarding definitions and terms used for clinical entities, methods, problems, and materials encountered by health professionals involved in peritoneal dialysis (PD) were undertaken in the past, the last one in 1990. Later on, some relevant sporadic attempts in a number of textbooks have been made, but they did not include the whole spectrum of PD. This glossary is an attempt to address the need for a universally accepted PD terminology including the latest advances in PD connection systems and fluids.

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.

On the usefulness of glycylglycine in hemodialysis and peritoneal dialysis solutions

&NA; This article reviews current knowledge on the usefulness of glycylglycine in preparing single stable hemodialysis (HD) and peritoneal dialysis (PD) solutions containing bicarbonate. The coexistence of bicarbonate and glycylglycine in a dialysis solution renders it a potent, stable buffer in which the well known reactions between bicarbonate and calcium and magnesium, and the subsequent formation of insoluble neutral calcium and magnesium carbonate salts, are avoided. Single stable bicarbonate‐glycylglycine (BiGG) solutions for HD and PD have been successfully prepared and studied, both experimentally and clinically. These studies have demonstrated the advantages of BiGG solutions in terms of simplicity, stability, convenience, tolerance, biocompatibility, protection of the peritoneum, and higher ultrafiltration, compared to standard acetate or lactate solutions, and on‐line prepared bicarbonate solutions. Progressive accumulation of glycylglycine or glycine, even after prolonged use, side effects, or signs of toxicity were not observed. In conclusion, BiGG solutions ensure a physiologic dialysis both from the theoretic and practical points of view. ASAIO Journal 1996;42:984‐992.

Sleep apnea syndrome, inflammation and oxidative stress in hemodialysis patients

Introduction: Sleep apnea syndrome (SAS) is an established cardiovascular risk factor in the general population related to inflammation and oxidative stress and is very common among hemodialysis patients. Cardiovascular disease and its complications is the main cause of death among hemodialysis patients. The aim of the present study was to investigate the role of SAS in the promotion of inflammation and oxidative stress and thus in the augmentation of cardiovascular risk in hemodialysis patients.

Recent developments in peritoneal dialysis

Significant developments over the past 10 years have established continuous ambulatory peritoneal dialysis as a successful kidney-replacement treatment. Peritonitis rates have fallen, and investigators are attempting to establish objective criteria for adequacy of dialysis. Malnutrition is a serious concern, but short-term experience with intraperitoneal amino acids promises success in the management of this complication, A significant improvement in the well-being of patients with end-stage renal disease was produced by recombinant human erythropoietin, and use of recombinant human growth hormone promises catch-up growth for children receiving long-term peritoneal dialysis treatment. As increasing numbers of patients are maintained on continuous ambulatory peritoneal dialysis over longer periods, we will begin to encounter β2-microglobulin-related amyloidosis possibly at the same rate in these patients as in those receiving long-term hemodialysis treatment.

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).

The Peritoneal Equilibration Test Should Be Included in Routine Monitoring of Peritoneal Dialysis Patients

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Dimitrios G. Oreopoulos—May He Rest in Peace

Dimitrios Oreopoulos, a unique colleague and friend of many in the renal community, died in April 2012, in Toronto, Canada. The international renal community mourns the loss of his wisdom, kindness, and enormous contribution to the field of peritoneal dialysis. He was one of the most recognizable

Kidney Stones in Chronic Dialysis Patients

While the kidneys of patients undergoing hemodialysis or peritoneal dialysis function poorly, they are not inert and may develop certain complications such as cysts, neoplasms (1, 2) and spontaneous hemorrhage (3). Nephrolithiasis also may be seen in dialysis patients and, in fact, happens frequently. Symptoms occur in a way similar to that seen in the general population with ureteric colic or as the passage of stones or stone-like particles. In 1974, Oreopoulos and Silverberg (4) first reported stones in two dialysis patients; one had been on hemodialysis for 18 months and the other had been on peritoneal dialysis for 9 months. Both were men who had no history of stone disease but developed renal colic and passed multiple urinary calculi, Chemical analysis and infrared spectroscopy showed that these stones were composed of calcium oxalate. Both patients had hypercalcemia (1 1.3 and 10.7 mg/ dL, respectively). Their daily urinary output was 100120 mL with a very low daily calcium excretion. In contrast, urinary oxalate concentration was high. These authors speculated that, in the presence of high oxalate concentration, hypercalcemia might increase the tendency for calcium oxalate precipitation thus forming the initial nucleus, which eventually may lead to stone formation. Later, in 1979, Caralps et al. ( 5 ) reported that 7.5% of their hemodialysis patients (12 out of 160) who had no history of renal calculi, passed at least one stone after the initiation of dialysis. This figure is significantly higher than the 2%-3% prevalence of kidney stones in the general population of Western countries (6). In their series, 6 more patients (3.7%) complained of renal colic without passing stones. All these patients were on hemodialysis for at least 6 months. The examination of some of these calculi by infrared spectroscopy revealed calcium oxalate crystals. These investigators measured the daily excretion of calcium, uric acid, and oxalic acid in the urine of 17 pre-dialysis chronic renal failure patients with creatinine clearances of 10-30 mL/min and no history of urinary lithiasis. Urinary calcium and uric acid values were lower than normal (mean urinary calcium, 86 mg and uric acid 4 13 mg per 24 h) while