Elias Thodis

Development of an easily applicable risk score model for contrast-induced nephropathy prediction after percutaneous coronary intervention: A novel approach tailored to current practice

BACKGROUND Several risk factors for contrast-induced nephropathy (CIN) after percutaneous coronary intervention (PCI) have been identified. The cumulative effect of these risk factors on renal function has been assessed with the development of risk score models in a number of studies. However, concerns were raised that estimates of the risk attributable to individual factors may be unreliable. We sought to develop a simple risk score for developing CIN after PCI irrespective of use of prophylactic measures and also capturing the effect of pre-intervention medication and presence of various co-morbidities. METHODS Consecutive patients treated with elective or urgent PCI at our cardiac catheterization laboratory were enrolled (derivation cohort n = 488, validation cohort n = 200). CIN was defined as increase ≥ 25% and/or ≥ 0.5 mg/dl in serum creatinine at 48 h after PCI vs baseline. Multivariable logistic regression analysis was then performed to identify independent predictors of CIN (pre-existing renal disease, metformin use, history of previous PCI, peripheral arterial disease and ≥ 300 ml of contrast volume). RESULTS The incidence of CIN in the development cohort was 10.2% with a significant trend across increasing score values (p < 0.001). The model demonstrated good discriminating power (c-statistic 0.759) and excellent calibration (calibration slope 0.91). The model was validated internally by bootstrapping in 1000 samples (c-statistic 0.753) and in a cohort of 200 patients (c-statistic 0.864) demonstrating stable performance. CONCLUSIONS The proposed risk score is easily applicable and allows for practically simple risk assessment compared to other published scores while at the same time overcomes drawbacks of previous model designs.

Peritoneal Catheters and Related Infections

Catheter related infectious complications (exit-site infections, tunnel infections, and peritonitis) remain the major reasons for technique failure during the three decades since, continuous ambulatory peritoneal dialysis (CAPD) treatment has been first established. Despite improvements in catheter’s survival rates, catheter related complications result in an increase in the cumulative patients’ morbidity and often leading to the catheter removal. The ideal catheter provides reliable and rapid dialysate flow rates without leaks or infections. Among several types, the double-cuff straight Tenckhoff catheter, developed in 1968, is still the most widely used, although its use is decreasing in favour of swanneck catheters. Although there are onlu few well-designed trials comparing catheters and catheters related infectious complications, controlling for all other important variables, no difference in these complications among the main types of catheters was seen. The single cuff catheters have been associated with a shorter survival rate and time to the first peritonitis episode than the double-cuff catheters. Also exit-site infections were found to be more frequent and significantly more resistant to treatment with single-cuff compared to double-cuff ones. Finally, better results have been reported with the latest developed presternal peritoneal dialysis catheter both regarding survival rates and exit-site infection and peritonitis rates. Recently a renewed interest in continuous flow peritoneal dialysis stimulated inventions of imaginative, double-lumen catheters since a suitable peritoneal access is a sine qua non condition for the development of this new technique of peritoneal dialysis.

Home dialysis as a first option: a new paradigm

Traditionally, the initial choice of dialysis for patients with end stage renal disease (ESRD) has been in-center hemodialysis (HD) or peritoneal dialysis (PD). Usually, the choice between these (PD vs. HD) has been based on the characteristics of the dialysis techniques. Obviously the choice of peritoneal dialysis implied dialysis at home, but its geographic location has been only a secondary consideration. Peritoneal dialysis has evolved as a dependable mode that gives good outcomes. This method has become more attractive with the option of overnight cyclers and the recent use of home helpers in some jurisdictions. At the same time the interest in home hemodialysis was rekindled by reports of good outcomes with short daily or nocturnal hemodialysis. Home dialysis (PD or HD) offers high quality of treatment, a high degree of patient independence, and is financially attractive. Therefore, we propose a change in our approach to the choice of the initial form of dialysis for patients with ESRD. Instead of choosing between HD and PD we should present the new patients the advantage of dialysis at home and instead of asking them to choose between peritoneal dialysis or hemodialysis, they should be offered the option to choose between dialysis at home (PD or HD) or in-hospital. This paper will review the advantages of the home-based dialysis methods and the arguments for this simple but vital change in the process of choosing the method of dialysis.

LIPOPROTEIN ABNORMALITIES IN HEMODIALYSIS AND CONTINUOUS AMBULATORY PERITONEAL DIALYSIS PATIENTS

Lipid abnormalities are important variables in the development of vascular atherosclerotic lesions in ESRD patients while Lp(a) represents an independent risk factor. In order to evaluate lipid changes in HD and CAPD patients, serum cholesterol (TC), HDLc, LDLc, TG, apo-lipoproteins (AI,AII,B,E), Lp(a), and albumin levels were estimated in 109 ESRD dialyzed patients, 46 in HD and 63 in CAPD (mean duration 50 ± 40 and 25 ± 19 months, respectively), and 45 volunteers with high serum levels of C and TG, without renal insufficiency. Both HD and PD group revealed statistically significantly higher levels than controls for TC, TG, LDL-C, Apo-B,-E, while HDL-C levels were significantly lower. Except for the lower serum albumin levels in both dialyzed groups after six months lower ApoAI levels and higher ApoB levels were observed in HD and PD patients respectively. Lp(a) levels remained unchanged in HD group, while a statistically significant increase appeared in PD patients that was negative correlated with the decreased serum albumin levels. These results indicate that renal replacement modalities result in a different effect in lipoprotein metabolism that may play an important role in atherosclerotic vascular disease of dialyzed ESRD patients.

The promising future of long-term peritoneal dialysis

Peritoneal dialysis (PD) has now been recognized as a successful alternative to hemodialysis (HD) for at least a period of 5–10 years [1]. In addition, PD is as cost-effective as HD (if not more so) [2–4]. After longer periods on PD however patients encounter complications leading to high technique failure and, despite few exceptions, to discontinuation of the treatment. Mortality rates are better than those on HD during the first 1–2 years but equalize later on [5]. Still technique failure remains high among patients on PD [6]. Technique failure has been attributed to the following factors:

Prevention of catheter related infections in patients on CAPD.

Catheter-related infections remain a serious problem for patients on peritoneal dialysis. Such infections can be reduced by careful patient selection and training, by the use of the best connection technology and screening and treating nasal carriage. To date, treatment is less than optimal and therefore, the primary goal should be prevention of catheter-related infections. Prevention is based on improving catheter design and implantation technique, while providing careful exit-site care. Regardless of how it is implemented, we must aggressively pursue the prevention of catheter-related infections by eradicating S.aureus exit-site carriage in PD patients. Based on its effectiveness in adult PD patients, its low rate of adverse effects, and its reasonable cost-effectiveness, application of mupirocin ointment at the exit-site is the current method of choice for preventing PD catheter infections caused byS. aureus. In addition to reducing S. aureus exit-site infections, mupirocin seems to reduce the rates of staphylococcal peritonitis and PD catheter loss. Whether the ointment should be applied in the nares, to the exit-site or both, and whether it should be used only in staphylococcal nasal carriers or all PD patients requires further study.

Metformin-related lactic acidosis in patients with acute kidney injury

BackroundMetformin is nowadays considered as first-line therapy in individuals with non-insulin dependent diabetes mellitus (NIDDM). Metformin-related lactic acidosis (MALA) occurs more frequently after inappropriate use especially in patients with acute kidney injury (AKI) or chronic kidney disease (CKD). Thus, its prescription in these patients is contraindicated, while the role of dialysis is under evaluation.MethodsWe describe two cases of severe metformin-related lactic acidosis with underlying acute kidney injury, which were treated with dialysis.ResultsIn both cases, lactic acidosis occurred on a background of acute decline in renal function, possibly due to drug accumulation. It is interesting that metformin was contraindicated in one case.ConclusionLactic acidosis is a rare but potentially fatal adverse effect of metformin, particularly in patients with AKI, which should always be considered in clinical practice. Dialysis seems to contribute significantly to the management of this life-threatening condition and the improvement in outcome.

Pivotal Role of Paricalcitol in the Treatment of Calcific Uremic Arteriolopathy in the Presence of a Parathyroid Adenoma

Calcific uremic arteriolopathy, or calciphylaxis, is a serious and life-threatening complication of end-stage renal disease. Its pathogenesis is not yet fully elucidated and treatment is controversial. In the presence of severe hyperparathyroidism, parathyroidectomy should be considered. We report a case of a woman on maintenance hemodialysis therapy with calciphylaxis and parathyroid adenoma who refused to undergo parathyroidectomy. She was treated successfully with a combination of noncalcium phosphate binders, cinacalcet, and paricalcitol. Subcutaneous plaques disappeared, and the necrotic lesion was healed. Discontinuation of paricalcitol led to an increase in serum parathyroid hormone levels and reappearance of the patients symptoms, whereas its reintroduction resulted in complete remission of the clinical picture. Paricalcitol, a less calcemic vitamin D analogue, is also a selective vitamin D receptor activator with a number of nonclassic actions (such as inhibition of inflammation and ossification-calcification) that could prove beneficial in cases of calciphylaxis.

Auditory Brainstem Responses in Patients under Treatment of Hemodialysis

This study evaluated the effects of end stage chronic renal failure (CRF) on auditory function and changes in auditory function following a single session of hemodialysis. The experimental group included 31 patients with end-stage renal failure on chronic hemodialysis. The control group consisted of 31 healthy volunteers. The patients were examined prior to and following a session of hemodialysis. Measurements included pure tone audiometry, tympanometry and acoustic reflex measurements, auditory brainstem responses (ABR), and blood now chemistry parameters. Controls underwent the same test battery, with the exception of biochemical and hematological assessment. Prior to hemodialysis sessions, all ABR latencies except interpeak latency I–III were significantly prolonged in the experimental group. A comparison between controls and the experimental group following hemodialysis indicated that wave V absolute latency and interpeak latencies III–V and I–V were significantly prolonged in the slow repetition rate paradigm. In the fast repetition rate, absolute latencies of waves I and V and III–V interpeak latencies were prolonged in the experimental group. Comparison of ABR recordings prior to and following hemodialysis showed overall significant difference between the measures. Post hoc analysis showed a significant improvement in wave I and V latencies in the slow repetition rate and wave V latency in the fast repetition rate. This study showed that neural conduction along the auditory pathway is delayed in patients with end stage CRF as compared to healthy subjects. Dialysis sessions improve overall neural auditory function. However, patients with end stage CRF show delayed conduction even after a session of hemodialysis.

Effect of a Calcium Antagonist (Verapamil) in the Permeability of the Peritoneal Membrane in Patients on Continuous Ambulatory Peritoneal Dialysis

Peritoneal clearances of small solutes, mass transfer, ultrafiltration, and the mass transfer area coefficient were measured in order to evaluate the effect of calcium antagonists on the permeability of the peritoneal membrane in patients on continuous ambulatory peritoneal dialysis. We studied 10 patients before and after the instillation of 10 mg (5 mg/l) of verapamil into the peritoneal cavity. Our results showed a significant increase of urea, creatinine, and uric acid clearances. A significant increase in ultrafiltration and mass transfer coefficient area was also observed (p less than 0.05), while the mass transfer of K+, Na+, and Ca2+ was essentially unchanged. These findings indicate that the intraperitoneal use of verapamil may induce an increase in the peritoneal permeability in patients on continuous ambulatory peritoneal dialysis.