Impacts of agricultural practices on pyrethroid resistance in Culex pipiens pipiens, an important vector of human diseases, from Tunisia.

Agricultural pesticides may play a profound role in selection of resistance in field populations of mosquito vectors. The aim of the present study was to examine the relationship between agricultural pesticide use and development of resistance to insecticides in Culex pipiens pipiens from Tunisia. Entomological surveys were conducted in three various districts from Tunisia differ in insect control in agriculture and in public health. A reference locality without any chemical activities was used to do different comparisons. Our results revealed that the level of permethrin resistance ranged from 40.9 to 7438. Practically no susceptible populations were found and resistance to permethrin was important, but significantly higher in site submitted to both agricultural and public health applications. However, resistance ratio has been decreased 7000 folds in site not submitted to agricultural pests. These observations expressed an important influence of agricultural applications on permethrin resistance and need an urgent coordination between the integrated vector control program and the Ministry of Agriculture to reduce the development of resistance in populations. The recorded resistance was slightly associated with DDT suggest the involvement of their common mechanism (target site). Synergist's tests indicated that different enzymes played an important role in the detoxification of this insecticide.

Impacts of agricultural practices on pyrethroid resistance in Culex pipiens pipiens, an important vector of human diseases, from Tunisia

@#Agricultural pesticides may play a profound role in selection of resistance in field populations of mosquito vectors. The aim of the present study was to examine the relationship between agricultural pesticide use and development of resistance to insecticides in Culex pipiens pipiens from Tunisia. Entomological surveys were conducted in three various districts from Tunisia differ in insect control in agriculture and in public health. A reference locality without any chemical activities was used to do different comparisons. Our results revealed that the level of permethrin resistance ranged from 40.9 to 7438. Practically no susceptible populations were found and resistance to permethrin was important, but significantly higher in site submitted to both agricultural and public health applications. However, resistance ratio has been decreased 7000 folds in site not submitted to agricultural pests. These observations expressed an important influence of agricultural applications on permethrin resistance and need an urgent coordination between the integrated vector control program and the Ministry of Agriculture to reduce the development of resistance in populations. The recorded resistance was slightly associated with DDT suggest the involvement of their common mechanism (target site). Synergist’s tests indicated that different enzymes played an important role in the detoxification of this insecticide.

Characterization of resistance to pirimiphos-methyl (an organophosphate insecticide) in Culex pipiens pipiens (Diptera: Culicidae) from Northern and Southern Tunisia.

Despite the public health importance of Culex pipiens pipiens, their resistance to pirimiphos-methyl insecticides has not been explored enough. Late third and early fourth larvae of Culex pipiens pipiens were collected from three localities between 2003 and 2005 in Northern and Southern Tunisia. All bioassays were carried out using pirimiphosmethyl and propoxur insecticides. Populations of Culex pipiens pipiens were susceptible, moderate and resistant to pirimiphos-methyl insecticide. Resistance to this compound ranged from 2.62 in sample # 2 to 19.9 in sample # 1. The moderate resistance (5.25) was recorded in sample # 3. Synergist's tests showed that the resistance to pirimiphos-methyl was not affected by detoxification enzymes. However, biochemical assays showed the involvement of both metabolic (esterases) and target site (insensitive acetylcholinesterase) resistance mechanisms. The highest frequencies of the resistant phenotypes ([RS] and [RR]) (<0.74) were detected in the most resistant samples (#1). Four esterases enzymes including C1 encoded by the Est-1 locus and three esterases encoded by the Ester super locus: A2-B2, A4-B4 (or A5-B5, which has the same electrophoretic mobility) and B12 were detected. The highest (0.61) and the lowest (0.22) frequencies of these esterases were recorded in samples # 1 (Sidi Hcine) and # 2 (El Fahs) which recorded the highest and the lowest level of resistance, respectively. Monitoring of insecticide resistance should be evaluated regularly for management of vector control.

Multiple resistance mechanisms associated with low pirimifos-methyl resistance in Culex pipiens pipiens in three populations of Tunisia.

The aim of this study was to evaluate the resistance status of Culex pipiens pipiens to pirimiphos-methyl insecticide. Three field populations of mosquitoes were collected from Tunisia and analyzed in laboratory. The samples studied showed low level of resistance not exceeding 5-folds. The low resistance recorded is particularly interesting, because it leaves a range of tools useable by vector control services. Both metabolic and target-site resistance mechanisms were identified. Different esterases of high activity including A2-B2, A4-B4 (and/or A5-B5) and B12 were observed in studied field samples using starch electrophoresis although opposite results were found using synergists tests on samples # 1 and 3. The polymorphism of AChE1 (Acetylcholinesterase) was analyzed and three phenotypes were detected: susceptible (ACHE1S, phenotype [SS]), resistant (ACHE1R, phenotype [RR]), and heterozygous (phenotype [RS]) of ACHE1. The resistance of Culex pipiens pipiens to pirimiphos-methyl remains low although the occurrences of multiple resistance mechanisms are able to confer high resistance levels to organophosphate insecticides. Therefore, continuous monitoring of resistance is fundamental for rational use of insecticides and mosquito control programs.

Multiple resistance mechanisms associated with low pirimifos-methyl resistance in Culex pipiens pipiens in three populations of Tunisia

@#The aim of this study was to evaluate the resistance status of Culex pipiens pipiens to pirimiphos-methyl insecticide. Three field populations of mosquitoes were collected from Tunisia and analyzed in laboratory. The samples studied showed low level of resistance not exceeding 5-folds. The low resistance recorded is particularly interesting, because it leaves a range of tools useable by vector control services. Both metabolic and target-site resistance mechanisms were identified. Different esterases of high activity including A2-B2, A4-B4 (and/or A5-B5) and B12 were observed in studied field samples using starch electrophoresis although opposite results were found using synergists tests on samples # 1 and 3. The polymorphism of AChE1 (Acetylcholinesterase) was analyzed and three phenotypes were detected: susceptible (ACHE1S, phenotype [SS]), resistant (ACHE1R, phenotype [RR]), and heterozygous (phenotype [RS]) of ACHE1. The resistance of Culex pipiens pipiens to pirimiphos-methyl remains low although the occurrences of multiple resistance mechanisms are able to confer high resistance levels to organophosphate insecticides. Therefore, continuous monitoring of resistance is fundamental for rational use of insecticides and mosquito control programs.

Characterization of resistance to pirimiphos-methyl (an organophosphate insecticide) in Culex pipiens pipiens (Diptera: Culicidae) from Northern and Southern Tunisia

@#Despite the public health importance of Culex pipiens pipiens, their resistance to pirimiphos-methyl insecticides has not been explored enough. Late third and early fourth larvae of Culex pipiens pipiens were collected from three localities between 2003 and 2005 in Northern and Southern Tunisia. All bioassays were carried out using pirimiphosmethyl and propoxur insecticides. Populations of Culex pipiens pipiens were susceptible, moderate and resistant to pirimiphos-methyl insecticide. Resistance to this compound ranged from 2.62 in sample # 2 to 19.9 in sample # 1. The moderate resistance (5.25) was recorded in sample # 3. Synergist’s tests showed that the resistance to pirimiphos-methyl was not affected by detoxification enzymes. However, biochemical assays showed the involvement of both metabolic (esterases) and target site (insensitive acetylcholinesterase) resistance mechanisms. The highest frequencies of the resistant phenotypes ([RS] and [RR]) (>0.74) were detected in the most resistant samples (#1). Four esterases enzymes including C1 encoded by the Est-1 locus and three esterases encoded by the Ester super locus: A2-B2, A4-B4 (or A5-B5, which has the same electrophoretic mobility) and B12 were detected. The highest (0.61) and the lowest (0.22) frequencies of these esterases were recorded in samples # 1 (Sidi Hcine) and # 2 (El Fahs) which recorded the highest and the lowest level of resistance, respectively. Monitoring of insecticide resistance should be evaluated regularly for management of vector control.

An observational study of the effectiveness of darbepoetin alpha administered in dialysis patients once every 2 weeks for 12 months.

AIMS: Erythropoiesis-stimulating agents (ESAs) are recommended for managing renal anemia. ALTERNATE is an observational study in European and Australian dialysis patients evaluating darbepoetin a (DA) once every 2 weeks (Q2W) in clinical practice. METHODS: Adult dialysis patients initiating treatment with DA Q2W were eligible regardless of previous/current ESA use. Data were collected 6 months before and 12 months after Q2W initiation. The primary endpoint was hemoglobin (Hb) concentration 12 months after initiation. RESULTS: A total of 6,112 patients were enrolled; 6,104 were eligible (87% hemodialysis, 12% peritoneal dialysis). Before initiation, 77.3%, 8.8%, and 7.8% of patients were receiving DA, epoetin beta, and epoetin alpha, respectively; 6% were ESA naïve. Mean (95% CI) Hb (g/dl) was 11.68 (11.63-11.72) 6 months before initiation, 12.00 (11.97-12.04) at initiation, and 11.62 (11.58-11.66) 12 months after initiation. Geometric mean (95% CI) weekly ESA dose (µg/wk) was 27.27 (26.62-27.93) immediately before initiation, 23.69 (23.28 - 24.10) at initiation, and 26.80 (26.12-27.49) 12 months after initiation. At month 12, 77.3% of patients were receiving DA Q2W. CONCLUSIONS: This large observational study demonstrates that Hb concentrations can be effectively maintained over 12 months in a general dialysis population with DA Q2W without an increase in ESA dose.

[The Veneto Region's Registry of Dialysis and Transplantation: 2006-2007 report]. / Registro Veneto di Dialisi e Trapianto - Report 2006-2007.

INCIDENCE: Five hundred and sixty patients began renal replacement therapy in 2006, giving an incidence of 117.51 pmp; in 2007 there were 579 new patients, for an incidence rate of 120.01 pmp. Analysis of the incidence between 1998 and 2007 for both raw and age-standardized data (based on the 2001 census) shows a slow, gradual increase that is statistically significant. Most of the patients were between 55 and 85 years old; the modal class for males was between 65 and 70, and between 75 and 80 for females. The median age of the population beginning replacement therapy is clearly over 65 years old. The year 2000 was particularly significant because the incidence of new patients undergoing renal replacement therapy over the age of 75 definitively exceeded that of the next younger class (65-74 years old), a trend that remained constant until 2007. In 2006 and 2007, males account for 64.4% and 66.4%, respectively, of new patients, a proportion that is constant over the years. The greater incidence of males is also to be found across the other age groups and tends to be even more noticeable in the oldest age class. Incidence by province is highly variable, however, there is a constant trend within provinces during these years, since the incidence in some provinces is lower than the regional average and higher in others. After adjusting for age, there are no significant differences in the incidence between provinces: the age structure of the population accounts for the variability of the incidence of terminal uremia across the Veneto provinces. The conditions most responsible for renal insufficiency requiring replacement therapy are vascular diseases, diabetes and nephropathies of unknown origin. Although diabetic and vascular nephropathies are subject to wide fluctuations, they remain stable over the years, whereas the frequency of nephropathy of unknown origin appears to be on the rise. The first treatment for most of the patients is hemodialysis. In 2006, 436 patients (78%) were given extracorporeal dialysis as first treatment, compared to 122 patients (22%) who were given peritoneal dialysis and 2 (0.35%) who received live-donor kidney transplant. In 2007 the situation was very similar, with 435 patients treated with extracorporeal dialysis, 142 with peritoneal dialysis and 1 by a live-donor transplant. The proportion between patients treated with hemodialysis and peritoneal dialysis was constant from 1998 to 2007. The choice between hemodialysis or peritoneal dialysis as the initial treatment modality depends on many factors, ranging from clinical indications to cultural attitudes at the facility to individual patient preferences. Logistic regression of the factors influencing the choice of dialysis treatment shows that peritoneal dialysis is offered primarily to patients between the ages of 45 and 65 who do not have an underlying systemic or nephropathy of unknown origin and who do not have any comorbidities. This confirms the positive selection made with regard to these patients, widely described in the literature. Initial treatment by transplant is an exceptional event: starting from 2003, it was used in only 1 or 2 patients per year. Seventy-two percent of patients starting replacement therapy present with at least one comorbidity. Thirty-six percent of patients also present with more than one associated disease. The RVDT has been gathering data on the vascular access used for new dialysis patients since 2006. Roughly 43% of patients start treatment with an arteriovenous fistula, 38% with a temporary catheter, less than 1% with a prosthesis, 9% with a tunneled catheter, and 10% with a peritoneal catheter. Logistic regression was used to evaluate what role age, primary nephropathies and comorbidities present at the start of treatment play in determining the choice of a temporary catheter. The logistic model estimates a 29% probability of starting treatment with a temporary access. This probability decreases if the patient suffers from a familiar or hereditary nephropathy but increases if the patient has secondary glomerulonephritis or is affected by a group of various diseases (multiple myeloma or other pathologies) or if the patient suffers at the same time from cardiac insufficiency or an infection. The estimated probability of starting hemodialysis with a mature fistula is 40%, but this figure diminishes significantly in female patients, if the patient has secondary glomerulonephritis, cardiac insufficiency or infections. PREVALENCE: As of December 31, 2006, there were 4,071 patients being treated with extracorporeal or peritoneal dialysis or by kidney transplant, leading to a prevalence of 852.82 patients pmp; as of December 31, 2007, there were 4,200 patients treated, with a corresponding prevalence of 869.14 pmp. The breakdown in prevalence by age group shows that the increase in prevalence is highly significant in the top two age classes, namely, between 65 and 75 years of age and over 75, while remaining negligible in the other classes. Between 1998 and 2007, the prevalence increased by 40% in patients over 75 and increased by 20% in the class of 65-to-75 year olds. The elderly contribute a greater weight in the renal replacement therapy population, reflected in the gradual increase of the median age of the prevalent population from 1998 to 2007. During 2006 and 2007, males made up 63.99% and 64.36% of the patients, respectively. This relative frequency mirrors the findings for incidence and is constant over the years. The distribution of primary diseases is very different in the prevalent population compared to findings in the incident patients. Primary glomerulonephritis, at fourth place among incident patients, is the most frequent disease in the prevalent population (although there is a clearly downward trend over the years). The percentages of diabetes and vascular disease, on the other hand, are lower compared to what is observed in the incident population. The prevalence expressed by treatment modality pmp increased for all three types. In analyzing the annual percentage rise in prevalence, using 1998 as the baseline, the most significant figure regards transplant patients, whose prevalence increased by over 60% between 1998 and 2007. Prevalence of hemodialysis patients rose moderately by only slightly over 10%. Peritoneal dialysis shows a rather linear increase, similar to the transplant trend. Our study used longitudinal regression models to analyze factors predictive of a patient starting and continuing to undergo the same type of treatment over the years. The results show that a patient has a greater probability of being treated with hemodialysis based on several primary nephropathies, when aged > 45, and in the presence of the main comorbidities. The predictive factors for peritoneal dialysis mentioned earlier have a diametrically opposed role. The presence of comorbidities (except high blood pressure), the type of nephropathy, and age > 65 lead to a lower probability of receiving a transplant. We analyzed peritoneal dialysis failures - defined as changing over to extracorporeal dialysis for any reason (clinical, psychological or social) - and the cumulative incidence of failure, taking into account the two competing outcomes of transplant and death. The only variable associated with peritoneal dialysis failure was the presence of infections. Older patients, patients with peripheral vascular disease, and those with neoplasia are less frequently taken off peritoneal dialysis to receive a transplant, an event occurring more frequently, however, in patients with hypertension. Death is dependent on age, on the presence of peripheral vascular disease and is less frequent in hypertensives. As is the case for peritoneal dialysis, the natural history of kidney transplant can have two competing outcomes: return to dialysis and death. The risk factors associated with return to dialysis are the presence of peripheral vascular disease, hypertension and infections; risk factors associated with death include age, the presence of cerebral vascular disease and neoplasia. From 1998 to 2007, the prevalence of hepatitis C virus-antibody-positive patients decreased by almost one third. The number of antigen-positive hepatitis B patients is declining slowly, but the levels remain in any case very low. The association between the two infections is disappearing: already at very low levels in 1998, that figure was halved by 2007. MORTALITY AND SURVIVAL: The mortality of uremic patients on renal replacement therapy was calculated both as a cumulative incidence, expressed as the number of deaths over patients at risk (alive at the beginning of the study year) and as a mortality rate, expressed as the number of deaths per patients/year. The figure was constant over the years, at around 10%. The mortality of males was no different from that of females; this finding differs from what is observed in the general population where male mortality is markedly higher than that of females. The mortality rate is dependent on the age group of the patient at start of treatment and shows an upward trend that is growing exponentially. The mortality rate in hemodialysis patients remained stable at 15% between 2000 and 2007, while the mortality rate in peritoneal dialysis patients gradually decreased down to 13%. The mortality rate for transplant patients was low and constant, at under 2%. The trend for the various causes of death is stable over the years and shows that the main cause of death is cardiac, accounting for between 30% and 35%, while mortality due to vascular, neoplastic, infection or cachexia-related causes are all roughly at the same rate, between 10% and 15%. (ABSTRACT TRUNCATED)

[Reliability of administrative databases in epidemiological research: the example of end-stage renal disease requiring renal replacement therapy in patients with diabetes]. / Attendibilita' dei database amministrativi nelle indagini epidemiologiche in ambito nefrologico: il caso dell'insufficienza renale che necessita terapia sostitutiva nella popolazione diabetica.

Health and administrative databases are widely used in epidemiology, mostly in studies of chronic diseases, but biases may undermine the external validity of the results. In nephrology, the use of these data sources is in its early days and needs to be validated. The aim of this study was to compare the data on the incidence of ESRD and death in a cohort of patients with type 2 diabetes (DM2) obtained from administrative databases with the results of a traditional, well-performed cohort study. The study was conducted in the Health District of Venice (Italy) on a cohort of 18,416 DM2 patients on hypoglycemic drug therapy enrolled from 1 January 1998 to 31 December 2002 from administrative databases.Comorbid conditions were recorded from hospital discharge records, the database of death certificates was used to identify patients who died within 31 December 2004, and the database of the Dialysis and Transplantation Registry of the Veneto Region served to identify patients who started renal replacement therapy within 31 December 2004. Record linkage was performed using the unique personal identification codes (fiscal number) of Italian citizens. The cumulative incidence of ESRD was estimated using Gray's method for competing risks. The mortality rate was 50.95 per 1000 person-years, the ESRD incidence was 0.68 per 1000 person-years, with a relative risk of 2.62 with respect to all other causes of ESRD. The crude cumulative incidence of death was 22% and that of ESRD 0.33% at the end of follow-up. The results were similar to those obtained in traditional cohort studies. The results of our study prove the external validity of the administrative database approach in epidemiological studies in nephrology.

[Biocompatible fluids for peritoneal dialysis: do they have a clinical impact?]. / Le soluzioni biocompatibili per dialisi peritoneale hanno un impatto clinico?

The bioincompatibility of conventional peritoneal dialysis fluid may be responsible for short- and long-term damage to the peritoneal membrane. New, more biocompatible fluids are now commercially available and convincing results have been obtained in surrogate markers for the viability and function of peritoneal resident cells. However, these fluids have not yet proved to have clinical effects such as better preservation of peritoneal membrane morphology and function. Several randomized studies have recently demonstrated clinically relevant systemic benefits, including improvement or preservation of the residual renal function and a decrease in serum AGE levels. In addition, a retrospective observational study has suggested better patient survival with the use of biocompatible peritoneal dialysis fluid as compared with conventional fluid. These achievements still have to be considered preliminary; however, they may eventually result in the adoption of the new fluids as the gold standard for peritoneal dialysis.

[Antimicrobial agents for preventing peritonitis in peritoneal dialysis: guideline from the Italian Society of Nephrology]. / Strategie antimicrobiche per la prevenzione delle peritoniti in dialisi peritoneale: Linea Guida.

BACKGROUND: The current 3rd edition of the Italian Society of Nephrology guidelines has been drawn up to summarize evidence of key intervention issues on the basis of systematic reviews (SR) of randomized trials (RCT) or RCT data only. The present guideline reports evidence of the use of antimicrobial agents for preventing peritonitis in peritoneal dialysis (PD). METHODS: SR of RCT and RCT on treatments aiming at preventing peritoneal dialysis peritonitis were identified referring to a Cochrane Library and Renal Health Library search (2005 update). Quality of SR and RCT was assessed according to current methodological standards. RESULTS: One SR and 19 RCT were found addressing this issue. Staphylococcus Aureus nasal carriage treatment with mupirocin reduces exit-site and tunnel infections but not peritonitis. Topical gentamicin treatment on the exit site reduces Staphylococcus Aureus infection and peritonitis incidence. Intravenous antibiotics administration prior to catheter placement significantly reduces the risk of early peritonitis but not exit-site and tunnel infections. Oral nistatin associated with antibiotic treatment significantly reduces the incidence of Candida peritonitis. No other prophylaxis measure seems to be effective based on available evidence. CONCLUSION: In patients on peritoneal dialysis current evidence supports the hypothesis that topical mupirocin reduces the risk of Staphylococcus Aureus peritonitis, intravenous antibiotics prior to catheter placement prevent the risk of early peritonitis, and oral nistatin reduces the risk of Candida peritonitis. Further studies are necessary to test the effectiveness of other interventions.

[Catheter-related interventions to prevent peritonitis in peritoneal dialysis: guideline from the Italian Society of Nephrology]. / Strategie correlate al catetere per la prevenzione delle peritoniti in dialisi peritoneale: Linea Guida.

BACKGROUND: The current 3rd edition of the Italian Society of Nephrology guidelines has been drawn up to summarize evidence of key intervention issues on the basis of systematic reviews (SR) of randomized trials (RCT) or RCT data only. The present guideline report evidence of catheter-related interventions to prevent peritonitis in peritoneal dialysis (PD). METHODS: SR of RCT and RCT of catheter-related interventions to prevent peritonitis in PD were identified referring to a Cochrane Library and Renal Health Library search (2005 update). RESULTS: Two SR and 17 RCT were found addressing this issue. Methodological quality of available RCT was suboptimal according to current methodological standards. The use of the Y-set systems with disinfectant and the twin-bag systems was associated with a significantly lower risk of peritonitis. No other catheter-related interventions were found to be of proven efficacy in preventing the risk of peritonitis and exit-site/tunnel infection in PD patients. CONCLUSION: It is still unknown whether any particular PD catheter design or implantation technique are effective to prevent peritonitis in patients on peritoneal dialysis. Further studies are necessary to test the effectiveness of new interventions.

[Treating peritonitis in peritoneal dialysis: guideline from the Italian Society of Nephrology]. / Terapia iniziale della peritonite in dialisi peritoneale: Linea Guida.

BACKGROUND: The current 3rd edition of the Italian Society of Nephrology guidelines has been drawn up to summarize evidence of key intervention issues on the basis of systematic reviews (SR) of randomized trials (RCT) or RCT data only. The present guideline reports evidence of interventions to treat peritonitis in peritoneal dialysis (PD). METHODS: SR of RCT and RCT on treatments for peritoneal dialysis peritonitis were identified referring to a Cochrane Library and Renal Health Library search (2005 update). Quality of SR and RCT was assessed according to current methodological standards. RESULTS: Thirty-six RCT were found addressing the intervention issue. Vancomycin or first generation cephalosporins may be used for treating peritoneal dialysis peritonitis due to Gram-positive agents. Third-generation cephalosporins or amino-glycosides may be used for Gram-negative agents peritonitis. Association of first-generation cephalosporins and agents against Gram-negative bacteria via the intraperitoneal route represents the most frequently used approach. Intraperitoneal administration of antibiotic agents is the most effective treatment of peritoneal dialysis peritonitis. Intermittent administration may be preferred to continuous administration of antibiotic agents in peritoneal dialysis peritonitis. CONCLUSION: In peritoneal dialysis peritonitis current evidence supports the hypothesis that intraperitoneal administration of antibiotics agents and intermittent administration may be preferred to other routes of administration and continuous administration. Further studies are necessary to test this hypothesis in selected patient populations.

Effectiveness of a cognitive rehabilitation program in mild dementia (MD) and mild cognitive impairment (MCI): a case control study.

Data support the evidence that neuropsychological rehabilitation is effective in Alzheimer disease (AD), to strengthen the pharmacological treatment to delay the progression of dementia. At moment, a few studies have examined the efficacy of non-pharmacological treatment in MCI. This is a controlled study that assesses the effectiveness of neuropsychological rehabilitation on cognitive and behavioral symptoms and functional status in a group of community-dwelling subjects with MCI and MD. Our results demonstrate that a systematic rehabilitation, that provides a computerized cognitive program training, produces an improvement in cognitive and affective status of patients with MCI and MD, while a rehabilitation program not providing a punctual stimulation of cognitive functions, does not have significant effects.

Acid-base balance in peritoneal dialysis.

In patients without functioning kidneys, alkali replenishment is accomplished by the addition, via dialysis solution, of either HCO 3 - itself or a metabolic precursor of this anion, such as lactate. The body base balance in peritoneal dialysis (PD) patients is self-regulated by the feedback between plasma bicarbonate concentration and dialytic base gain. Dialytic base gain is the only source of buffer for PD patients and this gain should counteract the metabolic acid production. Dialytic base gain depends on peritoneal buffer fluxes (lactate reabsorption minus bicarbonate lost). The plasma bicarbonate level is determined by the dialytic base gain and the metabolic acid production. Bicarbonate buffered PD solution provides some advantages over the conventional lactate buffered PD solution.

Use of different buffers in peritoneal dialysis.

A buffer is included in the peritoneal dialysis solution in order to offset the hydrogen ions normally produced during the metabolic processes. Nowadays, the buffer used is lactate, and its concentration in conventional peritoneal dialysis fluids is 35 or 40 mmol/L. Despite the general thought that peritoneal dialysis adequately corrects uremic acidosis, several studies have demonstrated that more than 50% of patients present mild to moderate acidosis with the solution containing 35 mmol/L of lactate, although with a 40 mmol/L solution this percentage decreases, a substantial number of patients still remain acidotic. This acid-base derangement is characterized by a normal pH and a below-normal plasma bicarbonate concentration, although the external body base balance is in equilibrium. There is evidence that this condition contributes to uremic osteodystrophy and has a detrimental effect on protein metabolism. Conventional solutions also affect mesothelial cell viability and local leukocyte function and have potential systemic effects such as the impairment of cellular redox state. New solutions containing pure bicarbonate or a mixture of bicarbonate and lactate have recently been investigated. A bicarbonate solution containing 34 mmol/L significantly increased plasma bicarbonate levels as compared with the lactate 35 mmol/L solution. It has been demonstrated that bicarbonate solutions have better biocompatibility than the lactate buffered solution and substantially reduce abdominal discomfort experienced by a certain percentage of patients during the solution infusion. These studies demonstrated that the bicarbonate-buffered CAPD solution is safe, well-tolerated, and does not present any, even potential, side effects. Thus, it seems reasonable to consider the bicarbonate buffered solution the standard instead of the alternative, and it might entirely replace lactate as buffer in peritoneal dialysis fluid.