Prevalence and Predictors of Emergency Medical Service Use in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction

AIM

We aim to describe prevalence of Emergency Medical Service (EMS) use, investigate factors predictive of EMS use, and determine if EMS use predicts treatment delay and mortality in our ST-elevation myocardial infarction (STEMI) cohort.

METHOD

We prospectively collected data on 5,602 patients presenting with STEMI for primary percutaneous coronary intervention (PCI) transported to PCI-capable hospitals in Victoria, Australia, from 2013-2018 who were entered into the Victorian Cardiac Outcomes Registry (VCOR). We linked this dataset to the Ambulance Victoria and National Death Index (NDI) datasets. We excluded late presentation, thrombolysed, and in-hospital STEMI, as well as patients presenting with cardiogenic shock and out-of-hospital cardiac arrest.

RESULTS

In total, 74% of patients undergoing primary PCI for STEMI used EMS. Older age, female gender, higher socioeconomic status, and a history of prior ischaemic heart disease were independent predictors of using EMS. EMS use was associated with shorter adjusted door-to-balloon (53 vs 72 minutes, p<0.001) and symptom-to-balloon (183 vs 212 minutes, p<0.001) times. Mode of transport was not predictive of 30-day or 12-month mortality.

CONCLUSIONS

EMS use in Victoria is relatively high compared with internationally reported data. EMS use reduces treatment delay. Predictors of EMS use in our cohort are consistent with those prevalent in prior literature. Understanding the patients who are less likely to use EMS might inform more targeted education campaigns in the future.

Risk-standardized mortality metric to monitor hospital performance for chest pain presentations

AIMS

Risk-standardized mortality rates (RSMR) have been used to monitor hospital performance in procedural and disease-based registries, but limitations include the potential to promote risk-averse clinician decisions and a lack of assessment of the whole patient journey. We aimed to determine whether it is feasible to use RSMR at the symptom-level to monitor hospital performance using routinely collected, linked, clinical and administrative data of chest pain presentations.

METHODS AND RESULTS

We included 192 978 consecutive adult patients (mean age 62 years; 51% female) with acute chest pain without ST-elevation brought via emergency medical services (EMS) to 53 emergency departments in Victoria, Australia (1/1/2015-30/6/2019). From 32 candidate variables, a risk-adjusted logistic regression model for 30-day mortality (C-statistic 0.899) was developed, with excellent calibration in the full cohort and with optimism-adjusted bootstrap internal validation. Annual 30-day RSMR was calculated by dividing each hospital's observed mortality by the expected mortality rate and multiplying it by the annual mean 30-day mortality rate. Hospital performance according to annual 30-day RSMR was lower for outer regional or remote locations and at hospitals without revascularisation capabilities. Hospital rates of angiography or transfer for patients diagnosed with non-ST elevation myocardial infarction (NSTEMI) correlated with annual 30-day RSMR, but no correlations were observed with other existing key performance indicators.

CONCLUSION

Annual hospital 30-day RSMR can be feasibly calculated at the symptom-level using routinely collected, linked clinical, and administrative data. This outcome-based metric appears to provide additional information for monitoring hospital performance in comparison with existing process of care key performance measures.

One-year quality-of-life outcomes of cardiac arrest survivors by initial defibrillation provider

OBJECTIVE

To assess the long-term functional and health-related quality-of-life (HRQoL) outcomes for out-of-hospital cardiac arrest (OHCA) survivors stratified by initial defibrillation provider.

METHODS

This retrospective study included adult non-traumatic OHCA with initial shockable rhythms between 2010 and 2019. Survivors at 12 months after arrest were invited to participate in structured telephone interviews. Outcomes were identified using the Glasgow Outcome Scale-Extended (GOS-E), EuroQol-5 Dimension (EQ-5D), 12-Item Short Form Health Survey and living and work status-related questions.

RESULTS

6050 patients had initial shockable rhythms, 3211 (53.1%) had a pulse on hospital arrival, while 1879 (31.1%) were discharged alive. Bystander defibrillation using the closest automated external defibrillator had the highest survival rate (52.8%), followed by dispatched first responders (36.7%) and paramedics (27.9%). 1802 (29.8%) patients survived to 12-month postarrest; of these 1520 (84.4%) were interviewed. 1088 (71.6%) were initially shocked by paramedics, 271 (17.8%) by first responders and 161 (10.6%) by bystanders. Bystander-shocked survivors reported higher rates of living at home without care (87.5%, 75.2%, 77.0%, p<0.001), upper good recovery (GOS-E=8) (41.7%, 30.4%, 30.6%, p=0.002) and EQ-5D visual analogue scale (VAS) ≥80 (64.9%, 55.9%, 52.9%, p=0.003) compared with first responder and paramedics, respectively. After adjustment, initial bystander defibrillation was associated with higher odds of EQ-5D VAS ≥80 (adjusted OR (AOR) 1.56, 95% CI 1.15-2.10; p=0.004), good functional recovery (GOS-E ≥7) (AOR 1.53, 95% CI 1.12-2.11; p=0.009), living at home without care (AOR 1.77, 95% CI 1.16-2.71; p=0.009) and returning to work (AOR 1.72, 95% CI 1.05-2.81; p=0.031) compared with paramedic defibrillation.

CONCLUSION

Survivors receiving initial bystander defibrillation reported better functional and HRQoL outcomes at 12 months after arrest compared with those initially defibrillated by paramedics.

Impact of prehospital opioid dose on angiographic and clinical outcomes in acute coronary syndromes

BACKGROUND

An adverse interaction whereby opioids impair and delay the gastrointestinal absorption of oral P2Y₁₂ inhibitors has been established, however the clinical significance of this in acute coronary syndrome (ACS) is uncertain. We sought to characterise the relationship between prehospital opioid dose and clinical outcomes in patients with ACS.

METHODS

Patients given opioid treatment by emergency medical services (EMS) with ACS who underwent percutaneous coronary intervention (PCI) between 1 January 2014 and 31 December 2018 were included in this retrospective cohort analysis using data linkage between the Ambulance Victoria, Victorian Cardiac Outcomes Registry and Melbourne Interventional Group databases. Patients with cardiogenic shock, out-of-hospital cardiac arrest and fibrinolysis were excluded. The primary end point was the risk-adjusted odds of 30-day major adverse cardiac events (MACE) between patients who received opioids and those that did not.

RESULTS

10 531 patients were included in the primary analysis. There was no significant difference in 30-day MACE between patients receiving opioids and those who did not after adjusting for key patient and clinical factors. Among patients with ST-elevation myocardial infarction (STEMI), there were significantly more patients with thrombolysis in myocardial infarction (TIMI) 0 or 1 flow pre-PCI in a subset of patients with high opioid dose versus no opioids (56% vs 25%, p<0.001). This remained significant after adjusting for known confounders with a higher predicted probability of TIMI 0/1 flow in the high versus no opioid groups (33% vs 11%, p<0.001).

CONCLUSIONS

Opioid use was not associated with 30-day MACE. There were higher rates of TIMI 0/1 flow pre-PCI in patients with STEMI prescribed opioids. Future prospective research is required to verify these findings and investigate alternative analgesia for ischaemic chest pain.

Age as a predictor of clinical outcomes and determinant of therapeutic measures for emergency medical services treated cardiogenic shock

BACKGROUND

The impact of age on outcomes in cardiogenic shock (CS) is poorly described in the pre-hospital setting. We assessed the impact of age on outcomes of patients treated by emergency medical services (EMS).

METHODS

This population-based cohort study included consecutive adult patients with CS transported to hospital by EMS. Successfully linked patients were stratified into tertiles by age (18-63, 64-77, and > 77 years). Predictors of 30-day mortality were assessed through regression analyses. The primary outcome was 30-day all-cause mortality.

RESULTS

A total of 3523 patients with CS were successfully linked to state health records. The average age was 68 ± 16 years and 1398 (40%) were female. Older patients were more likely to have comorbidities including pre-existing coronary artery disease, hypertension, dyslipidemia, diabetes mellitus, and cerebrovascular disease. The incidence of CS was significantly greater with increasing age (incidence rate per 100,000 person years 6.47 [95% CI: 6.1-6.8] in age 18-63 years, 34.34 [32.4-36.4] in age 64-77 years, 74.87 [70.6-79.3] in age > 77 years, P < 0.001). There was a step-wise increase in the rate of 30-day mortality with increasing age tertile. After adjustment, compared to the lowest age tertile, patients aged > 77 years had increased risk of 30-day mortality (adjusted hazard ratio = 2.26 [95% CI: 1.96-2.60]). Older patients were less likely to receive inpatient coronary angiography.

CONCLUSION

Older patients with EMS-treated CS have significantly higher rates of short-term mortality. The reduced rates of invasive interventions in older patients underscore the need for further development of systems of care to improve outcomes for this patient group.

LidocAine Versus Opioids In MyocarDial infarction: the AVOID-2 randomized controlled trial

AIMS

Opioid analgesia has been shown to interfere with the bioavailability of oral P2Y12 inhibitors prompting the search for safe and effective non-opioid analgesics to treat ischaemic chest pain.

METHODS AND RESULTS

The lidocAine Versus Opioids In MyocarDial infarction trial was a prospective, Phase II, prehospital, open-label, non-inferiority, randomized controlled trial enrolling patients with suspected STEACS with moderate to severe pain [numerical rating scale (NRS) at least 5/10]. Intravenous lidocaine (maximum dose 300 mg) or intravenous fentanyl (up to 50 µg every 5 min) were administered as prehospital analgesia. The co-primary end points were prehospital pain reduction and adverse events requiring intervention. Secondary end points included peak cardiac troponin I, cardiac MRI (cMRI) assessed myocardial infarct size and clinical outcomes to 30 days. A total of 308 patients were enrolled. The median reduction in pain score (NRS) was 4 vs. 3 in the fentanyl and lidocaine arms, respectively, for the primary efficacy end point [estimated median difference -1 (95% confidence interval -1.58, -0.42, P = 0.5 for non-inferiority, P = 0.001 for inferiority of lidocaine)]. Adverse events requiring intervention occurred in 49% vs. 36% of the fentanyl and lidocaine arms which met non-inferiority and superiority favouring lidocaine (P = 0.016 for superiority). No significant differences in myocardial infarct size and clinical outcomes at 30 days were seen.

CONCLUSION

IV Lidocaine did not meet the criteria for non-inferiority with lower prehospital pain reduction than fentanyl but was safe and better tolerated as analgesia in ST-elevation myocardial infarction (STEMI). Future trials testing non-opioid analgesics in STEMI and whether opioid avoidance improves clinical outcomes are needed.

TRIAL REGISTRATION

CTRN12619001521112p.

Temperature-related chest pain presentations and future projections with climate change

BACKGROUND

Climate change has led to increased interest in studying adverse health effects relating to ambient temperatures. It is unclear whether incident chest pain is associated with non-optimal temperatures and how chest pain presentation rates might be affected by climate change.

METHODS

The study included ambulance data of chest pain presentations in Melbourne, Australia from 1/1/2015 to 30/6/2019 with linkage to hospital and emergency discharge diagnosis data. A time series quasi-Poisson regression with a distributed lag nonlinear model was fitted to assess the temperature-chest pain presentation associations overall and according to age, sex, socioeconomic status, and event location subgroups, with adjustment for season, day of the week and long-term trend. Future excess chest pain presentations associated with cold and heat were projected under six general circulation models under medium and high emission scenarios.

RESULTS

In 206,789 chest pain presentations, mean (SD) age was 61.2 (18.9) years and 50.3 % were female. Significant heat- and cold-related increased risk of chest pain presentations were observed for mean air temperatures above and below 20.8 °C, respectively. Excess chest pain presentations related to heat were observed in all subgroups, but appeared to be attenuated for older patients (≥70 years), patients of higher socioeconomic status (SES), and patients developing chest pain at home. We projected increases in heat-related chest pain presentations with climate change under both medium- and high-emission scenarios, which are offset by decreases in chest pain presentations related to cold temperatures.

CONCLUSIONS

Heat- and cold- exposure appear to increase the risk of chest pain presentations, especially among younger patients and patients of lower SES. This will have important implications with climate change modelling of chest pain, in particular highlighting the importance of risk mitigation strategies to minimise adverse health impacts on hotter days.

Temperature-related chest pain presentations and future projections with climate change

Background

Climate change has led to increased interest in studying adverse health effects relating to ambient temperatures. It is unclear whether incident chest pain is associated with non-optimal temperatures and how chest pain presentation rates might be affected by climate change.

Methods

The study included ambulance data of chest pain presentations in Melbourne, Australia from 1/1/2015 to 30/6/2019 with linkage to hospital and emergency discharge diagnosis data. A time series quasi-Poisson regression with a distributed lag nonlinear model was fitted to assess the temperature-chest pain presentation associations, after adjusting for season, day of the week and long-term trend. Future excess chest pain presentations associated with cold and heat were projected under six general circulation models under medium and high emission scenarios.

Results

In 206,789 chest pain presentations, mean (SD) age was 61.2 (18.9) years and 50.3% were female. Significant heat- and cold-related increased risk of chest pain presentations were observed for mean air temperatures above and below 20.8°C, respectively (Figure 1). Excess chest pain presentations related to heat were observed in all subgroups, but appeared to be attenuated for older patients (≥70 years) and patients of higher socioeconomic status (SES). We projected no significant change in net temperature-related chest pain presentations with climate change under medium- and high-emission scenarios, with increases in heat-related chest pain presentations offset by decreases in chest pain presentations related to cold temperatures.

Conclusions

Heat- and cold-exposure appear to increase risk of chest pain presentations, especially among younger patients and patients of lower SES. In Melbourne, Australia, chest pain presentations overall were not projected to increase with climate change, but increases in heat-related chest pain presentations highlight the importance of risk mitigation strategies to minimise adverse health impacts on hotter days.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Alfred Health.

Impact of ambulance off-load delays on mortality in patients with chest pain

Background

Ambulance off-load delays in transferring patient care to emergency departments (EDs) are increasingly common, but it is unclear whether clinical outcomes are impacted.

Methods

Population-based cohort study of ambulance attendances for non-traumatic chest pain transported to ED in Victoria, Australia (1/1/2015–30/6/2019) excluding patients transported to hospital with “lights and sirens” or triaged as ED category 1. Multivariable models were used to assess the relationship between ambulance off-load times and 30-day mortality and ambulance re-attendance for chest pain.

Results

The study included 213,544 ambulance attendances for chest pain (mean age 62 [SD 18] years; 51% female). Median ambulance off-load times increased across the study period from 21 minutes (interquartile range [IQR] 15–30) in 2015 to 24 minutes (IQR 17–37) in 2019. Patients were divided into tertiles according to off-load times with 69,247 patients included in tertile 1 (0–17 minutes), 73,109 patients in tertile 2 (18–28 minutes), and 71,188 patients in tertile 3 (&gt;28 minutes). In multivariable models, ambulance off-load delays were associated with higher unadjusted and adjusted rates of 30-day mortality (1.57% tertile 3 vs. 1.29% tertile 1, adjusted risk difference 0.28% [95% CI 0.16% - 0.42%], p&lt;0.001) and ambulance re-attendance for chest pain (9.89% tertile 3 vs. 8.59% tertile 1, adjusted risk difference 1.30% [95% CI 1.00% - 1.61%], p&lt;0.001). Similarly, in analysis using off-load times as a continuous variable with restricted cubic splines, a non-linear increase in adjusted odds ratio for mortality was observed (Figure 1).

Conclusions

Delays in ambulance off-load times appear to be associated with increased mortality and ambulance re-attendance risk among chest pain cohorts. This study has important policy implications given the increasing frequency of off-load delays in many healthcare settings.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Alfred health

Variation in health-care quality and outcomes according to time of chest pain presentation: a state-wide prospective cohort study

Background

Previous studies examining temporal variation in cardiovascular care have largely been limited to assessing weekend and after-hours effects whereby those presenting on the weekend or after-hours have a poorer outcome. However, emerging evidence suggests more complex patterns in patterns and outcomes may exist.

Purpose

We aimed to determine patterns of temporal variation in chest pain presentations and subsequent health-care quality and outcomes.

Methods

This was an observational, prospective-cohort study of adult patients aged 18 and over who were attended by emergency medical services for non-traumatic chest pain between 1 January 2015 and 30 June 2019 in Victoria, Australia. Major exclusion criteria included pre-hospital diagnosis of ST elevation myocardial infarction or an out of hospital cardiac arrest. The exposure variable was time of day and day of week stratified into 168 hourly time periods. The primary outcome measure was 30-day mortality.

Results

The study cohort comprised 196,365 ambulance attendances for acute non-traumatic chest pain; mean age 62.4 years (SD 18.3) and 99,497 (50.7%) females. Three temporal patterns were observed for chest pain presentations (Figure 1): (1) a diurnal pattern with a sharp increase in presentations from 8 am, peaking around midday, before decreasing into late evening with a nadir between 3–4 am, (2) a weekend effect where Saturday and Sunday had a relatively lower rate of presentations compared to during the week, and (3) a Monday – Sunday gradient where more presentations were likely earlier in the week, than later. Six patterns were identified across pre-hospital and hospital key performance indicators (KPI) (diurnal, in/after-hours, weekend effect, Monday – Sunday gradient, a peak period and morning vs afternoon/evening effect. Risk of 30-day mortality was associated with weekend presentation (OR 1.15, 95% CI 1.06–1.24, p=0.001) and morning presentation between midnight and midday (OR 1.17, 95% CI 1.09–1.25, p&lt;0.001) (Figure 2).

Conclusion

Chest pain presentations, care quality and outcomes demonstrate complex temporal variation beyond the already established weekend and after-hours effect. Such relationships should be considered during resource allocation and quality improvement programs in order to improve treatment quality across all days and times of the week.

Funding Acknowledgement

Type of funding sources: None.

The influence of ambulance offload time on 30-day risks of death and re-presentation for patients with chest pain

OBJECTIVE

To assess whether ambulance offload time influences the risks of death or ambulance re-attendance within 30 days of initial emergency department (ED) presentations by adults with non-traumatic chest pain.

DESIGN, SETTING

Population-based observational cohort study of consecutive presentations by adults with non-traumatic chest pain transported by ambulance to Victorian EDs, 1 January 2015 - 30 June 2019.

PARTICIPANTS

Adults (18 years or older) with non-traumatic chest pain, excluding patients with ST elevation myocardial infarction (pre-hospital electrocardiography) and those who were transferred between hospitals or not transported to hospital (eg, cardiac arrest or death prior to transport).

MAIN OUTCOME MEASURES

Primary outcome: 30-day all-cause mortality (Victorian Death Index data).

SECONDARY OUTCOME

Transport by ambulance with chest pain to ED within 30 days of initial ED presentation.

RESULTS

We included 213 544 people with chest pain transported by ambulance to EDs (mean age, 62 [SD, 18] years; 109 027 women [51%]). The median offload time increased from 21 (IQR, 15-30) minutes in 2015 to 24 (IQR, 17-37) minutes during the first half of 2019. Three offload time tertiles were defined to include approximately equal patient numbers: tertile 1 (0-17 minutes), tertile 2 (18-28 minutes), and tertile 3 (more than 28 minutes). In multivariable models, 30-day risk of death was greater for patients in tertile 3 than those in tertile 1 (adjusted rates, 1.57% v 1.29%; adjusted risk difference, 0.28 [95% CI, 0.16-0.42] percentage points), as was that of a second ambulance attendance with chest pain (adjusted rates, 9.03% v 8.15%; adjusted risk difference, 0.87 [95% CI, 0.57-1.18] percentage points).

CONCLUSIONS

Longer ambulance offload times are associated with greater 30-day risks of death and ambulance re-attendance for people presenting to EDs with chest pain. Improving the speed of ambulance-to-ED transfers is urgently required.

HOSPITAL CHARACTERISTICS ARE ASSOCIATED WITH CLINICAL OUTCOMES IN PATIENTS WITH CARDIOGENIC SHOCK

ABSTRACT

Background: Regionalized systems of care for the management of cardiogenic shock (CS) are increasingly being utilized. This study aims to assess whether receiving hospital characteristics such as the availability of 24-hour coronary angiography, on-site cardiac surgery, and annual treated CS volume influence outcomes in patients transferred by emergency medical services (EMS) to hospital with CS. Methods: This population-based cohort study included consecutive adult patients with CS who were transferred to hospital by EMS between January 1, 2015 and June 30, 2019 in Victoria, Australia. Data were obtained from individually linked ambulance, hospital, and state death index data sets. The primary outcome assessed was 30-day mortality stratified by the availability of 24-hour coronary angiography (cardiac center) at the receiving hospital. Results: A total of 3,217 patients were transferred to hospital with CS. The population had an average age of 67.9 +/- 16.1 years, and 1,289 (40.1%) were female. EMS transfer to a cardiac center was associated with significantly reduced rates of 30-day mortality (adjusted odds ratio [aOR], 0.78; 95% confidence interval [CI], 0.64-0.95), compared with noncardiac centers. Compared with the lowest annual CS volume quartile (<18 cases per year), hospitals in the highest volume quartile (>55 cases per year) had reduced risk of 30-day mortality (aOR, 0.71; 95% CI, 0.56-0.91). A stepwise reduction in the adjusted probability of 30-day mortality was observed in patients transferred by EMS to trauma level 1 centers (34.6%), compared with cardiothoracic surgical centers (39.0%), noncardiac surgical metropolitan (44.9%), and rural (51.3%) cardiac centers, all P < 0.05. Conclusion: Receiving hospital characteristics are associated with survival outcomes in patients with CS. These finding have important implications for establishing regionalized systems of care for patients with CS who are transferred to hospital by EMS.

Gender Disparities in Cardiogenic Shock Treatment and Outcomes

Cardiogenic shock is associated with a high risk for morbidity and mortality. The impact of gender on treatment and outcomes is poorly defined. This study aimed to evaluate whether gender influences the clinical management and outcomes of patients with prehospital cardiogenic shock. Consecutive adult patients with cardiogenic shock who were transferred to hospital by emergency medical services (EMS) between January 1, 2015 and June 30, 2019 in Victoria, Australia were included. Data were obtained from individually linked ambulance, hospital, and state death index datasets. The primary outcome assessed was 30-day mortality, stratified by patient gender. Propensity score matching was performed for risk adjustment. Over the study period a total of 3,465 patients were identified and 1,389 patients (40.1%) were women. Propensity score matching yielded 1,330 matched pairs with no differences observed in baseline characteristics, including age, initial vital signs, pre-existing co-morbidities, etiology of shock, and prehospital interventions. In the matched cohort, women had higher rates of 30-day mortality (44.7% vs 39.2%, p = 0.009), underwent less coronary angiography (18.3% vs 27.2%, p <0.001), and revascularization with percutaneous coronary intervention (8.9% vs 14.2%, p <0.001), compared with men. In conclusion, in this large population-based study, women with cardiogenic shock who were transferred by EMS to hospital had significantly worse survival outcomes and reduced rates of invasive cardiac interventions compared to men. These data underscore the urgent need for targeted public health measures to redress gender differences in outcomes and variation with clinical care for patients with cardiogenic shock.

Determining the sensitivity of emergency dispatcher and paramedic diagnosis of stroke: statewide registry linkage study

Introduction

Correctly identifying people with suspected stroke is essential for ensuring rapid treatment. Our aims were to determine the sensitivity of emergency dispatcher and paramedic identification of patients with stroke, the factors associated with correct identification, and whether there were any implications for hospital arrival times.

Methods

Observational study using patient‐level data from the Australian Stroke Clinical Registry (2015–2017) linked with ambulance and emergency department records for the state of Victoria. The registry diagnosis was the reference standard to compare with the provisional diagnoses made by emergency services personnel classified as “suspected” and “not suspected” stroke/transient ischemic attack (TIA). Multivariable logistic and quintile regressions were used to determine factors associated with correct identification and timely arrival to hospital.

Results

Overall, 4717 (64%) were matched to ambulance transport records (median age: 73 years, 43% female). Stroke/TIA was suspected in 56% of registrants by call‐takers and 69% by paramedics. Older patients (75+ years) (adjusted odds ratio [aOR]: 0.61; 95% confidence interval [CI]: 0.49–0.75), females (aOR: 0.86; 95% CI: 0.75–0.99), those with severe stroke or intracerebral hemorrhage were less often suspected as stroke. Cases identified as stroke had a shorter arrival time to hospital (unadjusted median minutes: stroke, 54 [43, 72] vs not stroke, 66 [51, 89]).

Conclusions

Emergency dispatchers and paramedics identified over half of patients with stroke in the prehospital setting. Important patient characteristics, such as being female and those having a severe stroke, were found that may enable refinement of prehospital ambulance protocols and dispatcher/paramedic education. Those correctly identified as stroke, arrived earlier to hospital optimizing their chances of receiving time‐critical treatments.

Development and validation of a comprehensive early risk prediction model for patients with undifferentiated acute chest pain

Aims

Existing risk scores for undifferentiated chest pain focus on excluding coronary events and do not represent a comprehensive risk assessment if an alternate serious diagnosis is present. This study aimed to develop and validate an all-inclusive risk prediction model among patients with undifferentiated chest pain.

Methods

We developed and validated a multivariable logistic regression model for a composite measure of early all-inclusive risk (defined as hospital admission excluding a discharge diagnosis of non-specific pain, 30-day all-cause mortality, or 30-day myocardial infarction [MI]) among adults assessed by emergency medical services (EMS) for non-traumatic chest pain using a large population-based cohort (January 2015 to June 2019). The cohort was randomly divided into development (146,507 patients [70%]) and validation (62,788 patients [30%]) cohorts.

Results

The composite outcome occurred in 28.4%, comprising hospital admission in 27.7%, mortality within 30-days in 1.8%, and MI within 30-days in 0.4%. The Early Chest pain Admission, MI, and Mortality (ECAMM) risk model was developed, demonstrating good discrimination in the development (C-statistic 0.775, 95% CI 0.772-0.777) and validation cohorts (C-statistic 0.765, 95% CI 0.761-0.769) with excellent calibration. Discriminatory performance for the composite outcome and individual components was higher than existing scores commonly used in undifferentiated chest pain risk stratification.

Conclusions

The ECAMM risk score model can be used as an all-inclusive risk stratification assessment of patients with non-traumatic chest pain without the limitation of a single diagnostic outcome. This model could be clinically useful to help guide decisions surrounding the need for non-coronary investigations and safety of early discharge.

Incidence, diagnoses and outcomes of ambulance attendances for chest pain: A population-based cohort study

AIMS

Non-traumatic chest pain is one of the most common reasons for calls for emergency assistance and places a significant burden on health services. This study aimed to determine age- and sex-specific incidences, diagnoses, and outcomes of patients with chest pain attended by paramedics using a large population-based sample.

METHODS

Consecutive emergency medical services (EMS) attendances for non-traumatic chest pain in Victoria, Australia from January 2015 to June 2019 were included. Data were individually linked to emergency, hospital admission and mortality records.

RESULTS

During the study period (representing 22,186,930 person-years), chest pain was the reason for contacting EMS in 257,017 of 2,736,570 attendances (9.4%). Overall incidence of chest pain attendances was 1,158 (per 100,000 person-years) with a higher incidence observed with increasing age, among females, among Aboriginal and Torres Strait Islanders, in regional settings, and in socially disadvantaged areas. The most common diagnoses were non-specific pain (46%; 30-day mortality 0.5%), non-ST elevation myocardial infarction (5.3%; mortality 1.3%), pneumonia (3.8%; mortality 3.9%), stable coronary syndromes (3.5%; mortality 0.8%), unstable angina (3.3%; mortality 1.3%), and ST-elevation myocardial infarction (2.8%; mortality 7.0%), while pulmonary embolism (0.7%; mortality 3.2%) and aortic pathologies (0.2%; mortality 22.2%) were rare.

CONCLUSIONS

Chest pain accounts for one in ten ambulance calls, and underlying causes are diverse, with substantial differences according to age and sex. Almost half of patients are discharged from hospital with a diagnosis of non-specific pain and low rates of mortality.

Association of Socioeconomic Status With Outcomes and Care Quality in Patients Presenting With Undifferentiated Chest Pain in the Setting of Universal Health Care Coverage

BACKGROUND

This study aimed to assess whether there are disparities in incidence rates, care, and outcomes for patients with chest pain attended by emergency medical services according to socioeconomic status (SES) in a universal health coverage setting.

METHODS AND RESULTS

This was a population‐based cohort study of individually linked ambulance, emergency, hospital admission, and mortality data in the state of Victoria, Australia, from January 2015 to June 2019 that included 183 232 consecutive emergency medical services attendances for adults with nontraumatic chest pain (mean age 62 [SD 18] years; 51% women) and excluded out‐of‐hospital cardiac arrest and ST‐segment–elevation myocardial infarction. Age‐standardized incidence of chest pain was higher for patients residing in lower SES areas (lowest SES quintile 1595 versus highest SES quintile 760 per 100 000 person‐years; P<0.001). Patients of lower SES were less likely to attend metropolitan, private, or revascularization‐capable hospitals and had greater comorbidities. In multivariable models adjusted for clinical characteristics and final diagnosis, lower SES quintiles were associated with increased risks of 30‐day and long‐term mortality, readmission for chest pain and acute coronary syndrome, lower acuity emergency department triage categorization, emergency department length of stay >4 hours, and emergency department or emergency medical services discharge without hospital admission and were inversely associated with use of prehospital ECGs and transfer to a revascularization‐capable hospital for patients presenting to non‐percutaneous coronary intervention centers.

CONCLUSIONS

In this study, lower SES was associated with a higher incidence of chest pain presentations to emergency medical services and differences in care and outcomes. These findings suggest that substantial disparities for socioeconomically disadvantaged chest pain cohorts exist, even in the setting of universal health care access.

Incidence and Outcomes of Nontraumatic Shock in Adults Using Emergency Medical Services in Victoria, Australia

IMPORTANCE

Nontraumatic shock is a challenging clinical condition, presenting urgent and unique demands in the prehospital setting. There is a paucity of data assessing its incidence, etiology, and clinical outcomes.

OBJECTIVE

To assess the incidence, etiology, and clinical outcomes of patients treated by emergency medical services (EMS) with nontraumatic shock using a large population-based sample.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study included consecutive adult patients with shock not related to trauma who received care by EMS between January 1, 2015, and June 30, 2019, in Victoria, Australia. Data were obtained from individually linked ambulance, hospital, and state death index data sets. During the study period there were 2 485 311 cases attended by EMS, of which 16 827 met the study's inclusion criteria for shock.

MAIN OUTCOMES AND MEASURES

The primary outcome was 30-day mortality. Secondary outcomes included length of hospital stay, emergency department discharge disposition, rates of coronary angiography and revascularization procedures, and the use of mechanical circulatory support.

RESULTS

A total of 12 695 patients were successfully linked, with a mean (SD) age of 65.7 (19.1) years; 6411 (50.5%) were men. The overall population-wide incidence of EMS-treated prehospital shock was 76 (95% CI, 75-77) per 100 000 person-years. An increased incidence was observed in men (79 [77-81] per 100 000 person-years), older patients (eg, aged 70-79 years: 177 [171-183] per 100 000 person-years), regional locations (outer regional or remote: 100 [94-107] per 100 000 person-years), and in areas with increased socioeconomic disadvantage (lowest socioeconomic status quintile: 92 [89-95] per 100 000 person-years). Patients with hospital outcome data were stratified into shock etiologies; 3615 (28.5%) had cardiogenic shock: 3998 (31.5%), septic shock; 1457 (11.5%), hypovolemic shock; and 3625 (28.6%), other causes of shock. Nearly one-third of patients (4158 [32.8%]) were deceased at 30 days. In multivariable analyses, increased age (all etiologies: hazard ratio [HR], 1.04; 95% CI, 1.03-1.04), female sex (cardiogenic shock: HR, 1.26; 95% CI, 1.12-1.42), increased initial heart rate (all etiologies: 1.01; 95% CI, 1.00-1.01), prehospital intubation (all etiologies: HR, 3.93; 95% CI, 3.48-4.44), and preexisting comorbidities (eg, chronic kidney disease, all etiologies: HR, 1.25; 95% CI, 1.10-1.42) were independently associated with 30-day mortality, while higher socioeconomic status (all etiologies: HR, 0.96; 95% CI, 0.94-0.98) and increased initial systolic blood pressure (all etiologies: HR, 0.99; 95% CI, 0.99-0.99) were associated with lower risk.

CONCLUSIONS AND RELEVANCE

This population-level cohort study found that EMS-treated nontraumatic shock was a common condition, with a high risk of morbidity and mortality regardless of etiology. It disproportionately affected men, older patients, patients in regional areas, and those with social disadvantage. Further studies are required to assess how current systems of care can be optimized to improve outcomes.

Linking Ambulance Records with Hospital and Death Index Data to Evaluate Patient Outcomes

Objective

Linkage of electronic administrative datasets is becoming increasingly common, offering a powerful resource for research and analysis. However, routine linkage of prehospital data with emergency department (ED) presentation and hospital admission datasets is rare. We describe a methodology used to link ambulance data with hospital ED presentations, admissions, and death records, and examine potential biases between matched and unmatched patients.

Methods

Iterative deterministic linkage methodologies were employed to link clinical, operational, and secondary triage ambulance data to ED presentations, hospital admissions, and death records in Victoria, Australia. Descriptive analyses and standardised differences were used to examine potential biases between matched and unmatched patients.

Results

A total of 2,813,913 ambulance records were available for linkage. Of the patients that were transported to a public ED (n=1,753,268), 83.3% matched with an ED record. Only small differences were observed between matched and unmatched patients for sex, year, time of day and attending crew type. The data elements with the largest standardised differences were patient age (0.25) and paramedic diagnosis (0.25). Matched patients were older (mean ± standard deviation: 55.6±25.7 vs 49.0±26.0 years) and more likely to have a paramedic-suspected cardiac, respiratory, neurological, or gastrointestinal/genitourinary condition, suspected infection/sepsis, or pain.

Conclusion

This linked dataset will facilitate a large body of research into prehospital care and patient outcomes. Although future analysis of matched patients should acknowledge the linkage error rate, our findings suggest that results are likely to be generalisable to the broader ambulance population.

Linking Data From the Australian Stroke Clinical Registry With Ambulance and Emergency Administrative Data in Victoria

Objective: In Australia, approximately 3 in 4 people with acute stroke use an ambulance. Few examples of merging ambulance clinical records, hospital government data, and national registry data for stroke exist. We sought to understand the advantages of using linked datasets for describing the full clinical journey of people with stroke and the possibility of investigating their long-term outcomes based on pre-hospital management of stroke. Method: Patient-level data from the Australian Stroke Clinical Registry (AuSCR) (January 2013-October 2017) were linked with Ambulance Victoria (AV) records and Victorian Emergency Minimum Dataset (VEMD). Probabilistic iterative matching on personal identifiers were used and records merged with a project specific identification number. Results: Of the 7,373 episodes in the AuSCR and 6,001 in the AV dataset; 4,569 (62%) were matched. Unmatched records that were positive for “arrival by ambulance” in the AuSCR and VEMD (no corresponding record in AV) were submitted to AV. AV were able to identify 148/435 additional records related to these episodes. The final cohort included 4,717 records (median age: 73 years, female 42%, ischemic stroke 66%). Conclusion: The results of the data linkage provides greater confidence for use of these data for future research related to pre-hospital management of stroke.

Predictors of hospital prenotification for STEMI and association of prenotification with outcomes

BACKGROUND

Delay to reperfusion in ST-elevation myocardial infarction (STEMI) is detrimental, but can be minimised with prehospital notification by ambulance to the treating hospital. We aimed to assess whether prenotification was associated with improved first medical contact to balloon times (FMC-BT) and whether this resulted in better clinical outcomes. We also aimed to identify factors associated with use of prenotification.

METHODS

This was a retrospective study of prospective Victorian Cardiac Outcomes Registry data for patients undergoing primary percutaneous coronary intervention for STEMI from 2013-2018. Postcardiac arrest were excluded. Patients were grouped by whether they arrived by ambulance with prenotification (group 1), arrived by ambulance without prenotification (group 2) or self-presented (group 3). We compared groups by FMC-BT, incidence of major adverse cardiac and cerebrovascular events (MACCE), mortality and factors associated with the use of prenotification.

RESULTS

2891 patients were in group 1 (79.3% male), 1620 in group 2 (75.7% male) and 1220 in group 3 (82.9% male). Patients who had prenotification were more likely to present in-hours (p=0.004) and self-presenters had lowest rates of cardiogenic shock (p<0.001). Prenotification had shorter FMC-BT than without prenotification (104 min vs 132 min, p<0.001) Self-presenters had superior clinical outcomes, with no difference between ambulance groups. Groups 1 and 2 had similar 30-day MACCE outcomes (7.4% group 1 vs 9.1% group 2, p=0.05) and similar mortality (4.6% group 1 vs 5.9% group 2, p=0.07). In multivariable analysis, male gender, right coronary artery culprit and in-hours presentation independently predicted use of prenotification (all p<0.05).

CONCLUSION

Differences in clinical characteristics, particularly gender, time of presentation and culprit vessel may influence ambulance prenotification. Ambulance cohorts have high-risk features and worse outcomes compared with self-presenters. Improving system inequality in prehospital STEMI diagnosis is recommended for fastest STEMI treatment.

Sex differences in pre-hospital analgesia and outcomes in patients presenting with acute coronary syndromes

Background

Opioid analgesia remains the mainstay of pain management in acute coronary syndromes (ACS). Significant sex differences persist in ACS presentation, management and outcomes, but the impact of sex-differences on pre-hospital pain management of ACS with opioids is unknown. There is increasing awareness of the importance of pre-hospital factors in ACS, as well as emerging concerns with opioid use impairing the gastrointestinal absorption of oral P2Y12 inhibitors.

Purpose

This study examined if sex-differences in pre-hospital pain scores, opioid administration and clinical outcomes exist in ACS patients.

Methods

Patients presenting with ACS via ambulance (2014–2018) that underwent percutaneous coronary intervention (PCI) were prospectively collected via the Victorian Cardiac Outcomes Registry (VCOR), the Melbourne Interventional Group (MIG), and linked to the Ambulance Victoria database. The primary outcome was 30-day major adverse cardiac events (MACE). Secondary outcomes were descriptive analyses of pre-hospital pain score, intravenous morphine equivalent analgesic dosing, plus predictors of MACE and Thrombolysis In Myocardial Infarction (TIMI) 0–1 flow pre-PCI using logistic regression.

Results

10,547 patients were included (female: 2,775 [26.3%]). Opioids were administered to 1,585 (57%) females and 5,068 (65%) males (p&lt;0.001). Adjusted 30-day MACE was similar between opioid groups in both sexes (female: OR 1.21, CI 0.82–1.79, p=0.34; male: OR 0.89, 0.68–1.16, p=0.40). Median pain score at presentation was 6 (IQR 4,8) for both sexes. Median opioid dose was 2.5 mg (IQR 0,10) in females and 5 mg (IQR 0,10) in males (p&lt;0.001), with similar pain relief achieved. Adjusted rates of TIMI 0–1 pre-PCI were higher in patients administered opioids (female: OR 2.83, CI 2.14–3.56, p&lt;0.001; male: OR 2.95, CI 2.49–3.49, p&lt;0.001).

Conclusions

Female patients undergoing PCI received less opioid analgesia, but no sex-differences in pre-hospital pain scores were seen. Opioid administration was associated with impaired antegrade flow in the culprit artery in both sexes, but not short-term MACE. Randomised trials evaluating the clinical implications of opioid administration in ACS with sex subgroup analyses are needed to guide clinical practice.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Melbourne Interventional GroupVictorian Cardiac Outcomes Registry

Daylight savings time transitions and risk of out-of-hospital cardiac arrest: An interrupted time series analysis

BACKGROUND

Many studies have reported increases in the risk of acute cardiovascular events following daylight savings time (DST) transitions. We sought to investigate the effect of DST transition on the incidence of out-of-hospital cardiac arrest (OHCA).

METHODS

Between January 2000 and December 2020, we performed an interrupted time series analysis of the daily number of OHCA cases of medical aetiology from the Victorian Ambulance Cardiac Arrest Registry. The effect of DST transition on OHCA incidence was estimated using negative binomial models, adjusted for temporal trends, population growth, and public holidays.

RESULTS

A total of 89,409 adult OHCA of medical aetiology were included. Following the spring DST transition (i.e. shorter day), there was an immediate 13% (IRR 1.13, 95% CI: 1.02, 1.25; p = 0.02) increased risk of OHCA on the day of transition (Sunday) and the cumulative risk of OHCA remained higher over the first 2 days (IRR 1.17, 95% CI: 1.02, 1.34; p = 0.03) compared to non-transitional days. Following the autumn DST transition (i.e. longer day), there was a significant lagged effect on the Tuesday with a 12% (IRR 0.88, 95% CI: 0.77, 0.99; p = 0.04) reduced risk of OHCA. The cumulative effect following the autumn DST transition was also significant, with a 30% (IRR 0.70, 95% CI: 0.51, 0.96; p = 0.03) reduction in the incidence of OHCA by the end of the transitional week.

CONCLUSION

We observed both harmful and protective effects from DST transitions on the risk of OHCA. Strategies to reduce this risk in vulnerable populations should be considered.

The Impact of the COVID-19 Pandemic on Demand for Emergency Ambulances in Victoria, Australia

Objective: Relatively little has been reported about the impact of COVID-19 restrictions on emergency ambulance services. We describe the influence of the COVID-19 pandemic on the emergency ambulance system in Victoria, Australia.Methods: We performed an interrupted time series analysis of consecutive calls for ambulance from January 2018 to February 2021, including two waves of COVID-19. The COVID-19 lockdown period included seven months of stay-at-home restrictions (16/03/2020-18/10/2020). Nineteen weeks of post-lockdown data were included (19/10/2020-28/02/2021).Results: In total, 2,356,326 consecutive calls were included. COVID-19 lockdown was associated with an absolute reduction of 64,991 calls (almost 2,100 calls/week). According to time series analysis, lockdown was associated with a 12.6% reduction in weekly calls (IRR = 0.874 [95% CI 0.811, 0.941]), however no change in long-term trend (IRR = 1.000 [95% CI 0.996, 1.003]). During lockdown, the long-term trend of attendances to patients with suspected acute coronary syndromes (ACS, IRR = 1.006 [95% CI 1.004, 1.009]) and mental health-related issues (IRR = 1.005 [95% CI 1.002, 1.008]) increased. After lockdown, the call volume was 5.6% below pre-COVID-19 predictions (IRR = 0.944 [95% CI 0.909, 0.980]), however attendances for suspected ACS were higher than predicted (IRR = 1.069 [95% CI 1.009, 1.132]). Ambulance response times deteriorated, and total case times were longer than prior to the pandemic, driven predominantly by extended hospital transfer times.Conclusion: The COVID-19 pandemic had a dramatic impact on the emergency ambulance system. Despite lower call volumes post-lockdown than predicted, we observed deteriorating ambulance response times, extended case times and hospital delays. The pattern of attendance to patients with suspected ACS potentially highlights the collateral burden of delaying treatment for urgent conditions.

Impact of limited English proficiency on presentation and clinical outcomes of patients undergoing primary percutaneous coronary intervention

AIMS

To evaluate the association of limited English proficiency (LEP) with reperfusion times and outcomes in patients undergoing primary percutaneous coronary intervention (PPCI) for ST-elevation myocardial infarction (STEMI).

METHODS AND RESULTS

This cohort study included 5385 patients who underwent PPCI in 2013-2017 and were prospectively enrolled in the Victorian Cardiac Outcomes Registry. Data linkage to government administrative datasets was performed to identify patients' preferred spoken language, socioeconomic status, and ambulance utilization data. Patients who had a preferred spoken language other than English were defined as having LEP. Of the study cohort, 430 patients (8.0%) had LEP. They had longer mean symptom-to-door time (STDT) [164 (95% confidence interval, CI 149-181) vs. 136 (95% CI 132-140) min, P < 0.001] but similar mean door-to-balloon time [79 (95% CI 72-87) vs. 76 (95% CI 74-78) min, P = 0.41]. They also had higher major adverse cardiovascular and cerebrovascular events (MACCE; 13.5% vs. 9.9%; P = 0.02), severe left ventricular dysfunction (11.0% vs. 8.4%, P = 0.02), and heart failure (HF) hospitalizations within 30 days of PPCI (5.1% vs. 2.0%, P < 0.001). On multivariable analysis, LEP did not independently predict 30-day MACCE [odds ratio (OR) 1.16, 95% CI 0.79-1.69; P = 0.45] but was an independent predictor of both prolonged STDT ≥ 120 min (OR 1.25, 95% CI 1.02-1.52; P = 0.03) and 30-day HF hospitalizations (OR 2.01, 95% CI 1.21-3.36; P = 0.008).

CONCLUSION

Patients with LEP undergoing PPCI present later and are more likely to have HF readmissions within 30 days of percutaneous coronary intervention, but with similar short-term MACCE. More effort to provide education in varied languages on early presentation in STEMI is required.

Pre-hospital heparin use for ST-elevation myocardial infarction is safe and improves angiographic outcomes

AIMS

This study aims to evaluate if pre-hospital heparin administration by paramedics is safe and improves clinical outcomes.

METHODS AND RESULTS

Using the multicentre Victorian Cardiac Outcomes Registry, linked with state-wide ambulance records, we identified consecutive patients undergoing primary percutaneous coronary intervention for STEMI between January 2014 and December 2018. Information on thrombolysis in myocardial infarction (TIMI) flow at angiography was available in a subset of cases. Patients receiving pre-hospital heparin were compared to those who did not receive heparin. Findings at coronary angiography and 30-day clinical outcomes were compared between groups. Propensity-score matching was performed for risk adjustment. We identified a total of 4720 patients. Of these, 1967 patients had TIMI flow data available. Propensity-score matching in the entire cohort yielded 1373 matched pairs. In the matched cohort, there was no observed difference in 30-day mortality (no-heparin 3.5% vs. heparin 3.0%, P = 0.25), MACCE (no-heparin 7% vs. heparin 6.2%, P = 0.44), and major bleeding (no-heparin 1.9% vs. heparin 1.4%, P = 0.64) between groups. Propensity-score analysis amongst those with TIMI data produced 552 matched pairs. The proportion of cases with TIMI 0 or 1 flow in the infarct-related artery (IRA) was lower among those receiving pre-hospital heparin (66% vs. 76%, P < 0.001) compared to those who did not.

CONCLUSION 

In this multicentre, propensity-score matched study, the use of pre-hospital heparin by paramedics was safe and is associated with fewer occluded IRAs in patients presenting with STEMI.

Sex Differences in Prehospital Delays in Patients With ST-Segment-Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention

Background

Women with ST‐segment–elevation myocardial infarction experience delays in reperfusion compared with men with little data on each time component from symptom onset to reperfusion. This study analyzed sex discrepancies in patient delays, prehospital system delays, and hospital delays.

Methods and Results

Consecutive patients with ST‐segment–elevation myocardial infarction treated with percutaneous coronary intervention across 30 hospitals in the Victorian Cardiac Outcomes Registry (2013–2018) were analyzed. Data from the Ambulance Victoria Data warehouse were used to perform linkage to the Victorian Cardiac Outcomes Registry for all patients transported via emergency medical services (EMS). The primary end point was EMS call‐to‐door time (prehospital system delay). Secondary end points included symptom‐to‐EMS call time (patient delay), door‐to‐device time (hospital delay), 30‐day mortality, major adverse cardiovascular events, and major bleeding. End points were analyzed according to sex and adjusted for age, comorbidities, cardiogenic shock, cardiac arrest, and symptom onset time. A total of 6330 (21% women) patients with ST‐segment–elevation myocardial infarction were transported by EMS. Compared with men, women had longer adjusted geometric mean symptom‐to‐EMS call times (47.0 versus 44.0 minutes; P<0.001), EMS call‐to‐door times (58.1 versus 55.7 minutes; P<0.001), and door‐to‐device times (58.5 versus 54.9 minutes; P=0.006). Compared with men, women had higher 30‐day mortality (odds ratio [OR], 1.38; 95% CI, 1.06–1.79; P=0.02) and major bleeding (OR, 1.54; 95% CI, 1.08–2.20; P=0.02).

Conclusions

Female patients with ST‐segment–elevation myocardial infarction experienced excess delays in patient delays, prehospital system delays, and hospital delays, even after adjustment for confounders. Prehospital system and hospital delays resulted in an adjusted excess delay of 10 minutes compared with men.

Endotracheal Tube Intracuff Pressure Changes in Patients Transported by a Helicopter Emergency Medical Service: A Prospective Observational Study

OBJECTIVE

The pressure within an endotracheal tube cuff is of particular importance in helicopter emergency medical services (HEMS) transport because the unpressurized cabin is subjected to decreases in atmospheric pressure. This can cause the cuff to overinflate and may be associated with clinical complications. We sought to evaluate endotracheal tube cuff pressure changes among intubated patients during HEMS transport.

METHODS

A prospective observational study was performed including adult patients who were intubated and transported by helicopter between April 2017 and October 2018. Cuff pressures were measured before, during, and after HEMS transport with a commercial manometer.

RESULTS

A total of 208 patients were included. The median maximum flight altitude was 3,000 (interquartile range [IQR], 2,000-5,000) ft. The median initial cuff pressure before takeoff was 35 (IQR, 24-50) cm H₂O, which increased to 50 (IQR, 35-70) cm H₂O at maximum altitude. A total of 169 (81.3%) patients had a cuff pressure > 30 cm H₂O at maximum altitude. There was a moderate correlation between altitude and cuff pressure (r = 0.532, P < .001).

CONCLUSIONS

Cuff pressure increased during HEMS transport, demonstrating the need for routine cuff pressure monitoring during flight. Further research is required to determine if exposure to transient increases in cuff pressure for short durations is clinically significant.

An open-label, non-inferiority randomized controlled trial of lidocAine Versus Opioids In MyocarDial Infarction study (AVOID-2 study) methods paper

Background There is increasing evidence that opioids interfere with the oral bioavailability of P2Y₁₂ inhibitors leading to delayed onset of antiplatelet effects. Several strategies have been proposed to mitigate this interaction including utilizing alternative analgesic agents in the management of ischemic chest pain. Methods The lidocAine Versus Opioids In MyocarDial Infarction (AVOID-2) study is a phase II, pre-hospital, open-label, non-inferiority, randomized controlled trial conducted by Ambulance Victoria and Monash University in metropolitan Melbourne, Victoria, Australia. The purpose of the study is to compare the analgesic effect (reduction in pain by arrival to hospital) and safety (e.g. adverse drug reactions) (co-primary endpoints) of intravenous lidocaine versus intravenous fentanyl in 300 adult patients attended by ambulance with suspected ST-elevation myocardial infarction (STEMI). Secondary endpoints and a cardiac magnetic resonance imaging (MRI) sub-study will also compare infarct size between these two groups. Conclusions The evaluation of alternative analgesic agents in the management of acute coronary syndromes is urgently needed to manage the opioid-P2Y₁₂ inhibitor interaction. The results of this trial will have significant implications on the emergency management of acute coronary syndromes internationally.

Pre-Hospital Factors Influencing the Provision of Acute Care for Patients with Stroke: Preliminary Findings from A State-Wide Data Linkage Study

IntroductionImprovement in access to reperfusion therapy and reductions in treatment delays requires coordination of multiple systems and services including a well-organised and streamlined pre-hospital care system. Objectives and ApproachOur objective is to examine pre-hospital and hospital factors that influence long-term outcomes in patients with stroke. We linked and merged patient-level data from the Australian Stroke Clinical Registry (AuSCR) to Ambulance Victoria (AV), hospital administrative datasets (Victorian Admitted Episodes Data; VAED) and emergency department data (Victorian Emergency Minimum Dataset; VEMD) using probabilistic, iterative methods. Logistic regression models were used to determine clinical factors associated with access to evidence-based treatments. Results7,373 episodes in the AuSCR were available for linkage, of which 4,569 (62%) were matched with AV records (58% male, median age 72 years). Of these 4,569 matched records, 4,159 (58% male, median age 73 years) had a record in the VAED or VEMD. Stroke or transient ischaemic attack was suspected for 68% of patients by paramedics based on the AV data. Highest transport priority was used for 64% of patients. Patients suspected of stroke by paramedics were more likely to be treated in stroke unit (unadjusted odds ratio, 1.72; 1.47, 2.01) and more likely to receive thrombolysis if ischaemic stroke (unadjusted odd ratio: 4.64, 3.47, 6.20). Conclusion/ImplicationsLinkage of these administrative data with the AuSCR provide the opportunity to interrogate a range of questions to inform policy and practice of acute stroke care. Future analyses will investigate patient (such as comorbidities), clinical and system factors that influence provision of evidence-based care for patients with stroke and whether these influence outcomes at 6 months after stroke.

Drivers of Increasing Emergency Ambulance Demand

Objectives: Although the factors driving emergency department demand have been extensively investigated, a comparatively minimal amount is known about the factors that are driving an increase in emergency ambulance demand. Methods: We conducted a retrospective observational study of consecutive cases attended by Ambulance Victoria in Melbourne, Australia from 2008 to 2015. Incidence rates were calculated, and adjusted time series regression analyses were performed to assess the driving factors of ambulance demand. Results: A total of 2,443,952 consecutive cases were included. Demand grew by 29.2% over the 8-year period. The age-specific incidence increased significantly over time for patients aged < 60 years, but not for patients aged ≥ 60 years. After adjustment for seasonality and population growth, demand increased by 1.4% per annum (incident rate ratio [IRR] = 1.014 [1.011-1.017]). The largest annual growth in demand was observed in patients with a history of mental health issues (IRR = 1.058 [1.054-1.062]), alcohol/drug abuse (IRR = 1.061 [1.056-1.066]), or a Charlson Comorbidity Index [CCI] score ≥ 4 (IRR = 1.045 [1.039-1.051]). Cases involving patients of relative socio-economic/educational disadvantage, younger age, or with no preexisting health conditions according to the CCI also grew faster than the overall patient population. Cases requiring transport to hospital increased by 1.2% annually (IRR = 1.012 [1.009-1.016]), although patients not requiring medical intervention from paramedics increased by 6.7% annually (IRR = 1.067 [1.063-1.072]). Conclusions: Increases in ambulance demand exceeded population growth. Emergency ambulances were increasingly utilized for transport of patients who did not require medical intervention from paramedics. Identifying the characteristics of patients driving ambulance demand will enable targeted demand management strategies.

Ambulances are for emergencies: shifting behaviour through a research-informed behaviour change campaign

Background

A major review of Victoria’s ambulance services identified the need to improve public awareness of the role of ambulances as an emergency service. A communications campaign was developed to address this challenge. This research paper expands on an initial evaluation of the campaign by focusing on the long-term behavioural outcomes.

Methods

The behavioural evaluation involved two types of data collection – administrative data (routine collection from various health services) and survey data (cross-sectional community-wide surveys to measure behavioural intentions).

Results

Behavioural intentions for accessing two of the targeted non-emergency services increased after the second phase of the campaign commenced. There was also a significant change in the slope of call trends for emergency ambulances. This decrease is also likely attributed to the second phase of the campaign as significant level effects were identified 3 and 9 months after it commenced.

Conclusions

A long-term campaign developed through evidence review, stakeholder consultation and behavioural theory was successful in reducing the number of daily calls requesting an emergency ambulance in Victoria and in increasing intentions to use alternative services. This research highlights the importance of collaborative intervention design along with the importance of implementing a robust monitoring and evaluation framework.

OP7 Palliative care in paramedic practice: a retrospective cohort study

Introduction

Paramedics may be involved in the care of patients experiencing a health crisis associated with palliative care. However, little is known about the paramedic’s role in the care of these patients. This study therefore aimed to describe the incidence and nature of cases attended by paramedics, the treatment provided, and the transport destination if transported, where the reason for attendance was associated with a history of palliative care.

Methods

This retrospective cohort study included all adult patients (aged > 17 years) attended by paramedics in the Australian state of Victoria between 1 July 2015 and 30 June 2016 where terms associated with palliative care, dying or end of life were recorded in the patient care record. Secondary transfers were excluded. Descriptive statistics were used to analyse the sample. Categorical data are presented as frequencies and proportions, with comparisons made using the χ2 test.

Results

4,348 cases met inclusion criteria. Most patients were aged between 61–80 years (47.9%). The most common assessments recorded by paramedics were ‘respiratory’ (20.1%), ‘pain’ (15.8%), and ‘deceased’ (7.9%). 54.0% (n=2,346) received treatment from the paramedics, and 74.4% (n=3,237) were transported, with the most common destination a hospital (99.5%, n=3,221). Of those with pain as the primary impression, 359 (53.9%) received an analgesic. Nausea and/or vomiting was documented in 15.6% (n=680) of cases attended. Antiemetics administered in these cases included metoclopramide (n=71, 10.4%), prochlorperazine (n=21, 3.1%), and ondansetron (n=9, 1.3%). Resuscitation was attempted in 98 (29.1%) of the 337 cases coded as cardiac arrest. Among non-transported cases, there were 105 (9.6%) cases where paramedics re-attended the patient within 24 hours of the previous attendance.

Discussion and conclusion

Paramedics may become involved in the care of patients receiving palliative care due to exacerbation of symptoms or a new health emergency. As such, the paramedic has a key role in managing symptoms or liaising with other members of the patient’s palliative care team to provide appropriate care. The results should inform integrated systems of care that involve ambulance services in the planning and delivery of community-based palliative care.

Trends in survival from out-of-hospital cardiac arrests defibrillated by paramedics, first responders and bystanders

BACKGROUND

Although survival from out-of-hospital cardiac arrest (OHCA) is increasing, little is known about the long-term trends in survival for patients defibrillated by first responders and bystanders.

METHODS

Between 2000 and 2017, we included adult non-traumatic OHCA with an initial shockable rhythm from the Victorian Ambulance Cardiac Arrest Registry. Adjusted logistic regression analyses were used to assess trends in survival to hospital discharge according to whether the patient was initially shocked by paramedics, first responders or bystanders.

RESULTS

Of the 10,451 initial shockable arrests, 796 (7.6%) and 526 (5.0%) were initially shocked by first responders and bystanders, respectively. Between 2000-02 and 2015-17, the proportion of cases initially shocked by first responders and bystanders increased from 3.8% to 8.2% and from 2.0% to 11.2%, respectively. Over the same period, survival to hospital discharge increased from 11.6% to 28.8% for cases initially shocked by paramedics, from 10.5% to 37.8% for cases initially shocked by first responders, and from 6.7% to 55.5% for cases initially shocked by bystanders (p trend <0.001 for all). In the adjusted analyses, patients initially shocked by first responders (AOR 1.40, 95% CI: 1.18, 1.67; p < 0.001) and bystanders (AOR 2.11, 95% CI: 1.72, 2.59; p < 0.001) were more likely to survive to hospital discharge than those initially shocked by paramedics. The odds of survival increased year-on-year by 8.1% for patients shocked by paramedics (p < 0.001), 6.1% for patients shocked by first responders (p = 0.004), and 11.8% for patients shocked by bystanders (p < 0.001).

CONCLUSION

OHCA patients initially defibrillated by bystanders yielded the largest improvements in survival over time.

Palliative care in paramedic practice: A retrospective cohort study

BACKGROUND

Paramedics may be involved in the care of patients experiencing a health crisis associated with palliative care. However, little is known about the paramedic's role in the care of these patients.

AIM

To describe the incidence and nature of cases attended by paramedics and the care provided where the reason for attendance was associated with a history of palliative care.

DESIGN

This is a retrospective cohort study.

SETTING/PARTICIPANTS

Adult patients (aged >17 years) attended by paramedics in the Australian state of Victoria between 1 July 2015 and 30 June 2016 where terms associated with palliative care or end of life were recorded in the patient care record. Secondary transfers including inter-hospital transport cases were excluded.

RESULTS

A total of 4348 cases met inclusion criteria. Median age was 74 years (interquartile range 64-83). The most common paramedic assessments were 'respiratory' (20.1%), 'pain' (15.8%) and 'deceased' (7.9%); 74.4% ( n = 3237) were transported, with the most common destination being a hospital (99.5%, n = 3221). Of those with pain as the primary impression, 359 (53.9%) received an analgesic, morphine, fentanyl or methoxyflurane, and 356 (99.2%) were transported following analgesic administration. Resuscitation was attempted in 98 (29.1%) of the 337 cases coded as cardiac arrest. Among non-transported cases, there were 105 (9.6%) cases where paramedics re-attended the patient within 24 h of the previous attendance.

CONCLUSION

Paramedics have a significant role in caring for patients receiving palliative care. These results should inform the design of integrated systems of care that involve ambulance services in the planning and delivery of community-based palliative care.

Can pre-hospital administration reduce time to initial antibiotic therapy in septic patients?

OBJECTIVE

To quantify the potential time saved with pre-hospital antibiotic therapy in sepsis.

METHODS

Study data for adult patients transported by Ambulance Victoria (AV), and enrolled into the Australasian Resuscitation In Sepsis Evaluation (ARISE), were linked with pre-hospital electronic records.

RESULTS

An AV record was identified for 240 of 341 ARISE patients. The pre-hospital case notes referred to potential infection in 165 patients. The median time to first antibiotic administration from loading the patient into the ambulance was 107 (74-160) min.

CONCLUSIONS

ARISE patients in Victoria were frequently identified pre-hospital. An opportunity exists to study the feasibility of pre-hospital antibiotic therapy.