Safeguarding the retention of nurses: A systematic review on determinants of nurse's intentions to stay

AIM

To explore factors that influence registered nurses' intention to stay working in the healthcare sector.

DESIGN

A systematic review and narrative synthesis.

METHODS

CINAHL, Medline and Cochrane library databases were searched from Jan 2010 to Jan 2022 inclusive and research selected using a structured criterion, quality appraisal and data extraction and synthesis were guided by Campbell's Synthesis Without Meta-analysis.

RESULTS

Thirty-four studies identified that nurses stay if they have job satisfaction and/or if they are committed to their organizations. The factors permeating these constructs weigh differently through generations and while not an infallible explanation, demonstrate stark differences in workplace needs by age, which influence the intention to stay, job satisfaction, organizational commitment and ultimately nurse turnover.

PUBLIC CONTRIBUTION

Environmental, relational and individual factors have bearing on improving nurse satisfaction and commitment. Understanding why nurses stay through a generational behavioural and career stage lens can bolster safeguarding nurse retention.

Dissemination of sport-based psychosocial interventions in Europe: results from the EASMH project

Introduction

Among psychosocial interventions, recent studies have highlighted that sport-based interventions can positively impact on the long-term outcomes of patients with severe mental disorders, in terms of improving their quality of life and promoting social inclusion. Although sport-based interventions should be considered an effective strategy for promoting patients’ recovery, few data are available on their dissemination in the clinical routine care in Europe.

Objectives

to evaluate the availability of sport-based psychosocial interventions in European countries.

Methods

In the framework of the EU-Erasmus+, the European Alliance for Sport and Mental Health (EASMH) project has been funded. In order to evaluate the availability of sport-based interventions, an ad-hoc online survey, sent to national mental health centres, has been developed.

Results

103 responses were obtained (49 from Italy, 31 from UK, 17 from Finland and 12 from Romania). The respondents were mainly psychiatrists working in community mental health centers. Sport-based interventions were frequently provided by mental health services, in particular in Italy, UK and Finland. While in UK and Finland sport-based interventions are commonly offered to all patients, in the other countries these are provided only by patient’s request. The most frequent types of sport practised were: running, football, volleyball, tennis and table tennis and basketball. Almost all respondents reported to not use a dedicated monitoring tool for evaluating the efficacy of those interventions.

Conclusions

Sport-based interventions are not frequently provided in the routine clinical settings, although no monitoring tools are routinely adopted. The EASMHaims to fill this gap by disseminating good clinical practice related to sport-based interventions.

Disclosure

No significant relationships.

Explaining nursing attrition through the experiences of return-to-practice students: a mixed-methods study

BACKGROUND

Nurse shortage is an international issue that has adverse effects on health and the quality of care of whole populations.

AIMS

The study aimed to explore attrition experienced by return-to-practice students attending higher education institutions in England.

METHODS

A mixed-methods design, involving questionnaires (n=114) and in-depth interviews (n=20), was used.

FINDINGS

Just over half (52%) of respondents left nursing after ≥10 years. Most of these (84%) stayed in alternative employment during their break from nursing. There were two distinct reasons for leaving nursing: the inability to maintain a positive work/life balance and a lack of opportunity for career advancement while retaining nursing registration. Respondents reflected positively on their nursing experience yet frequently reported significant personal or professional incidents prompting their decision to leave.

CONCLUSION

The reasons nurses leave are complex. Professional bodies and managers need to work together to address concerns many nurses have during their careers that lead to them deciding to leave the profession.

Motivational interviewing to support modifiable risk factor change in individuals at increased risk of cardiovascular disease: A systematic review and meta-analysis

BACKGROUND

Programmes using motivational interviewing show potential in facilitating lifestyle change, however this has not been well established and explored in individuals at risk of, yet without symptomatic pre-existent cardiovascular disease. The objective of this systematic review and meta-analysis was to determine the effectiveness of motivational interviewing in supporting modifiable risk factor change in individuals at an increased risk of cardiovascular disease.

METHODS

Systematic review and meta-analysis with results were reported using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Health-related databases were searched for randomised controlled trials from 1980 to March 2020. Criteria for inclusion included; preventive programmes, motivational interviewing principles, modification of cardiovascular risk factors in adults of both genders, different ethnicities and employment status, and having at least 1 or more modifiable cardiovascular risk factor/s. Two reviewers independently extracted data and conducted a quality appraisal of eligible studies using an adapted Cochrane framework. The Cochrane framework supports to systematically identify, appraise and synthesize all the empirical evidence that meets the pre-specified eligibility criteria to answer a specific question.

FINDINGS

A total of 12 studies met the inclusion criteria. While completeness of intervention reporting was found to be adequate, the application of motivational interviewing was found to be insufficiently reported across all studies (mean overall reporting rate; 68%, 26% respectively). No statistical difference between groups in smoking status and physical activity was reported. A random effects analysis from 4 studies was conducted, this determined a synthesized estimate for standardised mean difference in weight of -2.00kg (95% CI -3.31 to -0.69 kg; p = 0.003), with high statistical heterogeneity. Pooled results from 4 studies determined a mean difference in LDL-c of -0.14mmol/l (5.414mg/dl), which was non-significant. The characteristics of interventions more likely to be effective were identified as: use of a blended approach delivered by a nurse expert in motivational interviewing from an outpatient-clinic. The application of affirmation, compassion and evocation, use of open questions, summarising, listening, supporting and raising ambivalence, combining education and barrier change identification with goal setting are also important intervention characteristics.

CONCLUSIONS

While motivational interviewing may support individuals to modify their cardiovascular risk through lifestyle change, the effectiveness of this approach remains uncertain. The strengths and limitations of motivational interviewing need to be further explored through robust studies.

Care bundles in the management of a COPD exacerbation

Chronic obstructive pulmonary disease (COPD), the umbrella term used to describe chronic lung diseases that cause limitations in lung airflow, is predicted to be the third leading cause of death by 2030. COPD is said to affect 3 million people in the UK, resulting in approximately 30 000 deaths each year. Related healthcare costs continue to escalate, not least because of increasing readmission rates associated with COPD emergencies. The use of care bundles to streamline care is becoming more popular in an attempt to tackle this issue. An integrative literature review was carried out to examine the effectiveness of the use of care bundles. The findings highlighted inconsistencies in the components of bundles, leading to inherent difficulties in assessing which specific component of the bundles led to positive outcomes. The results of this attempt to establish the effectiveness of care bundles in reducing readmission rates and quality of care were inconclusive. The authors recommend further research to investigate the individual components in the bundles and to introduce internationally agreed care bundles for the management of COPD.

Critical care outreach: A valuable resource?

BACKGROUND

Critical Care Outreach Services (CCOS) were recommended by the Department of Health in the United Kingdom in 2000. Despite being an established service, research studies have not explicitly demonstrated its efficacy.

AIM AND OBJECTIVES

To explore the impact of CCOS from the perspective of hospital ward staff to inform service improvement potential.

DESIGN

A pilot formative process evaluation was used to meet the study aims, including the development of a self-completion questionnaire.

METHODS

The exploratory questionnaire was distributed to a purposive sample of clinical staff (health care assistants, nurses, therapists, and doctors) on two medical and two surgical wards to establish the value of CCOS from the perspective of ward staff.

RESULTS

The questionnaire was distributed to 195 staff members, of who 58 replied (30%). A descriptive analysis of quantitative data and content analysis of free-text responses demonstrated that staff knew how and when to use the service, that it was highly valued by all members of the multidisciplinary team, and that CCOS were perceived to have diverse responsibilities. Service improvement suggestions included increased staffing and longer hours of operation.

CONCLUSIONS

Despite the lack of quality research supporting the efficacy of CCOS in previous research studies, the results of this project support the findings of previous evaluations that the value of the service lies in the support offered to ward staff and in the quality of care provided to patients.

RELEVANCE TO CLINICAL PRACTICE

Because of the size of this evaluation, it was impossible to draw any generalizable conclusions. However, results clearly indicate that value is given to the support that the Critical Care Outreach Service provides to ward staff.

The perioperative Team Brief: A patient safety initiative or another tick-box exercise?

The World Health Organization Surgical Safety Checklist has been the subject of many professional discussions following its introduction in 2008. Since the addition of the Team Brief and Debrief in 2010 and the acceptance of the Five Steps to Safer Surgery as the gold standard, compliance has steadily improved (as audited by Care Quality Commission Inspections). This review of the literature therefore examined the perioperative Team Brief and identified gaps in knowledge. Evidence appears to suggest that whilst compliance is good in quantitative terms, there may be inconsistencies within the quality of Team Briefs from organisation to organisation and surgeon to surgeon. Concluding further research is required to establish what an effective Team Brief looks, sounds and feels like to all involved.

Effects of the Care Certificate on healthcare assistants' ability to identify and manage deteriorating patients

The Care Certificate, launched in England in 2015, safeguards patients by ensuring all new healthcare assistants (HCAs) undertake a structured educational programme so that they can provide appropriate, safe and high standards of care in clinical settings. This article describes a service evaluation that aimed to identify the effects of the Care Certificate on HCAs' confidence and ability to identify, and initiate management of, unwell patients independently.

Emergency health education in a conflict stricken environment: A situational analysis

Introduction

Bosasso General Hospital is located in Puntland Somalia, an area affected by prolonged civil conflict, terrorism, clan fighting and piracy. International evidence highlights that staff skills and competence may have a significant impact on patient outcomes however there has been little research on emergency education in such an austere and volatile environment. The purpose of this study therefore was to identify current practices and gaps in delivering emergency medicine education in this resource-deprived environment.

Methods

A mixed methods approach was adopted to inform convergent parallel data collection techniques including questionnaire (n = 16), key informant (n = 5) and focus group interviews (n = 16). Data analysis, following data triangulation, produced descriptive quantitative statistics of themes such as emergency care, educational provision, enablers and barriers.

Results

The research showed that among health care staff at the hospital, 19% of the nurses felt that visiting nurses offer some knowledge on emergency care, while 38% of knowledge was gained from visiting doctors. Regarding knowledge of emergency medicine, 88.9% of the nurses felt that emergency medicine is basically first aid.

Discussion

Emergency care was perceived by the majority as essentially ‘first aid’. Many indicated that they received little or no regular or formal training on emergency care and related essential topics. In terms of challenges faced in delivering emergency care education demonstrated a common factor in the limited resources available which included lack of teaching materials, reading materials, online resources, health care professionals, equipment and mentors. Conclusions drawn suggest that the knowledge of emergency medicine by front line professionals is limited. Therefore, the development of field curricula, practical and theoretical training by visiting practitioners, provision of additional teaching aids, tools and equipment, integration of multiple disciplines in training and financial resource mobilisation would be beneficial in improving knowledge, attitudes and practices of emergency care.

Changing operating lists on the day of surgery: a service evaluation

This study aims to explore how often the operating list is changed on the day of surgery and the reasons why this may occur. The purpose was to analyse the wider potential impact that changing the list on the day of surgery may have on patient safety, patient satisfaction and theatre efficiency. Survey data was collected across a multi-specialty elective operating department. The findings demonstrated that a significant change in operating lists occurred in 37.3% of sessions, for a variety of potentially avoidable reasons. We concluded that improved organisation and communication before the planned session could reduce the occurrence of changes, thereby increasing patient safety, theatre efficiency and potentially reducing incidents.

Sedation and its psychological effects following intensive care

Significant psychological impacts, including post-traumatic stress disorder (PTSD), have been associated with patients under sedation in intensive care units (ICUs). However, it remains unknown if and how sedation is related to post-ICU psychological outcomes. This literature review explores the relationships between sedation, the depth of sedation and psychological disorders. A review of existing literature was undertaken systematically with key terms and included peer-reviewed primary research and randomised controlled trials (RCTs). To ensure subject relevance pre-2006, non-English and paediatric-based research was excluded. Findings highlighted that reduced sedation levels did not significantly reduce the outcome of PTSD, yet reduced ICU length of stay and length of mechanical ventilation (MV) were both associated with lighter sedation. Further research is recommended into more specific factual and delusional memories post ICU in relation to the level of sedation and to psychological distress.

Investigating perceptions of the academic educational environment across six undergraduate health care courses in the United Kingdom

AIM

To compare how health care professional students perceive their academic learning environment in one Higher Education Institution (HEI).

METHOD

The Dundee Ready Education Environment Measure (DREEM), a scale that measures students' perceptions of their academic classroom learning environments, and demographic items were completed by 673 undergraduate students enrolled in health professional courses at the University of Huddersfield, United Kingdom. Respondent scores, partitioned by demographic variables, were obtained on the total DREEM scale and on the individual sub-scales. Analysis of variance techniques were utilized to investigate associations between demographic variables on the total DREEM score and sub-scale scores.

RESULTS

All students from all year levels reported total DREEM scores between 101 - 150, indicating a more positive than negative perception of their academic learning environments. Both profession and year of study were found to be significantly associated with total DREEM scores, with occupational therapists, physiotherapists and nurses scoring higher than operating department practice students; and first year students scoring higher than third year students. A significant interaction between these two factors was found to exist, indicating that the impact of the year of study does not apply equally over the different professional groups of students.

CONCLUSIONS

Students in this study reported positive perceptions about their academic classroom learning environments and teaching delivered. Further interrogation of the DREEM sub-scale dimensions at a programme/cohort level may offer course teams' further information to inform continuous quality improvement.

Utilities for advanced basal cell carcinoma

OBJECTIVE

Most incidences of basal cell carcinoma are cured by a number of surgical or non-surgical treatments. However, a few patients have lesions which have metastasized or progressed to an extent that surgery or other treatment options are not possible. The lesions associated with advanced basal cell carcinoma (aBCC) can be disfiguring, affecting patients' psychological state, general quality-of-life (QoL), and potentially life expectancy. The objective of this study was to capture societal utility values for health states related to aBCC, using the time trade-off (TTO) methodology.

METHODS

Nine health states were developed with input from expert clinicians and literature. States included: complete response (CR), post-surgical, partial response (PR) (with differing sized lesions [2 or 6 cm]), stable disease (SD) (with differing size and number of lesions [2 or 6 cm, or multiple 2 cm]) and progressive disease (PD) (with differing sized lesions [2 or 6 cm]). A representative sample of 100 members of the UK general public participated in the valuation exercise. The TTO method was used to derive utility values based upon subjects' responses to decision scenarios; between living in the health state for 10 years or living in a state of full health for 10-x years.

RESULTS

Mean utility scores were calculated for each state. The least burdensome state as valued by subjects was CR (mean = 0.94; SD = 0.08), suggesting only a minimal impact on QoL. The state valued as having a greatest impact on QoL was PD, with a 6 cm lesion (mean = 0.67, SD = 0.25).

LIMITATIONS AND CONCLUSIONS

Not all possible presentations of aBCC were included; the disease is a challenging condition to characterise given its rarity, the nature of the patients affected, and its variable progression. Findings suggest that aBCC is associated with significant burden for individuals, even when their disease is stable or where surgical treatment has been successful.

Variation in the annual unsatisfactory rates of selected pathogens and indicators in ready-to-eat food sampled from the point of sale or service in Wales, United Kingdom

The Welsh Food Microbiological Forum "shopping basket" survey is a long running, structured surveillance program examining ready-to-eat food randomly sampled from the point of sale or service in Wales, United Kingdom. The annual unsatisfactory rates for selected indicators and pathogens for 1998 through 2008 were examined. All the annual unsatisfactory rates for the selected pathogens were <0.5%, and no pattern with the annual rate was observed. There was also no discernible trend observed for the annual rates of Listeria spp. (not moncytogenes), with all rates <0.5%. However, there was a trend observed for Esherichia coli, with a decrease in rate between 1998 and 2003, rapid in the first few years, and then a gradual increase in rate up to 2008. It was concluded that there was no discernible pattern to the annual unsatisfactory rates for Listeria spp. (not monocytogenes), L. monocytogenes, Staphylococcus aureus, and Bacillus cereus, but that a definite trend had been observed for E. coli.

Rethinking theory and practice: pre-registration student nurses experiences of simulation teaching and learning in the acquisition of clinical skills in preparation for practice

In the United Kingdom (UK) simulation learning has been recognised in the form of a regulatory agreement that may replace hours from clinical practice. This integration has become an embedded feature of the pre-registration nursing programme at a University in the North of England, along with strategic investment in staff and simulation suites developed to underpin this curriculum change albeit in the absence of sparse empirical evidence, hence the rationale for the study which was designed to explore the relationship between simulation, theory and practice. The study features a thematic analysis of evaluation questionnaires from pre-registration student nurses (n=>500) collected over a 2 year period which informed subsequent focus group interviews to explore the themes in more detail. Consistent data findings were the students' positive response to simulation as a learning approach facilitating the application of theory in a safe controlled environment. Students reported that they felt prepared for practice, recognising that simulated learning improved their humanistic and problem solving abilities as well as the development of psychomotor, technical skills, and overall confidence. The theory-practice gap is a recurring narrative in the nursing literature, the findings of this study recognises that simulation offers an opportunity to enact the integration of theory and practice illuminating this relationship in a controlled environment thus, reinforcing the theory-practice relationship for nursing students.

Prevalence of Listeria monocytogenes in ready-to-eat foods sampled from the point of sale in Wales, United Kingdom

A survey of Listeria in ready-to-eat food took place in Wales, United Kingdom, between February 2008 and January 2009. In total, 5,840 samples were taken and examined for the presence of Listeria species, including L. monocytogenes. Samples were tested using detection and enumeration methods, and the results were compared with current United Kingdom guidelines for the microbiological quality of ready-to-eat foods. The majority of samples were negative for Listeria by both direct plating and enriched culture. Seventeen samples (0.29%) had countable levels of Listeria species (other than L. monocytogenes), and another 11 samples (0.19%) had countable levels of L. monocytogenes. Nine samples (0.15%) were unsatisfactory or potentially hazardous when compared with United Kingdom guideline limits; six (0.10%) were in the unsatisfactory category (>100 CFU/g) for Listeria species (other than L. monocytogenes), and three (0.05%) were in the unacceptable or potentially hazardous category (>100 CFU/g) for L. monocytogenes. All three of these samples were from sandwiches (two chicken sandwiches and one ham-and-cheese sandwich). The most commonly isolated serotype of L. monocytogenes was 1/2a. This survey was used to determine the current prevalence of Listeria species and L. monocytogenes in ready-to-eat foods sampled from the point of sale in Wales.

An evaluation of simulated clinical practice for adult branch students

AIM

To evaluate simulation strategies used for adult branch nursing students in one university.

METHOD

A questionnaire was used to collect quantitative data and open comments (qualitative data). The evaluation was completed by 45 of a group of 60 second-year diploma nursing students.

FINDINGS

There was widespread agreement that simulation is a productive learning strategy that broadens theoretical learning and supports the practice element of nurse education. Areas commented on included developing confidence, individual support and linking theory to practice.

CONCLUSION

Simulation supports the practical learning experience. It will neither take the place of traditional methods of teaching nor replace good practice experience for nursing students, but can support both elements of nurse education.

Microbiological quality of ready-to-eat food served in schools in Wales, United Kingdom

A survey of the general microbiological quality of ready-to-eat food served in schools was undertaken across Wales, United Kingdom. Of the 2,351 samples taken, four were identified as containing unsatisfactory counts of Escherichia coli, four contained unsatisfactory counts of Staphylococcus aureus, and one contained an unacceptable count of Bacillus cereus when compared with guidelines for the microbiological quality of ready-to-eat food published by the United Kingdom Public Health Laboratory Service in 2000. No samples contained detectable levels of Salmonella, Listeria species, or Clostridium perfringens. When compared with data on the general microbiological quality of food available in Wales, the food sampled from schools was of relatively better microbiological quality.

Microbiological quality of randomly selected ready-to-eat foods sampled between 2003 and 2005 in Wales, UK

Since 1995, the publicly funded ready-to-eat food sampling and examination activities in Wales have been coordinated and structured, using a novel approach for the identification of samples and premises. The latest set of data from this surveillance system reports the results from 3391 ready-to-eat foods sampled between November 2003 and March 2005. During this seventeen-month period all samples were examined for aerobic colony count, Escherichia coli, Listeria spp., Bacillus cereus, Salmonella, Staphylococcus aureus and Listeria monocytogenes. The food types with the poorest microbiological quality were cream cakes, custard slices and egg mayonnaise sandwiches. The food type with the best microbiological quality was dried fruit. In conclusion, the results indicate that, in general terms, the ready-to-eat food types sampled and examined in this period posed little bacterial hazard to consumers.

Nucleation and growth of microbial lipase crystals from clarified concentrated fermentation broths

Bulk crystallization is emerging as a new industrial operation for protein recovery. Characterization of bulk protein crystallization is more complex than protein crystallization for structural study where single crystals are grown in flow cells. This is because both nucleation and crystal growth processes are taking place while the supersaturation falls. An algorithm is presented to characterize crystallization using the rates of the two kinetic processes, nucleation and growth. The values of these rates allow ready comparison of the crystallization process under different operating conditions. The crystallization, via adjustment to the isoelectric pH of a fungal lipase from clarified fermentation broth, is described for a batch stirred reactor. A maximum nucleation rate of five to six crystals formed per microliter of suspension per second and a high power dependency ( approximately 11) on the degree of supersaturation were found. The suspended protein crystals were found to grow at a rate of up to 15-20 nm/s and also to exhibit a high power dependency ( approximately 6) of growth rate on the degree of supersaturation.

Crystallization kinetics of calcium oxalate in fresh, minimally diluted urine: comparison of recurrent stone formers and healthy controls in a continuous mixed suspension mixed product removal crystallizer

A reproducible method has been developed for studying calcium oxalate crystallization from fresh, minimally diluted (92%) urine with the mixed suspension mixed product removal continuous crystallization technique. All samples were adjusted to give the same starting calcium and oxalate concentrations. Twenty-one recurrent male stone formers were compared with twenty-two healthy controls. There was no difference in crystal growth rates but crystal nucleation rates were much higher in the control group (p = 0.003). Using growth rate and nucleation rate results, the amount of crystalline material in suspension was shown to be lower in the urine from stone formers, and therefore the equilibrium supersaturation in the crystallizer was lower in the control group (p = 0.001). We propose that the ability of a healthy person's urine to maintain a lower supersaturation is a crucial protective factor distinguishing non-stone formers from stone formers.

Calcium oxalate crystallisation kinetics and the effects of calcium and gamma-carboxyglutamic acid

gamma-carboxyglutamic acid (GLA) is an amino acid with a high affinity for calcium. It is found in urine both as the free amino acid and incorporated into proteins such as osteocalcin. Free and bound GLA have been reported to be found at higher concentrations in the urine of stone formers than controls. We have investigated the effect of GLA and calcium, at physiological levels, on the crystallisation of calcium oxalate using a mixed suspension mixed product removal continuous crystalliser. GLA caused very significant changes in the crystallisation kinetics, but the effect was dependent on the calcium concentration. At 4 mM calcium, GLA decreased the growth rate and increased the nucleation rate; at 12 mM the reverse occurred. At all concentrations of calcium tested, GLA caused a significantly increased crystal mass to be produced. Our evidence supports the hypothesis that GLA modifies calcium oxalate crystallisation and could be a promoter of stone formation in vivo, particularly at moderately elevated levels of calcium excretion.

The effect of glycosaminoglycans on the crystallisation of calcium oxalate

The effect of glycosaminoglycans on urinary stone formation was evaluated using a mixed suspension, mixed product removal (MSMPR) crystallisation system together with scanning electron microscopy (SEM) to examine the resulting crystals. Chondroitin sulphate was found to decrease the nucleation rate and to promote both the growth rate and suspension density. Results obtained with hyaluronic acid, although inconclusive, are similar to those given by chondroitin sulphate. Heparin sodium salt had a powerful inhibitory effect on both the nucleation rate and the suspension density, the effect increasing in proportion to the heparin concentration. SEM examination showed that the octahedral habit of calcium oxalate dihydrate was modified by the addition of heparin sodium salt and confirmed that the average crystal size in the presence of chondroitin sulphate and hyaluronic acid was significantly greater than the control or that found in the presence of heparin sodium salt.

The role of magnesium in calcium oxalate urolithiasis

The aim of this study was to evaluate the effect of magnesium on calcium oxalate crystal formation, both in physiological conditions and at slightly higher oxalate concentrations, using a mixed suspension mixed product removal crystallizer and scanning electron microscopy. True supersaturation ratios were calculated by allowing for complexation in solution. Magnesium inhibited the nucleation rate at all oxalate concentrations. It also inhibited the growth rate at oxalate concentrations of less than approximately 2.0 mmol/l but promoted the growth rate at higher concentrations. This suggests that, provided the oxalate concentration is sufficiently high, increase of magnesium concentration can increase the crystal growth rate. At physiological concentrations of oxalate, however, magnesium decreases both nucleation and growth rates. The SEM photographs showed that the predominant crystal was calcium oxalate trihydrate at low magnesium concentrations, with calcium oxalate dihydrate being observed in larger quantities at high magnesium concentrations.

Observations on in vitro and in vivo calcium oxalate crystalluria in primary calcium stone formers and normal subjects

Fresh urine samples from stone formers (SF) and normal subjects (N) were rapidly evaporated at 37 degrees C to 1200 mosmol/kgH2O and the particle size distribution of the formed particles studied by Coulter Counter and chemical methods. No significant difference was found between the two groups in their relative supersaturation of calcium oxalate at the point of spontaneous precipitation. SF and N urines seem to have an equal driving force for particle precipitation. The major difference between them was in the volume of particles with diameters greater than 11.4 microns. SF urines showed an approximately 5-fold increase in total particle volume (after evaporation) and N urines had about a 2-fold increase over the volume in the freshly voided urine samples. The total volume of large particles (greater than 11.4 micron) increased more than 7-fold in SF urine while only a 2-fold increase was detected in the normal urines after evaporation.

Calcium oxalate precipitation in a flow system: an attempt to simulate the early stages of stone formation in the renal tubules

This paper describes in vitro studies on the generation of supersaturation and the early stages of calcium oxalate (CaOx) precipitation using a reverse osmosis hollow-fiber membrane to simulate the precipitation processes occurring in the distal convoluted tubule and the collecting system of the kidney. The article reports on the preliminary results of using a plug-flow configuration to simulate the reabsorption of water and generation of supersaturation during the approximately three-minute biological residence time of the urine in the upper part of the urinary tract. The results suggest that microcrystallization of CaOx . 2H2O in the renal tubules may play a role in stone formation processes. A survey of the effect of various inhibitors of CaOx precipitation indicates that pyrophosphate, magnesium, glutamic acid, heparin and citric acid reduce the tendency of CaOx crystals formed to agglomerate in this system.

Effects of magnesium on calcium oxalate crystallization

We evaluated the effect of a range of physiological concentrations of magnesium on calcium oxalate crystallization from artificial urine in a continuous mixed suspension mixed product removal crystallizer at 37C. Magnesium was found to decrease both the growth and nucleation rates of calcium oxalate crystals in the simulated renal environment.

The nucleation and growth kinetics of calcium oxalate in the presence of some synthetic urine constituents

We determined quantitative nucleation and growth kinetics of calcium oxalate in the presence of various combinations of urine constituents, using a continuous mixed suspension mixed product removal crystallizer and a Coulter counter. Nucleation rates of calcium oxalate from the pure component system were approximately an order of magnitude higher than those from an artificial urine. The presence of citrate inhibited nucleation rates under high conditions. The ions Na+, K+, NH4+, Cl-, and SO42- did not affect the overall kinetics in the synthetic urine. Di- and tri-hydrate products were formed, except when crystallizing from pure components, when only the thermodynamically stable monohydrate was observed.