Bed tilt and ramp positions are associated with increased first-pass success of adult endotracheal intubation in the emergency department: A registry study

OBJECTIVE

Successful endotracheal intubation in the ED requires optimum body positioning. In patients with obesity, the ramp position was suggested to achieve better intubating conditions. However, limited data are available on the airway management practices for patients with obesity in Australasian EDs. The aim of this study was to identify current patient positioning practices during endotracheal intubation and its association with first-pass success (FPS) at intubation and adverse event (AE) rates in obese and non-obese populations.

METHODS

Prospectively collected data from the Australia and New Zealand ED Airway Registry (ANZEDAR) between 2012 and 2019 were analysed. Patients were categorised into two groups according to their weight: <100 kg (non-obese) or ≥100 kg (obese). Four position categories were investigated; supine, pillow or occipital pad, bed tilt and ramp or head-up with relation to FPS and complication rate using logistic regression modelling.

RESULTS

A total of 3708 intubations from 43 EDs were included. Overall, the non-obese cohort had a greater FPS rate (85.9%) compared to the obese group (77.0%). The bed tilt position had the highest FPS rate (87.2%), whereas the supine position had the lowest (83.0%). AE rates were highest in the ramp position (31.2%) compared to all other positions (23.8%). Regression analysis showed ramp, or bed tilt positions and a consultant-level intubator were associated with higher FPS. Obesity, in addition to other factors, was independently associated with lower FPS.

CONCLUSION

Obesity was associated with lower FPS, which could be improved through performing a bed tilt or ramp positioning.

Development and preliminary usability testing of an electronic conversation guide incorporating patient values and prognostic information in preparation for older people's decision-making near the end of life

Initiating end-of-life conversations can be daunting for clinicians and overwhelming for patients and families. This leads to delays in communicating prognosis and preparing for the inevitable in old age, often generating potentially harmful overtreatment and poor-quality deaths. We aimed to develop an electronic resource, called Communicating Health Alternatives Tool (CHAT) that was compatible with hospital medical records software to facilitate preparation for shared decision-making across health settings with older adults deemed to be in the last year of life. The project used mixed methods including: literature review, user-directed specifications, web-based interface development with authentication and authorization; clinician and consumer co-design, iterative consultation for user testing; and ongoing developer integration of user feedback. An internet-based conversation guide to facilitate clinician-led advance care planning was co-developed covering screening for short-term risk of death, patient values and preferences, and treatment choices for chronic kidney disease and dementia. Printed summary of such discussion could be used to begin the process in hospital or community health services. Clinicians, patients, and caregivers agreed with its ease of use and were generally accepting of its contents and format. CHAT is available to health services for implementation in effectiveness trials to determine whether the interaction and documentation leads to formal decision-making, goal-concordant care, and subsequent reduction of unwanted treatments at the end of life.

The Emergency nurse Protocols Initiating Care-Sydney Triage to Admission Risk Tool (EPIC-START) trial: protocol for a stepped wedge implementation trial

INTRODUCTION

Emergency department (ED) overcrowding is a global problem and a threat to the quality and safety of emergency care. Providing timely and safe emergency care therein is challenging. To address this in New South Wales (NSW), Australia, the Emergency nurse Protocol Initiating Care-Sydney Triage to Admission Risk Tool (EPIC-START) was developed. EPIC-START is a model of care incorporating EPIC protocols, the START patient admission prediction tool, and a clinical deterioration tool to support ED flow, timely care, and patient safety. The aim of this study is to evaluate the impact of EPIC-START implementation across 30 EDs on patient, implementation, and health service outcomes.

METHODS AND ANALYSIS

This study protocol adopts an effectiveness-implementation hybrid design (Med Care 50: 217-226, 2012) and uses a stepped-wedge cluster randomised control trial of EPIC-START, including uptake and sustainability, within 30 EDs across four NSW local health districts spanning rural, regional, and metropolitan settings. Each cluster will be randomised independently of the research team to 1 of 4 dates until all EDs have been exposed to the intervention. Quantitative and qualitative evaluations will be conducted on data from medical records and routinely collected data, and patient, nursing, and medical staff pre- and post-surveys.

ETHICS AND DISSEMINATION

Ethical approval for the research was received from the Sydney Local Health District Research Ethics Committee (Reference Number 2022/ETH01940) on 14 December 2022.

TRIAL REGISTRATION

Australian and New Zealand Clinical trial, ACTRN12622001480774p. Registered on 27 October 2022.

24 hours - Life in the E.R.: A state-wide data linkage analysis of in-patients with prolonged emergency department length of stay in New South Wales, Australia

OBJECTIVE

Describe the characteristics and predictors of mortality for patients who spend more than 24 h in the ED waiting for an in-patient bed and compare baseline clinical and demographic characteristics between tertiary and non-tertiary hospitals.

METHODS

This was a state-wide analysis data linkage analysis of adult (age >16 years) ED presentations across New South Wales from 2019 to 2020. Cases were included if their mode of separation from ED indicated admission to an in-patient unit including critical care ward and their ED length of stay was greater than or equal to 24 h. Cases were categorised by service-related groups based on principle diagnosis.

RESULTS

A total of 26 854 eligible cases were identified. The most common diagnosis groups were psychiatry, cardiology and respiratory. The odds ratio (OR) for 30-day all-cause mortality in admitted patients with an ED length of stay greater than 24 h were highest in those aged >75 years (OR 15.18, 95% confidence interval [CI] 9.99-23.07, P < 0.001), oncology (OR 10.45, 95% CI 7.93-13.77, P < 0.001) and haematology patients (OR 2.95, 95% CI 2.01-4.33, P < 0.001).

CONCLUSION

Interventions and models of care to address ED access block need to focus on mental health patients, older patients particularly those with cardiorespiratory illness and oncology and haematology patients for whom risk of mortality is disproportionately higher.

Implementation evaluation of an evidence-based emergency nursing framework (HIRAID): study protocol for a step-wedge randomised control trial

INTRODUCTION

Poor patient assessment results in undetected clinical deterioration. Yet, there is no standardised assessment framework for >29 000 Australian emergency nurses. To reduce clinical variation and increase safety and quality of initial emergency nursing care, the evidence-based emergency nursing framework HIRAID (History, Identify Red flags, Assessment, Interventions, Diagnostics, communication and reassessment) was developed and piloted. This paper presents the rationale and protocol for a multicentre clinical trial of HIRAID.

METHODS AND ANALYSIS

Using an effectiveness-implementation hybrid design, the study incorporates a stepped-wedge cluster randomised controlled trial of HIRAID at 31 emergency departments (EDs) in New South Wales, Victoria and Queensland. The primary outcomes are incidence of inpatient deterioration related to ED care, time to analgesia, patient satisfaction and medical satisfaction with nursing clinical handover (effectiveness). Strategies that optimise HIRAID uptake (implementation) and implementation fidelity will be determined to assess if HIRAID was implemented as intended at all sites.

ETHICS AND DISSEMINATION

Ethics has been approved for NSW sites through Greater Western Human Research Ethics Committee (2020/ETH02164), and for Victoria and Queensland sites through Royal Brisbane & Woman's Hospital Human Research Ethics Committee (2021/QRBW/80026). The final phase of the study will integrate the findings in a toolkit for national rollout. A dissemination, communications (variety of platforms) and upscaling strategy will be designed and actioned with the organisations that influence state and national level health policy and emergency nurse education, including the Australian Commission for Quality and Safety in Health Care. Scaling up of findings could be achieved by embedding HIRAID into national transition to nursing programmes, 'business as usual' ED training schedules and university curricula.

TRIAL REGISTRATION NUMBER

ACTRN12621001456842.

Prospective, multicentre observational study of point-of-care ultrasound practice in emergency departments across Australia and New Zealand: The POCUS-ED Registry

OBJECTIVES

The present study aimed to describe the characteristics, performance, accuracy and significance of point-of-care ultrasound (POCUS) use in the ED, by utilising an expanded version of the ACEM-mandated special skills placement (SSP) logbook, to develop a novel clinical quality registry.

METHODS

A prospective, observational study was performed across EDs in Australia and New Zealand over a 12-month period. Trainees undertaking ACEM-approved ultrasound (US) SSPs recorded all US scan interpretations and follow-up imaging reports in an online database.

RESULTS

In total, 2647 USs were recorded by 26 special skills trainees across 10 EDs in Australia or New Zealand; of these 2356 scans (89%) were clinically indicated. Overall, 2493 scans (94%) were used for diagnostic assessment, of which 1147 (43%) had abnormal findings. Basic echocardiography, extended Focused Assessment with Sonography in Trauma and right upper quadrant scans were the most commonly used modalities. There were 134 US-guided procedures logged in the registry. Approximately 36% of scans were reported to alter the original provisional diagnosis, whereas in another 37% of cases, POCUS was thought to confirm the original clinical suspicion. The majority of scans (76.5%) entered into the registry were physically reviewed by the SSP supervisor.

CONCLUSIONS

This multicentred registry provides a detailed description of the current utilisation of POCUS within special skills US placements across EDs in Australia and New Zealand. This data should inform clinical leaders in emergency US to improve both POCUS education and governance around this important tool.

Review article: Effectiveness and risks of cricoid pressure during rapid sequence induction for endotracheal intubation in the emergency department: A systematic review

The use of cricoid pressure (CP) to prevent aspiration during rapid sequence induction (RSI) has become controversial, although CP is considered central to the practice of RSI. There is insufficient research to support its efficacy in reducing aspiration, and emerging concerns it reduces the first-pass success (FPS) of intubation. This systematic review aims to assess the safety and efficacy of CP during RSI in EDs by investigating its effect on FPS and the incidence of complications, including gastric regurgitation and aspiration. A systematic review of four databases was performed for all primary research investigating CP during RSI in EDs. The primary outcome was FPS; secondary outcomes included complications such as gastric regurgitation, aspiration, hypoxia, hypotension and oesophageal intubation. After screening 4208 citations, three studies were included: one randomised controlled trial (n = 54) investigating the incidence of aspiration during the application of CP and two registry studies (n = 3710) comparing the rate of FPS of RSI with and without CP. The results of these individual studies are not sufficient to draw concrete conclusions but do suggest that aspiration occurs regardless of the application of CP, and that FPS is not reduced by the application of CP. There is insufficient evidence to conclude whether applying CP during RSI in EDs affects the rate of FPS or the incidence of complications such as aspiration. Further research in the ED, including introducing CP usage into other existing airway registries, is needed.

Mapping haemodynamic changes with rapid sequence induction agents in the emergency department

OBJECTIVE

Patients intubated in the ED are at an increased risk of post-intubation hypotension. However, evidence regarding the most appropriate induction agent is lacking. The present study aims to describe and compare the haemodynamic effect of propofol, ketamine and thiopentone during rapid sequence induction.

METHODS

This is an observational study using data prospectively collected from the Australian and New Zealand Emergency Department Airway Registry between June 2012 and March 2019. The distribution of induction agents across medical and trauma patients were obtained with descriptive statistics. The relationship between induction agent, dose and change in pre- and post-intubation systolic blood pressure (SBP) was described using multivariable logistic regression. The SBP pre- and post-intubation was the primary measure of haemodynamic stability.

RESULTS

From the 5063 intubation episodes, 2229 met the inclusion criteria. Of those, 785 (35.2%) patients were induced with thiopentone, 773 (34.7%) with propofol and 671 (30.1%) with ketamine. Of the included population, 396 (17.8%) patients experienced a reduction in pre-intubation SBP exceeding 20%. Both propofol (P = 0.01) and ketamine (P = 0.01) had an independent and dose-dependent association with hypotension, noting that a higher proportion of patients induced with ketamine had a shock index exceeding 0.9.

CONCLUSION

Propofol was associated with post-intubation hypotension and it is recommended clinicians consider using the lowest effective dose to reduce this risk. Reflecting its perceived haemodynamic stability, patients who received ketamine were more likely to have a higher shock index; however, there was also an association with post-intubation hypotension.

Case series and review of emergency front-of-neck surgical airways from The Australian and New Zealand Emergency Department Airway Registry

BACKGROUND

An emergency front-of-neck access (eFONA), also called can't intubate, can't oxygenate (CICO) rescue, is a rare event. Little is known about the performance of surgical or percutaneous airways in EDs across Australia and New Zealand.

OBJECTIVE

To describe the management of cases resulting in an eFONA, and recorded in The Australian and New Zealand Emergency Department Airway Registry (ANZEDAR).

METHODS

A retrospective case series and review of ED patients undergoing surgical or percutaneous airways. Data were collected prospectively over 60 months between 2010 and 2015 from 44 participating EDs.

RESULTS

An eFONA/CICO rescue airway was performed on 15 adult patients: 14 cricothyroidotomies (0.3% of registry intubations) and one tracheostomy. The indication for intubation was 60% trauma and 40% medical aetiologies. The intubator specialty was emergency medicine in eight (53.3%) episodes. Thirteen (86.7%) cricothyroidotomies and the sole tracheostomy (6.7%) were performed at major referral hospitals with 12 (80%) surgical airways out of hours. In four (26.7%) cases, cricothyroidotomy was performed as the primary intubation method. Pre-oxygenation techniques were used in 14 (93.3%) episodes; apnoeic oxygenation in four (26.7%).

CONCLUSIONS

Most cases demonstrated deviations from standard difficult airway practice, which may have increased the likelihood of performance of a surgical airway, and its increased likelihood out of hours. Our findings may inform training strategies to improve care for ED patients requiring this critical intervention. We recommend further discussion of proposed standard terminology for emergency surgical or percutaneous airways, to facilitate clear crisis communication.

Current airway management practices after a failed intubation attempt in Australian and New Zealand emergency departments

OBJECTIVE

The aims of the present study were to describe current airway management practices after a failed intubation attempt in Australian and New Zealand EDs and to explore factors associated with second attempt success.

METHODS

Data were collected from a multicentre airway registry (The Australian and New Zealand Emergency Department Airway Registry). All intubation episodes that required a second attempt between March 2010 and November 2015 were analysed. Analysis for association with success at the second attempt was undertaken for patient factors including predicted difficulty of laryngoscopy, as well as for changes in laryngoscope type, adjunct devices, intubator and intubating manoeuvres.

RESULTS

Of the 762 patients with a failed first intubation attempt, 603 (79.1%) were intubated successfully at the second attempt. The majority of second attempts were undertaken by emergency consultants (36.8%) and emergency registrars (34.2%). A change in intubator occurred in 56.5% of intubation episodes and was associated with higher second attempt success (unadjusted odds ratio [OR] 1.85; 95% confidence interval [CI] 1.29-2.65). In 69.7% of second attempts at intubation, there was no change in laryngoscope type. Changes in laryngoscope type, adjunct devices and intubation manoeuvres were not significantly associated with success at the second attempt. In adjusted analyses, second attempt success was higher for a change from a non-consultant intubator to a consultant intubator from any specialty (adjusted OR 2.31; 95% CI 1.35-3.95) and where laryngoscopy was not predicted to be difficult (adjusted OR 2.58; 95% CI 1.58-4.21).

CONCLUSIONS

The majority of second intubation attempts were undertaken by emergency consultants and registrars. A change from a non-consultant intubator to a consultant intubator of any specialty for the second attempt and intubation episodes where laryngoscopy was predicted to be non-difficult were associated with a higher success rate at intubation. Participation in routine collection and monitoring of airway management practices via a Registry may enable the introduction of appropriate improvements in airway procedures and reduce complication rates.

Description and prediction of outcome of drowning patients in New South Wales, Australia: protocol for a data linkage study

INTRODUCTION

Despite being a preventable cause of death, drowning is a global public health threat. Australia records an average of 288 unintentional drowning deaths per year; an estimated annual economic burden of $1.24 billion AUD ($2017). On average, a further 712 hospitalisations occur due to non-fatal drowning annually. The Australian state of New South Wales (NSW) is the most populous and accounts for 34% of the average fatal drowning burden. This study aims to explore the demographics and outcome of patients who are admitted to hospitals for drowning in NSW and also investigates prediction of patients' outcome based on accessible data.

METHODS AND ANALYSIS

This protocol describes a retrospective, cross-sectional data linkage study across secondary data sources for any person (adult or paediatric) who was transferred by NSW Ambulance services and/or admitted to a NSW hospital for fatal or non-fatal drowning between 1/1/2010 and 31/12/2019. The NSW Admitted Patient Data Collection will provide data on admitted patients' characteristics and provided care in NSW hospitals. In order to map patients' pathways of care, data will be linked with NSW Ambulance Data Collection and the NSW Emergency Department Data Collection. Finally patient's mortality will be assessed via linkage with NSW Mortality data, which is made up of the NSW Register of Births, Deaths and Marriages and a Cause of Death Unit Record File. Regression analyses will be used to identify predicting values of independent variables with study outcomes.

ETHICS AND DISSEMINATION

This study has been approved by the NSW Population & Health Services Research Ethics Committee. Results will be disseminated through peer-reviewed publications, mass media releases and at academic conferences. The study will provide outcome data for drowning patients across NSW and study results will provide data to deliver evidence-informed recommendations for improving patient care, including updating relevant guidelines.

Apnoeic oxygenation was associated with decreased desaturation rates during rapid sequence intubation in multiple Australian and New Zealand emergency departments

Apnoeic oxygenation (ApOx) has been demonstrated to reduce the incidence of desaturation, although evidence of benefit has been conflicting depending on the technique used. The aim of this study was to compare the incidence of desaturation between patients who received ApOx via conventional nasal cannula (NC) and those who did not, using a large, multicentre airway registry.

METHODS

This study is an analysis of 24 months of prospectively collected data in the Australia and New Zealand Emergency Department Airway Registry (June 2013-June 2015). The registry includes information on all intubated adults from 43 emergency departments. Patients intubated during cardiac arrest (n=393), those who received active ventilation prior to the first intubation attempt (n=486), and where the use of ApOx was not recorded either way (n=312) were excluded. The proportion of patients who desaturated (Sa0₂ <93) in the group that received ApOx and those that did not were compared. To evaluate the association of ApOx with patient desaturation, a logistic regression model based on factors expected to influence desaturation was performed.

RESULTS

Of 2519 patients analysed, 1669 (66.3%) received ApOx via NC while 850 (33.7%) did not. Desaturation in the cohort receiving ApOx was 10.4% compared with standard care (no ApOx) 13.7%. ApOx had a protective effect for desaturation (OR 0.71 95% CI 0.53 to 0.95). Single intubation attempt was associated with reduced risk of desaturation of (OR 0.10, 95% CI 0.06 to 0.17); this was increased on second attempt (OR 0.37, 95% CI 0.21 to 0.68). Desaturation was also associated with the physician recording that they had anticipated a difficult airway (OR 1.83, 95% CI 1.34 to 2.48).

CONCLUSION

This large multicentre registry study provides evidence that ApOx delivered through a conventional NC is associated with a lower incidence of desaturation in patients undergoing rapid sequence intubation.

TRIAL REGISTRATION NUMBER

ACTRN12613001052729.

Prospective Validation of a Checklist to Predict Short-term Death in Older Patients After Emergency Department Admission in Australia and Ireland

BACKGROUND

Emergency departments (EDs) are pressured environment where patients with supportive and palliative care needs may not be identified. We aimed to test the predictive ability of the CriSTAL (Criteria for Screening and Triaging to Appropriate aLternative care) checklist to flag patients at risk of death within 3 months who may benefit from timely end-of-life discussions.

METHODS

Prospective cohorts of >65-year-old patients admitted for at least one night via EDs in five Australian hospitals and one Irish hospital. Purpose-trained nurses and medical students screened for frailty using two instruments concurrently and completed the other risk factors on the CriSTAL tool at admission. Postdischarge telephone follow-up was used to determine survival status. Logistic regression and bootstrapping techniques were used to test the predictive accuracy of CriSTAL for death within 90 days of admission as primary outcome. Predictability of in-hospital death was the secondary outcome.

RESULTS

A total of 1,182 patients, with median age 76 to 80 years (IRE-AUS), were included. The deceased had significantly higher mean CriSTAL with Australian mean of 8.1 (95% confidence interval [CI] = 7.7-8.6) versus 5.7 (95% CI = 5.1-6.2) and Irish mean of 7.7 (95% CI = 6.9-8.5) versus 5.7 (95% CI = 5.1-6.2). The model with Fried frailty score was optimal for the derivation (Australian) cohort but prediction with the Clinical Frailty Scale (CFS) was also good (areas under the receiver-operating characteristic [AUROC] = 0.825 and 0.81, respectively). Values for the validation (Irish) cohort were AUROC = 0.70 with Fried and 0.77 using CFS. A minimum of five of 29 variables were sufficient for accurate prediction, and a cut point of 7+ or 6+ depending on the cohort was strongly indicative of risk of death. The most significant independent predictor of short-term death in both cohorts was frailty, carrying a twofold risk of death. CriSTAL's accuracy for in-hospital death prediction was also good (AUROC = 0.795 and 0.81 in Australia and Ireland, respectively), with high specificity and negative predictive values.

CONCLUSIONS

The modified CriSTAL tool (with CFS instead of Fried's frailty instrument) had good discriminant power to improve certainty of short-term mortality prediction in both health systems. The predictive ability of models is anticipated to help clinicians gain confidence in initiating earlier end-of-life discussions. The practicalities of embedding screening for risk of death in routine practice warrant further investigation.

One hundred and counting: Centenarian use of emergency departments in New South Wales

OBJECTIVE

To study ED utilisation by people aged 100 years and over with a focus on patient demographics, reasons for presentation and patient flow factors.

METHODS

This is a retrospective descriptive analysis of linked ED Data Collection Registry for presentations to New South Wales (NSW) EDs over a 5 year period. Patients were included if they presented to an ED and were aged 100 years and over at the time of presentation. Demographics, triage category, presenting problem, ED length of stay, disposition and ED re-presentation were determined for this age group.

RESULTS

A total of 4033 presentations to 115 NSW EDs during 2010-2014 were analysed. We found that 78% of the patients were females and 76% still living at home. This group were the second most common age group to present to ED, after the 90-99 year age group, with 87% arriving via ambulance. Most presentations were triaged as a category 3 or 4, with the most common presenting problem being because of injury (28.5%) followed by respiratory disease (11.4%) and cardiovascular disease (10.0%). Overall, 64% required hospital admission and the average length of stay for all patients was 5.7 h.

CONCLUSIONS

Centenarians ED presentations are increasing over time with injuries as the most common reason for presentation. Most patients have prolonged ED length of stay and many require hospital admission. Early streaming of these patients through specialised geriatric assessment units may be more appropriate to reduce the demand on EDs and improve patient care. Models that facilitate rapid access to supported living arrangements and improved advanced care planning may be more realistic for many centenarians and different models of care need to be considered for this age group.

Which frailty scale for patients admitted via Emergency Department? A cohort study

OBJECTIVES

To determine the prevalence of frailty in Emergency Departments (EDs); examine the ability of frailty to predict poor outcomes post-discharge; and identify the most appropriate instrument for routine ED use.

METHODS

In this prospective study we simultaneously assessed adults 65+yrs admitted and/or spent one night in the ED using Fried, the Clinical Frailty Scale (CFS), and SUHB (Stable, Unstable, Help to walk, Bedbound) scales in four Australian EDs for rapid recognition of frailty between June 2015 and March 2016.

RESULTS

899 adults with complete follow-up data (mean (SD) age 80.0 (8.3) years; female 51.4%) were screened for frailty. Although different scales yielded vastly different frailty prevalence (SUHB 9.7%, Fried 30.4%, CFS 43.7%), predictive discrimination of poor discharge outcomes (death, poor self-reported health/quality of life, need for community services post-discharge, or reattendance to ED after the index hospitalization) for all identical final models was equivalent across all scales (AUROC 0.735 for Fried, 0.730 for CFS and 0.720 for SUHB).

CONCLUSION

This study confirms that screening for frailty in older ED patients can inform prognosis and target discharge planning including community services required. The CFS was as accurate as the Fried and SUHB in predicting poor outcomes, but more practical for use in busy clinical environments with lower level of disruption. Given the limitations of objectively measuring frailty parameters, self-report and clinical judgment can reliably substitute the assessment in EDs. We propose that in a busy ED environment, frailty scores could be used as a red flag for poor follow-up outcome.

Predictive validity of the CriSTAL tool for short-term mortality in older people presenting at Emergency Departments: a prospective study

ABSTRACT

To determine the validity of the Australian clinical prediction tool Criteria for Screening and Triaging to Appropriate aLternative care (CRISTAL) based on objective clinical criteria to accurately identify risk of death within 3 months of admission among older patients.

METHODS

Prospective study of ≥ 65 year-olds presenting at emergency departments in five Australian (Aus) and four Danish (DK) hospitals. Logistic regression analysis was used to model factors for death prediction; Sensitivity, specificity, area under the ROC curve and calibration with bootstrapping techniques were used to describe predictive accuracy.

RESULTS

2493 patients, with median age 78-80 years (DK-Aus). The deceased had significantly higher mean CriSTAL with Australian mean of 8.1 (95% CI 7.7-8.6 vs. 5.8 95% CI 5.6-5.9) and Danish mean 7.1 (95% CI 6.6-7.5 vs. 5.5 95% CI 5.4-5.6). The model with Fried Frailty score was optimal for the Australian cohort but prediction with the Clinical Frailty Scale (CFS) was also good (AUROC 0.825 and 0.81, respectively). Values for the Danish cohort were AUROC 0.764 with Fried and 0.794 using CFS. The most significant independent predictors of short-term death in both cohorts were advanced malignancy, frailty, male gender and advanced age. CriSTAL's accuracy was only modest for in-hospital death prediction in either setting.

CONCLUSIONS

The modified CriSTAL tool (with CFS instead of Fried's frailty instrument) has good discriminant power to improve prognostic certainty of short-term mortality for ED physicians in both health systems. This shows promise in enhancing clinician's confidence in initiating earlier end-of-life discussions.

Ketamine use for rapid sequence intubation in Australian and New Zealand emergency departments from 2010 to 2015: A registry study

OBJECTIVE

This study aimed to quantify the proportion of patients undergoing rapid sequence intubation using ketamine in Australian and New Zealand EDs between 2010 and 2015.

METHODS

The Australian and New Zealand Emergency Department Airway Registry is a multicentre airway registry prospectively capturing data from 43 sites. Data on demographics and physiology, the attending staff and indication for intubation were recorded. The primary outcome was the annual percentage of patients intubated with ketamine. A logistic regression analysis was conducted to evaluate the factors associated with ketamine use.

RESULTS

A total of 4658 patients met inclusion criteria. The annual incidence of ketamine use increased from 5% to 28% over the study period (P < 0.0001). In the logistic regression analysis, the presence of an emergency physician as a team leader was the strongest predictor of ketamine use (odds ratio [OR] 1.83, 95% confidence interval [CI] 1.44-2.34). The OR for an increase in one point on the Glasgow Coma Scale was 1.10 (95% CI 1.07-1.12), whereas an increase of 1 mmHg of systolic blood pressure had an OR of 0.98 (95% CI 0.98-0.99). Intubation occurring in a major referral hospital had an OR of 0.68 (95% CI 0.56-0.82), while trauma conferred an OR of 1.38 (95% CI 1.25-1.53).

CONCLUSIONS

Ketamine use increased between 2010 and 2015. Lower systolic blood pressure, the presence of an emergency medicine team leader, trauma and a higher Glasgow Coma Scale were associated with increased odds of ketamine use. Intubation occurring in a major referral centre was associated with lower odds of ketamine use.

Efficacy of a tool to predict short-term mortality in older people presenting at emergency departments: Protocol for a multi-centre cohort study

BACKGROUND

Prognostic uncertainty inhibits clinicians from initiating timely end-of-life discussions and advance care planning. This study evaluates the efficacy of the CriSTAL (Criteria for Screening and Triaging to Appropriate aLternative care) checklist in emergency departments.

METHODS

Prospective cohort study of patients aged ≥65 years with any diagnosis admitted via emergency departments in ten hospitals in Australia, Denmark and Ireland. Electronic and paper clinical records will be used to extract risk factors such as nursing home residency, physiological deterioration warranting a rapid response call, personal history of active chronic disease, history of hospitalisations or intensive care unit admission in the past year, evidence of proteinuria or ECG abnormalities, and evidence of frailty to be concurrently measured with Fried Score and Clinical Frailty Scale. Patients or their informal caregivers will be contacted by telephone around three months after initial assessment to ascertain survival, self-reported health, post-discharge frailty and health service utilisation since discharge. Logistic regression and bootstrapping techniques and AUROC curves will be used to test the predictive accuracy of CriSTAL for death within 90 days of admission and in-hospital death.

DISCUSSION

The CriSTAL checklist is an objective and practical tool for use in emergency departments among older patients to determine individual probability of death in the short-term. Its validation in this cohort is expected to reduce clinicians' prognostic uncertainty on the time to patients' death and encourage timely end-of-life conversations to support clinical decisions with older frail patients and their families about their imminent or future care choices.

A sequential case series of 23 intubations in a rural emergency department in New Zealand

OBJECTIVE

To describe the practice and procedure of emergency intubation in Whanganui Emergency Department, New Zealand and determine whether intubation can be carried out effectively in the rural setting.

METHOD

A prospective observational study using the Australia and New Zealand Airway Registry proforma to collect data on the indication, lead intubator, first-pass success rate and peri-procedural complications. Data were also collected on whether a formal airway assessment was carried out and whether a checklist was used.

RESULTS

Twenty-three patients were intubated in the emergency department over a 12-month period. Sixty-two percent (14/23 cases) were medical encounters and the remaining 38% of indications due to a trauma. Head injury was the most common indication (23%). Ninety-two percent of primary intubators were emergency department-based Fellowship of the Australasian College for Emergency Medicine or resident medical officers, while anaesthetic-trained operators accounted for just 8%. Our first-pass intubation success rate was 87% and 16% of cases had procedural complications. Sixty-five percent (15/23) carried out a formal airway assessment and a checklist was only used in 23% of cases.

CONCLUSION

This sequential case series is the first study looking at airway management in rural New Zealand emergency department airway practice. Overall intubation success rates were comparable to larger tertiary centres across Australasia. We have demonstrated that with adequate resources and adherence to interventions, a rural emergency department can provide effective airway management.

Emergency airway management in Australian and New Zealand emergency departments: A multicentre descriptive study of 3710 emergency intubations

OBJECTIVE

The aim of this study was to describe the practice of endotracheal intubation across a range of Australasian EDs.

METHODS

We established a multicentre airway registry (The Australian and New Zealand Emergency Department Airway Registry [ANZEDAR]) prospectively capturing intubations from 43 Australian and New Zealand EDs over 24 months using the ANZEDAR form. Information recorded included patient demographics, intubation indications, predicted difficulty, rapid sequence induction and endotracheal intubation preparation technique, induction drugs, airway adjuncts and complications. Factors associated with first attempt success were explored.

RESULTS

Of the 3710 intubations captured, 3533 were in adults (95.2%), 2835 (76.4%) for medical and 810 (21.8%) for trauma indications. Overall, 3127 (84.3%) patients were successfully intubated at the first attempt; the majority by ED doctors (2654 [72.1%]). A total of 10 surgical airways were performed, all of which were successful cricothyroidotomies. Propofol, thiopentone or ketamine were used with similar frequency for induction, and suxamethonium was the most often used muscle relaxant. Adverse events were reported in 964 (26%), the majority involving desaturation or hypotension.

CONCLUSION

Australasian ED doctors, predominantly specialist emergency physicians or trainees, perform the majority of ED intubations using rapid sequence induction as their preferred technique mainly for medical indications. First attempt success rate was not different between different types of EDs, and is comparable published international data. Complications are not infrequent, and are comparable to other published series. Monitoring and reporting of ED intubation practice will enable continued improvements in the safety of this high-risk procedure.

CXCL1 is a negative regulator of mast cell chemotaxis to airway smooth muscle cell products in vitro

BACKGROUND

Activated mast cells (MC) numbers on airway smooth muscle (ASM) are increased in eosinophilic asthma. In vitro, asthmatic cytokine-stimulated ASM cell-conditioned medium (CM) induces more MC chemotaxis than CM from nonasthmatic ASM cells. Intriguingly the nonasthmatic ASM CM inhibits MC chemotaxis to the asthmatic ASM CM. However, the inhibitory factor(s) in the nonasthmatic ASM CM is still to be identified.

OBJECTIVE

To identify the factor(s) released by nonasthmatic ASM cells that inhibits MC chemotaxis.

METHODS

Confluent, serum-starved ASM cells from donors with and without asthma were stimulated with IL-1β and T-helper (Th)1 (TNFα and IFNγ) or Th2 (IL-4, IL-13) cytokines, or left unstimulated. CM samples were collected after 24 h, and a potential inhibitory factor identified using cytokine protein arrays. Its production was assessed using ELISA and RT-PCR and inhibitory role investigated in MC chemotaxis and Ca(2+) mobilization assays.

RESULTS

Only CXCL1 was produced in greater amounts by nonasthmatic than asthmatic ASM cells following Th1 and Th2 cytokine stimulation. CXCL1 mRNA expression was also increased. Exogenous rh-CXCL1 significantly inhibited MC intracellular Ca(2+) mobilization and chemotaxis to either CXCL10, CXCL8 or CM collected from asthmatic ASM cells following Th1 or Th2 cytokine stimulation. Neutralizing CXCL1 in nonasthmatic ASM CM or blocking its receptor significantly promoted MC chemotaxis.

CONCLUSIONS

CXCL1 was a major factor regulating MC chemotaxis in vitro. Its differential release by ASM cells may explain the differences observed in MC localization to the ASM of people with and without asthma.

CLINICAL RELEVANCE

CXCL1 inhibition of MC recruitment to the ASM may lead to new targets to limit asthma pathophysiology.

TLR2 activation causes tachyphylaxis to β2 -agonists in vitro and ex vivo: modelling bacterial exacerbation

BACKGROUND

Asthma is a widespread chronic health problem exacerbated by common viral and bacterial infections. Further research is required to understand how infection worsens asthma control in order to advance therapeutic options in the future. Recent research has revealed that β2 -adrenergic receptor (β2 -AR) agonists lose bronchodilatory efficacy because the receptor-mediated molecular pathways responsible for their beneficial actions are desensitized by infection. To date, most studies have focussed on viral infection, leaving the impact of bacterial infection on β2 -AR desensitization relatively under-investigated. We address this in this study.

METHODS AND RESULTS

Utilizing an in vitro model of bacterial exacerbation in airway smooth muscle (ASM) cells, we show that activation of toll-like receptor 2 (TLR2; mimicking bacterial infection) in the presence of an inflammatory stimulus leads to β2 -AR desensitization. This occurs via TLR2-dependent upregulation of cyclooxygenase 2 (COX-2) mRNA expression and increased secretion of PGE2 . Importantly, PGE2 causes heterologous β2 -AR desensitization and reduces cAMP production in response to short-acting (salbutamol) and long-acting (formoterol) β2 -agonists. Thus, bacterial infectious stimuli act in a PGE2 -dependent manner to severely curtail the beneficial actions of β2 -agonists. The impact of β2 -AR desensitization is demonstrated by reduced gene expression of the critical anti-inflammatory molecule MKP-1 in response to β2 -agonists, as well as impaired bronchodilation in a mouse lung slices.

CONCLUSIONS

Taken together, our results show that, like viruses, bacteria induce prostanoid-dependent β2 -AR desensitization on ASM cells. Notably, COX-2 inhibition with the specific inhibitor celecoxib represses PGE2 secretion, presenting a feasible pharmacological option for treatment of infectious exacerbation in asthma in the future.

Effects of cigarette smoke extract on human airway smooth muscle cells in COPD

We hypothesised that the response to cigarette smoke in airway smooth muscle (ASM) cells from smokers with chronic obstructive pulmonary disease (COPD) would be intrinsically different from smokers without COPD, producing greater pro-inflammatory mediators and factors relating to airway remodelling. ASM cells were obtained from smokers with or without COPD, and then stimulated with cigarette smoke extract (CSE) or transforming growth factor-β1. The production of chemokines and matrix metalloproteinases (MMPs) were measured by ELISA, and the deposition of collagens by extracellular matrix ELISA. The effects of CSE on cell attachment and wound healing were measured by toluidine blue attachment and cell tracker green wound healing assays. CSE increased the release of CXCL8 and CXCL1 from human ASM cells, and cells from smokers with COPD produced more CSE-induced CXCL1. The production of MMP-1, -3 and -10, and the deposition of collagen VIII alpha 1 (COL8A1) were increased by CSE, especially in the COPD group which had higher production of MMP-1 and deposition of COL8A1. CSE decreased ASM cell attachment and wound healing in the COPD group only. ASM cells from smokers with COPD were more sensitive to CSE stimulation, which may explain, in part, why some smokers develop COPD.

Corticosteroids inhibit sphingosine 1-phosphate-induced interleukin-6 secretion from human airway smooth muscle via mitogen-activated protein kinase phosphatase 1-mediated repression of mitogen and stress-activated protein kinase 1

Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid that plays an important proinflammatory role in asthmatic airways. Corticosteroids are first-line antiinflammatories in asthma; however, their repressive effects on S1P-induced cytokine secretion have not been investigated. To address this, our in vitro study reveals the molecular mechanisms by which corticosteroids inhibit S1P-induced IL-6 expression in the pivotal immunomodulatory cell type, airway smooth muscle (ASM). We first uncover the cellular signaling pathways responsible: S1P activates a cyclic adenosine monophosphate/cAMP response-element-binding protein (CREB)/CRE-dependent pathway to induce IL-6 transcription, concomitant with stimulation of the mitogen-activated protein kinase (MAPK) superfamily and downstream mitogen and stress-activated protein kinase 1 (MSK1) and histone H3 phosphorylation. In this way, S1P stimulates parallel signaling pathways to induce IL-6 secretion via CRE-driven transcription of the IL-6 gene promoter in a relaxed chromatin environment achieved through histone H3 phosphorylation. Second, we investigated how corticosteroids mediate their repressive effects. The corticosteroid dexamethasone inhibits S1P-induced IL-6 protein secretion and mRNA expression, but CREB/CRE transrepression, inhibition of IL-6 mRNA stability, or subcellular relocation of MSK1 were not responsible for the repressive effects of dexamethasone. Rather, we show that dexamethasone rapidly induces up-regulation of the MAPK deactivator MAPK phosphatase 1 (MKP-1) and that MKP-1 blocks the MAPK-driven activation of MSK1 and phosphorylation of histone H3. This was confirmed by treatment with triptolide, an inhibitor of MKP-1 up-regulation, where repressive effects of corticosteroids were reversed. Our study reveals the molecular mechanism underlying the antiinflammatory capacity of corticosteroids to repress proinflammatory functions induced by the potent bioactive sphingolipid S1P in the lung.

Regulation of pulmonary inflammation by mesenchymal cells

Pulmonary inflammation and tissue remodelling are common elements of chronic respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and pulmonary hypertension (PH). In disease, pulmonary mesenchymal cells not only contribute to tissue remodelling, but also have an important role in pulmonary inflammation. This review will describe the immunomodulatory functions of pulmonary mesenchymal cells, such as airway smooth muscle (ASM) cells and lung fibroblasts, in chronic respiratory disease. An important theme of the review is that pulmonary mesenchymal cells not only respond to inflammatory mediators, but also produce their own mediators, whether pro-inflammatory or pro-resolving, which influence the quantity and quality of the lung immune response. The notion that defective pro-inflammatory or pro-resolving signalling in these cells potentially contributes to disease progression is also discussed. Finally, the concept of specifically targeting pulmonary mesenchymal cell immunomodulatory function to improve therapeutic control of chronic respiratory disease is considered.

The nucleotide-binding domain and leucine-rich repeat protein-3 inflammasome is not activated in airway smooth muscle upon toll-like receptor-2 ligation

Inflammasomes have emerged as playing key roles in inflammation and innate immunity. A growing body of evidence has suggested that the nucleotide-binding domain and leucine-rich repeat protein-3 (NLRP3) inflammasome is important in chronic airway diseases such as asthma and chronic obstructive pulmonary disease. Inflammasome activation results, in part, in pro-IL-1β processing and the secretion of the proinflammatory cytokine IL-1β. Because asthma exacerbations are associated with elevated concentrations of secreted IL-1β, we addressed whether the NLRP3 inflammasome is activated under in vitro conditions that mimic infectious exacerbations in asthma. Primary cultures of airway smooth muscle (ASM) cells were treated with infectious stimuli (mimicked using the Toll-like receptor-2 agonist Pam3CSK4, a synthetic bacterial lipopeptide). Whereas Pam3CSK4 robustly up-regulated ASM cytokine expression in response to TNF-α and significantly enhanced IL-1β mRNA expression, we were unable to detect IL-1β in the cell supernatants. Thus, IL-1β was not secreted and therefore was unable to act in an autocrine manner to promote the amplification of ASM inflammatory responses. Moreover, Toll-like receptor-2 ligation did not enhance NLRP3 or caspase-1 expression in ASM cells, and NLRP3 and caspase-1 protein were not present in the ASM layer of tracheal sections from human donors. In conclusion, these data demonstrate that the enhanced synthetic function of ASM cells, induced by infectious exacerbations of airway inflammation, is NLRP3 inflammasome-independent and IL-1β-independent. Activation of the NLRP3 inflammasome by invading pathogens may prove cell type-specific in exacerbations of airway inflammation in asthma.

Airway smooth muscle CXCR3 ligand production: regulation by JAK-STAT1 and intracellular Ca²⁺

In asthma, airway smooth muscle (ASM) chemokine (C-X-C motif) receptor 3 (CXCR3) ligand production may attract mast cells or T lymphocytes to the ASM, where they can modulate ASM functions. In ASM cells (ASMCs) from people with or without asthma, we aimed to investigate JAK-STAT1, JNK, and Ca²⁺ involvement in chemokine (C-X-C motif) ligand (CXCL)10 and CXCL11 production stimulated by interferon-γ, IL-1β, and TNF-α combined (cytomix). Confluent, growth-arrested ASMC were treated with inhibitors for pan-JAK (pyridone-6), JAK2 (AG-490), JNK (SP-600125), or the sarco(endo)plasmic reticulum Ca²⁺ATPase (SERCA) pump (thapsigargin), Ca²⁺ chelator (BAPTA-AM), or vehicle before and during cytomix stimulation for up to 24 h. Signaling protein activation as well as CXCL10/CXCL11 mRNA and protein production were examined using immunoblot analysis, real-time PCR, and ELISA, respectively. Cytomix-induced STAT1 activation was lower and CXCR3 ligand mRNA production was more sensitive to pyridone-6 and AG-490 in asthmatic than nonasthmatic ASMCs, but CXCL10/CXCL11 release was inhibited by the same proportion. Neither agent caused additional inhibition of release when used in combination with the JNK inhibitor SP-600125. Conversely, p65 NF-κB activation was higher in asthmatic than nonasthmatic ASMCs. BAPTA-AM abolished early CXCL10/CXCL11 mRNA production, whereas thapsigargin reduced it in asthmatic cells and inhibited CXCL10/CXCL11 release by both ASMC types. Despite these inhibitory effects, neither Ca²⁺ agent affected early activation of STAT1, JNK, or p65 NF-κB. In conclusion, intracellular Ca²⁺ regulated CXCL10/CXCL11 production but not early activation of the signaling molecules involved. In asthma, reduced ASM STAT1-JNK activation, increased NF-κB activation, and altered Ca²⁺ handling may contribute to rapid CXCR3 ligand production and enhanced inflammatory cell recruitment.

Mast cells produce novel shorter forms of perlecan that contain functional endorepellin: a role in angiogenesis and wound healing

Mast cells are derived from hematopoietic progenitors that are known to migrate to and reside within connective and mucosal tissues, where they differentiate and respond to various stimuli by releasing pro-inflammatory mediators, including histamine, growth factors, and proteases. This study demonstrated that primary human mast cells as well as the rat and human mast cell lines, RBL-2H3 and HMC-1, produce the heparan sulfate proteoglycan, perlecan, with a molecular mass of 640 kDa as well as smaller molecular mass species of 300 and 130 kDa. Utilizing domain-specific antibodies coupled with N-terminal sequencing, it was confirmed that both forms contained the C-terminal module of the protein core known as endorepellin, which were generated by mast cell-derived proteases. Domain-specific RT-PCR experiments demonstrated that transcripts corresponding to domains I and V, including endorepellin, were present; however, mRNA transcripts corresponding to regions of domain III were not present, suggesting that these cells were capable of producing spliced forms of the protein core. Fractions from mast cell cultures that were enriched for these fragments were shown to bind endothelial cells via the α(2)β(1) integrin and stimulate the migration of cells in "scratch assays," both activities of which were inhibited by incubation with either anti-endorepellin or anti-perlecan antibodies. This study shows for the first time that mast cells secrete and process the extracellular proteoglycan perlecan into fragments containing the endorepellin C-terminal region that regulate angiogenesis and matrix turnover, which are both key events in wound healing.

Thiazolidinediones inhibit airway smooth muscle release of the chemokine CXCL10: in vitro comparison with current asthma therapies

BACKGROUND

Activated mast cells are present within airway smooth muscle (ASM) bundles in eosinophilic asthma. ASM production of the chemokine CXCL10 plays a role in their recruitment. Thus the effects of glucocorticoids (fluticasone, budesonide), long-acting β2-agonists (salmeterol, formoterol) and thiazolidinediones (ciglitazone, rosiglitazone) on CXCL10 production by ASM cells (ASMC) from people with and without asthma were investigated in vitro.

METHODS

Confluent serum-deprived cells were treated with the agents before and during cytokine stimulation for 0-24 h. CXCL10 protein/mRNA, IκB-α levels and p65 activity were measured using ELISA, RT PCR, immunoblotting and p65 activity assays respectively. Data were analysed using ANOVA followed by Fisher's post-hoc test.

RESULTS

Fluticasone and/or salmeterol at 1 and 100 nM inhibited CXCL10 release induced by IL-1β and TNF-α, but not IFNγ or all three cytokines (cytomix). The latter was also not affected by budesonide and formoterol. In asthmatic ASMC low salmeterol, but not formoterol, concentrations increased cytomix-induced CXCL10 release and at 0.01 nM enhanced NF-κB activity. Salmeterol 0.1 nM together with fluticasone 0.1 and 10 nM still increased CXCL10 release. The thiazolidinediones ciglitazone and rosiglitazone (at 25 and 100 μM) inhibited cytomix-induced CXCL10 release but these inhibitory effects were not prevented by the PPAR-g antagonist GW9662. Ciglitazone did not affect early NF-κB activity and CXCL10 mRNA production.

CONCLUSIONS

Thus the thiazolidinediones inhibited asthmatic ASMC CXCL10 release under conditions when common asthma therapies were ineffective or enhanced it. They may provide an alternative strategy to reduce mast cell-ASM interactions and restore normal airway physiology in asthma.

Asthmatic airway smooth muscle CXCL10 production: mitogen-activated protein kinase JNK involvement

CXCL10 (IP10) is involved in mast cell migration to airway smooth muscle (ASM) bundles in asthma. We aimed to investigate the role of cytokine-induced MAPK activation in CXCL10 production by ASM cells from people with and without asthma. Confluent growth-arrested ASM cells were treated with inhibitors of the MAPKs ERK, p38, and JNK and transcription factor NF-κB, or vehicle, and stimulated with IL-1β, TNF-α, or IFN-γ, alone or combined (cytomix). CXCL10 mRNA and protein, JNK, NF-κB p65 phosphorylation, and Iκ-Bα protein degradation were assessed using real-time PCR, ELISA, and immunoblotting, respectively. Cytomix, IL-1β, and TNF-α induced CXCL10 mRNA expression more rapidly in asthmatic than nonasthmatic ASM cells. IL-1β and/or TNF-α combined with IFN-γ synergistically increased asthmatic ASM cell CXCL10 release. Inhibitor effects were similar in asthmatic and nonasthmatic cells, but cytomix-induced release was least affected, with only JNK and NF-κB inhibitors halving it. Notably, JNK phosphorylation was markedly less in asthmatic compared with nonasthmatic cells. However, in both, the JNK inhibitor SP600125 reduced JNK phosphorylation and CXCL10 mRNA levels but did not affect CXCL10 mRNA stability or Iκ-Bα degradation. Together, the JNK and NF-κB inhibitors completely inhibited their CXCL10 release. We concluded that, in asthmatic compared with nonasthmatic ASM cells, JNK activation was reduced and CXCL10 gene expression was more rapid following cytomix stimulation. However, in both, JNK activation did not regulate early events leading to NF-κB activation. Thus JNK and NF-κB provide independent therapeutic targets for limiting CXCL10 production and mast cell migration to the ASM in asthma.

Th1 cytokine-induced syndecan-4 shedding by airway smooth muscle cells is dependent on mitogen-activated protein kinases

In asthma, airway smooth muscle (ASM) chemokine secretion can induce mast cell recruitment into the airways. The functions of the mast cell chemoattractant CXCL10, and other chemokines, are regulated by binding to heparan sulphates such as syndecan-4. This study is the first demonstration that airway smooth muscle cells (ASMC) from people with and without asthma express and shed syndecan-4 under basal conditions. Syndecan-4 shedding was enhanced by stimulation for 24 h with the Th1 cytokines interleukin-1β (IL-1β) or tumor necrosis factor-α (TNF-α), but not interferon-γ (IFNγ), nor the Th2 cytokines IL-4 and IL-13. ASMC stimulation with IL-1β, TNF-α, and IFNγ (cytomix) induced the highest level of syndecan-4 shedding. Nonasthmatic and asthmatic ASM cell-associated syndecan-4 protein expression was also increased by TNF-α or cytomix at 4-8 h, with the highest levels detected in cytomix-stimulated asthmatic cells. Cell-associated syndecan-4 levels were decreased by 24 h, whereas shedding remained elevated at 24 h, consistent with newly synthesized syndecan-4 being shed. Inhibition of ASMC matrix metalloproteinase-2 did not prevent syndecan-4 shedding, whereas inhibition of ERK MAPK activation reduced shedding from cytomix-stimulated ASMC. Although ERK inhibition had no effect on syndecan-4 mRNA levels stimulated by cytomix, it did cause an increase in cell-associated syndecan-4 levels, consistent with the shedding being inhibited. In conclusion, ASMC produce and shed syndecan-4 and although this is increased by the Th1 cytokines, the MAPK ERK only regulates shedding. ASMC syndecan-4 production during Th1 inflammatory conditions may regulate chemokine activity and mast cell recruitment to the ASM in asthma.

Human lung mast cells modulate the functions of airway smooth muscle cells in asthma

BACKGROUND

Activated mast cell densities are increased on the airway smooth muscle in asthma where they may modulate muscle functions and thus contribute to airway inflammation, remodelling and airflow obstruction.

OBJECTIVES

To determine the effects of human lung mast cells on the secretory and proliferative functions of airway smooth muscle cells from donors with and without asthma.

METHODS

Freshly isolated human lung mast cells were stimulated with IgE/anti-IgE. Culture supernatants were collected after 2 and 24 h and the mast cells lysed. The supernatants/lysates were added to serum-deprived, subconfluent airway smooth muscle cells for up to 48 h. Released chemokines and extracellular matrix were measured by ELISA, proliferation was quantified by [(3) H]-thymidine incorporation and cell counting, and intracellular signalling by phospho-arrays.

RESULTS

Mast cell 2-h supernatants reduced CCL11 and increased CXCL8 and fibronectin production from both asthmatic and nonasthmatic muscle cells. Leupeptin reversed these effects. Mast cell 24-h supernatants and lysates reduced CCL11 release from both muscle cell types but increased CXCL8 release by nonasthmatic cells. The 24-h supernatants also reduced asthmatic, but not nonasthmatic, muscle cell DNA synthesis and asthmatic cell numbers over 5 days through inhibiting extracellular signal-regulated kinase (ERK) and phosphatidylinositol (PI3)-kinase pathways. However, prostaglandins, thromboxanes, IL-4 and IL-13 were not involved in reducing the proliferation.

CONCLUSIONS

Mast cell proteases and newly synthesized products differentially modulated the secretory and proliferative functions of airway smooth muscle cells from donors with and without asthma. Thus, mast cells may modulate their own recruitment and airway smooth muscle functions locally in asthma.

Histamine and tryptase modulate asthmatic airway smooth muscle GM-CSF and RANTES release

Degranulating mast cells are increased in the airway smooth muscle (ASM) of asthmatics, where they may influence ASM function. The aim of the present study was to determine whether histamine and tryptase modulate ASM cell granulocyte-macrophage colony-stimulating factor (GM-CSF) and RANTES (regulated on activation, normal T-cell expressed and secreted) release and also to examine which receptors are involved in this release. Confluent, quiescent ASM cells from asthmatic and nonasthmatic donors were treated with histamine (1 microM-100 microM) with and without histamine receptor antagonist pre-treatment, or the protease-activated receptor (PAR)-2 agonists tryptase (0.5-5 nM) and SLIGKV (100 and 400 microM). The cells were then stimulated with interleukin (IL)-1beta and/or tumour necrosis factor (TNF)-alpha (10 ng.mL(-1)) or left unstimulated for 24 h. Release of GM-CSF and RANTES was determined by ELISA and prostaglandin (PG)E(2) measured by enzyme immunoassay. Neither histamine nor tryptase induced ASM GM-CSF or RANTES secretion. However, histamine increased IL-1beta-induced GM-CSF release and markedly reduced TNF-alpha-induced RANTES release by both asthmatic and nonasthmatic cells to a similar extent, but did not modulate PGE(2) release. All changes involved activation of the histamine H1 receptor as they were partially or fully blocked by chlorpheniramine, but not ranitidine. Tryptase, via its proteolytic activity, also potentiated GM-CSF, but not RANTES, release from asthmatic and nonasthmatic ASM cells induced by both cytokines. PAR-2 involvement in the tryptase potentiation was unlikely because SLIGKV had no effect. In conclusion, mast cells, through histamine and tryptase, may locally modulate airway smooth muscle-induced inflammation in asthma.

Effect of IL-6 trans-signaling on the pro-remodeling phenotype of airway smooth muscle

Increased levels of IL-6 are documented in asthma, but its contribution to the pathology is unknown. Asthma is characterized by airway wall thickening due to increased extracellular matrix deposition, inflammation, angiogenesis, and airway smooth muscle (ASM) mass. IL-6 binds to a specific membrane-bound receptor, IL-6 receptor-alpha (mIL-6Ralpha), and subsequently to the signaling protein gp130. Alternatively, IL-6 can bind to soluble IL-6 recpetor-alpha (sIL-6Ralpha) to stimulate membrane receptor-deficient cells, a process called trans-signaling. We discovered that primary human ASM cells do not express mIL-6Ralpha and, therefore, investigated the effect of IL-6 trans-signaling on the pro-remodeling phenotype of ASM. ASM required sIL-6Ralpha to activate signal transducer and activator 3, with no differences observed between cells from asthmatic subjects compared with controls. Further analysis revealed that IL-6 alone or with sIL-6Ralpha did not induce release of matrix-stimulating factors (including connective tissue growth factor, fibronectin, or integrins) and had no effect on mast cell adhesion to ASM or ASM proliferation. However, in the presence of sIL-6Ralpha, IL-6 increased eotaxin and VEGF release and may thereby contribute to local inflammation and vessel expansion in airway walls of asthmatic subjects. As levels of sIL-6Ralpha are increased in asthma, this demonstration of IL-6 trans-signaling in ASM has relevance to the development of airway remodeling.