Prehospital Critical Care Research Articles

Impact of a physician - critical care practitioner pre-hospital service in Wales on trauma survival: a retrospective analysis of linked registry data.

The Emergency Medical Retrieval and Transfer Service for Wales launched in 2015. This service delivers senior pre-hospital doctors and advanced critical care practitioners to the scene of time-critical life- and limb-threatening incidents to provide advanced decision-making and pre-hospital clinical care. The impact of the service on 30-day mortality was evaluated retrospectively using a data linkage system. The study included patients who sustained moderate-to-severe blunt traumatic injuries (injury severity score≥9) between 27 April 2015 and 30 November 2018. The association between pre-hospital management by the Emergency Medical Retrieval and Transfer Service and 30-day mortality was assessed using multivariable logistic regression. In total, data from 4035 patients were analysed, of which 412 (10%) were treated by the Emergency Medical Retrieval and Transfer Service. A greater proportion of patients treated by the Emergency Medical Retrieval and Transfer Service had an injury severity score≥16 and Glasgow coma scale≤12 (288 (70%) vs. 1435 (40%) and 126 (31%) vs. 325 (9%), respectively). The unadjusted 30-day mortality rate was 11.7% for patients managed by the Emergency Medical Retrieval and Transfer Service compared with 9.6% for patients managed by standard pre-hospital care services. However, after adjustment for differences in case-mix, the 30-day mortality rate for patients treated by the Emergency Medical Retrieval and Transfer Service was 37% lower (adjusted odds ratio 0.63 (95%CI 0.41-0.97); p=0.037). The introduction of an emergency medical retrieval service was associated with a reduction in 30-day mortality for patients with blunt traumatic injury.

An analysis of prehospital critical care events and management patterns from 97 539 emergency helicopter medical service missions: A retrospective registry-based study.

It is largely unknown how often physicians in emergency helicopter medical services (HEMS) encounter various critical care events and if HEMS exposure is associated with particular practice patterns or outcomes. This study aimed: to describe the frequency and distribution of critical care events; to investigate whether HEMS exposure is associated with differences in practice patterns and determine if HEMS exposure factors are associated with mortality. A retrospective registry-based study. Physician-staffed HEMS in Finland between January 2012 and August 2019. Ninety-four physicians who worked at least 6 months in the HEMS during the study period. Physicians with undeterminable HEMS exposure were excluded from practice pattern comparisons and mortality analysis, leaving 80 physicians. The primary outcome measure was a physician's average annual frequencies for operational events and clinical interventions. Our secondary outcomes were the proportion of missions cancelled or denied, time onsite (OST) and proportion of unconscious patients intubated. Our tertiary outcome was adjusted 30-day mortality of patients. The physicians encountered 62 [33 to 98], escorted 31 [17 to 41] and transported by helicopter 2.1 [1.3 to 3.5] patients annually, given as median [interquartile range; IQR]. Rapid sequence intubation was performed 11 [6.2 to 16] times per year. Physicians were involved in out-of-hospital cardiac arrest (OHCA) 10 [5.9 to 14] and postresuscitation care 5.5 [3.1 to 8.1] times per year. Physicians with longer patient intervals had shorter times onsite. Proportionally, they cancelled more missions and intubated fewer unconscious patients. A short patient interval [odds ratio (OR); 95% confidence interval (CI)] was associated with decreased mortality (0.87; 95% CI, 0.76 to1.00), whereas no association was observed between mortality and HEMS career length. Prehospital exposure is distributed unevenly, and some physicians receive limited exposure to prehospital critical care. This seems to be associated with differences in practice patterns. Rare HEMS patient contacts may be associated with increased mortality.

Shock index as a predictor for short-term mortality in helicopter emergency medical services: A registry study.

The value of shock-index has been demonstrated in hospital triage, but few studies have evaluated its prehospital use. The aim of our study was to evaluate the association between shock-index in prehospital critical care and short-term mortality. We analyzed data from the national helicopter emergency medical services database and the Population Register Centre. The shock-index was calculated from the patients' first measured parameters. The primary outcome measure was 1- and 30-day mortality. A total of 22 433 patients were included. The 1-day mortality was 7.5% and 30-day mortality was 16%. The median shock-index was 0.68 (0.55/0.84) for survivors and 0.67 (0.49/0.93) for non-survivors (P=.316) at 30-days. Association between shock-index and mortality followed a U-shaped curve in trauma (shock-index<0.5: odds ratio 2.5 [95% confidence interval 1.8-3.4], shock-index>1.3: odds ratio 4.4 [2.7-7.2] at 30days). Patients with neurological emergencies with a low shock-index had an increased risk of mortality (shock-index<0.5: odds ratio 1.8 [1.5-2.3]) whereas patients treated after successful resuscitation from out-of-hospital cardiac arrest, a higher shock-index was associated with higher mortality (shock-index>1.3: odds ratio 3.5 [2.3-5.4). The association was similar for all ages, but older patients had higher mortality in each shock-index category. The shock-index is associated with short time mortality in most critical patient categories in the prehospital setting. However, the marked overlap of shock-index in survivors and non-survivors in all patient categories limits its predictive value.

Characteristics of Nontrauma Patients Receiving Prehospital Blood Transfusion with the Same Triggers as Trauma Patients: A Retrospective Observational Cohort Study

Objective: While prehospital blood transfusion (PHBT) for trauma patients has been established in many services, the literature on PHBT use for nontrauma patients is limited. We aimed to describe and compare nontrauma and trauma patients receiving PHBT who had similar hemodynamic triggers. Methods: We analyzed 3.5 years of registry data from a single prehospital critical care unit. The PHBT protocol included two packed red blood cell units and was later completed with two freeze-dried plasma units. The transfusion triggers were a strong clinical suspicion of massive hemorrhage and systolic blood pressure below 90 mmHg or absent radial pulse. Results: Thirty-six nontrauma patients and 96 trauma patients received PHBT. The nontrauma group had elderly patients (median 65 [interquartile range, IQR, 56–73] vs 37 [IQR 25–57] years, p < 0.0001) and included patients with gastrointestinal bleeding (n = 15; 42%), vascular catastrophes (n = 9; 25%), postoperative bleeding (n = 6; 17%), obstetrical bleeding (n = 4; 11%) and other (n = 2; 6%). Cardiac arrest occurred in nine (25%) nontrauma and in 15 (16%) trauma patients. Of these, 5 (56%) and 10 (67%) survived to hospital admission and 3 (33%) and 2 (13%) to hospital discharge. On admission, the nontrauma patients had lower hemoglobin (median 95 [84–119] vs 124 [108–133], p < 0.0001), higher pH (median 7.40 [7.27–7.44] vs 7.30 [7.19–7.36], p = 0.0015) and lower plasma thromboplastin time (median 55 [45–81] vs 72 [58–86], p = 0.0261) than the trauma patients. Conclusions: We identified four nontrauma patient groups in need of PHBT, and the patients appeared to be seriously ill. Efficacy of prehospital transfusion in nontrauma patients should be evaluated futher in becoming studies.

Short-term and long-term survival in critical patients treated by helicopter emergency medical services in Finland: a registry study of 36 715 patients

ObjectivesThis study aimed to describe the short-term and long-term mortality of patients treated by prehospital critical care teams in Finland.Design and settingWe performed a registry-based retrospective study that included all...

Consensus on research priorities for Essex & Herts Air Ambulance: a Delphi study

BackgroundConsensus methods such as the Delphi technique have been used widely for research priority setting in health care. Within pre-hospital emergency medicine, such approaches have helped to establish national and international research priorities. However, in a dynamic field such as pre-hospital critical care, it is necessary to regularly review the continued relevance of findings. Further, considering the variability between pre-hospital critical care providers, it is also important to determine priorities at the local level. Essex & Herts Air Ambulance (EHAAT) sought to develop a five-year research strategy that aligns with their clinical work streams and organisational priorities.MethodsAll staff and Trustees were invited to participate in an online Delphi study with three Rounds. The Delphi was administered via email and Online Surveys software. The first Round invited participants to submit up to five research questions that they felt were of greatest importance to EHAAT to advance the care provided to patients. In Round 2, participants were asked to rate the importance of questions from Round 1, while Round 3 required participants to rank questions that were prioritised in Round 2 in order of importance.Results22 participants submitted a total of 86 research questions in Round 1, which were reduced to 69 questions following deduplication and refinement. 11 participants rated the importance of the questions in Round 2, resulting in 14 questions being taken forward to Round 3. Following the ranking exercise in Round 3, completed by 12 participants, a top five research priorities were identified. The question deemed most important was “How does a pre-hospital doctor-paramedic team affect the outcome of patients with severe head injuries?”.ConclusionsThe top five research priorities identified through the Delphi process will inform EHAAT’s research strategy. Findings suggest that there is still work to be done in addressing research priorities described in previous literature.

Conducting a conventional multi-casualty incident in COVID-19 personal protective equipment - a semi-structured interview

BackgroundThe risk of COVID-19 transmission to healthcare professionals is likely to continue for the foreseeable future. The wearing of personal protective equipment (PPE) presents a number of potential challenges to responders that may impact upon the management of patients in a multi-casualty incident.This report describes a multi-agency multi-casualty incident. It identifies learning points specifically related to the challenges of conducting a conventional multi-casualty incident in COVID-19 PPE.CaseThe multi casualty incident in Reading, UK on the 20 June 2020 involved six stab injury victims and was attended by four pre-hospital critical care teams. This was the first conventional multi-casualty incident that pre-hospital critical care teams had attended during the COVID-19 era and it was conducted in COVID-19 PPE (1). The scene was an urban park where three patients were confirmed to be in Traumatic Cardiac Arrest (TCA) from stab wounds and another three patients had also suffered stab injuries. By the time the incident had concluded three patients were pronounced dead at the scene. Two patients were transported to the local trauma unit and one patient was transported to the regional Major Trauma Centre depending on the severity of their injuries.ConclusionsWe conducted a semi structured telephone interview with the critical care clinicians who were involved in the incident. The interviews focused specifically on the challenges of responding whilst wearing COVID-19 PPE, rather than the wider challenges of responding to such an incident. The key learning points identified were:Improving the identifiability of clinicians in level 3 PPEwearing identification tabardsusing visible labelling on PPE suitsImproving communication by radiousing a belt to carry the radiousing an earpiece and push to talk system.Training in conducting multi casualty incidents in level 3 PPE.

Pre-hospital critical care management of severe hypoxemia in victims of Covid-19: a case series

ObjectiveDespite critical hypoxemia, Covid-19 patients may present without proportional signs of respiratory distress. We report three patients with critical respiratory failure due to Covid-19, in which all presented with severe hypoxemia refractory to supplemental oxygen therapy. We discuss possible strategies for ventilatory support in the emergency pre-hospital setting, and point out some pitfalls regarding the management of these patients. Guidelines for pre-hospital care of critically ill Covid-19 patients cannot be established based on the current evidence base, and we have to apply our understanding of respiratory physiology and mechanics in order to optimize respiratory support.MethodsThree cases with similar clinical presentation were identified within the Norwegian national helicopter emergency medical service (HEMS) system. The HEMS units are manned by a consultant anaesthesiologist.Patient’s next of kin and the Regional committee for medical and health research ethics approved the publication of this report.ConclusionPatients with Covid-19 and severe hypoxemia may pose a considerable challenge for the pre-hospital emergency medical services. Intubation may be associated with a high risk of complications in these patients and should be carried out with diligence when considered necessary. The following interventions are worth considering in Covid-19 patients with refractory hypoxemia before proceeding to intubation. First, administering oxygen via a tight fitting BVM with an oxygen flow rate that exceeds the patient’s ventilatory minute volume. Second, applying continuous positive airway pressure, while simultaneously maintaining a high FiO2. Finally, assuming the patient is cooperative, repositioning to prone position.

Prehospital Transfusion of Red Blood Cells and Plasma by an Urban Ground-Based Critical Care Team

Prehospital blood component therapy poses a possible treatment option among patients with severe bleeding. The aim of this paper was to characterize patients receiving prehospital blood component therapy by a paramedic-doctor-staffed, ground-based prehospital critical care (PHCC) service. Bleeding patients with a clinical need for prehospital blood transfusion were included prospectively. The following data were collected: indication for transfusion, mechanism of injury, vital parameters, units of red blood cells (RBCs)/plasma transfused, degree of shock, demographics, and mortality. Twenty-one patients received blood products: 12 (57%) traumatic injuries and nine (43%) non-traumatic bleeds, with a median of 1.5 (range 1.0-2.0) units of RBCs and 1.0 (range 0.0-2.0) unit of plasma. The most frequent trigger to initiate transfusion was on-going excessive bleeding and hypotension. Improved systolic blood pressure (SBP) and milder degrees of shock were observed after transfusion. Mean time from initiation of transfusion to hospital arrival was 24 minutes. In-hospital, 11 patients (61%) received further transfusion and 13 (72%) had urgent surgery within 24 hours. Overall, 28-day mortality was 29% at 24-hours and 33% at 28-days. Prehospital blood component therapy is feasible in a ground-based prehospital service in a medium-sized Scandinavian city. Following transfusion, patient physiology and degree of shock were significantly improved.

Scoping the Demand for Night Operation of Essex & Herts Air Ambulance: A Prospective Observational Study

ObjectiveHelicopter emergency medical services play an important role in the prehospital care of critically ill and injured patients, providing enhanced interventions and direct transfer to specialist centers. Essex & Herts Air Ambulance (EHAAT) delivers prehospital critical care to patients in Essex, Hertfordshire, and the surrounding areas. Historically, EHAAT's resources have not operated during the night. This study aimed to ascertain demand for prehospital critical care in Essex and Hertfordshire during night hours. MethodsA prospective observational design was used. Data were collected by 11 critical care paramedics during night shifts on a critical care desk using an online survey. Details were recorded for incidents in Essex and Hertfordshire between 21:00 and 07:00 deemed appropriate for a prehospital critical care response. ResultsA total of 108 incidents were recorded across 52 nights, equating to an average of 2.08 incidents per night. For 52 incidents, there was no critical care resource available to attend. The majority of incidents fell in closer proximity to EHAAT's North Weald base than its Earls Colne base. ConclusionThe findings suggest a potential need for prehospital critical care during night hours in Essex and Hertfordshire and support the operation of a resource from EHAAT's North Weald base.

Arterial and end-tidal carbon dioxide partial pressure difference during prehospital anaesthesia in critically ill patients.

Normoventilation is crucial for many critically ill patients. Ventilation is routinely guided by end-tidal capnography during prehospital anaesthesia, based on the assumption of the gap between arterial partial pressure of carbon dioxide (PaCO2 ) and end-tidal carbon dioxide partial pressure (PetCO2 ) of approximately 0.5kPa (3.8mmHg). We retrospectively analysed the airway registry and patient chart data of patients who had been anaesthetised and intubated endotracheally by the prehospital critical care team and had their prehospital arterial blood gases analysed. Bland-Altman analysis was used to estimate the bias and limits of agreement. Altogether 502 patients were included in the study, with a median age of 58years. The most common patient groups were post-resuscitation (155, 31%), neurological emergencies (96, 19%), intoxication (75, 15%) and trauma (68, 14%). The median of the gap between PaCO2 and PetCO2 was 1.3kPa (interquartile range 0.7 to 2.2) (9.8 (5.3-16.5) mmHg). Mean bias of PetCO2 was -1.6kPa/12.0mmHg (standard deviation 1.7kPa/12.8mmHg) with 95% confidence limits of agreement -4.9 to 1.9kPa (-36.8 to 14.3mmHg). The gap was≥1.0kPa (>7.5mmHg) in 297 (66%, 95% confidence interval 55 to 63) patients. Our results suggest that end-tidal capnography alone might not be an adequate method to achieve normoventilation for critically ill patients intubated and mechanically ventilated in prehospital setting. Thus, an arterial blood gas analysis might be useful to recognize patients with an increased gap between PaCO2 and PetCO2 .

End-tidal and arterial carbon dioxide gradient in serious traumatic brain injury after prehospital emergency anaesthesia: a retrospective observational study

ObjectivesIn the UK, 20% of patients with severe traumatic brain injury (TBI) receive prehospital emergency anaesthesia (PHEA). Current guidance recommends an end-tidal carbon dioxide (ETCO2) of 4.0–4.5 kPa (30.0–33.8 mm...

Novel Use of a Disposable Vascular Pressure Device for Arterial Pressure Monitoring in Prehospital Critical Care

Introduction Arterial catheterization is a commonly performed procedure in intensive care units (ICUs) to guide the management of critically ill patients who require precise hemodynamic monitoring however this technology is not available in the prehospital setting due to cumbersome and expensive equipment requirements. We compared the accuracy and reliability of a disposable vascular pressure device (DVPD) to the “gold standard”, transducer-pressure bag invasive arterial monitoring system used in intensive care units to determine if the DVPD can be reliably used in place of the traditional pressure transducer set-up. Methods This study was a single-center, prospective, observational study performed in the adult ICUs of a large academic, university hospital. A convenience cohort of hemodynamically stable, adult critically ill patients with femoral, brachial or radial arterial catheters was recruited for this study. The Compass Pressure device is a disposable vascular pressure-sensing device used to assure venous access versus inadvertent arterial access during central line placement. The device is produced by Centurion Medical Products. The DVPD was attached to an in-situ arterial catheter and measures the mean intravascular pressure via an embedded sensor and displays the pressure via the integrated LCD screen. Using a three-way stopcock, the DVPD was compared to a standard arterial set-up. We compared the mean arterial pressure (MAP) in the standard setup to the DVPD using Bland Altman plots and methods that accounted for repeated measures in the same subject. Results Data was collected on 14 of the 15 subjects enrolled (DVPD malfunctioned on one subject). Five measurements were obtained on each patient comparing DVPD to standard arterial set-up at one-minute intervals over the course of five minutes. A total of 70 observations were made. Among the 15 subjects, most (10 (67%)) were radial or brachial sites. The average MAP scores and standard deviation values (SD) obtained by the standard set up were 83.5 mmHg (14.8) and 81.1 mmHg (19.3) by the DVPD. Just over half (51.4%) of measurements were within +/-5 mmHg difference. Using Bland Altman plotting methods, standard arterial measurements were 2.4 mmHg higher (95% confidence interval: 0.60, 4.1) than the DVPD. Differences between the two devices varied significantly across MAP values. The standard arterial line measurements were significantly higher than the DAPD at low MAP values, whereas at the DAPD was measurements were significant higher at high MAP values. Conclusions The DVPD provides an acceptable estimate of mean arterial pressure and may be suitable for arterial pressure monitoring in settings where standard monitoring set-ups are not available. The DVPD appears to provide “worst case” values as it underestimates low arterial BP and overestimates high arterial BP. Future trials should investigate the DVPD in hypotensive patients and patients with laminar flow/low pulsitility, such as ventricular assist devices and extracorporeal membrane oxygenation (ECMO).. 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14

Developing clinical performance indicators for pre-hospital blood transfusion: The Thames Valley Air Ambulance approach.

In this article, we describe how we developed and validated key performance indicators (KPIs) for pre-hospital blood transfusion and offer suggestions for other organisations wishing to develop performance metrics. KPIs are metrics that compare actual care against an ideal structure, process or outcome standard. An increasing number of UK-based pre-hospital critical care services now carry blood components to enable pre-hospital blood transfusion. A working group of pre-hospital physicians and paramedics was formed to create and validate performance indicators that reflected a high-quality pre-hospital transfusion. This was performed by literature searching and reviewing consensus documents that guide the best practice and then adjusting the indicators as the process evolved. Throughout the year, the performance against the domains was monitored monthly and outputs communicated within the clinical staff of the organisation; at the end of the year, the domains were amended. The final list of performance indicators was as follows: (a) rationale for transfusion documented in the notes; (b) rationale for transfusion in line with Thames Valley Air Ambulance blood transfusion guideline; (c) aggressive management of hypothermia; (d) tranexamic acid administered within an hour of injury; (e) evidence of bleeding in hospital; (f) monitoring of adverse effects of blood transfusion; (g) overall-was the use of blood justified; and (h) no units wasted this month. This study has shown that it is feasible to devise and implement clinical performance indicators for pre-hospital blood transfusion and that their use has increased the focus on this important area.

Prehospital critical care is associated with increased survival in adult trauma patients in Scotland

BackgroundScotland has three prehospital critical care teams (PHCCTs) providing enhanced care support to a usually paramedic-delivered ambulance service. The effect of the PHCCTs on patient survival following trauma in Scotland...

Improper monitoring and deviations from physiologic treatment goals in patients with brain injury in the early phases of emergency care

Severe traumatic brain injury (TBI), out-of-hospital cardiac arrest (OHCA) and intracerebral- and subarachnoid hemorrhage (ICH/SAH) are conditions associated with high mortality and morbidity. The aim of this study was to investigate the feasibility of obtaining continuous physiologic data and to identify possible harmful physiological deviations in these patients, in the early phases of emergency care. Patients with ICH/SAH, OHCA and severe TBI treated by the Physician-staffed Emergency Medical Service (P-EMS) between September and December 2016 were included. Physiological data were obtained from site of injury/illness, during transport, in the emergency department (ED) and until 3 h after admittance to the intensive care unit. Physiological deviations were based on predefined target values within each 5-min interval. 13 patients were included in the study, of which 38% survived. All patients experienced one or more episodes of hypoxia, 38% experienced episodes of hypercapnia and 46% experienced episodes of hypotension. The mean proportion of time without any monitoring in the pre-hospital phase was 29%, 47% and 56% for SpO2, end-tidal CO2 and systolic blood pressure, respectively. For the ED these proportions were 57%, 71% and 56%, respectively. Continuous physiological data was not possible to obtain in this study of critically ill and injured patients with brain injury. The patients had frequent deviations in blood pressure, SpO2 and end tidal CO2-levels, and measurements were frequently missing. There is a potential for improved monitoring as a tool for quality improvement in pre-hospital critical care.

A Blended Prehospital Ultrasound Curriculum for Critical Care Paramedics

ObjectivePoint-of-care ultrasound is a nascent and growing area of prehospital care. Most previously described ultrasound curricula for paramedics examine a single type of ultrasound scan. Here, we describe the implementation and evaluation of a prehospital ultrasound curriculum using a blended model of traditional didactics and hands-on experience with online prereading. MethodsWe recruited a prospective convenience sample of critical care paramedics without prior ultrasound experience to take part in a 2-day ultrasound course. All participants completed prereading modules built from online resources followed by a didactic review of the material and hands-on practice. Ultrasound examinations included extended focused abdominal sonography in trauma, cardiac ultrasound, thoracic ultrasound, and vascular ultrasound. A written examination evaluated ultrasound theory and image interpretation, and a practical examination evaluated image acquisition. ResultsSeventeen critical care paramedics completed the course with a mean grade on the written examination of 76%, with 76% of paramedics achieving the predetermined passing mark of 70% or greater. All paramedics passed the practical examination. ConclusionThe implementation of a prehospital critical care ultrasound program is feasible in our provincial emergency medical services system. Further assessment is necessary to determine future knowledge and skill retention as well as clinical application and utility in real-world settings.

The effect of prehospital critical care on survival following out-of-hospital cardiac arrest: A prospective observational study

AimTo examine the effect of prehospital critical care on survival following OHCA, compared to routine advanced life support (ALS) care. MethodsWe undertook a prospective multi-centre cohort study including two ambulance services and six prehospital critical care services in the United Kingdom (UK), between September 2016 and October 2017. Inclusion criteria were adult patients with non-traumatic OHCA treated by either prehospital critical care teams or ALS paramedics. Patients who received prehospital critical care were matched to those receiving ALS using propensity score matching. Primary outcome was survival to hospital discharge; secondary outcome was survival to hospital admission. ResultsThe primary analysis included 658 patients with OHCA receiving prehospital critical care and 1847 patients receiving ALS care. Rates of survival to hospital discharge (primary outcome) were 11.9% in both groups; rates of survival to hospital admission (secondary outcome) were 34.4% and 27.7% in the prehospital critical care and ALS group, respectively. The corresponding odds ratios for survival to hospital discharge and survival to hospital admission with prehospital critical care were 1.06 (95% confidence interval 0.75–1.49) and 1.39 (95% confidence interval 1.10–1.75), respectively. Results were consistent across subgroups and sensitivity analyses. ConclusionsDespite a positive association with the secondary outcome of survival to hospital admission, prehospital critical care was not associated with increased rates of survival to hospital discharge following OHCA.

The cost-effectiveness of prehospital critical care for out-of-hospital cardiac arrest

The cost-effectiveness of prehospital critical care for out-of-hospital cardiac arrest

Cost-effectiveness of advanced life support and prehospital critical care for out-of-hospital cardiac arrest in England: a decision analysis model

ObjectivesThis research aimed to answer the following questions: What are the costs of prehospital advanced life support (ALS) and prehospital critical care for out-of-hospital cardiac arrest (OHCA)? What is the...