Prehospital mortality in an EMS system using medical priority dispatching: a community based cohort study

Characteristics of low acuity prehospital emergency patients with 48-h mortality, an observational cohort study

BACKGROUND

Every year an emergency medical technician or paramedic treats and transports up to several hundred patients. Only some patients are acutely seriously ill, and a few of these show only discrete signs and symptoms of their condition. This study aims to describe patients who died within 48 h of being admitted non-emergently to hospital by ambulance, examine the extent to which critically ill patients are recognized prehospitally, and identify clinical warning signs that might be frequently overlooked.

METHOD

Registry based follow-up study on patients receiving an ambulance from the Copenhagen EMS in 2018. Data was included regarding the dispatch of the ambulance from the emergency services disposition system, ICD-10 hospital admission diagnoses from the National Patient Register, 48-h mortality from the Central Person Register and assessment and treatment in the ambulance by reviewing the electronic pre-hospital patient record.

RESULTS

In 2018 2279 patients died within 48 h after contact with the EMS, 435 cases met inclusion criteria. The patients' median age was 83 years (IQR 75-90), and 374 (86.0%) had one or more underlying serious medical conditions. A triage category based on vitals and presentation was not assigned by the EMS in 286 (68.9%) cases, of which 38 (13.3%) would meet red and 126 (44.1%) orange criteria. For 409 (94.0%) patients, it was estimated that death within 48 h could not have been avoided prehospitally, and for 26 (6.0%) patients it was uncertain. We found 27 patients with acute aortic syndrome as admission diagnosis, of these nine (33.3%) had not been admitted urgently to a hospital with vascular surgery specialty.

CONCLUSIONS

It was estimated that death within 48 h could generally not be avoided prehospitally. The patients' median age was 83 years, and they often had serious comorbidity. Patients whose vital parameters met red or orange triage criteria were to a lesser degree triaged prehospitally, compared to patients in the yellow or green categories. Patients with acute aortic syndrome were not recognized by EMS 33.3% of the time.

Prehospital triage of patients diagnosed with perforated peptic ulcer or peptic ulcer bleeding: an observational study of patients calling 1-1-2

BACKGROUND

Triage systems are used in emergency medical services to systematically prioritize prehospital resources according to individual patient conditions. Previous studies have shown cases of preventable deaths in emergency medical services even when triage systems are used, indicating a potential undertriage among some conditions. The aim of this study was to investigate the triage level among patients diagnosed with perforated peptic ulcer (PPU) or peptic ulcer bleeding (PUB).

METHODS

In a three-year period in Central Denmark Region, all patients hospitalized within 24 h after a 1-1-2 emergency call and who subsequently received either a PPU or a PUB (hereinafter combined and referred to as PPU/PUB) or a First Hour Quintet (FHQ: respiratory failure, stroke, trauma, cardiac chest pain, and cardiac arrest) diagnosis were investigated. A modified Poisson regression was used to estimate the relative risk of receiving the highest and lowest prehospital response level. Also, a linear regression analysis was used to estimate the relative risk of 30-day mortality.

RESULTS

Of 8658 evaluated patients, 263 were diagnosed with PPU/PUB. After adjusting for relevant confounding variables, patients diagnosed with PPU/PUB were less likely to receive ambulance transportation compared to patients diagnosed with stroke, RR = 1.41 (CI: 1.28-1.56); trauma, RR = 1.28 (CI: 1.15-1.42); cardiac chest pain, RR = 1.47 (CI: 1.33-1.62); and cardiac arrest, RR = 1.44 (CI: 1.31-1.42). Among patients diagnosed with PPU/PUB, 6.5% (CI: 3.3-9.7) did not receive ambulance transportation. The proportion of patients not receiving ambulance transportation was higher among patients diagnosed with PPU/PUB compared to patients diagnosed with an FHQ diagnosis. The 30-day mortality rate among patients diagnosed with PPU/PUB was 7.8% (CI: 4.2-11.1). This was lower than the 30-day mortality rate among patients diagnosed with respiratory failure (P = 0.010), stroke (P = 0.001), and cardiac arrest (P < 0.001), but comparable to the 30-day mortality among patients diagnosed with cardiac chest pain (P = 0.080) and trauma (P = 0.281).

CONCLUSION

Among patients calling 1-1-2, fewer patients diagnosed with PPU/PUB received ambulance transportation than patients diagnosed with FHQ diagnoses, despite a high mortality among patients diagnosed with PPU/PUB.

A comparison of two emergency medical dispatch protocols with respect to accuracy

Background

Emergency medical dispatching should be as accurate as possible in order to ensure patient safety and optimize the use of ambulance resources. This study aimed to compare the accuracy, measured as priority level, between two Swedish dispatch protocols – the three-graded priority protocol Medical Index and a newly developed prototype, the four-graded priority protocol, RETTS-A.

Methods

A simulation study was carried out at the Emergency Medical Communication Centre (EMCC) in Stockholm, Sweden, between October and March 2016. Fifty-three voluntary telecommunicators working at SOS Alarm were recruited nationally. Each telecommunicator handled 26 emergency medical calls, simulated by experienced standard patients. Manuscripts for the scenarios were based on recorded real-life calls, representing the six most common complaints. A cross-over design with 13 + 13 calls was used. Priority level and medical condition for each scenario was set through expert consensus and used as gold standard in the study.

Results

A total of 1293 calls were included in the analysis. For priority level, n = 349 (54.0%) of the calls were assessed correctly with Medical Index and n = 309 (48.0%) with RETTS-A (p = 0.012). Sensitivity for the highest priority level was 82.6% (95% confidence interval: 76.6–87.3%) in the Medical Index and 54.0% (44.3–63.4%) in RETTS-A. Overtriage was 37.9% (34.2–41.7%) in the Medical Index and 28.6% (25.2–32.2%) in RETTS-A. The corresponding proportion of undertriage was 6.3% (4.7–8.5%) and 23.4% (20.3–26.9%) respectively.

Conclusion

In this simulation study we demonstrate that Medical Index had a higher accuracy for priority level and less undertriage than the new prototype RETTS-A. The overall accuracy of both protocols is to be considered as low. Overtriage challenges resource utilization while undertriage threatens patient safety. The results suggest that in order to improve patient safety both protocols need revisions in order to guarantee safe emergency medical dispatching.

Medical priority dispatch codes-comparison with National Early Warning Score

Background

In Finland, calls for emergency medical services are prioritized by educated non-medical personnel into four categories—from A (highest risk) to D (lowest risk)—following a criteria-based national dispatch protocol. Discrepancies in triage may result in risk overestimation, leading to inappropriate use of emergency medical services units and to risk underestimation that can negatively impact patient outcome. To evaluate dispatch protocol accuracy, we assessed association between priority assigned at dispatch and the patient’s condition assessed by emergency medical services on the scene using an early warning risk assessment tool.

Methods

Using medical charts, clinical variables were prospectively recorded and evaluated for all emergency medical services missions in two hospital districts in Northern Finland during 1.1.2014–30.6.2014. Risk assessment was then re-categorized as low, medium, or high by calculating the National Early Warning Score (NEWS) based on the patients’ clinical variables measured at the scene.

Results

A total of 12,729 emergency medical services missions were evaluated, of which 616 (4.8%) were prioritized as A, 3193 (25.1%) as B, 5637 (44.3%) as C, and 3283 (25.8%) as D. Overall, 67.5% of the dispatch missions were correctly estimated according to NEWS. Of the highest dispatch priority missions A and B, 76.9 and 78.3%, respectively, were overestimated. Of the low urgency missions (C and D), 10.7% were underestimated; 32.0% of the patients who were assigned NEWS indicating high risk had initially been classified as low urgency C or D priorities at the dispatch.

Discussion and conclusion

The present results show that the current Finnish medical dispatch protocol is suboptimal and needs to be further developed. A substantial proportion of EMS missions assessed as highest priority were categorized as lower risk according to the NEWS determined at the scene, indicating over-triage with the protocol. On the other hand, only a quarter of the high risk NEWS patients were classified as the highest priority at dispatch, indicating considerable under-triage with the protocol.

Electronic supplementary material

The online version of this article (doi:10.1186/s13049-016-0336-y) contains supplementary material, which is available to authorized users.

Primary Trauma Triage Performed by Bystanders: An Observation Study

OBJECTIVE

The aim of this study was to evaluate whether bystanders with no training in triage can correctly prioritize three injured patients by using a triage instrument.

METHOD

An observational study was conducted. Participants performed a primary triage on three paper-based patient cases and answered 11 questions during a public event in the center of Stockholm, Sweden.

RESULTS

A total of 69 persons participated in the study. The success rate among all the participants for correct triage of the three patient cases was 52 percent. The female participants and younger participants (<55 years of age) performed correct triage to a greater extent. The over-triage was 12.5 percent and under-triage was 6.3 percent.

CONCLUSION

Participants with no prior knowledge of triage instruments may be capable of triaging injured patients with the help of an easy triage instrument. The over- and under-triage percentages were low, and this may indicate that the developed triage instrument is relatively easy to use. It may also indicate that bystanders can identify a severely injured patient. Nordberg M , Castrén M , Lindström V . Primary trauma triage performed by bystanders: an observation study. Prehosp Disaster Med. 2016;31(4):353-357.

Preventable deaths following emergency medical dispatch--an audit study

Background

Call taker triage of calls to the 112 emergency number, can be error prone because rapid decisions must be made based on limited information. Here we investigated the preventability and common characteristics of same-day deaths among patients who called 112 and were not assigned an ambulance with lights and sirens by the Emergency Medical Communication Centre (EMCC).

Methods

An audit was performed by an external panel of experienced prehospital consultant anaesthesiologists. The panel focused exclusively on the role of the EMCC, assessing whether same-day deaths among 112 callers could have been prevented if the EMCC had assessed the situations as highly urgent. The panels’ assessments were based on review of patient charts and voice-log recordings of 112 calls. All patient related material was reviewed by the audit panel and all cases where then scored as preventable, potentially preventable or non-preventable during a two day meeting. The study setting was three of five regions in Denmark with a combined population of 4,182,613 inhabitants, which equals 75% of the Danish population. The study period was 18 months, from mid-2011 to the end of 2012.

Results

Linkage of prospectively collected EMCC data with population-based registries resulted in the identification of 94,488 non-high-acuity 112 callers. Among these callers, 152 (0.16% of all) died on the same day as the corresponding 112 call, and were included in this study. The mean age of included patients was 74.4 years (range, 31–100 years) and 45.4% were female. The audit panel found no definitively preventable deaths; however, 18 (11.8%) of the analysed same-day deaths (0.02% of all non-high-acuity callers) were found to be potentially preventable. In 13 of these 18 cases, the dispatch protocol was either not used or not used correctly.

Conclusion

Same-day death rarely occurred among 112 callers whose situations were assessed as not highly urgent. No same-day deaths were found to be definitively preventable by a different EMCC call assessment, but a minority of same-day deaths could potentially have been prevented with more accurate triage. Better adherence with dispatch protocol could improve the safety of the dispatch process.

Implementing a nationwide criteria-based emergency medical dispatch system: a register-based follow-up study

BACKGROUND

A criteria-based nationwide Emergency Medical Dispatch (EMD) system was recently implemented in Denmark. We described the system and studied its ability to triage patients according to the severity of their condition by analysing hospital admission and case-fatality risks.

METHODS

This was a register-based follow-up study of all 1-1-2 calls in a 6-month period that were triaged according to the Danish Index - the new criteria-based dispatch protocol. Danish Index data were linked with hospital and vital status data from national registries. Confidence intervals (95%) for proportions with binomial data were computed using exact methods. To test for trend the Wald test was used.

RESULTS

Information on level of emergency according to the Danish Index rating was available for 67,135 patients who received ambulance service. Emergency level A (urgent cases) accounted for 51.4% (n = 34,489) of patients, emergency level B for 46.3% (n = 31,116), emergency level C for 2.1% (n = 1,391) and emergency level D for 0.2% (n = 139). For emergency level A, the median time from call receipt to ambulance dispatch was 2 min 1 s, and the median time to arrival was 6 min 11 s. Data concerning admission and case fatality was available for 55,270 patients. The hospital admission risk for emergency level A patients was 64.4% (95% CI = 63.8-64.9). There was a significant trend (p < 0.001) towards lower admission risks for patients with lower levels of emergency. The case fatality risk for emergency level A patients on the same day as the 1-1-2 call was 4.4% (95% CI = 4.1-4.6). The relative case-fatality risk among emergency level A patients compared to emergency level B-D patients was 14.3 (95% CI: 11.5-18.0).

CONCLUSION

The majority of patients were assessed as Danish Index emergency level A or B. Case fatality and hospital admission risks were substantially higher for emergency level A patients than for emergency level B-D patients. Thus, the newly implemented Danish criteria-based dispatch system seems to triage patients with high risk of admission and death to the highest level of emergency. Further studies are needed to determine the degree of over- and undertriage and prognostic factors.

Utilization of Warning Lights and Siren Based on Hospital Time-Critical Interventions

Objective:

The objective of this study was to evaluate the time saved by usage of lights and siren (L&S) during emergency medical transport and measure the total number of time-critical hospital interventions gained by this time difference.

Methods:

A retrospective study was performed of all advanced life support (ALS) transports using lights and siren to this university emergency department during a three-week period. Consecutive times were measured for 112 transports and compared with measured transport times for a personal vehicle traveling the same day of the week and time of day without lights and siren. The time-critical hospital interventions are defined as procedures or treatments that could not be performed in the prehospital setting requiring a physician. The project assessed whether the patients received the hospital interventions within the average time saved using lights and siren transport.

Results:

The average difference in time with versus without L&S was -2.62 minutes (95% CI: -2.60− -2.63, paired t-test p <0.0001). The average transport time with L&S was 14.5 ±7.9 minutes (min) (1 standard deviation/minute (min), range = 1–36 min.). The average transport time without L&S was 17.1 ±8.3 min (range = 1−40 min). Of the 112 charts evaluated, five patients (4.5%) received time-critical hospital interventions. No patients received time-critical interventions within the time saved by utilizing lights and siren. Longer distances did not result in time saved with lights and siren.

Conclusions:

Limiting lights and siren use to the patients requiring hospital interventions will decrease the risks of injury and death, while adding the benefit of time saved in these critical patients.

Evaluation of an algorithm for estimating a patient's life threat risk from an ambulance call

Background

Utilizing a computer algorithm, information from calls to an ambulance service was used to calculate the risk of patients being in a life-threatening condition (life threat risk), at the time of the call. If the estimated life threat risk was higher than 10%, the probability that a patient faced a risk of dying was recognized as very high and categorized as category A+. The present study aimed to review the accuracy of the algorithm.

Methods

Data collected for six months from the Yokohama new emergency system was used. In the system, emergency call workers interviewed ambulance callers to obtain information necessary to assess triage, which included consciousness level, breathing status, walking ability, position, and complexion. An emergency patient's life threat risk was then estimated by a computer algorithm applying logistic models. This study compared the estimated life threat risk occurring at the time of the emergency call to the patients' state or severity of condition, i.e. death confirmed at the scene by ambulance crews, resulted in death at emergency departments, life-threatening condition with occurrence of cardiac and/or pulmonary arrest (CPA), life-threatening condition without CPA, serious but not life-threatening condition, moderate condition, and mild condition. The sensitivity, specificity, predictive values, and likelihood ratios of the algorithm for categorizing A+ were calculated.

Results

The number of emergency dispatches over the six months was 73,992. Triage assessment was conducted for 68,692 of these calls. The study targets account for 88.8% of patients who were involved in triage calls. There were 2,349 cases where the patient had died or had suffered CPA. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio of the algorithm at predicting cases that would result in a death or CPA were 80.2% (95% confidence interval: 78.6% - 81.8%), 96.0% (95.8% - 96.1%), 42.6% (41.1% - 44.0%), 99.2% (99.2% - 99.3%), 19.9 (18.8 - 21.1), and 0.21 (0.19 - 0.22), respectively.

Conclusion

A patient's life threat risk was quantitatively assessed at the moment of the emergency call with a moderate level of accuracy.

Geographic-Time Distribution of Ambulance Calls in Singapore: Utility of Geographic Information System in Ambulance Deployment (CARE 3)

Introduction: Pre-hospital ambulance calls are not random events, but occur in patterns and trends that are related to movement patterns of people, as well as the geographical epidemiology of the population. This study describes the geographic-time epidemiology of ambulance calls in a large urban city and conducts a time demand analysis. This will facilitate a Systems Status Plan for the deployment of ambulances based on the most cost-effective deployment strategy. Materials and Methods: An observational prospective study looking at the geographic-time epidemiology of all ambulance calls in Singapore. Locations of ambulance calls were spot-mapped using Geographic Information Systems (GIS) technology. Ambulance response times were mapped and a demand analysis conducted by postal districts. Results: Between 1 January 2006 and 31 May 2006, 31,896 patients were enrolled into the study. Mean age of patients was 51.6 years (S.D. 23.0) with 60.0% male. Race distribution was 62.5% Chinese, 19.4% Malay, 12.9% Indian and 5.2% others. Trauma consisted 31.2% of calls and medical 68.8%. 9.7% of cases were priority 1 (most severe) and 70.1% priority 2 (moderate severity). Mean call receipt to arrival at scene was 8.0 min (S.D. 4.8). Call volumes in the day were almost twice those at night, with the most calls on Mondays. We found a definite geographical distribution pattern with heavier call volumes in the suburban town centres in the Eastern and Southern part of the country. We characterised the top 35 districts with the highest call volumes by time periods, which will form the basis for ambulance deployment plans. Conclusion: We found a definite geographical distribution pattern of ambulance calls. This study demonstrates the utility of GIS with despatch demand analysis and has implications for maximising the effectiveness of ambulance deployment. Keywords: Demand analysis, Despatch, Emergency Medical Services

A framework for the design of ambulance sirens

Ambulance sirens are essential for assisting the safe and rapid arrival of an ambulance at the scene of an emergency. In this study, the parameters upon which sirens may be designed were examined and a framework for emergency vehicle siren design was proposed. Validity for the framework was supported through acoustic measurements and the evaluation of ambulance transit times over 240 emergency runs using two different siren systems. Modifying existing siren sounds to add high frequency content would improve vehicle penetration, detectability and sound localization cues, and mounting the siren behind the radiator grill, rather than on the light bar or under the wheel arch, would provide less unwanted noise while maintaining or improving the effective distance in front of the vehicle. Ultimately, these considerations will benefit any new attempt to design auditory warnings for the emergency services.

Emergency call processing and survival from out-of-hospital ventricular fibrillation

OBJECTIVES

Our aim was to report the effect of the emergency call processing in the dispatching centre on survival from out-of-hospital ventricular fibrillation (VF).

METHODS

This retrospective cohort study was conducted in Helsinki Emergency Medical Services. All consecutive cases with out-of-hospital bystander witnessed VF of cardiac origin between 1 January 1997 and 31 December 2002 were included. Data were collected prospectively. Call processing times, call numbers per dispatcher and telephone guided cardiopulmonary resuscitation (CPR) were studied. Discharge alive from hospital was used as primary end point.

RESULTS

The study population consisted of 373 cases. Cardiac arrest (CA) was recognised in 296 cases (79.4%) by the dispatcher. Survival to discharge was 37.2% (110/296) if CA was recognised and 28.6% (22/77) if it was not recognised (p=0.1550). When the dispatcher handled <4 VF calls during the study period survival to discharge was 22.1% (17/77) compared to 38.2% (50/131) and 39.4% (65/165) when the call volume was 4-9 or >9 (p=0.0227). The mean time to dispatch a first responding unit (FRU) was 77.1+/-44.3 s. Survival to discharge was 39.4% (65/165) when the FRU dispatching time was <60s and 32.2% (67/208) when dispatching took > or =60 s (p=0.1496). The mean time to CA recognition was 170.2+/-130.1 s. Spontaneous circulation was achieved more rapidly when the time was <150 s (p=0.0426), but there was no difference in survival to discharge. Telephone guided CPR instructions were given in 123 cases (35.5%). Survival to discharge was 43.1% (53/123) when CPR instructions were given and 31.7% (72/223) when they were not given (p=0.0453).

CONCLUSIONS

We showed that low CA call numbers per dispatcher is associated with a decreased probability of survival. Giving telephone guided CPR instructions should be promoted as they influence the outcome. Further studies are needed to determine optimal call processing times.

Analysis of multiple casualty incidents - a prospective cohort study

BACKGROUND

Our aim was to report the rate and causes for multiple casualty incidents (MCI) to analyse the prehospital part of responding to MCIs, report mortality and find areas for improvement.

METHODS

A prospective cohort study conducted in an urban emergency medical service (EMS) between 1.3.1998 and 28.2.2004.

RESULTS

Fifty-nine MCIs involving 263 patients (167 walking, 96 non-walking) occurred. The incidence of MCIs was 1.8/100,000 inhabitants year(-1). Traffic accidents were the most common cause followed by residential fires, intoxications and stabbings or shootings. Early MCI alarm by the dispatching centre was performed in 18 MCIs. Deviations from standard emergency medical care occurred in 12% of patients. Lack of immobilization of the neck or back in trauma patients and lack of administration of 100% oxygen in suspected carbon monoxide intoxication were the most common deviations. Deviations were related to the lack of presence of on-scene medical command (P = 0.0013) and inadequate resources (P = 0.0342). One hundred and ninety-two patients were transported to emergency departments. Mortality during the prehospital phase was 4.9% (13/263) and during the next 28 days 2.3% (6/263). Adequate resources for safe and effective management of a MCI were related to an early MCI alarm by the dispatching centre (P = 0,022) and to the presence of on-scene medical command (P < 0,001).

CONCLUSIONS

Traffic accidents, residential fires and intoxications were the leading causes for MCIs. Emergency medical service could respond to most MCIs efficiently and safely. Majority of deviations from standard medical care seemed potentially preventable. Several areas for improvement were identified. From prehospital links, the dispatching centre and on-scene medical command had a vital role in the successful management of MCIs.