Safer and more efficient vital signs monitoring protocols to identify the deteriorating patients in the general hospital ward: an observational study

Background

The frequency at which patients should have their vital signs (e.g. blood pressure, pulse, oxygen saturation) measured on hospital wards is currently unknown. Current National Health Service monitoring protocols are based on expert opinion but supported by little empirical evidence. The challenge is finding the balance between insufficient monitoring (risking missing early signs of deterioration and delays in treatment) and over-observation of stable patients (wasting resources needed in other aspects of care).

Objective

Provide an evidence-based approach to creating monitoring protocols based on a patient's risk of deterioration and link these to nursing workload and economic impact.

Design

Our study consisted of two parts: (1) an observational study of nursing staff to ascertain the time to perform vital sign observations; and (2) a retrospective study of historic data on patient admissions exploring the relationships between National Early Warning Score and risk of outcome over time. These were underpinned by opinions and experiences from stakeholders.

Setting and participants

Observational study: observed nursing staff on 16 randomly selected adult general wards at four acute National Health Service hospitals. Retrospective study: extracted, linked and analysed routinely collected data from two large National Health Service acute trusts; data from over 400,000 patient admissions and 9,000,000 vital sign observations.

Results

Observational study found a variety of practices, with two hospitals having registered nurses take the majority of vital sign observations and two favouring healthcare assistants or student nurses. However, whoever took the observations spent roughly the same length of time. The average was 5:01 minutes per observation over a 'round', including time to locate and prepare the equipment and travel to the patient area. Retrospective study created survival models predicting the risk of outcomes over time since the patient was last observed. For low-risk patients, there was little difference in risk between 4 hours and 24 hours post observation.

Conclusions

We explored several different scenarios with our stakeholders (clinicians and patients), based on how 'risk' could be managed in different ways. Vital sign observations are often done more frequently than necessary from a bald assessment of the patient's risk, and we show that a maximum threshold of risk could theoretically be achieved with less resource. Existing resources could therefore be redeployed within a changed protocol to achieve better outcomes for some patients without compromising the safety of the rest. Our work supports the approach of the current monitoring protocol, whereby patients' National Early Warning Score 2 guides observation frequency. Existing practice is to observe higher-risk patients more frequently and our findings have shown that this is objectively justified. It is worth noting that important nurse-patient interactions take place during vital sign monitoring and should not be eliminated under new monitoring processes. Our study contributes to the existing evidence on how vital sign observations should be scheduled. However, ultimately, it is for the relevant professionals to decide how our work should be used.

Study registration

This study is registered as ISRCTN10863045.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health and Social Care Delivery Research programme (NIHR award ref: 17/05/03) and is published in full in Health and Social Care Delivery Research; Vol. 12, No. 6. See the NIHR Funding and Awards website for further award information.

Evaluating the performance of the National Early Warning Score in different diagnostic groups

BACKGROUND

The National Early Warning Score (NEWS) is used in hospitals across the UK to detect deterioration of patients within care pathways. It is used for most patients, but there are relatively few studies validating its performance in groups of patients with specific conditions.

METHODS

The performance of NEWS was evaluated against 36 other Early Warning Scores, in 123 patient groups, through use of the area under the receiver operating characteristic (AUROC) curve technique, to compare the abilities of each Early Warning Score to discriminate an outcome within 24hrs of vital sign recording. Outcomes evaluated were death, ICU admission, or a combined outcome of either death or ICU admission within 24 hours of an observation set.

RESULTS

The National Early Warning Score 2 performs either best or joint best within 120 of the 123 patient groups evaluated and is only outperformed in prediction of unanticipated ICU admission. When outperformed by other Early Warning Scores in the remaining 3 patient groups, the performance difference was marginal.

CONCLUSIONS

Consistently high performance indicates that NEWS is a suitable early warning score to use for all diagnostic groups considered by this analysis, and patients are not disadvantaged through use of NEWS in comparison to any of the other evaluated Early Warning Scores.

Operative and non-operative management for intestinal emergencies: findings from a single-centre retrospective cohort study

BACKGROUND

Patients with an intestinal emergency who do not have surgery are poorly characterised. This study used electronic healthcare records to provide a rapid insight into the number of patients admitted with an intestinal emergency and compare short-term outcomes for non-operative and operative management.

METHODS

A single-centre retrospective cohort study was conducted at a tertiary NHS hospital (from 1 December 2013 to 31 January 2020). Patients were identified using diagnosis codes for intestinal emergencies, based on the inclusion criteria for the National Emergency Laparotomy Audit. Relevant data were extracted from electronic healthcare records (n=3,997).

RESULTS

Nearly half of patients admitted with an intestinal emergency received nonoperative management (43.7%). Of those who underwent surgery, 63.7% were started laparoscopically. The non-operative group had a shorter hospital stay (median: 5.4 days vs 8.2 days [started laparoscopically] or 16.8 days [started open]) and fewer unintended intensive care admissions than the surgical group (2.4% vs 8.7% [started laparoscopically] 21.1% [started open]). However, 30-day mortality for non-operative treatment was double that for surgery (22.4% vs 10.1%). The 30-day mortality rate was found to be even higher for non-operative management (50.3%) compared with surgery (19.5%) in a sub-analysis of patients with admission National Early Warning Score ≥4 (n=683).

CONCLUSION

The proportion of patients with intestinal emergencies who do not have surgery is greater than expected, and it appears that many respond well to non-operative treatment. However, 30-day mortality for non-operative management was high, and the low number of admissions to intensive care suggests that major invasive treatment was not appropriate for most in this group.

The effect of a novel, digital physical activity and emotional well-being intervention on health-related quality of life in people with chronic kidney disease: trial design and baseline data from a multicentre prospective, wait-list randomised controlled trial (kidney BEAM)

BACKGROUND

Physical activity and emotional self-management has the potential to enhance health-related quality of life (HRQoL), but few people with chronic kidney disease (CKD) have access to resources and support. The Kidney BEAM trial aims to evaluate whether an evidence-based physical activity and emotional wellbeing self-management programme (Kidney BEAM) leads to improvements in HRQoL in people with CKD.

METHODS

This was a prospective, multicentre, randomised waitlist-controlled trial, with health economic analysis and nested qualitative studies. In total, three hundred and four adults with established CKD were recruited from 11 UK kidney units. Participants were randomly assigned to the intervention (Kidney BEAM) or a wait list control group (1:1). The primary outcome was the between-group difference in Kidney Disease Quality of Life (KDQoL) mental component summary score (MCS) at 12 weeks. Secondary outcomes included the KDQoL physical component summary score, kidney-specific scores, fatigue, life participation, depression and anxiety, physical function, clinical chemistry, healthcare utilisation and harms. All outcomes were measured at baseline and 12 weeks, with long-term HRQoL and adherence also collected at six months follow-up. A nested qualitative study explored experience and impact of using Kidney BEAM.

RESULTS

340 participants were randomised to Kidney BEAM (n = 173) and waiting list (n = 167) groups. There were 96 (55%) and 89 (53%) males in the intervention and waiting list groups respectively, and the mean (SD) age was 53 (14) years in both groups. Ethnicity, body mass, CKD stage, and history of diabetes and hypertension were comparable across groups. The mean (SD) of the MCS was similar in both groups, 44.7 (10.8) and 45.9 (10.6) in the intervention and waiting list groups respectively.

CONCLUSION

Results from this trial will establish whether the Kidney BEAM self management programme is a cost-effective method of enhancing mental and physical wellbeing of people with CKD.

TRIAL REGISTRATION

NCT04872933. Registered 5th May 2021.

Novel predictors of mortality in emergency bowel surgery: a single-centre cohort study

Pre-operative risk stratification is a key part of the care pathway for emergency bowel surgery, as it facilitates the identification of high-risk patients. Several novel risk scores have recently been published that are designed to identify patients who are frail or significantly unwell. They can also be calculated pre-operatively from routinely collected clinical data. This study aimed to investigate the ability of these scores to predict 30-day mortality after emergency bowel surgery. A single centre cohort study was performed using our local data from the National Emergency Laparotomy Audit database. Further data were extracted from electronic hospital records (n = 1508). The National Early Warning Score, Laboratory Decision Tree Early Warning Score and Hospital Frailty Risk Score were then calculated. The most abnormal National or Laboratory Decision Tree Early Warning Score in the 24 or 72 h before surgery was used in analysis. Individual scores were reasonable predictors of mortality (c-statistic 0.699-0.740) but all were poorly calibrated. A National Early Warning Score ≥ 4 was associated with a high overall mortality rate (> 10%). A logistic regression model was developed using age, National Early Warning Score, Laboratory Decision Tree Early Warning Score and Hospital Frailty Risk Score as predictor variables, and its performance compared with other established risk models. The model demonstrated good discrimination and calibration (c-statistic 0.827) but was marginally outperformed by the National Emergency Laparotomy Audit score (c-statistic 0.861). All other models compared performed less well (c-statistics 0.734-0.808). Pre-operative patient vital signs, blood tests and markers of frailty can be used to accurately predict the risk of 30-day mortality after emergency bowel surgery.

Detecting Deteriorating Patients in the Hospital: Development and Validation of a Novel Scoring System

Rationale: Late recognition of patient deterioration in hospital is associated with worse outcomes, including higher mortality. Despite the widespread introduction of early warning score (EWS) systems and electronic health records, deterioration still goes unrecognized. Objectives: To develop and externally validate a Hospital- wide Alerting via Electronic Noticeboard (HAVEN) system to identify hospitalized patients at risk of reversible deterioration. Methods: This was a retrospective cohort study of patients 16 years of age or above admitted to four UK hospitals. The primary outcome was cardiac arrest or unplanned admission to the ICU. We used patient data (vital signs, laboratory tests, comorbidities, and frailty) from one hospital to train a machine-learning model (gradient boosting trees). We internally and externally validated the model and compared its performance with existing scoring systems (including the National EWS, laboratory-based acute physiology score, and electronic cardiac arrest risk triage score). Measurements and Main Results: We developed the HAVEN model using 230,415 patient admissions to a single hospital. We validated HAVEN on 266,295 admissions to four hospitals. HAVEN showed substantially higher discrimination (c-statistic, 0.901 [95% confidence interval, 0.898-0.903]) for the primary outcome within 24 hours of each measurement than other published scoring systems (which range from 0.700 [0.696-0.704] to 0.863 [0.860-0.865]). With a precision of 10%, HAVEN was able to identify 42% of cardiac arrests or unplanned ICU admissions with a lead time of up to 48 hours in advance, compared with 22% by the next best system. Conclusions: The HAVEN machine-learning algorithm for early identification of in-hospital deterioration significantly outperforms other published scores such as the National EWS.

How long do nursing staff take to measure and record patients' vital signs observations in hospital? A time-and-motion study

Introduction

Monitoring vital signs in hospital is an important part of safe patient care. However, there are no robust estimates of the workload it generates for nursing staff. This makes it difficult to plan adequate staffing to ensure current monitoring protocols can be delivered.

Objective

To estimate the time taken to measure and record one set of patient's vital signs; and to identify factors associated with the time required to measure and record one set of patient's vital signs.

Methods

We undertook a time-and-motion study of 16 acute medical or surgical wards across four hospitals in England. Two trained observers followed a standard operating procedure to record the time taken to measure and record vital signs. We used mixed-effects models to estimate the mean time using whole vital signs rounds, which included equipment preparation, time spent taking vital signs at the bedside, vital signs documentation, and equipment storing. We tested whether our estimates were influenced by nurse, ward and hospital factors.

Results

After excluding non-vital signs related interruptions, dividing the length of a vital signs round by the number of vital signs assessments in that round yielded an estimated time per vital signs set of 5 min and 1 second (95% Confidence Interval (CI) = 4:39–5:24). If interruptions within the round were included, the estimated time was 6:26 (95% CI = 6:01–6:50). If only time taking each patient's vital signs at the bedside was considered, after excluding non-vital signs related interruptions, the estimated time was 3:45 (95% CI = 3:32–3:58). We found no substantial differences by hospital, ward or nurse characteristics, despite different systems for recording vital signs being used across the hospitals.

Discussion

The time taken to observe and record a patient's vital signs is considerable, so changes to recommended assessment frequency could have major workload implications. Variation in estimates derived from previous studies may, in part, arise from a lack of clarity about what was included in the reported times. We found no evidence that nurses save time when using electronic vital signs recording, or that the grade of staff measuring the vital signs influenced the time taken.

Conclusions

Measuring and recording vital signs is time consuming and the impact of interruptions and preparation away from the bedside is considerable. When considering the nursing workload around vital signs assessment, no assumption of relative efficiency should be made if different technologies or staff groups are deployed.

Early warning score adjusted for age to predict the composite outcome of mortality, cardiac arrest or unplanned intensive care unit admission using observational vital-sign data: a multicentre development and validation

OBJECTIVES

Early warning scores (EWS) alerting for in-hospital deterioration are commonly developed using routinely collected vital-sign data from the whole in-hospital population. As these in-hospital populations are dominated by those over the age of 45 years, resultant scores may perform less well in younger age groups. We developed and validated an age-specific early warning score (ASEWS) derived from statistical distributions of vital signs.

DESIGN

Observational cohort study.

SETTING

Oxford University Hospitals (OUH) July 2013 to March 2018 and Portsmouth Hospitals (PH) NHS Trust January 2010 to March 2017 within the Hospital Alerting Via Electronic Noticeboard database.

PARTICIPANTS

Hospitalised patients with electronically documented vital-sign observations OUTCOME: Composite outcome of unplanned intensive care unit admission, mortality and cardiac arrest.

METHODS AND RESULTS

Statistical distributions of vital signs were used to develop an ASEWS to predict the composite outcome within 24 hours. The OUH development set consisted of 2 538 099 vital-sign observation sets from 142 806 admissions (mean age (SD): 59.8 (20.3)). We compared the performance of ASEWS to the National Early Warning Score (NEWS) and our previous EWS (MCEWS) on an OUH validation set consisting of 581 571 observation sets from 25 407 emergency admissions (mean age (SD): 63.0 (21.4)) and a PH validation set consisting of 5 865 997 observation sets from 233 632 emergency admissions (mean age (SD): 64.3 (21.1)). ASEWS performed better in the 16-45 years age group in the OUH validation set (AUROC 0.820 (95% CI 0.815 to 0.824)) and PH validation set (AUROC 0.840 (95% CI 0.839 to 0.841)) than NEWS (AUROC 0.763 (95% CI 0.758 to 0.768) and AUROC 0.836 (95% CI 0.835 to 0.838) respectively) and MCEWS (AUROC 0.808 (95% CI 0.803 to 0.812) and AUROC 0.833 (95% CI 0.831 to 0.834) respectively). Differences in performance were not consistent in the elder age group.

CONCLUSIONS

Accounting for age-related vital sign changes can more accurately detect deterioration in younger patients.

Modification of Enrichment Protocols for TECRA Listeria Visual Immunoassay Method 995.22: Collaborative Study

A collaborative study was conducted to validate new enrichment methods for the TECRA Listeria Visual Immunoassay (TLVIA). These new methods incorporate a newly formulated medium, TECRA Listeria Enrichment Broth, which does not contain the highly toxic antifungal agent, cycloheximide. The new procedures will provide an alternative to the enrichment procedures described in AOAC Method 995.22. Three food types (raw ground beef, lettuce, and ice cream) were analyzed in the United States, and 2 food types (cooked turkey and cooked fish fillets) were analyzed in Australasia. Thirty collaborators participated in the study, 16 in Australasia and 14 in the United States. With the exception of one batch of ground beef, comparison of the proportion of positive test portions (p ≥ 0.05) showed no significant difference between the TLVIA and the reference method for the 5 foods at 3 inoculation levels. For the one batch of naturally contaminated raw ground beef, the TLVIA gave significantly more confirmed positive results than the reference method.

Predicting hospital mortality for intensive care unit patients: Time-series analysis

Current mortality prediction models and scoring systems for intensive care unit patients are generally usable only after at least 24 or 48 h of admission, as some parameters are unclear at admission. However, some of the most relevant measurements are available shortly following admission. It is hypothesized that outcome prediction may be made using information available in the earliest phase of intensive care unit admission. This study aims to investigate how early hospital mortality can be predicted for intensive care unit patients. We conducted a thorough time-series analysis on the performance of different data mining methods during the first 48 h of intensive care unit admission. The results showed that the discrimination power of the machine-learning classification methods after 6 h of admission outperformed the main scoring systems used in intensive care medicine (Acute Physiology and Chronic Health Evaluation, Simplified Acute Physiology Score and Sequential Organ Failure Assessment) after 48 h of admission.

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.

Nurse staffing levels, missed vital signs and mortality in hospitals: retrospective longitudinal observational study

Background

Low nurse staffing levels are associated with adverse patient outcomes from hospital care, but the causal relationship is unclear. Limited capacity to observe patients has been hypothesised as a causal mechanism.

Objectives

This study determines whether or not adverse outcomes are more likely to occur after patients experience low nurse staffing levels, and whether or not missed vital signs observations mediate any relationship.

Design

Retrospective longitudinal observational study. Multilevel/hierarchical mixed-effects regression models were used to explore the association between registered nurse (RN) and health-care assistant (HCA) staffing levels and outcomes, controlling for ward and patient factors.

Setting and participants

A total of 138,133 admissions to 32 general adult wards of an acute hospital from 2012 to 2015.

Main outcomes

Death in hospital, adverse event (death, cardiac arrest or unplanned intensive care unit admission), length of stay and missed vital signs observations.

Data sources

Patient administration system, cardiac arrest database, eRoster, temporary staff bookings and the Vitalpac system (System C Healthcare Ltd, Maidstone, Kent; formerly The Learning Clinic Limited) for observations.

Results

Over the first 5 days of stay, each additional hour of RN care was associated with a 3% reduction in the hazard of death [hazard ratio (HR) 0.97, 95% confidence interval (CI) 0.94 to 1.0]. Days on which the HCA staffing level fell below the mean were associated with an increased hazard of death (HR 1.04, 95% CI 1.02 to 1.07), but the hazard of death increased as cumulative staffing exposures varied from the mean in either direction. Higher levels of temporary staffing were associated with increased mortality. Adverse events and length of stay were reduced with higher RN staffing. Overall, 16% of observations were missed. Higher RN staffing was associated with fewer missed observations in high-acuity patients (incidence rate ratio 0.98, 95% CI 0.97 to 0.99), whereas the overall rate of missed observations was related to overall care hours (RN + HCA) but not to skill mix. The relationship between low RN staffing and mortality was mediated by missed observations, but other relationships between staffing and mortality were not. Changing average skill mix and staffing levels to the levels planned by the Trust, involving an increase of 0.32 RN hours per patient day (HPPD) and a similar decrease in HCA HPPD, would be associated with reduced mortality, an increase in staffing costs of £28 per patient and a saving of £0.52 per patient per hospital stay, after accounting for the value of reduced stays.

Limitations

This was an observational study in a single site. Evidence of cause is not definitive. Variation in staffing could be influenced by variation in the assessed need for staff. Our economic analysis did not consider quality or length of life.

Conclusions

Higher RN staffing levels are associated with lower mortality, and this study provides evidence of a causal mechanism. There may be several causal pathways and the absolute rate of missed observations cannot be used to guide staffing decisions. Increases in nursing skill mix may be cost-effective for improving patient safety.

Future work

More evidence is required to validate approaches to setting staffing levels. Other aspects of missed nursing care should be explored using objective data. The implications of findings about both costs and temporary staffing need further exploration.

Trial registration

This study is registered as ISRCTN17930973.

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 in Health Services and Delivery Research; Vol. 6, No. 38. See the NIHR Journals Library website for further project information.

The association between nurse staffing and omissions in nursing care: A systematic review

AIMS

To identify nursing care most frequently missed in acute adult inpatient wards and to determine evidence for the association of missed care with nurse staffing.

BACKGROUND

Research has established associations between nurse staffing levels and adverse patient outcomes including in-hospital mortality. However, the causal nature of this relationship is uncertain and omissions of nursing care (referred as missed care, care left undone or rationed care) have been proposed as a factor which may provide a more direct indicator of nurse staffing adequacy.

DESIGN

Systematic review.

DATA SOURCES

We searched the Cochrane Library, CINAHL, Embase and Medline for quantitative studies of associations between staffing and missed care. We searched key journals, personal libraries and reference lists of articles.

REVIEW METHODS

Two reviewers independently selected studies. Quality appraisal was based on the National Institute for Health and Care Excellence quality appraisal checklist for studies reporting correlations and associations. Data were abstracted on study design, missed care prevalence and measures of association. Synthesis was narrative.

RESULTS

Eighteen studies gave subjective reports of missed care. Seventy-five per cent or more nurses reported omitting some care. Fourteen studies found low nurse staffing levels were significantly associated with higher reports of missed care. There was little evidence that adding support workers to the team reduced missed care.

CONCLUSIONS

Low Registered Nurse staffing is associated with reports of missed nursing care in hospitals. Missed care is a promising indicator of nurse staffing adequacy. The extent to which the relationships observed represent actual failures, is yet to be investigated.

What impact does nursing care left undone have on patient outcomes? Review of the literature

Aims and objectives

Systematic review of the impact of missed nursing care on outcomes in adults, on acute hospital wards and in nursing homes.

Background

A considerable body of evidence supports the hypothesis that lower levels of registered nurses on duty increase the likelihood of patients dying on hospital wards, and the risk of many aspects of care being either delayed or left undone (missed). However, the direct consequence of missed care remains unclear.

Design

Systematic review.

Methods

We searched Medline (via Ovid), CINAHL (EBSCOhost) and Scopus for studies examining the association of missed nursing care and at least one patient outcome. Studies regarding registered nurses, healthcare assistants/support workers/nurses’ aides were retained. Only adult settings were included. Because of the nature of the review, qualitative studies, editorials, letters and commentaries were excluded. PRISMA guidelines were followed in reporting the review.

Results

Fourteen studies reported associations between missed care and patient outcomes. Some studies were secondary analyses of a large parent study. Most of the studies used nurse or patient reports to capture outcomes, with some using administrative data. Four studies found significantly decreased patient satisfaction associated with missed care. Seven studies reported associations with one or more patient outcomes including medication errors, urinary tract infections, patient falls, pressure ulcers, critical incidents, quality of care and patient readmissions. Three studies investigated whether there was a link between missed care and mortality and from these results no clear associations emerged.

Conclusions

The review shows the modest evidence base of studies exploring missed care and patient outcomes generated mostly from nurse and patient self‐reported data. To support the assertion that nurse staffing levels and skill mix are associated with adverse outcomes as a result of missed care, more research that uses objective staffing and outcome measures is required.

Relevance to clinical practice

Although nurses may exercise judgements in rationing care in the face of pressure, there are nonetheless adverse consequences for patients (ranging from poor experience of care to increased risk of infection, readmissions and complications due to critical incidents from undetected physiological deterioration). Hospitals should pay attention to nurses’ reports of missed care and consider routine monitoring as a quality and safety indicator.

A portable magneto-optical trap with prospects for atom interferometry in civil engineering

The high precision and scalable technology offered by atom interferometry has the opportunity to profoundly affect gravity surveys, enabling the detection of features of either smaller size or greater depth. While such systems are already starting to enter into the commercial market, significant reductions are required in order to reach the size, weight and power of conventional devices. In this article, the potential for atom interferometry based gravimetry is assessed, suggesting that the key opportunity resides within the development of gravity gradiometry sensors to enable drastic improvements in measurement time. To push forward in realizing more compact systems, techniques have been pursued to realize a highly portable magneto-optical trap system, which represents the core package of an atom interferometry system. This can create clouds of 10⁷ atoms within a system package of 20 l and 10 kg, consuming 80 W of power.This article is part of the themed issue 'Quantum technology for the 21st century'.

Are observation selection methods important when comparing early warning score performance?

INTRODUCTION

Sicker patients generally have more vital sign assessments, particularly immediately before an adverse outcome, and especially if the vital sign monitoring schedule is driven by an early warning score (EWS) value. This lack of independence could influence the measured discriminatory performance of an EWS.

METHODS

We used a population of 1564,143 consecutive vital signs observation sets collected as a routine part of patients' care. We compared 35 published EWSs for their discrimination of the risk of death within 24h of an observation set using (1) all observations in our dataset, (2) one observation per patient care episode, chosen at random and (3) one observation per patient care episode, chosen as the closest to a randomly selected point in time in each episode. We compared the area under the ROC curve (AUROC) as a measure of discrimination for each of the 35 EWSs under each observation selection method and looked for changes in their rank order.

RESULTS

There were no significant changes in rank order of the EWSs based on AUROC between the different observation selection methods, except for one EWS that included age among its components. Whichever method of observation selection was used, the National Early Warning Score (NEWS) showed the highest discrimination of risk of death within 24h. AUROCs were higher when only one observation set was used per episode of care (significantly higher for many EWSs, including NEWS).

CONCLUSIONS

Vital sign measurements can be treated as if they are independent - multiple observations can be used from each episode of care--when comparing the performance and ranking of EWSs, provided no EWS includes age.

Protein kinase C regulates ezrin-radixin-moesin phosphorylation in canine osteosarcoma cells

The development of metastasis is the most significant cause of death for both canine and human patients with osteosarcoma (OS). Ezrin has been associated with tumour progression and metastasis in human, canine and murine OS. Ezrin activation is dynamically regulated by protein kinase C (PKC) during metastatic progression in human and murine OS. To include the dog in the development of therapeutics that target ezrin biology, we characterized four new canine OS cell lines and confirmed the relationship between PKC and ezrin in these cells. Three of four cell lines formed tumours in mice that were histologically consistent with OS. All cell lines were markedly aneuploid and expressed ezrin and PKC. Finally, both ezrin phosphorylation and cell migration were inhibited using a PKC inhibitor. These data suggest that an association between PKC-mediated activation of ezrin and the metastatic phenotype in canine OS cells.

A study of the effectiveness of ergonomically-based functional screening tests and their relationship to reducing worker compensation injuries

OBJECTIVES

This paper summarizes a series of studies of the effectiveness of ergonomically based functional screening tests for post offer pre-placement of applicants for physically demanding jobs, and their relationship to reducing worker compensation injuries. Three predictive validation studies and a meta-analysis of injury rates pre- and post-implementation of physical ability testing at 175 locations are included.

METHODS

The strength and energy expenditure demands of physically-strenuous warehouse jobs in three industries were documented through ergonomic analysis. A battery of strength and endurance tests were developed to assess applicants' abilities to meet the measured physical demands. Predictive validation studies were performed for the jobs in each of the three industries. In each study, new-hires were given the physical ability test battery and then placed on the job. Management was not informed of the results of the tests. Injury experience and work history were then monitored over a two year period in each study. Injury rates and retention were then compared for individuals who passed and individuals who failed the battery. As the battery was implemented in other locations, the injury rate for individuals starting employment in the year prior to implementation was compared to the injury rate for individuals starting employment in the year after implementation.

CONCLUSIONS

A meta-analysis of the three predictive validation studies indicated that new-hires who passed the battery had a 47% lower worker compensation injury rate and 21% higher retention. A meta-analysis of the 175 pre/post-implementation studies indicated a 41% reduction in worker compensation injuries associated with implementation of ergonomically based physical ability tests.

Intracellular signalling pathways in the vasoconstrictor response of mouse afferent arterioles to adenosine

AIMS

Adenosine causes vasoconstriction of afferent arterioles of the mouse kidney through activation of adenosine A(1) receptors and Gi-mediated stimulation of phospholipase C. In the present study, we further explored the signalling pathways by which adenosine causes arteriolar vasoconstriction.

METHODS AND RESULTS

Adenosine (10(-7) M) significantly increased the intracellular calcium concentration in mouse isolated afferent arterioles measured by fura-2 fluorescence. Pre-treatment with thapsigargin (2 microM) blocked the vasoconstrictor action of adenosine (10(-7) M) indicating that release of calcium from the sarcoplasmic reticulum (SR), stimulated presumably by IP(3), is involved in the adenosine contraction mechanism of the afferent arteriole. In agreement with this notion is the observation that 2 aminoethoxydiphenyl borate (100 microM) blocked the adenosine-induced constriction whereas the protein kinase C inhibitor calphostin C had no effect. The calcium-activated chloride channel inhibitor IAA-94 (30 microM) inhibited the adenosine-mediated constriction. Patch clamp experiments showed that adenosine treatment induced a depolarizing current in preglomerular smooth muscle cells which was abolished by IAA-94. Furthermore, the vasoconstriction caused by adenosine was significantly inhibited by 5 microM nifedipine (control 8.3 +/- 0.2 microM, ado 3.6 +/- 0.6 microM, ado + nifedipine 6.8 +/- 0.2 microM) suggesting involvement of voltage-dependent calcium channels.

CONCLUSION

We conclude that adenosine mediates vasoconstriction of afferent arterioles through an increase in intracellular calcium concentration resulting from release of calcium from the SR followed by activation of Ca(2+)-activated chloride channels leading to depolarization and influx of calcium through voltage-dependent calcium channels.

An RFID-based system for assisted living: challenges and solutions

Radio-frequency Identification (RFID) offers a potentially flexible and low cost method of locating objects and tracking people within buildings. RFID systems generally require less infrastructure to be installed than other solutions but have their own limitations. As part of an assisted living system, RFID tools may be useful to locate lost objects, support blind and partially sighted people with daily living activities and assist in the rehabilitation of adults with acquired brain injury. This paper outlines the requirements and the role of RFID in assisting people in these three areas. The development of a prototype RFID home support tool is described and some of the issues and challenges raised are discussed. The system is designed to support assisted living for elderly and infirm people in a simple, usable and extensible way in particular for supporting the finding and identification of commonly used and lost objects such as spectacles. This approach can also be used to extend the tagged domain to commonly visited areas, and provide support for the analysis of common activities, and rehabilitation.

Reporter gene recombination in juxtaglomerular granular and collecting duct cells by human renin promoter-Cre recombinase transgene

To assess the feasibility of using the renin promoter for expressing Cre recombinase in juxtaglomerular (JG) cells only, we generated five independent transgenic mouse lines (designated hRen-Cre) expressing Cre recombinase under control of a 12.2-kb human renin promoter. In the kidneys of adult mice Cre mRNA (RT-PCR) was found in the renal cortex, with Cre protein (immunohistochemistry) being localized in afferent arterioles and to a lower degree in interlobular arteries. Cre mRNA levels were regulated in a renin-typical fashion by changes in oral salt intake, water restriction, or isoproterenol infusion, indicating the presence of key regulatory elements within 12.2 kb of the 5′-flanking region of the human renin gene. hRen-Cre mice were interbred with both the ROSA26-EGFP and ROSA26-lacZ reporter strains to assess renin promoter activity from Cre-mediated excision of a floxed stop cassette and subsequent enhanced green fluorescent protein (EGFP) and β-galactosidase (β-gal) detection. In adult mice, β-gal staining and EGFP were observed in afferent arterioles and interlobular arteries, overlapping with Cre protein expression. In addition, intense β-gal staining was found in cortical and medullary collecting ducts where Cre expression was minimal. In embryonic kidneys, β-gal staining was detected in the developing collecting duct system beginning at embryonic day 12, showing substantial activity of the human renin promoter in the branching ureteric bud. Our data indicate that besides its well-known activity in JG cells and renal vessels the human renin promoter is transiently active in the collecting duct system during kidney development, complicating the use of this approach for JG cell-specific excision of floxed targets.

Reduced autoregulatory effectiveness in adenosine 1 receptor-deficient mice

Adjustments of renal vascular resistance in response to changes in blood pressure are mediated by an interplay between the myocyte-inherent myogenic and the kidney-specific tubuloglomerular feedback (TGF) mechanisms. Using mice with deletion of the A(1) adenosine receptor (A1AR) gene, we tested the prediction that the absence of TGF, previously established to result from A1AR deficiency, is associated with a reduction in the efficiency of autoregulation. In anesthetized wild-type (A1AR+/+) and A1AR-deficient mice (A1AR-/-), glomerular filtration rate (GFR) and renal blood flow (RBF) were determined before and after reducing renal perfusion pressure through a suprarenal aortic clamp. In response to a blood pressure reduction by 15.9 +/- 1.34 mmHg in A1AR-/- (n = 9) and by 14.2 +/- 0.9 mmHg in A1AR+/+ mice (n = 8; P = 0.31), GFR fell by 187.9 +/- 37 mul/min and by 72.3 +/- 10 mul/min in A1AR-/- and A1AR+/+ mice, respectively (P = 0.013). Similarly, with pressure reductions of 14.8 +/- 1.1 and 13.3 +/- 1.5 mmHg in A1AR-/- (n = 9) and wild-type mice (n = 8), respectively (P = 0.43), RBF fell by 0.17 +/- 0.02 ml/min in A1AR-/- mice and by only 0.08 +/- 0.02 ml/min in wild-type animals (P = 0.0039). Autoregulatory indexes for both GFR and RBF were significantly higher in A1AR-/- compared with A1AR+/+ mice, indicating reduced regulatory responsiveness in the knockout animals. We conclude that autoregulation of renal vascular resistance is less complete in A1AR-deficient mice, an effect that is presumably related to absence of TGF regulation in these animals.

Compensation of proximal tubule malabsorption in AQP1-deficient mice without TGF-mediated reduction of GFR

AIM

By crossing aquaporin 1 (AQP1)-/- and adenosine 1 receptor (A1AR)-/- mice, we generated an animal model that combines a proximal tubular absorption defect with absence of tubuloglomerular feedback (TGF) regulation of glomerular filtration rate (GFR). The aim of studies in these animals was to determine whether a TGF-induced reduction of GFR is a prerequisite for preventing potentially fatal fluid losses.

METHODS AND RESULTS

In contrast to AQP1 deficient mice, AQP1/A1AR-/- mice were found to have a normal GFR. TGF responses were abolished in these animals, in contrast to AQP1-/- mice in which TGF responses of single nephron glomerular filtration rate (SNGFR) were left-shifted. Proximal tubule fluid absorption in AQP1/A1AR-/- mice was reduced to levels previously reported for AQP1-/- mice. However, SNGFR was significantly higher in AQP1/A1AR-/- than AQP1-/- mice (10.6 +/- 0.8 nL min(-1) vs. 5.9 +/- 0.7 nL min(-1)). As a consequence of the normal GFR and the reduced proximal reabsorption distal fluid delivery was markedly higher in the double knockout compared with normal or AQP1-/- mice (5.5 +/- 0.5 nL min(-1) vs. 2.35 +/- 0.3 nL min(-1) in AQP1-/-). Despite the approximate doubling of distal fluid and Cl delivery, AQP1/A1AR-/- mice have a normal salt excretion, normal arterial blood pressure, and only a small increase in plasma renin concentration.

CONCLUSION

The ability to compensate for proximal tubule malabsorption without a TGF-induced reduction of GFR attests to a remarkable adaptability of distal tubule transport mechanisms.

Plasma renin in mice with one or two renin genes

AIM

In the present study we have investigated whether the presence of a second renin gene exerts an overriding influence on plasma renin such that mice with two renin genes have consistently higher renin levels than mice with only one renin gene.

METHODS

Plasma renin was determined as the rate of angiotensin I generation using a radioimmunoassay (RIA) kit with (plasma renin concentration, PRC) or without (plasma renin activity, PRA) the addition of purified rat angiotensinogen as substrate.

RESULTS

In male 129SvJ, DBA/2 and Swiss Webster mice, strains possessing both Ren-1 and Ren-2, PRC (ng Ang I mL(-1) h(-1)) averaged 178 +/- 36, 563 +/- 57 and 550 +/- 43 while PRA was 2.9 +/- 0.5, 3.6 +/- 0.8 and 7.8 +/- 1.2. In male C57BL/6, C3H and BALB/c mice that express only Ren-1, PRC averaged 426 +/- 133, 917 +/- 105 and 315 +/- 72, and PRA was 3.4 +/- 1.0, 6.9 +/- 1.7 and 4.5 +/- 1.2. In the two renin gene A1AR-/- mice compared with the one renin gene A1AR+/+, PRC averaged 538 +/- 321 and 415 +/- 159 while PRA averaged 3.2 +/- 1.1 and 4.4 +/- 1.4 ng Ang I mL(-1) h(-1). Aldosterone levels showed no significant differences between one renin (C57BL/6, C3H and BALB/c) and two renin (129SvJ, DBA/2 and Swiss Webster) gene mice. Furthermore, by quantitative real-time polymerase chain reaction (RT-PCR) we found no correlation between the number of renin genes and whole kidney renin mRNA levels from one and two renin gene mice.

CONCLUSION

Our data show that baseline plasma renin is not systematically higher in mice with two renin genes than in one renin gene mice. Thus, the presence of a second renin gene does not seem to be a major determinant of differences in PRC between different mouse strains.

The role of cathepsin C in Papillon-Lefèvre syndrome, prepubertal periodontitis, and aggressive periodontitis

We have previously reported that loss-of-function mutations in the cathepsin C gene (CTSC) result in Papillon-Lefèvre syndrome, an autosomal recessive condition characterized by palmoplantar keratosis and early-onset, severe periodontitis. Others have also reported CTSC mutations in patients with severe prepubertal periodontitis, but without any skin manifestations. The possible role of CTSC variants in more common types of non-mendelian, early-onset, severe periodontitis ("aggressive periodontitis") has not been investigated. In this study, we have investigated the role of CTSC in all three conditions. We demonstrate that PLS is genetically homogeneous and the mutation spectrum that includes three novel mutations (c.386T>A/p.V129E, c.935A>G/p.Q312R, and c.1235A>G/p.Y412C) in 21 PLS families (including eight from our previous study) provides an insight into structure-function relationships of CTSC. Our data also suggest that a complete loss-of-function appears to be necessary for the manifestation of the phenotype, making it unlikely that weak CTSC mutations are a cause of aggressive periodontitis. This was confirmed by analyses of the CTSC activity in 30 subjects with aggressive periodontitis and age-sex matched controls, which demonstrated that there was no significant difference between these two groups (1,728.7 +/- SD 576.8 micro moles/mg/min vs. 1,678.7 +/- SD 527.2 micro moles/mg/min, respectively, p = 0.73). CTSC mutations were detected in only one of two families with prepubertal periodontitis; these did not form a separate functional class with respect to those observed in classical PLS. The affected individuals in the other prepubertal periodontitis family not only lacked CTSC mutations, but in addition did not share the haplotypes at the CTSC locus. These data suggest that prepubertal periodontitis is a genetically heterogeneous disease that, in some families, just represents a partially penetrant PLS.

Economic costs associated with inadequate drug prescribing: an exploratory study in Chiapas, Mexico

An exploratory study assessing the economic consequences of inadequate prescribing by health-care providers was carried out in two cities of Chiapas State, South Mexico. Two research methods were used: (a) an exit survey with pharmacy users (1190 interviews) and (b) in-depth individual interviews with patients at hospital level (19 interviews). For comparative purposes, three tracer conditions were selected: acute respiratory infection (ARI), diarrhoeal disease (DD) and hypertension. The main findings were that doctors, drug vendors at pharmacies, traditional healers, users of health-care services themselves (through self-prescription) and other health staff are all sources of inadequate prescribing and impose a substantial economic burden of unnecessary cost on health-care users. In general, treatment costs were high compared with standard treatments, and prescriptions included a high proportion of non-essential drugs (50-64%). Additional costs to the standard treatment were particularly high when the prescription was by a medical doctor (US$ 3.57 per ARI prescription and US$ 8.37 for DD). Losses attributable to inadequate prescribing averaged US$ 47 per patient. The study concludes that training programmes on rational drug use aimed exclusively at medical doctors can only have a limited effect in reducing economic losses due to inadequate prescribing. Such efforts should be extended to other providers who are very active in prescribing drugs and providing health advice. The main challenge that the Mexican health system will be facing in the foreseeable future is not only to improve equity of access to essential drugs, but also to improve quality of drug advice and prescription and rational use of drugs by the population.

Cyclooxygenase cloning in dogfish shark, Squalus acanthias, and its role in rectal gland Cl secretion

The present studies were carried out with the aims to determine the cDNA sequence for cyclooxygenase (COX) in an elasmobranch species and to study its role in regulation of chloride secretion in the perfused shark rectal gland (SRG). With the use of long primers (43 bp) derived from regions of homology between zebrafish and rainbow trout COX-2 genes, a 600-bp product was amplified from SRG and was found to be almost equally homologous to mammalian COX-1 and COX-2 (65%). The full-length cDNA sequence was obtained by 5'-RACE and by analyzing an EST clone generated by the EST Project of the Mt. Desert Island Biological Laboratory Marine DNA Sequencing Center. The longest open reading frame encodes a 593-amino acid protein that has 68 and 64% homology to mammalian COX-1 and COX-2, respectively. The gene and its protein product is designated as shark COX (sCOX). The key residues in the active site (Try(385), His(388), and Ser(530)) are conserved between the shark and mammalian COX. sCOX contains Val(523) that has been shown to be a key residue determining the sensitivity to COX-2-specific inhibitors including NS-398. The mRNA of sCOX, detected by RT-PCR, was found in all tissues tested, including rectal gland, kidney, spleen, gill, liver, brain, and heart, but not in fin. In the perfused SRG, vasoactive intestinal peptide (VIP) at 5 nM induced rapid and marked Cl(-) secretion (basal: <250 microeq x h(-1) x g(-1); peak response: 3,108 +/- 479 microeq x h(-1) x g(-1)). In the presence of 50 microM NS-398, both the peak response (2,131 +/- 307 microeq x h(-1) x g(-1)) and the sustained response to VIP were significantly reduced. When NS-398 was removed, there was a prompt recovery of chloride secretion to control values. In conclusion, we have cloned the first COX in an elasmobranch species (sCOX) and shown that sCOX inhibition suppresses VIP-stimulated chloride secretion in the perfused SRG.

Mediation of tubuloglomerular feedback by adenosine: evidence from mice lacking adenosine 1 receptors

Adenosine is a determinant of metabolic control of organ function increasing oxygen supply through the A2 class of adenosine receptors and reducing oxygen demand through A1 adenosine receptors (A1AR). In the kidney, activation of A1AR in afferent glomerular arterioles has been suggested to contribute to tubuloglomerular feedback (TGF), the vasoconstriction elicited by elevations in [NaCl] in the macula densa region of the nephron. To further elucidate the role of A1AR in TGF, we have generated mice in which the entire A1AR coding sequence was deleted by homologous recombination. Homozygous A1AR mutants that do not express A1AR mRNA transcripts and do not respond to A1AR agonists are viable and without gross anatomical abnormalities. Plasma and urinary electrolytes were not different between genotypes. Likewise, arterial blood pressure, heart rates, and glomerular filtration rates were indistinguishable between A1AR(+/+), A1AR(+/-), and A1AR(-/-) mice. TGF responses to an increase in loop of Henle flow rate from 0 to 30 nl/min, whether determined as change of stop flow pressure or early proximal flow rate, were completely abolished in A1AR(-/-) mice (stop flow pressure response, -6.8 +/- 0.55 mmHg and -0.4 +/- 0.2 in A1AR(+/+) and A1AR(-/-) mice; early proximal flow rate response, -3.4 +/- 0.4 nl/min and +0.02 +/- 0.3 nl/min in A1AR(+/+) and A1AR(-/-) mice). Absence of TGF responses in A1AR-deficient mice suggests that adenosine is a required constituent of the juxtaglomerular signaling pathway. A1AR null mutant mice are a promising tool to study the functional role of A1AR in different target tissues.

The reliability of the SCAN test: results from a primary school population in the UK

The SCAN test utilizes a pre-recorded tape, with carrier phrase and target words spoken by an American English speaker, to screen for central auditory processing disorders in children. The aim of the present study was to establish whether the normative data, derived from American school children, are applicable to a UK primary school population. The SCAN test was administered to 133 British primary school children with normal hearing, stratified into one-year age bands. Mean scores from the UK sample were found to be significantly lower than US mean scores for the most of the age bands. Analysis of word errors indicates accent and word familiarity effects. This evaluation of the SCAN indicates that the test is not directly applicable to British children as currently normalized. The present study provides interim norms for the American recording for age bands six to 11 years. It is recommended that the test material is recorded by a UK English speaker, with substitution of high error-rate target words, followed by normative data collection for the new test material.