In Silico Finite Element Analysis of the Foot Ankle Complex Biomechanics: A Literature Review

Computational approaches, especially finite element analysis (FEA), have been rapidly growing in both academia and industry during the last few decades. FEA serves as a powerful and efficient approach for simulating real-life experiments, including industrial product development, machine design, and biomedical research, particularly in biomechanics and biomaterials. Accordingly, FEA has been a "go-to" high biofidelic software tool to simulate and quantify the biomechanics of the foot-ankle complex, as well as to predict the risk of foot and ankle injuries, which are one of the most common musculoskeletal injuries among physically active individuals. This paper provides a review of the in silico FEA of the foot-ankle complex. First, a brief history of computational modeling methods and finite element (FE) simulations for foot-ankle models is introduced. Second, a general approach to build an FE foot and ankle model is presented, including a detailed procedure to accurately construct, calibrate, verify, and validate an FE model in its appropriate simulation environment. Third, current applications, as well as future improvements of the foot and ankle FE models, especially in the biomedical field, are discussed. Finally, a conclusion is made on the efficiency and development of FEA as a computational approach in investigating the biomechanics of the foot-ankle complex. Overall, this review integrates insightful information for biomedical engineers, medical professionals, and researchers to conduct more accurate research on the foot-ankle FE models in the future.

Consensus Development Project (CDP): An overview of staffing for safe and effective nursing care

We present an overview of the research evidence on nurse staffing levels in acute hospitals, and how it has been applied to policy and practice, focussing primarily on the UK. Drawing on research reviews and examples of specific studies, we outline the current state of knowledge. Much of the evidence comes from cross-sectional studies. More recently, longitudinal studies allow a causal link between staffing and outcomes to be inferred. Lack of specificity on staffing levels has hindered application of research findings to practice; research rarely specifies how many nurses are needed for safe and effective care. The most significant impediment to achieving safe staffing has been an underestimation of the number of RNs needed and overestimation of the potential for substitution, resulting in low baseline staffing and a national shortage of RNs. Repeatedly, new staffing solutions are sought rather than tackle the problem of too few RNs head-on.

Beyond ratios - flexible and resilient nurse staffing options to deliver cost-effective hospital care and address staff shortages: A simulation and economic modelling study

BACKGROUND

In the face of pressure to contain costs and make best use of scarce nurses, flexible staff deployment (floating staff between units and temporary hires) guided by a patient classification system may appear an efficient approach to meeting variable demand for care in hospitals.

OBJECTIVES

We modelled the cost-effectiveness of different approaches to planning baseline numbers of nurses to roster on general medical/surgical units while using flexible staff to respond to fluctuating demand.

DESIGN AND SETTING

We developed an agent-based simulation, where hospital inpatient units move between being understaffed, adequately staffed or overstaffed as staff supply and demand (as measured by the Safer Nursing Care Tool patient classification system) varies. Staffing shortfalls are addressed by floating staff from overstaffed units or hiring temporary staff. We compared a standard staffing plan (baseline rosters set to match average demand) with a higher baseline 'resilient' plan set to match higher than average demand, and a low baseline 'flexible' plan. We varied assumptions about temporary staff availability and estimated the effect of unresolved low staffing on length of stay and death, calculating cost per life saved.

RESULTS

Staffing plans with higher baseline rosters led to higher costs but improved outcomes. Cost savings from lower baseline staff mainly arose because shifts were left understaffed and much of the staff cost saving was offset by costs from longer patient stays. With limited temporary staff available, changing from low baseline flexible plan to the standard plan cost £13,117 per life saved and changing from the standard plan to the higher baseline 'resilient' plan cost £8,653 per life saved. Although adverse outcomes from low baseline staffing reduced when more temporary staff were available, higher baselines were even more cost-effective because the saving on staff costs also reduced. With unlimited temporary staff, changing from low baseline plan to the standard cost £4,520 per life saved and changing from the standard plan to the higher baseline cost £3,693 per life saved.

CONCLUSION

Shift-by-shift measurement of patient demand can guide flexible staff deployment, but the baseline number of staff rostered must be sufficient. Higher baseline rosters are more resilient in the face of variation and appear cost-effective. Staffing plans that minimise the number of nurses rostered in advance are likely to harm patients because temporary staff may not be available at short notice. Such plans, which rely heavily on flexible deployments, do not represent an efficient or effective use of nurses.

STUDY REGISTRATION

ISRCTN 12307968 Tweetable abstract: Economic simulation model of hospital units shows low baseline staff levels with high use of flexible staff are not cost-effective and don't solve nursing shortages.

The Safer Nursing Care Tool as a guide to nurse staffing requirements on hospital wards: observational and modelling study

Background

The Safer Nursing Care Tool is a system designed to guide decisions about nurse staffing requirements on hospital wards, in particular the number of nurses to employ (establishment). The Safer Nursing Care Tool is widely used in English hospitals but there is a lack of evidence about how effective and cost-effective nurse staffing tools are at providing the staffing levels needed for safe and quality patient care.

Objectives

To determine whether or not the Safer Nursing Care Tool corresponds to professional judgement, to assess a range of options for using the Safer Nursing Care Tool and to model the costs and consequences of various ward staffing policies based on Safer Nursing Care Tool acuity/dependency measure.

Design

This was an observational study on medical/surgical wards in four NHS hospital trusts using regression, computer simulations and economic modelling. We compared the effects and costs of a ‘high’ establishment (set to meet demand on 90% of days), the ‘standard’ (mean-based) establishment and a ‘flexible (low)’ establishment (80% of the mean) providing a core staff group that would be sufficient on days of low demand, with flexible staff re-deployed/hired to meet fluctuations in demand.

Setting

Medical/surgical wards in four NHS hospital trusts.

Main outcome measures

The main outcome measures were professional judgement of staffing adequacy and reports of omissions in care, shifts staffed more than 15% below the measured requirement, cost per patient-day and cost per life saved.

Data sources

The data sources were hospital administrative systems, staff reports and national reference costs.

Results

In total, 81 wards participated (85% response rate), with data linking Safer Nursing Care Tool ratings and staffing levels for 26,362 wards × days (96% response rate). According to Safer Nursing Care Tool measures, 26% of all ward-days were understaffed by ≥ 15%. Nurses reported that they had enough staff to provide quality care on 78% of shifts. When using the Safer Nursing Care Tool to set establishments, on average 60 days of observation would be needed for a 95% confidence interval spanning 1 whole-time equivalent either side of the mean. Staffing levels below the daily requirement estimated using the Safer Nursing Care Tool were associated with lower odds of nurses reporting ‘enough staff for quality’ and more reports of missed nursing care. However, the relationship was effectively linear, with staffing above the recommended level associated with further improvements. In simulation experiments, ‘flexible (low)’ establishments led to high rates of understaffing and adverse outcomes, even when temporary staff were readily available. Cost savings were small when high temporary staff availability was assumed. ‘High’ establishments were associated with substantial reductions in understaffing and improved outcomes but higher costs, although, under most assumptions, the cost per life saved was considerably less than £30,000.

Limitations

This was an observational study. Outcomes of staffing establishments are simulated.

Conclusions

Understanding the effect on wards of variability of workload is important when planning staffing levels. The Safer Nursing Care Tool correlates with professional judgement but does not identify optimal staffing levels. Employing more permanent staff than recommended by the Safer Nursing Care Tool guidelines, meeting demand most days, could be cost-effective. Apparent cost savings from ‘flexible (low)’ establishments are achieved largely by below-adequate staffing. Cost savings are eroded under the conditions of high temporary staff availability that are required to make such policies function.

Future work

Research is needed to identify cut-off points for required staffing. Prospective studies measuring patient outcomes and comparing the results of different systems are feasible.

Trial registration

Current Controlled Trials ISRCTN12307968.

Funding

This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full inHealth Services and Delivery Research; Vol. 8, No. 16. See the NIHR Journals Library website for further project information.

Nurse staffing, nursing assistants and hospital mortality: retrospective longitudinal cohort study

Objective

To determine the association between daily levels of registered nurse (RN) and nursing assistant staffing and hospital mortality.

Design

This is a retrospective longitudinal observational study using routinely collected data. We used multilevel/hierarchical mixed-effects regression models to explore the association between patient outcomes and daily variation in RN and nursing assistant staffing, measured as hours per patient per day relative to ward mean. Analyses were controlled for ward and patient risk.

Participants

138 133 adult patients spending >1 days on general wards between 1 April 2012 and 31 March 2015.

Outcomes

In-hospital deaths.

Results

Hospital mortality was 4.1%. The hazard of death was increased by 3% for every day a patient experienced RN staffing below ward mean (adjusted HR (aHR) 1.03, 95% CI 1.01 to 1.05). Relative to ward mean, each additional hour of RN care available over the first 5 days of a patient’s stay was associated with 3% reduction in the hazard of death (aHR 0.97, 95% CI 0.94 to 1.0). Days where admissions per RN exceeded 125% of the ward mean were associated with an increased hazard of death (aHR 1.05, 95% CI 1.01 1.09). Although low nursing assistant staffing was associated with increases in mortality, high nursing assistant staffing was also associated with increased mortality.

Conclusion

Lower RN staffing and higher levels of admissions per RN are associated with increased risk of death during an admission to hospital. These findings highlight the possible consequences of reduced nurse staffing and do not give support to policies that encourage the use of nursing assistants to compensate for shortages of RNs.

Post-operative mortality, missed care and nurse staffing in nine countries: A cross-sectional study

Background

Variation in post-operative mortality rates has been associated with differences in registered nurse staffing levels. When nurse staffing levels are lower there is also a higher incidence of necessary but missed nursing care. Missed nursing care may be a significant predictor of patient mortality following surgery.

Aim

Examine if missed nursing care mediates the observed association between nurse staffing levels and mortality.

Method

Data from the RN4CAST study (2009–2011) combined routinely collected data on 422,730 surgical patients from 300 general acute hospitals in 9 countries, with survey data from 26,516 registered nurses, to examine associations between nurses’ staffing, missed care and 30-day in-patient mortality. Staffing and missed care measures were derived from the nurse survey. A generalized estimation approach was used to examine the relationship between first staffing, and then missed care, on mortality. Bayesian methods were used to test for mediation.

Results

Nurse staffing and missed nursing care were significantly associated with 30-day case-mix adjusted mortality. An increase in a nurse’s workload by one patient and a 10% increase in the percent of missed nursing care were associated with a 7% (OR 1.068, 95% CI 1.031–1.106) and 16% (OR 1.159 95% CI 1.039–1.294) increase in the odds of a patient dying within 30 days of admission respectively. Mediation analysis shows an association between nurse staffing and missed care and a subsequent association between missed care and mortality.

Conclusion

Missed nursing care, which is highly related to nurse staffing, is associated with increased odds of patients dying in hospital following common surgical procedures. The analyses support the hypothesis that missed nursing care mediates the relationship between registered nurse staffing and risk of patient mortality. Measuring missed care may provide an ‘early warning’ indicator of higher risk for poor patient outcomes.

Nursing skill mix in European hospitals: cross-sectional study of the association with mortality, patient ratings, and quality of care

OBJECTIVES

To determine the association of hospital nursing skill mix with patient mortality, patient ratings of their care and indicators of quality of care.

DESIGN

Cross-sectional patient discharge data, hospital characteristics and nurse and patient survey data were merged and analysed using generalised estimating equations (GEE) and logistic regression models.

SETTING

Adult acute care hospitals in Belgium, England, Finland, Ireland, Spain and Switzerland.

PARTICIPANTS

Survey data were collected from 13 077 nurses in 243 hospitals, and 18 828 patients in 182 of the same hospitals in the six countries. Discharge data were obtained for 275 519 surgical patients in 188 of these hospitals.

MAIN OUTCOME MEASURES

Patient mortality, patient ratings of care, care quality, patient safety, adverse events and nurse burnout and job dissatisfaction.

RESULTS

Richer nurse skill mix (eg, every 10-point increase in the percentage of professional nurses among all nursing personnel) was associated with lower odds of mortality (OR=0.89), lower odds of low hospital ratings from patients (OR=0.90) and lower odds of reports of poor quality (OR=0.89), poor safety grades (OR=0.85) and other poor outcomes (0.80<OR<0.93), after adjusting for patient and hospital factors. Each 10 percentage point reduction in the proportion of professional nurses is associated with an 11% increase in the odds of death. In our hospital sample, there were an average of six caregivers for every 25 patients, four of whom were professional nurses. Substituting one nurse assistant for a professional nurse for every 25 patients is associated with a 21% increase in the odds of dying.

CONCLUSIONS

A bedside care workforce with a greater proportion of professional nurses is associated with better outcomes for patients and nurses. Reducing nursing skill mix by adding nursing associates and other categories of assistive nursing personnel without professional nurse qualifications may contribute to preventable deaths, erode quality and safety of hospital care and contribute to hospital nurse shortages.

Patient satisfaction and non-UK educated nurses: a cross-sectional observational study of English National Health Service Hospitals

OBJECTIVES

To examine whether patient satisfaction with nursing care in National Health Service (NHS) hospitals in England is associated with the proportion of non-UK educated nurses providing care.

DESIGN

Cross-sectional analysis using data from the 2010 NHS Adult Inpatient Survey merged with data from nurse and hospital administrator surveys. Logistic regression models with corrections for clustering were used to determine whether the proportions of non-UK educated nurses were significantly related to patient satisfaction before and after taking account of other hospital, nursing and patient characteristics.

SETTING

31 English NHS trusts.

PARTICIPANTS

12,506 patients 16 years of age and older with at least one overnight stay that completed a satisfaction survey; 2962 bedside care nurses who completed a nurse survey; and 31 NHS trusts.

MAIN OUTCOME MEASURE

Patient satisfaction.

RESULTS

The percentage of non-UK educated nurses providing bedside hospital care, which ranged from 1% to 52% of nurses, was significantly associated with patient satisfaction. After controlling for potential confounding factors, each 10-point increase in the percentage of non-UK educated nurses diminished the odds of patients reporting good or excellent care by 12% (OR=0.88), and decreased the odds of patients agreeing that they always had confidence and trust in nurses by 13% (OR=0.87). Other indicators of patient satisfaction also revealed lower satisfaction in hospitals with higher percentages of non-UK educated nurses.

CONCLUSIONS

Use of non-UK educated nurses in English NHS hospitals is associated with lower patient satisfaction. Importing nurses from abroad to substitute for domestically educated nurses may negatively impact quality of care.

'Care left undone' during nursing shifts: associations with workload and perceived quality of care

BACKGROUND

There is strong evidence to show that lower nurse staffing levels in hospitals are associated with worse patient outcomes. One hypothesised mechanism is the omission of necessary nursing care caused by time pressure-'missed care'.

AIM

To examine the nature and prevalence of care left undone by nurses in English National Health Service hospitals and to assess whether the number of missed care episodes is associated with nurse staffing levels and nurse ratings of the quality of nursing care and patient safety environment.

METHODS

Cross-sectional survey of 2917 registered nurses working in 401 general medical/surgical wards in 46 general acute National Health Service hospitals in England.

RESULTS

Most nurses (86%) reported that one or more care activity had been left undone due to lack of time on their last shift. Most frequently left undone were: comforting or talking with patients (66%), educating patients (52%) and developing/updating nursing care plans (47%). The number of patients per registered nurse was significantly associated with the incidence of 'missed care' (p<0.001). A mean of 7.8 activities per shift were left undone on wards that are rated as 'failing' on patient safety, compared with 2.4 where patient safety was rated as 'excellent' (p < 0.001).

CONCLUSIONS

Nurses working in English hospitals report that care is frequently left undone. Care not being delivered may be the reason low nurse staffing levels adversely affects quality and safety. Hospitals could use a nurse-rated assessment of 'missed care' as an early warning measure to identify wards with inadequate nurse staffing.

Pollutant removal efficiency of alternative filtration media in stormwater treatment

Sorption experiments were used to assess the ability of various materials (sand, compost, packing wood, ash, zeolite, recycled glass and Enviro-media) to remove heavy metal contaminants typically found in stormwater. Compost was found to have the best physicochemical properties for sorption of metal ions (Cu, Zn and Pb) compared with sand, packing wood, ash, zeolite and Enviro-media. The compost sorption of these metal ions conformed to the linear form of the Langmuir adsorption equation with the Langmuir constants (q,) for Zn(ll) being 11.2 mg/g at pH 5. However, compost was also found to leach a high concentration of dissolved organic carbon (DOC, 4.31 mg/g), compared with the other tested materials. Various combinations of sand, compost and other materials were observed to have excellent heavy metal removal (75-96% of Zn and 90-93% of Cu), with minimal DOC leaching (0.0013-2.43 mg/g). The sorption efficiency of the different Enviro-media mixes showed that a combination of traditional (sand) and alternative materials can be used as an effective medium for the treatment of dissolved metal contaminants commonly found in stormwater. The application of using recycled organic materials and other waste materials (such as recycled glass) also provides added value to the products life cycle.

Quantifying the impact of runoff events on microbiological contaminant concentrations entering surface drinking source waters

Concentrations of microbiological contaminants in streams increase during rainfall-induced higher flow 'event' periods as compared to 'baseflow' conditions. If the stream feeds a drinking water reservoir, such periods of heightened pathogen loads may pose a challenge to the water treatment plant and subsequently a health concern to water consumers downstream. In order to manage this risk, it is desirable to first quantify the differences in surface water quality between baseflow and event conditions. The Event Mean Concentration (EMC) is a flow-weighted average concentration of a contaminant over the duration of a single event, proposed here as a standard parameter for quantifying the net effect of events on microbial water quality. Application of the EMC concept was assessed using flow and quality data for several events from an urbanised catchment. Expected mean EMCs were significantly larger than expected mean baseflow concentrations (p-value< or =0.012) for three microbial agents - Escherichia coil (13,000 [n = 7] v. 610 [n = 16] mpn/100 ml), Cryptosporidium (234 [n = 6] v. 51 [n = 16] oocysts/10 litres) and Campylobacter (48 [n = 5] v. 2.1 [n = 16] mpn/100ml). These parameter estimates were complemented by estimating data variability and uncertainty in the form of second-order random variables. As such the results are in a format appropriate for potential use as components in probabilistic risk assessments evaluating the effect runoff events have on drinking water quality.

Schistosoma mansoni larvicidal activity of murine bronchoalveolar lavage cells

We have investigated the ability of cells obtained from both normal and immune mice by bronchoalveolar lavage (BACs) to kill Schistosoma mansoni larvae in vitro. In cultures with mechanically derived schistosomules, high levels of larvicidal activity were displayed by BACs from both normal and irradiated cercaria-immunized C57BL/6 mice. Based on effector-to-target-cell ratios, BAC-mediated killing was two- to threefold more efficient than killing mediated by macrophage-rich cell populations obtained from the peritoneal cavity. BACs from normal A/J mice were essentially as larvicidal as normal C57BL/6 cells. However, BACs from a strain of mouse (P/J) with a known macrophage defect possessed negligible larvicidal activity. Macrophages made up 85 to 95% of BACs from all three strains tested. In contrast to cells of the IC-21 macrophage cell line, B6 BACs did not show enhanced killing activity when preincubated with lymphokine-containing supernatants. Lung schistosomules harvested 10 days after cercarial penetration were refractory to BAC-mediated killing.

Effect of impaired renal function on tamoxifen

There is no information available in the literature on the blood levels of tamoxifen in patients with decreased renal function. As serious side effects of tamoxifen administered at high doses have been reported, a patient with decreased renal function and metastatic breast cancer was studied to determine the blood levels of tamoxifen while under therapy. Since no abnormally elevated levels of tamoxifen were found in this patient during the month of therapy, results of this study indicate that tamoxifen can be administered to patients with some degree of renal impairment without the risk of giving rise to abnormally elevated blood levels.