Organ donor screening for carbapenem-resistant gram-negative bacteria in Italian intensive care units: the DRIn study.

The 759 cases of brain death declaration (BDD [Italian law, 6 hours of observation time]) that occurred in 190 Italian intensive care units (ICUs) between May and September 2012 were studied to quantify carbapenem-resistant gram-negative bacteria (CR-GN) isolated in organ donors, to evaluate adherence to national screening guidelines, and to identify risk factors for CR-GN isolation. Mandatory blood, bronchoalveolar lavage, and urine cultures were performed on the BDD day in 99% of used donors. Because results were rarely made available before transplant, >20% of transplants were performed before obtaining any microbiological information, and organs from 15 of 22 CR-GN cases were used. Two (lung-liver) of the 37 recipients died, likely because of donor-derived early CR-GN sepsis. ICU stay >3 days (odds ratio [OR] = 7.49, P = .004), fever (OR = 3.11, P = .04), age <60 years (OR = 2.80, P = .06), and positive ICU epidemiology (OR = 8.77, P = .07) were associated with CR-GN isolation. An association between single ICU and risk of CR-GN was observed, as a result of differences across ICUs (ICC = 29%; 95% confidence interval [CI] 6.5%-72%) probably related to inadequate practices of infection control. Continuous education aimed at implementing priority actions, including stewardship programs for a rational use of antimicrobials, is a priority in healthcare systems and transplant networks. Improved awareness among ICU personnel regarding the importance of early CR-GN detection and timely alert systems might facilitate decisions regarding organ suitability and eventually save recipient lives.

Physical activity and renal function in the Italian kidney transplant population.

BACKGROUND: The well-documented benefits of physical activity (PA) are still poorly characterized in long-term kidney transplant outcome. This study analyzed the impact over a 10-year follow-up of PA on graft function in Italian kidney transplant recipients (KTRs). METHODS: Since 2002, the Italian Transplant-Information-System collected donor and recipient baseline and transplant-related parameters in KTRs. In 2015, 'penchant for PA' (PA ≥ 30-min, 5 times/week) was added. Stable patients aged ≥18 years at the time of first-transplantation were eligible. KTRs with at least 10-year follow-up were also analyzed. Mixed-effect regression models were used to compare eGFR changes over time in active versus non-active patients. RESULTS: PA information was available for 6,055 KTRs (active 51.6%, non-active 48.4%). Lower penchant for PA was found in overweight and obese patients (OR = 0.84; OR = 0.48, respectively), in those with longer dialysis vintage (OR = 0.98 every year of dialysis), and older age at transplant. Male subjects showed greater penchant for PA (OR = 1.25). A slower decline of eGFR over time was observed in active KTRs compared to non-active, and this finding was confirmed in the subgroup with at least 10-year follow-up (n = 2,060). After applying the propensity score matching to reduce confounding factors, mixed-effect regression models corroborated such better long-term trend of graft function preservation in active KTRs. CONCLUSIONS: Penchant for PA is more frequent among male and younger KTRs. Moreover, in our group of Italian KTRs, active patients revealed higher eGFR values and preserved kidney function over time, up to 10-years of follow-up.

Longitudinal Analysis of Cardiovascular Risk Factors in Active and Sedentary Kidney Transplant Recipients.

Background: Despite the benefits of physical activity on cardiovascular risk in kidney transplant recipients (KTRs), the long-term effects of exercise have been poorly investigated. This is a three-year observational study comparing graft function and cardiovascular risk factors in active KTRs (AKTRs) vs. sedentary KTRs (SKTRs). Methods: KTRs with stable renal function were assigned to active or sedentary group in relation to the level of daily physical activity based on World Health Organization (WHO) recommendations (<150 or >150 minutes/week, respectively). Complete blood count, renal function indices, lipid profile, blood pressure and anthropometric measures were collected yearly for an observation period of three years. The comparisons between the two groups were performed by repeated measures analyses of covariance (ANCOVAs), with age as a covariate. Results: Fifty-four subjects were included in the study. Thirty of them were identified as AKTRs (M/F 26/4, aged 45 ± 12 years) and 24 as SKTRs (M/F 18/6, aged 51 ± 14 years). Baseline characteristics were similar between the groups except body mass index (BMI) that was significantly higher in SKTRs (p = 0.043). Furthermore, over the three-year observation period, BMI decreased in AKTRs and increased in SKTRs (p = 0.006). Graft function was stable in AKTRs, while it showed a decline over time in SKTRs, as indicated by the rise in serum creatinine levels (p = 0.006) and lower eGFR (p = 0.050). Proteinuria, glucose and uric acid levels displayed a decrease in AKTRs and an increase in SKTRs during the three-year period (p = 0.015, p = 0.004 and p = 0.013, respectively). Finally, concerning lipid profiles, AKTRs had a significant reduction over time of triglycerides levels, which conversely showed a clinically relevant increase in SKTRs (p = 0.014). Conclusions: Our findings indicate that regular weekly exercise training may counteract the increased cardiovascular risks and also prevent graft function decline in KTRs.

A national mandatory-split liver policy: A report from the Italian experience.

To implement split liver transplantation (SLT) a mandatory-split policy has been adopted in Italy since August 2015: donors aged 18-50 years at standard risk are offered for SLT, resulting in a left-lateral segment (LLS) graft for children and an extended-right graft (ERG) for adults. We aim to analyze the impact of the new mandatory-split policy on liver transplantation (LT)-waiting list and SLT outcomes, compared to old allocation policy. Between August 2015 and December 2016 out of 413 potentially "splittable" donors, 252 (61%) were proposed for SLT, of whom 53 (21%) donors were accepted for SLT whereas 101 (40.1%) were excluded because of donor characteristics and 98 (38.9%) for absence of suitable pediatric recipients. The SLT rate augmented from 6% to 8.4%. Children undergoing SLT increased from 49.3% to 65.8% (P = .009) and the pediatric LT-waiting list time dropped (229 [10-2121] vs 80 [12-2503] days [P = .045]). The pediatric (4.5% vs 2.5% [P = .398]) and adult (9.7% to 5.2% [P < .001]) LT-waiting list mortality reduced; SLT outcomes remained stable. Retransplantation (HR = 2.641, P = .035) and recipient weight >20 kg (HR = 5.113, P = .048) in LLS, and ischemic time >8 hours (HR = 2.475, P = .048) in ERG were identified as predictors of graft failure. A national mandatory-split policy maximizes the SLT donor resources, whose selection criteria can be safely expanded, providing favorable impact on the pediatric LT-waiting list and priority for adult sick LT candidates.

The effect of differing kidney disease treatment modalities and organ donation and transplantation practices on health expenditure and patient outcomes.

The Effect of Differing Kidney Disease Treatment Modalities and Organ Donation and Transplantation Practices on Health Expenditure and Patient Outcomes (EDITH) aims to obtain information on long-term kidney transplant outcomes, long-term health outcomes of living kidney donors and detailed outcomes and costs related to the different treatment modalities of end-stage kidney disease. Nine partners from seven European Union countries will participate in this project.

Infections in liver and lung transplant recipients: a national prospective cohort.

Infections are a major complication of solid organ transplants (SOTs). This study aimed to describe recipients' characteristics, and the frequency and etiology of infections and transplant outcome in liver and lung SOTs, and to investigate exposures associated to infection and death in liver transplant recipients. The study population included recipients of SOTs performed in Italy during a 1-year period in ten Italian lung transplant units and eight liver transplant units. Data on comorbidities, infections, retransplantation, and death were prospectively collected using a web-based system, with a 6-month follow-up. The cumulative incidence of infection was 31.7% and 47.8% in liver and lung transplants, respectively, with most infections occurring within the first month after transplantation. Gram-negatives, which were primarily multidrug-resistant, were the most frequent cause of infection. Death rates were 0.42 per 1000 recipient-days in liver transplants and 1.41 per 1000 recipient-days in lung transplants. Infection after SOT in adult liver recipients is associated to an increased risk of death (OR = 13.25; p-value < 0.001). Given the frequency of infection caused by multidrug-resistant microorganisms in SOT recipients in Italy and the heavy impact of infections on the transplant outcome, the reinforcement of surveillance and control activities to prevent the transmission of multidrug-resistant microorganisms in SOT recipients represents a priority. The implementation of the study protocol in liver and lung transplant units and the sharing of results have increased the awareness about the threat due to antimicrobial resistance in the country.

Organ transplantation from "increased infectious risk donors": the experience of the Nord Italia Transplant program - A retrospective study.

The purpose of this study was to assess the safety and the clinical outcome associated with organ transplantation from increased infectious risk donors (IRD). We retrospectively identified all adult deceased IRD referred to the Nord Italia Transplant program coordinating center from November 2006 to November 2011. All potential donors were screened for social risk factors that may increase the risk of donor-derived infection with human immunodeficiency (HIV), hepatitis B virus (HBV), or hepatitis C virus (HCV). All recipients were followed monthly for the first 6 months post-transplant. A total of 86 potential IRD were identified during the study period. Three hundred and seventy-nine organs from IRD were offered to the transplant centers, but only 185 (48.8%) were used for transplantation. Organs from IRD were transplanted into 174 recipients. The complete follow-up data were available for 152 of 174 (87.3%) recipients. During a mean follow-up of 11.7 months (median 12; range 2.4-12), no transmission of HIV, HBV, or syphilis was documented by serology and nucleic acid testing (NAT) testing. Two patients transplanted with organs from HCV-RNA-positive donors, as expected, developed post-transplant HCV infection. In conclusion, the use of organs from IRD was associated with a safe increase in the transplant procedures in our country.

Renal transplantation in sensitized children and young adults: a nationwide approach.

Background: High levels of preformed anti-HLA antibodies dramatically diminish renal transplant outcomes. Most desensitization programmes guarantee good intermediate outcomes but quite disappointing long-term prognosis. The search for a fully compatible kidney increases time on the waiting list. Methods: In February 2011, a nationwide hyperimmune programme (NHP) was begun in Italy: all available kidneys are primarily proposed to highly sensitized patients with a panel reactive antibody above 80%. In this manuscript, we evaluate the outcome of paediatric patients transplanted with this approach. Results: Twenty-one patients were transplanted. Complete data are available for 20 patients. Mean age at transplantation was 14.5 years [standard deviation (SD) ± 5.5)]. Mean time on the waiting list was 29.3 months (SD ± 27.5). Median follow-up was 29.2 months (range: 11.2-59.3). The average number of HLA mismatches in these patients was 2.3 versus 3.7 in 48 standard patients transplanted in the same period (P < 0.001). Only one graft was lost. Two cases of humoral rejection occurred and were successfully treated. No cellular rejection was reported. Median creatinine clearance was 84, 88, 77 and 77 mL/min/1.73 m 2 respectively 1, 6, 12 and 24 months after transplant. Conclusions: Transplantation of sensitized patients avoiding prohibited antigens is feasible, at least in a selected cohort of patients. In order to be able to further improve this approach, which in our opinion is very successful, it would be necessary to expand the donor pool, possibly increasing the number of countries participating in the programme. In this series, time on the waiting list did not increase significantly. This allocation policy should ideally lead to an outcome comparable to that expected in standard patients, which is particularly desirable in young patients who have the longest life expectancy. Since long-term results of desensitization programmes are not (yet) convincing, we suggest that these programmes should be reserved for selected cases where compatible organs cannot be found within a reasonable time span.

From the EU Legislation to the Application of the Single European Code: Support to the Implementation.

The Italian National Transplant Centre (CNT) is coordinating with the Italian National Blood Centre (CNS) the Joint Action '!' (www.eurocet128.eu), already built the European Tissue Establishment and Tissue and Cell Product Compendia between 2011 and 2014 in order to provide European Member States with a tool which would grant traceability of tissues and cells at human transplant purpose across the European Union. The two compendia are available on an online platform hosted and managed by the European Commission.

Impact of cord blood banking technologies on clinical outcome: a Eurocord/Cord Blood Committee (CTIWP), European Society for Blood and Marrow Transplantation and NetCord retrospective analysis.

BACKGROUND: Techniques for banking cord blood units (CBUs) as source for hematopoietic stem cell transplantation have been developed over the past 20 years, aimed to improve laboratory efficiency without altering the biologic properties of the graft. A large-scale, registry-based assessment of the impact of the banking variables on the clinical outcome is currently missing. STUDY DESIGN AND METHODS: A total of 677 single cord blood transplants (CBTs) carried out for acute leukemia in complete remission in centers affiliated with the European Society for Blood and Marrow Transplantation were selected. An extensive set of data concerning CBU banking were collected and correlations with clinical outcome were assessed. Clinical endpoints were transplant-related mortality, engraftment, and graft-versus-host disease (GVHD). RESULTS: The median time between collection and CBT was 4.1 years (range, 0.2-16.3 years). Volume reduction (VR) of CBUs before freezing was performed in 59.2% of available reports; in half of these the frozen volume was less than 30 mL. Cumulative incidences of neutrophil engraftment on Day 60, 100-day acute GVHD (II-IV), and 4-year chronic GVHD were 87, 29, and 21 ± 2%. The cumulative incidence of nonrelapse mortality (NRM) at 100 days and 4-year NRM were, respectively, 16 ± 2 and 30 ± 2%. Neither the variables related to banking procedures nor the interval between collection and CBT influenced the clinical outcome. CONCLUSION: These findings indicate a satisfactory validation of the techniques associated with CBU VR across the banks. Cell viability assessment varied among the banks, suggesting that efforts to improve the standardization of CBU quality controls are needed.

Liver transplant recipients and prioritization of anti-HCV therapy: an Italian cohort analysis.

BACKGROUND AND AIMS: In patients with hepatitis C virus (HCV), recurrence of infection after liver transplant (LT) is universal and associated with worst survival. We present the results of an Italian cohort to compare the 3-year outcome of HCV-Ab-positive and HCV-Ab-negative LT recipients and to assess the potential interaction between HCV-Ab sero-status and other risk factors for LT failure. METHODS: The study is a multicentre cohort including a sample of liver transplant centres. Participant's information was collected at the local level. The best functional form of variables was decided according to the objective methods based on information theory. Association between transplant failure and potential risk factors was assessed in univariate and multivariate Poisson regression model with random intercept. RESULTS: Between June 2007 and May 2009, 1164 LT recipients were enrolled in 16 Italian transplant centres, of them 275 (23.63%) experienced LT failure. Incidence rates of LT failure was 0.32 and 0.23 per 1000 person-days in HCV-Ab-positive and HCV-Ab-negative recipients respectively (P = 0.003). Inferential models according to Akaike information criterion indicated that donor-recipient age difference and donor-recipient sex matching were more informative to predict LT failure than the age and the sex as separate variables. Multivariate analysis provided evidence that HCV-Ab sero-status, time after LT, donor-recipient age difference, donor-recipient sex matching and recipient's MELD score were significantly associated with LT failure. Moreover, the effect of HCV-Ab sero-status on LT failure was modified by the simultaneous action of time after LT and donor-recipient age difference. No interaction was found between recipient's HCV-Ab sero-status and either recipient's MELD or donor-recipient sex matching. CONCLUSION: In view of the imminent introduction of new anti-HCV therapies, our study provides information to assess which LT recipients should be prioritized for receiving these highly effective, but expensive, new treatments. This is particularly relevant for those clinical settings where healthcare prioritization is endorsed by national authorities.

Failure mode and effects analysis of witnessing protocols for ensuring traceability during IVF.

Traceability of cells during IVF is a fundamental aspect of treatment, and involves witnessing protocols. Failure mode and effects analysis (FMEA) is a method of identifying real or potential breakdowns in processes, and allows strategies to mitigate risks to be developed. To examine the risks associated with witnessing protocols, an FMEA was carried out in a busy IVF centre, before and after implementation of an electronic witnessing system (EWS). A multidisciplinary team was formed and moderated by human factors specialists. Possible causes of failures, and their potential effects, were identified and risk priority number (RPN) for each failure calculated. A second FMEA analysis was carried out after implementation of an EWS. The IVF team identified seven main process phases, 19 associated process steps and 32 possible failure modes. The highest RPN was 30, confirming the relatively low risk that mismatches may occur in IVF when a manual witnessing system is used. The introduction of the EWS allowed a reduction in the moderate-risk failure mode by two-thirds (highest RPN = 10). In our experience, FMEA is effective in supporting multidisciplinary IVF groups to understand the witnessing process, identifying critical steps and planning changes in practice to enable safety to be enhanced.

Health-related quality of life after solid organ transplantation: the role of sport activity.

The aim of the study was to investigate the effects of sport activity on health-related quality of life (HRQoL) of solid organ transplant recipients participating in sports competitions. A group of 168 sportive transplanted patients (STP), a group of 97 nonsportive transplanted patients (NSTP), and a group of 152 sportive healthy controls (SHC) were compared on the eight scales of the SF-36 questionnaire. STP and NSTP reported significantly lower scores than SHC on the physical functioning scale. STP did not differ from SHC in the Role-Physical, General Health, and Vitality scales, while NSTP reported significantly lower scores. STP obtained higher scores than NSTP and SHC on Mental Health. Among STP, the effect of quantity of sport activity was significant on General Health and Role Emotional, with more sport activity associated with higher HRQoL. Organ failure and post-transplant therapies may have negative consequences on HRQoL. Sports activities and participation in sports competitions can reduce this impact, improving general and psychological functioning of solid organ transplant recipients.

Heterogeneity of West Nile virus genotype 1a in Italy, 2011.

West Nile virus (WNV) is currently circulating in several European countries and, over recent decades, concomitantly with enhanced surveillance studies and improved diagnostic capabilities, an increase in the geographical distribution and in the number of cases in Europe has been documented. In Italy in 2011, 14 human cases of WNV neuroinvasive infections due to lineage 1 strains were registered in several Italian regions. Here we report WNV partial sequences obtained from serum samples of two patients living in different regions of Italy (Veneto and Sardinia). Phylogenetic analysis, performed on a fragment (566 nt) of the envelope gene, showed that WNV strains circulating in Italy in 2011 belong to lineage 1a, but are different from lineage 1a strains isolated in 2008-2009.The data reported here are consistent with the hypothesis of multiple recent introductions of WNV lineage 1a strains into Italy.

Effects of combined strength and endurance training on exercise capacity in kidney transplant cyclists and runners.

INTRODUCTION: After transplantation, engaging in regular physical activity (PA) or sport is recommended for health. Participation to competitive sports is increasingly common among kidney transplant recipients while little is known on how training affects the physical performance in transplanted athletes. AIM: The purpose of this case study was to assess the effects of a tailored training program on exercise parameters in kidney transplant cyclists (CKTRs) and runners (RKTRs). METHODS: Twelve male transplanted athletes were enrolled. The workload at aerobic and anaerobic thresholds, the submaximal aerobic power (V'O2 stage) and rate of perceived exertion (RPE) during an incremental cycling or running test, and the peak instantaneous force (PIF) during a countermovement jump were assessed at baseline (T0) and after 6 months of tailored training (T6) consisting in strength and aerobic exercises. Exercise adherence, blood lipid profile and renal function were also investigated. RESULTS: Eight CKTRs and 4 RKTRs completed the 6-month training period, with a significant increase of training volume (minutes/week). The exercise adherence was met by 90% in both groups. At T6, there were significant (p<0.05) improvements of maximum workload attained, the workload corresponding to the aerobic threshold and PIF, while workloads at anaerobic threshold, V'O2 stage and RPE were unchanged. Blood cholesterol significantly decreased (p<0.01), while the other blood parameters were unchanged. CONCLUSIONS: These findings indicate that the combined strength and endurance training is well tolerated and may improve exercise performance in this selected population of KTRs.

The EUROCET Network: Support for Coding, Vigilance and Surveillance.

BACKGROUND: In the last years, there have been increasing concerns about the safety and traceability of human tissues and cells in Europe. In order to regulate this part of medical practice, the European Commission issued 3 directives between 2004 and 2006 and endorsed EUROCET to support member states in fulfilling some of their obligations. MATHODS: EUROCET created a connection with the European Union (EU) Competent Authorities (CAs) and set up a website where lists of the CAs, the authorized Tissue Establishments (TEs) and the activity data are published and updated. Moreover, EUROCET is involved within the Vigilance and Surveillance of Substances of Human Origin (SOHO V&S) project, aiming to support the EU member states in the establishment of vigilance and surveillance systems for tissues and cells. EUROCET is also working with EU stakeholders to develop a common coding system concerning donation and products. RESULTS: There are 33 countries in EUROCET and 57 CAs. 3,974 TEs are recorded: 1,108 for tissues, 1,480 for haematopoietic progenitor cells and 1,386 for assisted reproduction. On the website, it is possible to find the 2010 activity data report. CONCLUSION: Based on its cooperation with the CAs, EUROCET represents them in the European network. Nowadays, the EU member states can rely on a web portal and database in order to put the tissue and cell directives into practice.

[Physical activity and renal transplantation]. / Attivita' fisica nei pazienti con trapianto di rene.

A sedentary lifestyle is an important risk factor leading to cardiovascular disease. Cardiovascular disease is particularly frequent in kidney transplant recipients, with a mortality rate of 38%. In this population, besides the classic risk factors (genetics, age, smoking, etc.) and disease-related factors (chronic renal failure, dialysis vintage) there are the side effects of immunosuppressive therapy such as diabetes and metabolic syndrome. Despite the general advice given on an appropriate lifestyle, most transplanted patients lead a sedentary life which may result in overweight. In this study the physiopathological effects of a sedentary lifestyle were analyzed with reference to the recent literature regarding the efficacy of physical activity in transplanted patients. Studies in the general population have demonstrated the beneficial effect of physical activity on the prevention of cardiovascular disease. There are only few studies within the kidney transplant population regarding regular physical activity and these studies were performed with heterogeneous protocols and different observation periods, and are therefore difficult to compare. Overall, positive results in terms of maximal aerobic capacity, muscle strength and perception of well-being have been obtained in the short and medium term (1 year). Further studies are necessary to verify the effect of physical activity on long-term patient and graft survival. In order to enhance physical activity in transplanted patients, local programs in collaboration with sports rehabilitation centers are to be recommended.

Bioelectrical impedance vector analysis (BIVA) in renal transplant recipients during an unsupervised physical exercise program.

BACKGROUND: Muscle weakness, incorrect body water distribution and reduced exercise tolerance are the main characteristics found in renal transplant recipients after surgical treatment. Regular physical supervised exercise programs, at moderate intensity, have been promoted to contrast these aspects, while few data are available for long-term unsupervised mixed exercise plans. Bioelectrical impedance vector analysis (BIVA) provides a semi-quantitative evaluation of body cell mass and body water. This study aims to approach the role of the BIVA analysis in the follow-up of Renal Transplant Group (RTG) and analyze the impact of unsupervised exercise program. METHODS: Thirteen male RTG and ten healthy subjects, adherent to a tailored exercise program, at moderate intensity and prescribed in an unsupervised way, have been followed up for one year. Every six months all the subjects have been submitted to the ergometric test, echocardiographic exam and an analysis of body composition by bioimpedance. They were compared to a healthy control group (HG). RESULTS: A significant reduction of the BMI was observed at the end of the study in the RTG group (T0 24.8±3.2, T12 24.2±3.2 kg/m2; P<0.05). BIVA has shown a lower right quadrant for RTG. All echocardiographic parameters were in a normal range, and no differences were found over time. CONCLUSIONS: Unsupervised tailored and mixed exercise intervention reduces some cardiovascular risks factors. However, it does not modify the frailty of RTG. BIVA analysis seems to have appropriate sensitivity to highlight this aspect.

Evaluation on the Use of Italian High-Speed Rail to Support Transportation Network for Transplantation Activities.

BACKGROUND: One of the main activities connected with transplantation is the rapid and timely transportation of patients, medical teams, and human organs from donation to transplantation centers under the compliance of national guidelines and principles of quality, performance, and safety. High-speed transportation on a railway network is becoming relevant both in terms of performance and extensiveness of the service. METHODS AND OBJECTIVES: Our study explores the feasibility of adopting a high-speed rail network for the transportation of those organs with large cold ischemia time and those less influenced by transportation-related perturbations (ie, temperature, speed, vibrations), assessing savings and relative performance improvement. In this study, only kidneys have been considered; the transplantation database has been integrated with the national high-speed railway network and timetables. A function is implemented that allocates to air transportations those records with 1 of the 2 ends situated on islands, remote regions, and abroad, while rail transportation is preferred where constraints on capacity and compliance with cold ischemia time are met. Road transportation is still feasible for those records involving 2 adjacent regions and for intraregional transportation. RESULTS: The opportunity of integrated road-rail transportation in place of air or all-road transportation allows users to lower generalized costs and reduce driven distance for personnel and vehicles allocated to a regional transplantation center's fleet and staff. Savings in fleet and staff usage can serve to improve the performances at the local level. CONCLUSIONS: The knowledge and analysis of transportation alternatives for human organs with less stringent safety and preservation criteria allow a more efficient allocation of resources both at the local and national level-without compromising quality and reliability of the system.