Frequency of and associations with alterations of medical emergency team calling criteria in a teaching hospital emergency department

BACKGROUND

Medical emergency team (METs), activated by vital sign-based calling criteria respond to deteriorating patients in the hospital setting. Calling criteria may be altered where clinicians feel this is appropriate. Altered calling criteria (ACC) has not previously been evaluated in the emergency department (ED) setting.

OBJECTIVES

The objectives of this study were to (i) describe the frequency of ACC in a teaching hospital ED and the number and type of vital signs that were modified and (ii) associations between ACC in the ED and differences in the baseline patient characteristics and adverse outcomes including subsequent MET activations, unplanned intensive care unit (ICU) admissions and death within 72 h of admission.

METHODS

Retrospective observational study of patients presenting to an academic, tertiary hospital ED in Melbourne, Australia between January 1st, 2019 and December 31st, 2019. The primary outcome was frequency and nature of ACC in the ED. Secondary outcomes included differences in baseline patient characteristics, frequency of MET activation, unplanned ICU admission, and mortality in the first 72 h of admission between those with and without ACC in the ED.

RESULTS

Amongst 14 159 ED admissions, 725 (5.1%) had ACC, most frequently for increased heart or respiratory rate. ACC was associated with older age and increased comorbidity. Such patients had a higher adjusted risk of MET activation (odds ratio [OR]: 3.14, 95% confidence interval [CI]: 2.50-3.91, p = <0.001), unplanned ICU admission (OR: 1.97, 95% CI: 1.17-3.14, p = 0.016), and death (OR: 3.87, 95% CI: 2.08-6.70, p = 0.020) within 72 h.

CONCLUSIONS

ACC occurs commonly in the ED, most frequently for elevated heart and respiratory rates and is associated with worse patient outcomes. In some cases, ACC requires consultant involvement, more frequent vital sign monitoring, expeditious inpatient team review, or ICU referral.

Individualised Estimation of Quality-adjusted Survival Benefit and Cost-effectiveness of Proton Beam Therapy in Intermediate-stage Hodgkin Lymphoma

AIMS

Radiotherapy for Hodgkin lymphoma leads to the irradiation of organs at risk (OAR), which may confer excess risks of late effects. Comparative dosimetry studies show that proton beam therapy (PBT) may reduce OAR irradiation compared with photon radiotherapy, but PBT is more expensive and treatment capacity is limited. The purpose of this study is to inform the appropriateness of PBT for intermediate-stage Hodgkin lymphoma (ISHL).

MATERIALS AND METHODS

A microsimulation model simulating the course of ISHL, background mortality and late effects was used to estimate comparative quality-adjusted life years (QALYs) lived and healthcare costs after consolidative pencil beam scanning PBT or volumetric modulated arc therapy (VMAT), both in deep-inspiration breath-hold. Outcomes were compared for 606 illustrative patients covering a spectrum of clinical presentations, varying by two age strata (20 and 40 years), both sexes, three smoking statuses (never, former and current) and 61 pairs of OAR radiation doses from a comparative planning study. Both undiscounted and discounted outcomes at 3.5% yearly discount were estimated. The maximum excess cost of PBT that might be considered cost-effective by the UK's National Institute for Health and Care Excellence was calculated.

RESULTS

OAR doses, smoking status and discount rate had large impacts on QALYs gained with PBT. Current smokers benefited the most, averaging 0.605 undiscounted QALYs (range -0.341 to 2.171) and 0.146 discounted QALYs (range -0.067 to 0.686), whereas never smokers benefited the least, averaging 0.074 undiscounted QALYs (range -0.196 to 0.491) and 0.017 discounted QALYs (range -0.030 to 0.086). For the gain in discounted QALYs to be considered cost-effective, PBT would have to cost at most £4812 more than VMAT for current smokers and £645 more for never smokers. This is below preliminary National Health Service cost estimates of PBT over photon radiotherapy.

CONCLUSION

In a UK setting, PBT for ISHL may not be considered cost-effective. However, the degree of unquantifiable uncertainty is substantial.

Medication-related Medical Emergency Team activations: a case review study of frequency and preventability

OBJECTIVES

Despite recognition of clinical deterioration and medication-related harm as patient safety risks, the frequency of medication-related Rapid Response System activations is undefined. We aimed to estimate the incidence and preventability of medication-related Medical Emergency Team (MET) activations and describe the associated adverse medication events.

METHODS

A case review study of consecutive MET activations at two acute, academic teaching hospitals in Melbourne, Australia with mature Rapid Response Systems was conducted. All MET activations during a 3-week study period were assessed for a medication cause including identification of the contributing adverse medication event and its preventability, using validated tools and recognised classification systems.

RESULTS

There were 9439 admissions and 628 MET activations during the study period. Of these, 146 (23.2%) MET activations were medication related: an incidence of 15.5 medication-related MET activation per 1000 admissions. Medication-related MET activations occurred a median of 46.6 hours earlier (IQR 22-165) in an admission than non-medication-related activations (p=0.001). Furthermore, this group also had more repeat MET activations during their admission (p=0.021, OR=1.68, 95% CI 1.09 to 2.59). A total of 92 of 146 (63%) medication-related MET activations were potentially preventable. Tachycardia due to omission of beta-blocking agents (10.9%, n=10 of 92) and hypotension due to cumulative toxicity (9.8%, n=9 of 92) or inappropriate use (10.9%, n=10 of 92) of antihypertensives were the most common adverse medication events leading to potentially preventable medication-related MET activations.

CONCLUSIONS

Medications contributed to almost a quarter of MET activations, often early in a patient's admission. One in seven MET activations were due to potentially preventable adverse medication events. The most common of these were omission of beta-blockers and clinically inappropriate antihypertensive use. Strategies to prevent these events would increase patient safety and reduce burden on the MET.

Characteristics and outcomes of surgical patients admitted to an overnight intensive recovery unit: A retrospective observational study

Postoperative 'enhanced care' models that sit between critical care and ward-based care may allow for more cost-effective and efficient utilisation of resources for high-risk surgical patients. In this retrospective observational study, we describe an overnight intensive recovery model in a tertiary hospital, termed 'recovery high dependency unit', and the characteristics, treatment, disposition at discharge and in-hospital outcomes of patients admitted to this unit. We included all adult patients (≥18 years) admitted to the recovery high dependency unit for at least one hour between July 2017 and June 2020. Over this three-year period, 1257 patients were included in the study. The median length of stay in the recovery high dependency unit was 12.6 (interquartile range 9.1-15.9) hours and the median length of hospital stay was 8.3 (interquartile range 5.0-17.3) days. Hospital discharge data showed that 1027 (81.7%) patients were discharged home and that 37 (2.9%) patients died. Non-invasive ventilation was delivered to 59 (4.7%) patients and 290 (23.1%) required vasopressor support. A total of 164 patients (13.0%) were admitted to the intensive care unit following their recovery high dependency unit admission. Of the 1093 patients who were discharged to the ward, 70 patients (6.4%) had a medical emergency team call within 24 hours of discharge from the recovery high dependency unit. In this study of a recovery high dependency unit patient cohort, there was a relatively low need for intensive care unit admission postoperatively and a very low incidence of medical emergency team calls post-discharge to the ward. Other institutions may consider the introduction and evaluation of this model in the care of their higher risk surgical patients.

Midodrine use in critically ill patients: a narrative review

Midodrine is a peripherally acting, oral α-agonist that is increasingly used in intensive care units despite conflicting evidence for its effectiveness. It has pharmacological effects on blood vessels as well as pupillary, cardiac, renal, gastrointestinal, genitourinary, lymphatic and skin tissue. It has approval for use as a treatment for orthostatic hypotension, but a surge in interest over the past decade has prompted its use for a growing number of off-label indications. In critically ill patients, midodrine has been used as either an adjunctive oral therapy to wean vasoplegic patients off low dose intravenous vasopressor infusions, or as an oral vasopressor agent to prevent or minimise the need for intravenous infusion. Clinical trials have mostly focused on midodrine as an intravenous vasopressor weaning agent. Early retrospective studies supported its use for this indication, but more recent randomised controlled trials have largely refuted this practice. Key questions remain on its role in managing critically ill patients before intensive care admission, during intensive care stay, and following discharge. This narrative review presents a comprehensive overview of midodrine use for the critical care physician and highlights why lingering questions around ideal patient selection, dosing, timing of initiation, and efficacy of midodrine for critically ill patients remain unanswered.

Improving the quality of family meeting documentation in the ICU at the end of life

Objective

Improve documentation quality of end-of-life family meetings in a tertiary intensive care unit (ICU).

Design

Before-and-after interventional quality improvement project between October 2018 and February 2020 utilising an electronic pro-forma record.

Setting

Australian, University affiliated, mixed medical-surgical 22 bed adult ICU.

Participants

Patients who were admitted to the ICU for active management and subsequently died during that ICU admission. We enrolled 50 patients who died before and 50 patients after the introduction of the electronic family meeting pro-forma record.

Intervention

Through collaboration with ICU medical and nursing staff, End-of-life Special Interest Group and Clinical Documentation Committee we developed the ICU Family Meeting Discussion Note as an electronic pro-forma record with multiple key fields of entry.

Main outcome measures

Patient records were examined for the presence of documented details around patient's admission, family meetings and specific elements surrounding the patient's death.

Results

The introduction of a pro-forma record markedly improved the quality of documentation of end-of-life care related family meetings. Documentation increased in recording hospital admission date/time (6% vs 84%), meeting location (14% vs 70%), the reason patients were absent from the meeting (34% vs 72%), the Medical Treatment Decision Maker (MTDM) (10% vs 44%), the patient's resuscitation status (22% vs 54%), and treatment options discussed (78% vs 94%) (p ⩽ 0.005 for all).

Conclusion

Introducing an electronic pro-forma record to facilitate family meeting documentation increased the frequency of important recorded information. Further studies are required to assess whether documentation quality improvements are sustainable and whether they affect patient- or relative-centred outcomes.

Intraoperative low tidal volume ventilation and the risk of ICD-10 coded delirium and the use for antipsychotic medications

BACKGROUND

Low tidal volume (V_T) ventilation and its associated increase in arterial carbon dioxide (PaCO₂) may affect postoperative neurologic function. We aimed to test the hypothesis that intraoperative low V_T ventilation affect the incidence of postoperative ICD-10 coded delirium and/or the need for antipsychotic medications.

METHODS

This is a post-hoc analysis of a large randomized controlled trial evaluating low vs. conventional V_T ventilation during major non-cardiothoracic, non-intracranial surgery. The primary outcome was the incidence of ICD-10 delirium and/or the use of antipsychotic medications during hospital stay, and the absolute difference with its 95% confidence interval (CI) was calculated.

RESULTS

We studied 1206 patients (median age of 64 [55-72] years, 59.0% males, median ARISCAT of 26 [19-37], and 47.6% of ASA 3). ICD-10 coded delirium and /or antipsychotic medication use was diagnosed in 11.2% with similar incidence between low and conventional V_T ventilation (11.1% vs. 11.3%; absolute difference, -0.24 [95%CI, -3.82 to 3.32]; p = 0.894). There was no interaction between allocation group and type of surgery.

CONCLUSION

In adult patients undergoing major surgery, low V_T ventilation was not associated with increased risk of ICD-10 delirium and/or the use of antipsychotic medications during hospital stay.

TRIAL REGISTRATION

ANZCTR Identifier: ACTRN12614000790640 .

An audit of perioperative end-of-life care practices and documentation relating to patients who died in a surgical unit in three Victorian hospitals

The number of older, frail patients undergoing surgery is increasing, prompting consideration of the benefits of intensive treatment. Despite collaborative decision-making processes such as advance care planning being supported by recent Australian legislation, their role in perioperative care is yet to be defined. Furthermore, there has been little evaluation of the quality of end-of-life care in the surgical population. We investigated documentation of the premorbid functional status, severity of illness, intensity of treatment, operative management and quality of end-of-life care in patients who died in a surgical unit, with a retrospective study of surgical mortality which was performed across three hospitals over a 23-month period in Victoria, Australia. Among 99 deceased patients in the study cohort, 68 had a surgical operation. Preoperative functional risk assessment by medical staff was infrequently documented in the medical notes (5%) compared with activities of daily living (69%) documented by nursing staff. Documented preoperative discussions regarding the risk of death were rarely and inconsistently done, but when done were extensive. Documented end-of-life care discussions were identified in 71%, but were frequently brief, inconsistent, and in 60% did not occur until 48 hours from death. In 35.4% of instances, documented discussions involved junior staff (registrars or residents), and 43.4% involved intensive care unit staff. Palliative or terminal care referrals also occurred late (1-2 days prior to death). Not-for-resuscitation orders were frequently changed when approaching the end of life. Overall, 57% of deceased patients had a documented opportunity for farewell with family. We conclude that discussions and documentation of end-of-life care practices could be improved and recommend that all surgical units undertake similar audits to ensure that end-of-life care discussions occur for high-risk and palliative care surgical patients and are documented appropriately.

Intra-operative ventilator mechanical power as a predictor of postoperative pulmonary complications in surgical patients: A secondary analysis of a randomised clinical trial

BACKGROUND

Studies in critically ill patients suggest a relationship between mechanical power (an index of the energy delivered by the ventilator, which includes driving pressure, respiratory rate, tidal volume and inspiratory pressure) and complications.

OBJECTIVE

We aimed to assess the association between intra-operative mechanical power and postoperative pulmonary complications (PPCs).

DESIGN

Post hoc analysis of a large randomised clinical trial.

SETTING

University-affiliated academic tertiary hospital in Melbourne, Australia, from February 2015 to February 2019.

PATIENTS

Adult patients undergoing major noncardiothoracic, nonintracranial surgery.

INTERVENTION

Dynamic mechanical power was calculated using the power equation adjusted by the respiratory system compliance (CRS). Multivariable models were used to assess the independent association between mechanical power and outcomes.

MAIN OUTCOME MEASURES

The primary outcome was the incidence of PPCs within the first seven postoperative days. The secondary outcome was the incidence of acute respiratory failure.

RESULTS

We studied 1156 patients (median age [IQR]: 64 [55 to 72] years, 59.5% men). Median mechanical power adjusted by CRS was 0.32 [0.22 to 0.51] (J min-1)/(ml cmH2O-1). A higher mechanical power was also independently associated with increased risk of PPCs [odds ratio (OR 1.34, 95% CI, 1.17 to 1.52); P < 0.001) and acute respiratory failure (OR 1.40, 95% CI, 1.21 to 1.61; P < 0.001).

CONCLUSION

In patients receiving ventilation during major noncardiothoracic, nonintracranial surgery, exposure to a higher mechanical power was independently associated with an increased risk of PPCs and acute respiratory failure.

TRIAL REGISTRATION

Australia and New Zealand Clinical Trials Registry no: 12614000790640.

The impact of non-pharmacological therapies on cardiovascular outcomes in patients with refractory angina: a systematic review and meta-analysis of randomized controlled trials

 

Despite advances in revascularization techniques and optimal medical management, refractory angina (RFA) represents an essential group of patients where progress has stalled, and in which therapeutic approaches remain uncertain.

Numerous randomized control trials have reported clinical outcomes on a variety of treatments but to date no direct outcome comparison has been made. Our aim is to investigate and compare the outcomes of these different non-pharmacological technologies in RFA, centring on major adverse cardiac events and all-cause mortality.

We performed a systematic review and meta-analysis of randomized controlled trials using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A comprehensive search was performed of PubMed, EMBASE (Excerpta Medica database),Cochrane, ClinicalTrials.gov, Google Scholar databases of randomized controlled trials, and scientific session abstracts. Studies were deemed eligible if they met the following criteria: (1) full-length publications in peer-reviewed journals; (2) evaluated non-pharmacological therapies use in patients with no further revascularization options while on optimal medical treatment; (3) patients had ongoing angina, Canadian Cardiovascular Society class II–IV; and (4) included a placebo/control arm. We calculated risk ratios for all-cause mortality, combined MACE events. We assessed heterogeneity using χ2 and I2 tests.

We analysed 3292 citations with 51 randomized control trials testing 9 therapies including angiogenic proteins, stem-cell therapy, lipoprotein apheresis, coronary sinus reducer, spinal cord stimulator, percutaneous laser revascularization, shock-wave therapy, transmyocardial laser revascularization and enhanced external counter pulsation all meeting the inclusion criteria (table 1). Our analysis identified stem cell therapy as the only therapy with a reduction in all-cause mortality (Odds ratio, 0.45; CI, 0.21–1.00) (figure 1). A corresponding reduction in major adverse cardiac events (MACE) was also seen with stem cell therapy (OR 0.48: CI 0.30–0.75) alongside patients who received angiogenic proteins (OR 0.72: CI 0.55–0.93) and cardiac shockwave therapy (OR, 0.21: CI 0.10–0.46) Improvements in secondary measures of angina symptoms or frequency were seen with stem cell therapy, angiogenic proteins, coronary sinus reducer, spinal cord stimulator, shock-wave therapy, transmyocardial laser revascularization and enhanced external counterpulsation.

This is the largest meta-analysis comparing outcomes of novel technologies used in refractory angina. This suggests that stem cell therapy is the only non-pharmacological therapy for RFA associated with a reduction in mortality, MACE and anginal symptoms. We propose further larger randomized control trials, to support these findings.

Funding Acknowledgement

Type of funding sources: None. Table 1. Randomized control trials and outcomesFigure 1. All-cause mortality forest plot

Evaluation of medical emergency team medication management practices in acute hospitals: A multicentre study

BACKGROUND

Medical emergency teams use medications to rescue deteriorating patients. Medication management is the system of steps and processes, including prescribing, distribution, administration, and monitoring, to achieve the best outcomes from medication use. Systems or standards for medication management by medical emergency teams have not been defined.

OBJECTIVES

The aim of the study was to propose potential solutions to improve medical emergency team medication management by evaluating medication supply and related medication management practices during medical emergency team activations and understanding clinicians' perceptions about medical emergency team medication management in acute hospitals.

METHODS

A prospective multicentre audit of intensive care unit-equipped hospitals in Victoria, Australia, was conducted. After advertisement and invitation via scheduled email newsletters to hospitals, a representative of the medical emergency team from each hospital self-administered an online audit tool during December 2019 and January 2020. Audit data were analysed descriptively, and perceptions were analysed using content analysis.

RESULTS

Responses were received from 32 of the 44 (72.7%) eligible hospitals. At 17 of the 32 (53.1%) hospitals, arrest trolleys provided medications for medical emergency team activations, in addition to arrest calls. At 15 of the 32 (46.9%) hospitals, separate, dedicated medical emergency team medication supplies were used to care for deteriorating patients. Dedicated medical emergency team supplies contained a median of 20 (range = 8-37) medications, predominantly cardiovascular (median = 8, mode = 7, range = 4-16) and neurological medications (median and mode = 6, range = 0-11). Variation was observed in all storage and other supply-related medication management practices studied. The four most frequent categories of clinicians' perceptions described systematic challenges with availability of the right medication in the right place at the right time.

CONCLUSIONS

Current supply and related medication management practices and clinicians' perceptions demonstrated further development is necessary for medication management to meet the needs of medical emergency team clinicians and their patients.

ICU trainee perception of end of life care provided during medical emergency team activation events

BACKGROUND

Hospital Medical Emergency Team (MET) activation events involving end of life care (EOLC) are common. The issues faced by medical staff attending these events are incompletely described.

METHODS

We conducted an anonymous, voluntary, internet-based survey of registered trainees of the College of Intensive Care Medicine of Australia and New Zealand in May 2019. The participants eligible were those trainees working in an adult intensive care unit in Victoria, Australia during the study period. The main outcome measures were self-reported levels of confidence, barriers to communication, frequency of conflict and distress, senior support, supervision and access to training.

RESULTS

Of 124 trainees surveyed, 75 (60%) responded. Overall, 78 % of respondents felt confident to manage EOLC MET calls, but the frequently reported barriers to effective patient / next of kin communication included 1) lack of private meeting rooms, 2) resource and time constraints and 3) lack of patient and family availability during a MET call to discuss medical treatment limitations. Two thirds of respondents reported emotional distress at least occasionally, this being frequent in one in five. Most trainees (68%) experienced conflict with other medical teams at least occasionally. Factors associated with experiencing distress at least occasionally include greater trainee age, patients' being unable to participate in discussion due to illness, resource and time constraints and negative encounters with other medical teams.

CONCLUSIONS

Victorian intensive care trainees were confident managing EOLC MET activation events. However, distress was reported commonly and strategies are required to address the areas of concern. This article is protected by copyright. All rights reserved.

Effect of Intraoperative Low Tidal Volume vs Conventional Tidal Volume on Postoperative Pulmonary Complications in Patients Undergoing Major Surgery: A Randomized Clinical Trial

IMPORTANCE

In patients who undergo mechanical ventilation during surgery, the ideal tidal volume is unclear.

OBJECTIVE

To determine whether low-tidal-volume ventilation compared with conventional ventilation during major surgery decreases postoperative pulmonary complications.

DESIGN, SETTING, AND PARTICIPANTS

Single-center, assessor-blinded, randomized clinical trial of 1236 patients older than 40 years undergoing major noncardiothoracic, nonintracranial surgery under general anesthesia lasting more than 2 hours in a tertiary hospital in Melbourne, Australia, from February 2015 to February 2019. The last date of follow-up was February 17, 2019.

INTERVENTIONS

Patients were randomized to receive a tidal volume of 6 mL/kg predicted body weight (n = 614; low tidal volume group) or a tidal volume of 10 mL/kg predicted body weight (n = 592; conventional tidal volume group). All patients received positive end-expiratory pressure (PEEP) at 5 cm H2O.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of postoperative pulmonary complications within the first 7 postoperative days, including pneumonia, bronchospasm, atelectasis, pulmonary congestion, respiratory failure, pleural effusion, pneumothorax, or unplanned requirement for postoperative invasive or noninvasive ventilation. Secondary outcomes were postoperative pulmonary complications including development of pulmonary embolism, acute respiratory distress syndrome, systemic inflammatory response syndrome, sepsis, acute kidney injury, wound infection (superficial and deep), rate of intraoperative need for vasopressor, incidence of unplanned intensive care unit admission, rate of need for rapid response team call, intensive care unit length of stay, hospital length of stay, and in-hospital mortality.

RESULTS

Among 1236 patients who were randomized, 1206 (98.9%) completed the trial (mean age, 63.5 years; 494 [40.9%] women; 681 [56.4%] undergoing abdominal surgery). The primary outcome occurred in 231 of 608 patients (38%) in the low tidal volume group compared with 232 of 590 patients (39%) in the conventional tidal volume group (difference, -1.3% [95% CI, -6.8% to 4.2%]; risk ratio, 0.97 [95% CI, 0.84-1.11]; P = .64). There were no significant differences in any of the secondary outcomes.

CONCLUSIONS AND RELEVANCE

Among adult patients undergoing major surgery, intraoperative ventilation with low tidal volume compared with conventional tidal volume, with PEEP applied equally between groups, did not significantly reduce pulmonary complications within the first 7 postoperative days.

TRIAL REGISTRATION

ANZCTR Identifier: ACTRN12614000790640.

Use of enhanced stent visualisation compared to angiography alone to guide percutaneous coronary intervention

OBJECTIVE

We aimed to assess the use of enhanced stent visualisation (ESV) on outcomes, after PCI with overlapping stents, specifically using CLEARstent technology.

BACKGROUND

Stent underexpansion and overlap are both significant risk factors for restenosis and stent thrombosis. Enhanced stent visualisation (e.g. CLEARstent) systems could provide important data to reduce under-expansion and stent overlap.

METHODS

This was a cohort study based on this institution's percutaneous coronary intervention (PCI) registry. A total of 2614 patients who had PCI for stable angina or acute coronary syndromes (ACS, excluding cardiogenic shock) with overlapping 2nd generation drug eluting stents (DES) in the same vessel between May 2015 and January 2018 were included in the analysis. Patients were divided into ESV (n = 1354) and no ESV guided intervention (n = 1260). The primary end-point was major adverse cardiovascular events (MACE: target vessel revascularisation, target vessel myocardial infarction and all-cause mortality) recorded at a median follow up of 2.4 years.

RESULTS

Groups were comparable for patient characteristics (age, diabetes mellitus, ACS presentation). A significant difference in MACE was observed between patients who underwent ESV-guided PCI (9.5%) compared with patients who underwent Standard PCI (14.4%, p = .018). This difference was mainly driven by reduced rates of target vessel revascularisation and recurrent myocardial infarction. Overall this difference persisted after multivariate Cox analysis (HR 0.86, 95% CI: 0.73-0.98) and propensity matching (HR = 0.88, 95% CI: 0.69-0.99).

CONCLUSION

We suggest that routine clinical use of ESV technology during PCI can be useful, and is associated with better medium-term angiographic and clinical outcomes. Further study is required to build on this promising signal.

Low tidal volume ventilation during anaesthesia for major surgery: protocol and statistical analysis plan

BACKGROUND

Mechanical ventilation is mandatory in patients undergoing general anaesthesia for major surgery. Tidal volumes higher than 10 mL/kg of predicted body weight have been advocated for intraoperative ventilation, but recent evidence suggests that low tidal volumes may benefit surgical patients. To date, the impact of low tidal volume compared with conventional tidal volume during surgery has only been assessed in clinical trials that also combine different levels of positive end-expiratory pressure (PEEP) in each arm. We aimed to assess the impact of low tidal volume compared with conventional tidal volume during general anaesthesia for surgery on the incidence of postoperative respiratory complications in adult patients receiving moderate levels of PEEP.

STUDY DESIGN AND METHODS

Single-centre, two-arm, randomised clinical trial. In total, 1240 adult patients older than 40 years scheduled for at least 2 hours of surgery under general anaesthesia and routinely monitored with an arterial line were included. Patients were ventilated intraoperatively with a moderate level of PEEP (5 cmH₂O) and randomly assigned to tidal volume of 6 mL/kg predicted body weight (low tidal volume) or 10 mL/kg predicted body weight (conventional tidal volume in Australia).

MAIN OUTCOME MEASURE

The primary outcome is the occurrence of postoperative respiratory complications, recorded as a composite endpoint of adverse respiratory events during the first 7 postoperative days.

RESULTS AND CONCLUSIONS

This is the first well powered study comparing the effect of low tidal volume ventilation versus high tidal volume ventilation during surgery on the incidence of postoperative respiratory complications in adult patients receiving moderate levels of PEEP.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN12614000790640).

P2720Diagnostic accuracy of Quantitative Flow Ratio (QFR) and Vessel Fractional Flow Reserve (vFFR) compared to Fractional Flow Reserve (FFR) based on 7.5 frames/second coronary angiography

Background

Fractional flow reserve (FFR) is the gold standard for the physiological assessment of intermediate coronary artery lesions. Recently, several novel methods for computation of FFR based on 3-dimensional quantitative coronary angiography have been developed. These techniques allow analyses to be performed retrospectively and do not require induction of hyperaemia. The development and validation of these techniques are based on good quality coronary angiography with high frames per second (15 fps) acquisition. The diagnostic accuracy of Quantitative Flow Ratio (QFR) and Vessel Fractional Flow Reserve (vFFR) in real world “radiation-save mode” coronary angiography has not been studied.

Purpose

To validate the accuracy of QFR and vFFR compared to FFR based on a series of coronary angiography acquired at 7.5 fps.

Methods

We retrospectively analyzed 134 vessels (102 patients) with intermediate coronary artery stenosis (30–90%) in whom an FFR measurement had been performed. All the coronary angiography were acquired at 7.5 fps. 33 vessels (20 patients) were excluded from the study due to unsuitable coronary anatomy, invalid FFR measurements, poor image quality and lack of 2 projections ≥25° apart. A total of 101 vessels (82 patients) were included in the final analysis. Contrast-QFR (cQFR), fixed-QFR (fQFR) and vFFR analysis were performed in these vessels by two independent trained experts blinded to the FFR readings. FFR measurements at hyperaemic steady state was taken as the gold standard reference.

Results

Good intra- and inter-observer reliability was noted for fQFR, cQFR and vFFR analysis (intra-observer mean difference for fQFR: 0.016±0.060, p=0.066; cQFR: 0.009±0.053, p=0.230; vFFR: 0.008±0.040, p=0.175; inter-observer mean difference for fQFR: 0.001±0.036, p=0.847; cQFR: −0.001±0.049; p=0.910, vFFR: −0.005±0.037, p=0.393). fQFR and cQFR showed good correlation with FFR (r=0.694, p<0.001 and r=0.674, p<0.001, respectively) while vFFR showed moderate correlation with FFR (r=0.388, p<0.001). Similarly, fQFR and cQFR showed good accuracy for the detection of functionally significant coronary stenosis (fQFR AUC 0.882 (95% CI 0.803–0.938) and cQFR AUC 0.886 (95% CI 0.807–0.940)) while vFFR showed moderate accuracy with AUC 0.719 (95% CI 0.621–0.804). For identifying functionally significant stenosis (FFR ≤0.80), the overall diagnostic accuracy were 81.2%, 85.2%, 75.3% for fQFR, cQFR and vFFR, repectively. The sensitivity and specificity were 72.7%, 89.9% (fQFR); 83.5%, 31.8% (cQFR) and 68.2%, 87.3% (vFFR).

Conclusion

Functional assessment of intermediate coronary stenosis based on 7.5 fps angiography-derived computational modelling is feasible. Our study shows that fQFR and cQFR have a better diagnostic accuracy for detecting functionally significant coronary stenosis compared to vFFR. At the lower radiation-save mode 7.5 fps angiography, cQFR does not appear to provide additional diagnostic accuracy compared to fQFR.

The frequency and nature of clinician identified medication-related rapid response system calls

AIM

The contribution of adverse medication events to clinical deterioration is unknown. This study aimed to determine the frequency and nature of rapid response system (RRS) calls that clinicians perceived were medication-related using RRS quality arm data.

METHODS

Analysis of routine data prospectively collected by clinicians responding to RRS calls in an Australian acute tertiary academic hospital.

RESULTS

Between January 2013 and June 2017, 12,221 adult patients triggered the RRS for 25,906 medical emergency team (MET) and 512 code blue calls. Clinicians identified 433 medication-related RRS calls (1.6%) involving 406 patients (3.3%). These included 418 MET calls (1.3 medication-related MET calls per 1000 admissions) and 15 code blue calls (0.045 medication-related code blue calls per 1000 admissions). Medication-related calls occurred earlier in the admission (p = 0.002) and were more common for patients triggering multiple calls during the same admission (p < 0.001), compared to non-medication-related calls. Medication-related calls most commonly were triggered by low blood pressure (38.3%) and involved cardiovascular (43.0%) and nervous system medications (36.0%). Dose-related toxicity (n = 178) was the most frequent adverse medication event contributing to medication-related calls.

CONCLUSION

One in 30 patients triggering a RRS call experienced medication-related clinical deterioration, most often due to dose related toxicity of cardiovascular system medications. The perceived frequency and potential preventability of this medication-related harm suggest further research is required to increase recognition of medication-related RRS calls by responding clinicians and to reduce the incidence.

P6426The use of direct oral anti-coagulations (DOACs) compared to vitamin k antagonist in patients with left ventricular thrombus after acute myocardial infarction

Aim

Current guidelines recommend the use of Vitamin K Antagonist (VKA) for up to 3–6 months for the treatment of LV thrombus post- acute myocardial infarction (AMI). However based on evidence supporting the non-inferiority and potential superiority of Direct Oral Anti-Coagulation's (DOAC) compared to VKA for other indications such as atrial fibrillation, DOACs are being increasingly used off licence for the treatment of left ventricular (LV) thrombus post AMI. In this study we investigated the effect of DOACs compared to VKA on LV thrombus resolution and their safety profile in patients presenting with AMI.

Methods and results

This was a prospective observational study of 2,328 consecutive patients undergoing Percutaneous Coronary Intervention (PCI) for AMI between 2015- 2018, at a UK cardiac centre. Patients' details were collected from the hospital electronic database. The primary end-point was the rate of resolution of LV thrombus with bleeding rates as a secondary outcome.

Left ventricular (LV) thrombus was diagnosed by echocardiography, or cardiac magnetic resonance imaging in 98 (5.1%) patients. Sixty patients (61.2%) were started on VKA and 38 patients (38.8%) on DOAC therapy (Rivaroxaban: 57.9%, Apixaban, 36.8% and Edoxaban: 5.3%). Both groups were well matched in terms of baseline characteristics including age, previous cardiac history (previous MI, PCI, CABG), and cardiovascular risk factors (Hypertension, Diabetes, Hypercholesterolaemia).

Over the follow up period (median 1.8 years), overall rates of LV thrombus resolution were 86%. There was greater and earlier LV thrombus resolution in the DOAC group compared to patients treated with warfarin (75% vs 53%, p=0.0018, at 1 year), which persisted after adjusting for baseline variables (OR 1.8 95% CI 1.2–2.9). Major bleeding such as intracranial bleed, major GI bleed and bleed requiring hospital admission were lower in DOAC group, compared with VKA group (0% vs 5%, p=0.030) with no difference in rates of systemic thromboembolism (p=0.388).

Conclusion

This data suggests improved thrombus resolution in post ACS LV thrombosis in patient treated with DOACs compared to vitamin K antagonists. This improvement in thrombus resolution was accompanied with a better safety profile for the DOAC patients' vs VKA treated patients. This supports the need for randomised controlled trials to confirm this observational data.

Acknowledgement/Funding

None

P2671The addition of admission lactate to the CREST risk score to determine prognosis in out of hospital cardiac arrest: the C-AREST score

Introduction

There has been an increasing focus on the development of scoring systems for patients admitted following resuscitation from out-of-hospital cardiac arrest (OHCA) to determine both prognosis and short-term management. One such system, the CREST score, has been shown to predict circulatory aetiology death in patients without ST-elevation myocardial infarction, however with an increasing number of OHCAs seen, general scoring systems to predict outcome in OHCA would be helpful.

Aims

We sought to determine whether the addition of an admission lactate ≥8 mmol/l to the existing CREST score was able to better predict in-hospital mortality in patients admitted with OHCA.

Methods and results

We retrospectively analysed the data of 500 patients admitted with an OHCA of presumed cardiac origin to our tertiary cardiac centre between June 2014 and Oct 2018. Mean age was 62.6y (±14.7), 379 (76%) were male and 250 (50%) were Caucasian. 313 (62.6%) were admitted with ST elevation myocardial infarction or equivalent. 48.6% (243/500) of patients died in hospital and of those that survived, 20.2% (52/257) were left with hypoxic brain injury (CPC score 3–4).

When analysed independently, all individual factors other than history of Coronary artery disease (OR 1.47, p=0.084) significantly predicted in-hospital mortality: Admission lactate ≥8 mmol/l (OR 6.78, p<0.0001), non-shockable Rhythm (OR 10.9, p<0.0001), Ejection fraction <30% (OR 5.84, p<0.0001), Shock at presentation (OR 5.49, p<0.0001) and ischaemic Time >25 minutes (OR 12.8, p<0.0001).

When each factor was assigned one point and totalled, both increasing CREST and C-AREST scores were associated with increasing in-hospital mortality: CREST (0–5 points): 4.3%, 30.5%, 41.5%, 85.6%, 95.2%, 100% vs C-AREST (0–6 points): 9.1%, 28.3%, 41.9%, 62.8%, 97.6%, 96.4%, 100%. When analysed with stepwise logistic regression, the addition of admission lactate ≥8 mmol/l to the model improved the prediction of in-hospital mortality: CREST (40.8% of variance explained) vs C-AREST (43.3%), with admission lactate remaining an independently significant predictor (OR 3.67, p=0.002).

Conclusion

We describe a novel modification to the previously described CREST scoring system for OHCA: the C-AREST score. The addition of admission lactate ≥8 mmol/l may have a role in differentiating those in intermediate risk categories (score between 2 and 3) where the predicted in hospital mortality would otherwise vary greatly. Given the relative ease of obtaining admission lactate, this scoring system may further improve stratification of patients who may or may not benefit from invasive management.

P6516The association between prior coronary artery bypass graft surgery and outcome after percutaneous coronary intervention (PCI): an observational study of 123,780 patients

Background

Limited information exists regarding procedural success and clinical outcomes in patients with previous CABG undergoing percutaneous coronary intervention (PCI). We sought to compare outcomes in patients undergoing PCI with or without previous coronary artery bypass grafts (CABG).

Methods

This was an observational cohort study of 123,780 consecutive PCI procedures from the Pan-London (United Kingdom) PCI registry, from January 2005 to December 2015. The primary end-point was all-cause mortality at a median follow-up of 3.0 years (interquartile range 1.2–4.6 years).

Results

12,641 (10.2%) patients had a history of previous CABG, of whom 29.3% (n=3,703) underwent PCI to native vessels and 70.7% (n=8,938) to bypass grafts. There were significant differences in the demographic, clinical, and procedural characteristics of these groups. The risk of mortality during follow-up was significantly higher in patients with prior CABG (23.2%) (p=0.0005) compared to patients with no history of prior CABG (12.1%) and was seen for patients who underwent either native vessel (20.1%) or bypass graft PCI (24.2%, p<0.0001). However, after adjustment for baseline characteristics, there was no significant difference in outcomes seen between the groups when PCI was performed in native vessels in patients with previous CABG (HR 1.02, 95% CI 0.77–1.34; P=0.89) but a significant increase in mortality among patients with PCI to bypass grafts (HR 1.33 95% CI 1.03–1.71, P=0.026). This was seen after multivariate adjustment and propensity matching.

Figure 1. Kaplan-Meier Curves

Conclusion

Patients with prior CABG are older, with a greater comorbid burden and more complex procedural characteristics, but after adjustment for these differences clinical outcomes are similar to patients undergoing PCI without prior CABG. In these patients, native vessel PCI was associated with better outcomes compared to the treatment of vein grafts.

P2665An observational study assessing the impact of a cardiac arrest centre on patient outcome

Background

Out-of-hospital cardiac arrest (OHCA) is a major cause of death in Europe and the United States. There has been recent literature to suggest that the centralisation of OHCA services may benefit patient outcomes. In 2015, two major tertiary cardiac centres in the UK agglomerated to form a large dedicated tertiary cardiac centre. The previous centre had strict criteria on which OHCA patients could be admitted, with the vast majority of cases being STEMI-related. After the agglomeration, admission criteria were relaxed to include all OHCA cases within geographic range with a suspected cardiac cause.

Purpose

This study aimed to compare the short-term mortality of patients admitted with an OHCA to a tertiary cardiac centre before-and-after a major agglomeration of services had taken place and admission criteria had been relaxed.

Methods

We retrospectively analysed the data of patients admitted before and after agglomeration (2015) with OHCA who were resuscitated via conventional cardiopulmonary resuscitation. Baseline demographic characteristics were recorded, along with factors relating to the cardiac arrest. Primary endpoint was in-hospital mortality.

Results

A total of 650 patients (189 before and 461 after the agglomeration) with an OHCA between 2013 and 2018 were analysed. Patients admitted pre merger were older (67.7 vs 62.4 years, p=0.022), otherwise there were similar baseline demographic characteristics between patients admitted before and after the agglomeration (pre vs post) in terms of gender (74.4% vs 75.9% male, p=0.827), ethnicity (66.7% vs 58.9% Caucasian, p=0.588) and existing coronary artery disease (22.8% vs 22.7%, p=0.432). There were also similar peri-arrest characteristics, with a comparable number of patients having a non-shockable rhythm (15.4% vs 25.4%, p=0.164) and similar total downtimes between the groups (33 vs 32.3 mins, p=0.883). Interestingly there was a decrease in those with cardiogenic shock on arrival (92.3% vs 57.0%, p=0.0001) and fewer patients with an ejection fraction <30% (63.2 vs 38.7%, p=0.0003) post-agglomeration.

There was a greater proportion of non-ACS-related OHCA admission after the agglomeration (16.9% vs 24.1%, p=0.047) and a corresponding decrease in those admitted with a STEMI (81.5% vs 62.3%, p=0.032) and those treated with PCI (77.8% vs 54.0%, p=0.034). Despite this, in-hospital mortality was lower after the agglomeration (69.7% vs 47.1%, p=0.019), which persisted after adjustment for the previously described demographic and arrest-related characteristics using stepwise logistic regression (p=0.036) between the two groups.

Conclusion

Despite an increase in non-ACS-related-OHCA cases, the formation of a centralised invasive heart centre was associated with improved survival in OHCA patients. This suggests there may be a benefit for an out-of-hospital cardiac arrest-centre model of care, supporting a centralised strategy for immediate post-resuscitation care in OHCA patients.

Acknowledgement/Funding

None

Rapid response team review of hemodynamically unstable ward patients: The accuracy of cardiac index assessment

PURPOSE

Intensive care doctors commonly attend rapid response team (RRT) reviews of hospital-ward patients with hemodynamic instability and estimate the patient's likely cardiac index (CI). We aimed to non-invasively measure the CI of such patients and assess the level of agreement between such measurements and clinically estimated CI categories (low <2L/min/m2, normal 2-2.99L/min/m2 or high ≥3L/min/m2).

MATERIALS AND METHODS

A prospective, observational study of non-invasive measurement and clinical estimation of CI categories in 50 adult hospital-ward patients who activated the RRT for 'hemodynamic instability' (tachycardia > 100BPM or hypotension < 90mmHg or both).

RESULTS

The CI was measured in 47/50(94%) patients and the mean CI was 3.5(95% CI 3.2-3.7) L/min/m2. Overall, 30(64%) patients had a high CI, 13(28%) and 4(9%) had a normal and a low CI, respectively. The level of agreement between measured and clinically estimated CI categories was low(19.2%). Sensitivity and positive predictive values of clinical estimation were low(0% and 3.3% for high CI, and 0% and 50% for low CI, respectively).

CONCLUSIONS

Non-invasive CI measurement was possible in almost all hospital-ward patients triggering RRT review for hemodynamic instability. In such patients, the CI was high, and intensive care clinicians were unable to identify a low or a high CI state.

The association of clinical frailty with outcomes of patients reviewed by rapid response teams: an international prospective observational cohort study

Background

Frailty is a state of vulnerability to poor resolution of homeostasis after a stressor event and is strongly associated with adverse outcomes. Therefore, the assessment of frailty may be an essential part of evaluation in any healthcare encounter that might result in an escalation of care. The purpose of the study was to assess the frequency and association of frailty with clinical outcomes in patients subject to rapid response team (RRT) review.

Methods

In this multi-national prospective observational cohort study, centres with existing RRTs collected data over a 7-day period, with follow up of all patients at 24 h following their RRT call and at hospital discharge or 30 days following the event trigger (whichever came sooner). Investigators also collected data on the triggers and interventions provided and a bedside assessment on the level of patients’ frailty using a clinical frailty scale.

Results

Amongst 1133 patients, 40% were screened as frail, which was associated with older age (p < 0.001), admission under a medical speciality (p < 0.001), increased severity of illness at the time of the RRT review (p = 0.0047), and substantially higher frequency of limitations of care (p < 0.001). Importantly, 72% of patients screened as frail were either dead or dependent on hospital care by 30 days (p < 0.001). In the multivariable analysis, the significant risk factors for the composite endpoint “poor recovery” (died or were hospital-dependent by 30 days) were age (odds ratio (OR), 1.04; 95% confidence interval (CI), 1.03–1.05; p < 0.001), frailty level (p < 0.001), existing limitation of care (OR, 2.0; 95% CI, 1.3–3.0; p < 0.001), and the quick sequential organ failure assessment (qSOFA) score (p < 0.001).

Conclusions

Higher frailty scores were associated with increased mortality and dependence on health care at 30 days. Our results indicate that frailty has an influence on the clinical trajectory of deteriorating patients and that such assessment should be included in discussion of goals and expectations of care.

Trial registration

Netherlands Trial Registry, NTR5535. Registered on 23 December 2015.

Failure to expand the motor unit size to compensate for declining motor unit numbers distinguishes sarcopenic from non-sarcopenic older men

Key points

The age‐related loss of muscle mass is related to the loss of innervating motor neurons and denervation of muscle fibres.

Not all denervated muscle fibres are degraded; some may be reinnervated by an adjacent surviving neuron, which expands the innervating motor unit proportional to the numbers of fibres rescued.

Enlarged motor units have larger motor unit potentials when measured using electrophysiological techniques.

We recorded much larger motor unit potentials in relatively healthy older men compared to young men, but the older men with the smallest muscles (sarcopenia) had smaller motor unit potentials than healthy older men.

These findings suggest that healthy older men reinnervate large numbers of muscle fibres to compensate for declining motor neuron numbers, but a failure to do so contributes to muscle loss in sarcopenic men.

Abstract

Sarcopenia results from the progressive loss of skeletal muscle mass and reduced function in older age. It is likely to be associated with the well‐documented reduction of motor unit numbers innervating limb muscles and the increase in size of surviving motor units via reinnervation of denervated fibres. However, no evidence exists to confirm the extent of motor unit remodelling in sarcopenic individuals. The aim of the present study was to compare motor unit size and number between young (n = 48), non‐sarcopenic old (n = 13), pre‐sarcopenic (n = 53) and sarcopenic (n = 29) men. Motor unit potentials (MUPs) were isolated from intramuscular and surface EMG recordings. The motor unit numbers were reduced in all groups of old compared with young men (all P < 0.001). MUPs were higher in non‐sarcopenic and pre‐sarcopenic men compared with young men (P = 0.039 and 0.001 respectively), but not in the vastus lateralis of sarcopenic old (P = 0.485). The results suggest that extensive motor unit remodelling occurs relatively early during ageing, exceeds the loss of muscle mass and precedes sarcopenia. Reinnervation of denervated muscle fibres probably expands the motor unit size in the non‐sarcopenic and pre‐sarcopenic old, but not in the sarcopenic old. These findings suggest that a failure to expand the motor unit size distinguishes sarcopenic from pre‐sarcopenic muscles.

The age‐related loss of muscle mass is related to the loss of innervating motor neurons and denervation of muscle fibres.

Not all denervated muscle fibres are degraded; some may be reinnervated by an adjacent surviving neuron, which expands the innervating motor unit proportional to the numbers of fibres rescued.

Enlarged motor units have larger motor unit potentials when measured using electrophysiological techniques.

We recorded much larger motor unit potentials in relatively healthy older men compared to young men, but the older men with the smallest muscles (sarcopenia) had smaller motor unit potentials than healthy older men.

These findings suggest that healthy older men reinnervate large numbers of muscle fibres to compensate for declining motor neuron numbers, but a failure to do so contributes to muscle loss in sarcopenic men.

Eptifibatide is associated with significant cost savings and similar clinical outcomes to abciximab when used during primary percutaneous coronary intervention for ST-elevation myocardial infarction: An observational cohort study of 3863 patients

INTRODUCTION

Glycoprotein IIb/IIIa inhibitors are recommended by guidelines in patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention. There are few studies directly comparing these agents. The aim of this study was to assess whether eptifibatide is a safe and cost-effective alternative to abciximab in the treatment of primary percutaneous coronary intervention for ST-segment elevation myocardial infarction.

METHODS

This was an observational cohort study of 3863 patients who received a GPIIb/IIIa inhibitor whilst undergoing primary percutaneous coronary intervention from 2007 to 2014. Patients who did not receive a GPIIb/IIIa inhibitor were excluded. Time to first major adverse cardiac event defined as death, non-fatal myocardial infarction, stroke or target vessel revascularization, and total hospital costs were compared between the groups.

RESULTS

In all, 1741 patients received abciximab with 2122 receiving eptifibatide. Patients who received eptifibatide had higher rates of previous MI/percutaneous coronary intervention and were more likely to undergo a procedure from the radial route. Unadjusted Kaplan-Meier analysis revealed no significant difference in the 1-year event rates between patients given eptifibatide versus abciximab (p = 0.201). Age-adjusted Cox analysis demonstrated no difference in 1-year outcome between abciximab and eptifibatide (hazard ratio: 0.83; 95% confidence interval: 0.73-1.39), which persisted after multivariate adjustment (hazard ratio: 0.92; 95% confidence interval: 0.79-1.56) including the incorporation of a propensity score (hazard ratio: 0.88; 95% confidence interval: 0.71-1.44). Eptifbatide was associated with significant cost savings being 87% cheaper overall compared to abciximab (on average £650 cheaper per patient and saving approximately £950,000).

CONCLUSION

This observational data suggest that eptifibatide is associated with similar outcomes and significant cost savings compared to abciximab when used in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Circulating levels of dickkopf-1, osteoprotegerin and sclerostin are higher in old compared with young men and women and positively associated with whole-body bone mineral density in older adults

Bone mineral density declines with increasing older age. We examined the levels of circulating factors known to regulate bone metabolism in healthy young and older adults. The circulating levels of dickkopf-1, osteocalcin, osteoprotegerin and sclerostin were positively associated with whole-body bone mineral density (WBMD) in older adults, despite the average WBMD being lower and circulating dickkopf-1, osteoprotegerin and sclerostin being higher in old than young.

INTRODUCTION

This study aims to investigate the relationship between whole-body bone mineral density (WBMD) and levels of circulating factors with known roles in bone remodelling during 'healthy' ageing.

METHODS

WBMD and fasting plasma concentrations of dickkopf-1, fibroblast growth factor-23, osteocalcin, osteoprotegerin, osteopontin and sclerostin were measured in 272 older subjects (69 to 81 years; 52% female) and 171 younger subjects (18-30 years; 53% female).

RESULTS

WBMD was lower in old than young. Circulating osteocalcin was lower in old compared with young, while dickkopf-1, osteoprotegerin and sclerostin were higher in old compared with young. These circulating factors were each positively associated with WBMD in the older adults and the relationships remained after adjustment for covariates (r values ranging from 0.174 to 0.254, all p < 0.01). In multivariate regression, the body mass index, circulating sclerostin and whole-body lean mass together accounted for 13.8% of the variation with WBMD in the older adults. In young adults, dickkopf-1 and body mass index together accounted for 7.7% of variation in WBMD.

CONCLUSION

Circulating levels of dickkopf-1, osteocalcin, osteoprotegerin and sclerostin are positively associated with WBMD in community-dwelling older adults, despite the average WBMD being lower and circulating dickkopf-1, osteoprotegerin and sclerostin being higher in old than young.

Rapid response systems: recognition and rescue of the deteriorating hospital patient

The last 25 years have witnessed significant change in the approach to the deteriorating patient. This article reviews and discusses the merits and drawbacks of the various systems used across the world.

Nutrition in the intensive care unit - you must breathe what you eat

The imprecision in prescribing of enteral nutrition in critically ill patients must result in occasions of overfeeding as well as underfeeding. Overfeeding could cause increased CO₂ production and thus increased work of breathing and prolonged ventilator dependence. This possibility is supported by the limited relevant literature. We examined this possibility mathematically using the data in The Augmented versus Routine Approach to Giving Energy Trial (TARGET) feasibility study and in its main study protocol. Patients in the energy-dense feeding arm will receive 50% more calories and produce 52% more CO₂ than patients in the standard feeding arm. The full TARGET study is ideally positioned to answer the practical clinical question of whether increased feeding in critically ill patients can be delivered without prolonging ventilator dependence.

Age-related neuromuscular changes affecting human vastus lateralis

KEY POINTS

Skeletal muscle size and strength decline in older age. The vastus lateralis, a large thigh muscle, undergoes extensive neuromuscular remodelling in healthy ageing, as characterized by a loss of motor neurons, enlargement of surviving motor units and instability of neuromuscular junction transmission. The loss of motor axons and changes to motor unit potential transmission precede a clinically-relevant loss of muscle mass and function.

ABSTRACT

The anterior thigh muscles are particularly susceptible to muscle loss and weakness during ageing, although how this is associated with changes to neuromuscular structure and function in terms of motor unit (MU) number, size and MU potential (MUP) stability remains unclear. Intramuscular (I.M.) and surface electromyographic signals were recorded from the vastus lateralis (VL) during voluntary contractions held at 25% maximal knee extensor strength in 22 young (mean ± SD, 25.3 ± 4.8 years) and 20 physically active older men (71.4 ± 6.2 years). MUP size, firing rates, phases, turns and near fibre (NF) jiggle were determined and MU number estimates (MUNEs) were made by comparing average surface MUP with maximal electrically-evoked compound muscle action potentials. Quadriceps cross-sectional area was measured by magnetic resonance imaging. In total, 379 individual MUs were sampled in younger men and 346 in older men. Compared to the MU in younger participants, those in older participants had 8% lower firing rates and larger MUP size (+25%), as well as increased complexity, as indicated by phases (+13%), turns (+20%) and NF jiggle (+11%) (all P < 0.0005). The MUNE values (derived from the area of muscle in range of the surface-electrode) in older participants were ∼70% of those in the young (P < 0.05). Taking into consideration the 30% smaller cross-sectional area of the VL, the total number of MUs in the older muscles was between 50% and 60% lower compared to in young muscles (P < 0.0005). A large portion of the VL MU pool is lost in older men and those recruited during moderate intensity contractions were enlarged and less stable. These MU changes were evident before clinically relevant changes to muscle function were apparent; nevertheless, the changes in MU number and size are probably a prelude to future movement problems.

Changes in markers of oxidative stress and DNA damage in human visceral adipose tissue from subjects with obesity and type 2 diabetes

AIMS

In the past 30 years, prevalence of obesity has almost trebled resulting in an increased incidence of type 2 diabetes mellitus and other co-morbidities. Visceral adipose tissue is believed to play a vital role, but underlying mechanisms remain unclear. Our aim was to investigate changes in markers of oxidative damage in human visceral adipose tissue to determine levels of oxidative burden that may be attributed to obesity and/or diabetes.

METHODS

Visceral adipose tissue samples from 61 subjects undergoing abdominal surgery grouped as lean, obese and obese with type 2 diabetes mellitus, were examined using 3 different markers of oxidative stress. Malondialdehyde (MDA) concentration was measured as a marker of lipid peroxidation, telomere length and Comet assay as markers of oxidative DNA damage.

RESULTS

No significant difference in MDA concentration, telomere length and DNA damage was observed between groups, although longer telomere lengths were seen in the obese with diabetes group compared to the obese group (P<0.05). Lower MDA concentration and longer telomere length were seen in subjects with diabetes compared to those without (P<0.05). DNA damage, analysed via Comet assay, was significantly lower in subjects with diabetes compared to those without (P<0.05).

CONCLUSION

A paradoxical decrease in oxidative stress and DNA damage was observed in samples from subjects with type 2 diabetes mellitus. Further work is required to investigate this further, however this phenomenon may be due to an up regulation of antioxidant defences in adipose tissue.

Does a 'direct' transfer protocol reduce time to coronary angiography for patients with non-ST-elevation acute coronary syndromes? A prospective observational study

OBJECTIVE

National guidelines recommend 'early' coronary angiography within 96 h of presentation for patients with non-ST elevation acute coronary syndromes (NSTE-ACS). Most patients with NSTE-ACS present to their district general hospital (DGH), and await transfer to the regional cardiac centre for angiography. This care model has inherent time delays, and delivery of timely angiography is problematic. The objective of this study was to assess a novel clinical care pathway for the management of NSTE-ACS, known locally as the Heart Attack Centre-Extension or HAC-X, designed to rapidly identify patients with NSTE-ACS while in DGH emergency departments (ED) and facilitate transfer to the regional interventional centre for 'early' coronary angiography.

METHODS

This was an observational study of 702 patients divided into two groups; 391 patients treated before the instigation of the HAC-X pathway (Pre-HAC-X), and 311 patients treated via the novel pathway (Post-HAC-X). Our primary study end point was time from ED admission to coronary angiography. We also assessed the length of hospital stay.

RESULTS

Median time from ED admission to coronary angiography was 7.2 (IQR 5.1-10.2) days pre-HAC-X compared to 1.0 (IQR 0.7-2.0) day post-HAC-X (p<0.001). Median length of hospital stay was 3.0 (IQR 2.0-6.0) days post-HAC-X v 9.0 (IQR 6.0-14.0) days pre-HAC-X (p<0.0005). This equates to a reduction of six hospital bed days per NSTE-ACS admission.

CONCLUSIONS

The introduction of this novel care pathway was associated with significant reductions in time to angiography and in total hospital bed occupancy for patients with NSTE-ACS.

Erratum: A two-step kinetics model for numerical simulation of explosions and detonations in H2-O2 mixtures

[This corrects the article DOI: 10.1098/rspa.2001.0853.].

Associations between muscle strength, spirometric pulmonary function and mobility in healthy older adults

Pathological obstruction in lungs leads to severe decreases in muscle strength and mobility in patients suffering from chronic obstructive pulmonary disease. The purpose of this study was to investigate the interdependency between muscle strength, spirometric pulmonary functions and mobility outcomes in healthy older men and women, where skeletal muscle and pulmonary function decline without interference of overt disease. A total of 135 69- to 81-year-old participants were recruited into the cross-sectional study, which was performed as a part of European study MyoAge. Full, partial and no mediation models were constructed to assess the interdependency between muscle strength (handgrip strength, knee extension torque, lower extremity muscle power), spirometric pulmonary function (FVC, FEV1 and FEF50) and mobility (6-min walk and Timed Up and Go tests). The models were adjusted for age, sex, total fat mass, body height and site of enrolment. Partial mediation models, indicating both direct and pulmonary function mediated associations between muscle strength and mobility, fitted best to the data. Greater handgrip strength was significantly associated with higher FVC, FEV1 and FEF50 (p < 0.05). Greater muscle power was significantly associated with better performance in mobility tests. Results suggest that decline in mobility with aging may be caused by decreases in both muscle strength and power but also mediated through decreases in spirometric pulmonary function. Future longitudinal studies are warranted to better understand how loss of function and mass of the respiratory muscles will affect pulmonary function among older people and how these changes are linked to mobility decline.