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

Healthcare and economic cost burden of emergency medical services treated non-traumatic shock using a population-based cohort in Victoria, Australia

OBJECTIVES

We aimed to assess the healthcare costs and impact on the economy at large arising from emergency medical services (EMS) treated non-traumatic shock.

DESIGN

We conducted a population-based cohort study, where EMS-treated patients were individually linked to hospital-wide and state-wide administrative datasets. Direct healthcare costs (Australian dollars, AUD) were estimated for each element of care using a casemix funding method. The impact on productivity was assessed using a Markov state-transition model with a 3-year horizon.

SETTING

Patients older than 18 years of age with shock not related to trauma who received care by EMS (1 January 2015-30 June 2019) in Victoria, Australia were included in the analysis.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome assessed was the total healthcare expenditure. Secondary outcomes included healthcare expenditure stratified by shock aetiology, years of life lived (YLL), productivity-adjusted life-years (PALYs) and productivity losses.

RESULTS

A total of 21 334 patients (mean age 65.9 (±19.1) years, and 9641 (45.2%) females were treated by EMS with non-traumatic shock with an average healthcare-related cost of $A11 031 per episode of care and total cost of $A280 million. Annual costs remained stable throughout the study period, but average costs per episode of care increased (Ptrend=0.05). Among patients who survived to hospital, the average cost per episode of care was stratified by aetiology with cardiogenic shock costing $A24 382, $A21 254 for septic shock, $A19 915 for hypovolaemic shock and $A28 057 for obstructive shock. Modelling demonstrated that over a 3-year horizon the cohort lost 24 355 YLLs and 5059 PALYs. Lost human capital due to premature mortality led to productivity-related losses of $A374 million. When extrapolated to the entire Australian population, productivity losses approached $A1.5 billion ($A326 million annually).

CONCLUSION

The direct healthcare costs and indirect loss of productivity among patients with non-traumatic shock are high. Targeted public health measures that seek to reduce the incidence of shock and improve systems of care are needed to reduce the financial burden of this syndrome.

Structured Weaning From the Impella Left Ventricular Micro-Axial Pump in Acute Myocardial Infarction With Cardiogenic Shock and Protected Percutaneous Coronary Intervention: Experience From a Non-Cardiac Surgical Centre

BACKGROUND

The Impella (Abiomed, Danvers, MA, USA) temporary percutaneous left ventricular assist device is increasingly used as mechanical circulatory support in patients with acute myocardial infarction-cardiogenic shock (AMICS) or those undergoing high-risk protected percutaneous coronary intervention (PCI). The optimal weaning regimen remains to be defined.

METHOD

We implemented a structured weaning protocol in a series of 10 consecutive patients receiving Impella support for protected PCI or AMICS treated with PCI in a high volume non-cardiac surgery centre. Weaning after revascularisation was titrated to native heart recovery using both haemodynamic and echocardiographic parameters.

RESULTS

Ten patients (eight male, two female; aged 43-70 years) received Impella support for AMICS (80%) or protected PCI (20%). Cardiogenic shock was of Society for Cardiac Angiography & Interventions grade C-E of severity in 80%, and median left ventricular end-diastolic pressure was 31 mmHg. Protocol implementation allowed successful weaning in eight of 10 patients with a median support time of 29 hours (range, 4-48 hours). Explantation was associated with an increase in heart rate (81 vs 88 bpm; p=0.005), but no significant change in Cardiac Index (2.9 vs 2.9 L/min/m2), mean arterial pressure (79 vs 82 mmHg), vasopressor requirement (10% vs 10%), or serum lactate (1.0 vs 1.0). Median durations of intensive care and hospital stay were 3 and 6 days, respectively. At 30 days, the mortality rate was 20%, with median left ventricular ejection fraction of 40%.

CONCLUSIONS

A structured and dynamic weaning protocol for patients with AMICS and protected PCI supported by the Impella device is feasible in a non-cardiac surgery centre. Larger studies are needed to assess generalisability of such a weaning protocol.

Association of socioeconomic status in the incidence, quality-of-care metrics, and outcomes for patients with cardiogenic shock in a pre-hospital setting

AIMS

The relationship between lower socioeconomic status (SES) and poor cardiovascular outcomes is well described; however, there exists a paucity of data exploring this association in cardiogenic shock (CS). This study aimed to investigate whether any disparities exist between SES and the incidence, quality of care or outcomes of CS patients attended by emergency medical services (EMS).

METHODS AND RESULTS

This population-based cohort study included consecutive patients transported by EMS with CS between 1 January 2015 and 30 June 2019 in Victoria, Australia. Data were collected from individually linked ambulance, hospital, and mortality datasets. Patients were stratified into SES quintiles using national census data produced by the Australian Bureau of Statistics.A total of 2628 patients were attended by EMS for CS. The age-standardized incidence of CS amongst all patients was 11.8 [95% confidence interval (95% CI), 11.4-12.3] per 100 000 person-years, with a stepwise increase from the highest to lowest SES quintile (lowest quintile 17.0 vs. highest quintile 9.7 per 100 000 person-years, P-trend < 0.001). Patients in lower SES quintiles were less likely to attend metropolitan hospitals and more likely to be received by inner regional and remote centres without revascularization capabilities. A greater proportion of the lower SES groups presented with CS due to non-ST elevation myocardial infarction (NSTEMI) or unstable angina pectoris (UAP), and overall were less likely to undergo coronary angiography. Multivariable analysis demonstrated an increased 30-day all-cause mortality rate in the lowest three SES quintiles when compared with the highest quintile.

CONCLUSION

This population-based study demonstrated discrepancies between SES status in the incidence, care metrics, and mortality rates of patients presenting to EMS with CS. These findings outline the challenges in equitable healthcare delivery within this cohort.

Comparison of mortality in emergency department patients with immediate versus delayed hypotension

BACKGROUND

Hypotension in the emergency department (ED) is known to be associated with increased mortality, however, the relationship between timing of hypotension and mortality has not been investigated. The objective of the study was to compare the mortality rate of patients presenting with hypotension with those who develop hypotension while in the ED.

METHODS

This was a retrospective cohort study in a large academic medical center collected from January 2018-December 2021. Patients were included if they were ≥ 18 years old and had at least one recorded systolic blood pressure (SBP) ≤ 90 in the ED. Patients were separated into medical and trauma presentations by chief compliant. The primary outcome was in-hospital mortality, which included any deaths between ED arrival and hospital discharge. Further analysis examined the association of time to the first hypotensive SBP measurement with mortality.

RESULTS

There were 212,085 adult patients who presented to the ED during the study period, with 4053 (1.9%) patients having at least one hypotensive blood pressure measurement. The mortality rate was 0.8% for all patients and 10.0% for patients with hypotension. There were 676 unique chief complaints, of which 86 (12.7%) were determined to be trauma related. This grouping resulted in 176,947(83.4%) patients classified as medical and 35,138(16.6%) patients as trauma. For patients presenting with medical complaints, there was not a significant difference in mortality for patients who were hypotensive on arrival and those who developed hypotension during their ED stay (RR 1.19 [95% CI:0.97-1.39]). Similarly, there was no difference for patients with trauma (RR 0.6 [95% CI: 0.31-1.24]). However, for all patients, there was a significant trend toward decreased mortality for every hour after arrival until the development of hypotension, and increased mortality with increasing number of hypotensive measurements recorded.

CONCLUSION

This study demonstrated hypotension in the ED was associated with a very significantly increased risk of in-hospital mortality. However, there was no significant increase in mortality between those patients with hypotension on arrival those who develop hypotension while in the ED. These finding underscore the importance of careful hemodynamic monitoring for patients in the ED throughout their stay.

State of Shock: Contemporary Vasopressor and Inotrope Use in Cardiogenic Shock

Cardiogenic shock is characterized by tissue hypoxia caused by circulatory failure arising from inadequate cardiac output. In addition to treating the pathologic process causing impaired cardiac function, prompt hemodynamic support is essential to reduce the risk of developing multiorgan dysfunction and to preserve cellular metabolism. Pharmacologic therapy with the use of vasopressors and inotropes is a key component of this treatment strategy, improving perfusion by increasing cardiac output, altering systemic vascular resistance, or both, while allowing time and hemodynamic stability to treat the underlying disease process implicated in the development of cardiogenic shock. Despite the use of mechanical circulatory support recently garnering significant interest, pharmacologic hemodynamic support remains a cornerstone of cardiogenic shock management, with over 90% of patients receiving at least 1 vasoactive agent. This review aims to describe the pharmacology and hemodynamic effects of current pharmacotherapies and provide a practical approach to their use, while highlighting important future research directions.

Towards a Lightweight Classifier to Detect Hypovolemic Shock

Predicting the ability of an individual to compensate for blood loss during hemorrhage and detect the likely onset of hypovolemic shock is necessary to permit early clinical intervention. Towards this end, the compensatory reserve metric (CRM) has been demonstrated to directly correlate with an individual's ability to maintain compensatory mechanisms during loss of blood volume from onset (one-hundred percent health) to exsanguination (zero percent health). This effort describes a lightweight, three-class predictor (good, fair, poor) of an individual's compensatory reserve using a linear support-vector machine (SVM) classifier. A moving mean filter of the predictions demonstrates a feasible model for implementation of real-time hypovolemia monitoring on a wearable device, requiring only 408 bytes to store the models' coefficients and minimal processor cycles to complete the computations.

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.

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.