The association of out-of-hospital cardiac arrest barriers to cardiopulmonary resuscitation initiation and continuation during the emergency call: A retrospective cohort study.

Background: In a previous study, we identified eight types of potential barriers to bystander cardiopulmonary resuscitation (CPR) initiation and continuation until the arrival of emergency medical services (EMS) on scene, in the context of emergency calls for out-of-hospital cardiac arrest (OHCA). Many cases had multiple barriers. In this study, we aimed to estimate the independent effects of these barriers after adjusting for case characteristics. Methods: We used data for the 295 non-trauma OHCAs from the St John Western Australian (SJ-WA) OHCA Database. Excluded cases were: EMS-witnessed OHCA, callers not with/close to the patient, OHCA not recognised during the emergency call, bystander CPR in progress prior to the call and calls coded as obvious death by SJ-WA. We conducted two multivariable logistic regression models including the eight barriers (callers: 1) perceived inappropriateness of CPR, 2) emotional distress, 3) reluctance to perform CPR, 4) physical limitations, 5) access to the patient, 6) leaving the scene, 7) communication failure, and 8) on-scene distractions) and case characteristics. Results: The callers perceiving CPR as inappropriate (adjusted odds ratio [AOR] = 0.20, 0.11-0.37) and witnessed arrest (AOR = 2.88, 95% CI 1.48-5.60) were independently associated with CPR initiation. Caller distractions such as performing other tasks or relaying information to other bystanders were negatively significantly associated with callers continuing CPR to EMS arrival (AOR = 0.27, 0.10-0.73). Conclusions: Perceptions of inappropriateness and caller distractions were independent risk factors for the delivery of bystander CPR. Further research around how call-takers navigate these barriers and encourage callers should be performed.

Barriers to CPR initiation and continuation during the emergency call relating to out-of-hospital cardiac arrest: A descriptive cohort study.

AIM: To describe the barriers to cardiopulmonary resuscitation (CPR) initiation and continuation in emergency calls for out-of-hospital cardiac arrest (OHCA). METHODS: We analysed 295 consecutive emergency calls relating to OHCA over a four-month period (1 January - 30 April 2021). Calls included were paramedic-confirmed, non-traumatic, non-EMS-witnessed OHCA, where the caller was with the patient. Calls were listened to in full and coded in terms of barriers to CPR initiation and continuation, and patient and caller characteristics. RESULTS: Overall, CPR was performed in 69% of calls and, in 85% of these, callers continued performing CPR until EMS arrival. Nearly all callers (99%) experienced barriers to CPR initiation and/or continuation during the call. The barriers identified were classified into eight categories: reluctance, appropriateness, emotion, bystander physical ability, patient access, leaving the scene, communication failure, caller actions and call-taker instructions. Of these, bystander physical ability was the most prevalent barrier to both CPR initiation and continuation, occurring in 191 (65%) calls, followed by communication failure which occurred in 160 (54%) calls. Callers stopping or interrupting CPR performance due to being fatigued was lower than expected (n = 54, 26% of callers who performed CPR). Barriers to CPR initiation that related to bystander physical ability, caller actions, communication failure, emotion, leaving the scene, patient access, procedural barriers, and reluctance were mostly overcome by the caller (i.e., CPR was performed). CONCLUSION: Barriers to CPR initiation and continuation were commonly experienced by callers, however they were frequently overcome. Future research should investigate the strategies that were successful.

"If you miss that first step in the chain of survival, there is no second step"-Emergency ambulance call-takers' experiences in managing out-of-hospital cardiac arrest calls.

When a person has an out-of-hospital cardiac arrest (OHCA), calling the ambulance for help is the first link in the chain of survival. Ambulance call-takers guide the caller to perform life-saving interventions on the patient before the paramedics arrive at the scene, therefore, their actions, decisions and communication are integral to saving the patient's life. In 2021, we conducted open-ended interviews with 10 ambulance call-takers with the aim of understanding their experiences of managing these phone calls; and to explore their views on using a standardised call protocol and triage system for OHCA calls. We took a realist/essentialist methodological approach and applied an inductive, semantic and reflexive thematic analysis to the interview data to yield four main themes expressed by the call-takers: 1) time-critical nature of OHCA calls; 2) the call-taking process; 3) caller management; 4) protecting the self. The study found that call-takers demonstrated deep reflection on their roles in, not only helping the patient, but also the callers and bystanders to manage a potentially distressing event. Call-takers expressed their confidence in using a structured call-taking process and noted the importance of skills and traits such as active listening, probing, empathy and intuition, based on experience, in order to supplement the use of a standardised system in managing the emergency. This study highlights the often under-acknowledged yet critical role of the ambulance call-taker in being the first member of an emergency medical service that is contacted in the event of an OHCA.

Association between initial presenting level of consciousness and patient acuity - A potential application for secondary triage in emergency ambulance calls.

INTRODUCTION: Conscious state assessment is important for the triage of emergency patients. In this study, we measured the association between ambulance patients' conscious state and high versus lower acuity, with a view to informing telephone triage assessment of conscious state. METHODS: Data were analysed from one year of emergency ambulance incidents in Perth, Western Australia. Patient conscious state at the time of paramedic arrival was compared to acuity (based on paramedic assessment and management). We determined the proportion of high-acuity patients across six levels of consciousness (Alert, Confused, Drowsy, Voice Response, Pain Response, Unresponsive) overall, and within individual protocols of the Medical Priority Dispatch System (MPDS). RESULTS: The proportion of high acuity patients increased with each step across the consciousness scale. Applying conscious state as a binary predictor of acuity, the largest increases occurred moving the threshold from Alert to Confused (22.0-48.6% high acuity) and Drowsy to Voice Response (61.9-89.5% high acuity). The Area Under the Curve (AUC) of the Receiver Operating Characteristic was 0.65. Within individual protocols, the highest AUC was in Cardiac Arrest (0.89), Overdose/Poisoning (0.81), Unknown Problem (0.76), Diabetic Problem, (0.74) and Convulsions/Fitting (0.73); and lowest in Heart problems (0.55), Abdominal Pain (0.55), Breathing Problems (0.55), Back Pain (0.53), and Chest Pain (0.52). CONCLUSION: Based on these proportions of high acuity patients, it is reasonable to consider patients with any altered conscious state a high priority. The value of conscious state assessment for predicting acuity varies markedly between MPDS protocols. These findings could help inform secondary triage of ambulance patients during the emergency call.

Ambulance dispatch prioritisation for traffic crashes using machine learning: A natural language approach.

INTRODUCTION: Demand for emergency ambulances is increasing, therefore it is important that ambulance dispatch is prioritised appropriately. This means accurately identifying which incidents require a lights and sirens (L&S) response and those that do not. For traffic crashes, it can be difficult to identify the needs of patients based on bystander reports during the emergency phone call; as traffic crashes are complex events, often with multiple patients at the same crash with varying medical needs. This study aims to determine how well the text sent to paramedics en-route to the traffic crash scene by the emergency medical dispatcher (EMD), in combination with dispatch codes, can predict the need for a L&S ambulance response to traffic crashes. METHODS: A retrospective cohort study was conducted using data from 2014 to 2016 traffic crashes attended by emergency ambulances in Perth, Western Australia. Machine learning algorithms were used to predict the need for a L&S response or not. The features were the Medical Priority Dispatch System (MPDS) determinant codes and EMD text. EMD text was converted for computation using natural language processing (Bag of Words approach). Machine learning algorithms were used to predict the need for a L&S response, defined as where one or more patients (a) died before hospital admission, (b) received L&S transport to hospital, or (c) had one or more high-acuity indicators (based on an a priori list of medications, interventions or observations. RESULTS: There were 11,971 traffic crashes attended by ambulances during the study period, of which 22.3 % were retrospectively determined to have required a L&S response. The model with the highest accuracy was using an Ensemble machine learning algorithm with a score of 0.980 (95 % CI 0.976-0.984). This model predicted the need for an L&S response using both MPDS determinant codes and EMD text. DISCUSSION: We found that a combination of EMD text and MPDS determinate codes can predict which traffic crashes do and do not require a lights and sirens ambulance response to the scene with a high degree of accuracy. Emergency medical services could deploy machine learning algorithms to improve the accuracy of dispatch to traffic crashes, which has the potential to result in improved system efficiency.

"I'm sorry, my English not very good": Tracking differences between Language-Barrier and Non-Language-Barrier emergency ambulance calls for Out-of-Hospital Cardiac Arrest.

BACKGROUND: One-fifth of Australia's population do not speak English at home. International studies have found emergency calls with language barriers (LB) result in longer delays to out-of-hospital cardiac arrest (OHCA) recognition, and lower rates of bystander cardiopulmonary resuscitation (CPR) and survival. This study compared LB and non-LB OHCA call time intervals in an Australian emergency medical service (EMS). METHODS: The retrospective cohort study measured time intervals from call commencement for primary outcomes: (1) address acquisition; (2) OHCA recognition; (3) CPR initiation; (4) telecommunicator CPR (t-CPR) compressions, in all identified LB calls and a 2:1 random sample of non-LB EMS calls from January to June 2019. Results for time intervals #1, 2, and 4 were benchmarked against the American Heart Association's (AHA) t-CPR minimal acceptable time standards. Patient survival outcomes were compared. RESULTS: We identified 50 (14%) LB calls from a cohort of 353 calls. LB calls took longer than non-LB calls (n=100) for: address acquisition (median 29 vs 14 secs, p<0.001), OHCA recognition (103 vs 85 secs, p=0.02), and CPR initiation (206 vs 164 secs, p=0.01), but not for t-CPR compressions (292 vs 248 secs, p=0.12). Rates of OHCA recognition and 30-day-survival did not differ but smaller proportions of LB calls met the AHA standards. CONCLUSION: Time delays found in LB calls point to phases of the call which need further qualitative investigation to understand how to improve communication. Overall, training call-takers for LB calls may assist caller understanding and cooperation during OHCAs.

'I think he's dead': A cohort study of the impact of caller declarations of death during the emergency call on bystander CPR.

BACKGROUND: In emergency calls for out-of-hospital cardiac arrest (OHCA), dispatchers are instrumental in the provision of bystander cardiopulmonary resuscitation (CPR) through the recruitment of the caller. We explored the impact of caller perception of patient viability on initial recognition of OHCA by the dispatcher, rates of bystander CPR and early patient survival outcomes. METHODS: We conducted a retrospective cohort study of 422 emergency calls where OHCA was recognised by the dispatcher and resuscitation was attempted by paramedics. We used the call recordings, dispatch data, and electronic patient care records to identify caller statements that the patient was dead, initial versus delayed recognition of OHCA by the dispatcher, caller acceptance to perform CPR, provision of bystander-CPR, prehospital return of spontaneous circulation (ROSC), and ROSC on arrival at the Emergency Department. RESULTS: Initial recognition of OHCA by the dispatcher was more frequent in cases with a declaration of death by the caller than in cases without (92%, 73/79 vs. 66%, 227/343, p < 0.001). Callers who expressed such a view (19% of cases) were more likely to decline CPR (38% vs. 10%, adjusted odds ratio 4.59, 95% confidence interval 2.49-8.52, p < 0.001). Yet, 15% (12/79) of patients described as non-viable by callers achieved ROSC. CONCLUSION: Caller statements that the patient is dead are helpful for dispatchers to recognise OHCA early, but potentially detrimental when recruiting the caller to perform CPR. There is an opportunity to improve the rate of bystander-CPR and patient outcomes if dispatchers are attentive to caller statements about viability.

Motor Vehicle Crash Characteristics That Are Predictive of High Acuity Patients: An Analysis of Linked Ambulance and Crash Data.

BACKGROUND: Motor vehicle crashes (MVCs) comprise a significant component of emergency medical service workload. Due to the potential for life-threatening injuries, ambulances are often dispatched at the highest priority to MVCs. However, previous research has shown that only a small proportion of high-priority ambulance responses to MVCs encounter high acuity patients. Alternative methods for triaging patients over the phone are required to reduce the burden of over-triage. One method is to use information readily available at the scene (e.g. whether a person was a motorcyclist, ejection status or whether an airbag deployed) as potential predictors of high acuity. Methods: A retrospective cohort study was conducted of all MVC patients in Perth attended by St John Western Australia between 2014 and 2016. Ambulance data was linked with Police crash data. The outcome variable of interest was patient acuity, where high acuity was defined as where a patient (1) died on-scene or (2) was transported by ambulance on priority one (lights & sirens) from the scene to hospital. Crash characteristics that are predictive of high acuity patients were identified by estimating crude odds ratios and 95% confidence intervals. Results: Of the 18,917 MVC patients attended by SJ-WA paramedics, 6.4% were classified as high acuity patients. The odds of being a high acuity patient was greater for vulnerable road users (motorcyclists, pedestrians and cyclists) than for motor vehicle occupants (OR 3.19, 95% CI, 2.80-3.64). A 'not ambulant patient' (one identified by paramedics as unable to walk or having an injury incompatible with being able to walk) had 15 times the odds of being high acuity than ambulant patients (OR 15.34, 95% CI, 11.48-20.49). Those who were trapped in a vehicle compared to those not trapped (OR 4.68, 95% CI, 3.95-5.54); and those who were ejected (both partial and full) from the vehicle compared to those not ejected (OR 6.49, 95% CI, 4.62-9.12) had higher odds of being high acuity patients. Discussion: There were two important findings from this study: (1) few MVC patients were deemed to be high acuity; and (2) several crash scene characteristics were strong predictors of high acuity patients.

"Sorry, what did you say?" Communicating defibrillator retrieval and use in OHCA emergency calls.

BACKGROUND: The defibrillator prompt, which directs callers to retrieve a defibrillator during out-of-hospital cardiac arrest, is crucial to the emergency call because it can save lives. We evaluated communicative effectiveness of the prompt instated by the Medical Priority Dispatch System™ Version 13, namely: if there is a defibrillator (AED) available, send someone to get it now, and tell me when you have it. METHODS: Using Conversation Analysis and descriptive statistics, we examined linguistic features of the defibrillator sequences (call-taker prompt and caller response) in 208 emergency calls where non-traumatic out-of-hospital cardiac arrest was confirmed by the emergency medical services, and they attempted resuscitation, in the first six months of 2019. Defibrillator sequence durations were measured to determine impact on time to CPR prompt. The proportion of cases where bystanders retrieved defibrillators was also assessed. RESULTS: There was low call-taker adoption of the Medical Priority Dispatch System™ Version 13 prompt (99/208) compared to alternative prompts (86/208) or no prompt (23/208). Caller responses to the Version 13 prompt tended to be longer, more ambiguous or unrelated, and have more instances of repair (utterances to address comprehension trouble). Defibrillators were rarely brought to the scene irrespective of defibrillator prompt utilised. CONCLUSION: While the Version 13 prompt aims to ensure the use of an available automatic external defibrillator, its effectiveness is undermined by the three-clause composition of the prompt and exclusion of a question structure. We recommend testing of a re-phrased defibrillator prompt in order to maximise comprehension and caller action.

Caller resistance to perform cardio-pulmonary resuscitation in emergency calls for cardiac arrest.

A key objective of an emergency call for cardiac arrest is to recruit a bystander to perform cardio-pulmonary resuscitation (CPR) until the ambulance arrives. Emergency medical services worldwide work towards increasing the rate of bystander-CPR, and existing research has identified a number of physical barriers to the provision of bystander-CPR. Yet, little is known about the specific ways in which emergency callers resist recruitment to perform basic first-aid, sometimes in the absence of any physical obstacle. This study investigated 65 emergency calls for cardiac arrest received in Australia in 2014 and 2015, in which the callers initially resisted CPR. We used conversation analysis to examine callers' practices to resist recruitment and call-takers' practices to counter this resistance. We found that callers who resisted CPR typically provided an account. When callers accounted for their resistance on deontic grounds, they expressed that CPR was not a possible course of action (e.g. "I can't do it"). When callers provided an epistemic account, their justification was based on their knowledge or opinion (e.g. "I think it's too late"). Our findings suggest that epistemic resistance can be a barrier to bystander-CPR. We identified two practices used by call-takers to address caller resistance based on epistemics. Providing more context on the purpose of CPR (e.g. "this is to help him in the meantime") seemed effective in persuading callers to perform CPR. By contrast, aligning with the caller's epistemic and deontic rights (e.g. "it's up to you") did not seem effective in persuading callers.

'We're going to do CPR': A linguistic study of the words used to initiate dispatcher-assisted CPR and their association with caller agreement.

BACKGROUND: In emergency ambulance calls for out-of-hospital cardiac arrest (OHCA), dispatcher-assisted cardiopulmonary resuscitation (CPR) plays a crucial role in patient survival. We examined whether the language used by dispatchers to initiate CPR had an impact on callers' agreement to perform CPR. METHODS: We analysed 424 emergency calls relating to cases of paramedic-confirmed OHCA where OHCA was recognised by the dispatcher, the caller was with the patient, and resuscitation was attempted by paramedics. We investigated the linguistic choices used by dispatchers to initiate CPR, and the impact of those choices on caller agreement to perform CPR. RESULTS: Overall, CPR occurred in 85% of calls. Caller agreement was low (43%) when dispatchers used terms of willingness ("do you want to do CPR?"). Caller agreement was high (97% and 84% respectively) when dispatchers talked about CPR in terms of futurity ("we are going to do CPR") or obligation ("we need to do CPR"). In 38% (25/66) of calls where the caller initially declined CPR, the dispatcher eventually secured their agreement by making several attempts at initiating CPR. CONCLUSION: There is potential for increased agreement to perform CPR if dispatchers are trained to initiate CPR with words of futurity and/or obligation.

'She's sort of breathing': What linguistic factors determine call-taker recognition of agonal breathing in emergency calls for cardiac arrest?

BACKGROUND: In emergency ambulance calls, agonal breathing remains a barrier to the recognition of out-of-hospital cardiac arrest (OHCA), initiation of cardiopulmonary resuscitation, and rapid dispatch. We aimed to explore whether the language used by callers to describe breathing had an impact on call-taker recognition of agonal breathing and hence cardiac arrest. METHODS: We analysed 176 calls of paramedic-confirmed OHCA, stratified by recognition of OHCA (89 cases recognised, 87 cases not recognised). We investigated the linguistic features of callers' response to the question "is s/he breathing?" and examined the impact on subsequent coding by call-takers. RESULTS: Among all cases (recognised and non-recognised), 64% (113/176) of callers said that the patients were breathing (yes-answers). We identified two categories of yes-answers: 56% (63/113) were plain answers, confirming that the patient was breathing ("he's breathing"); and 44% (50/113) were qualified answers, containing additional information ("yes but gasping"). Qualified yes-answers were suggestive of agonal breathing. Yet these answers were often not pursued and most (32/50) of these calls were not recognised as OHCA at dispatch. CONCLUSION: There is potential for improved recognition of agonal breathing if call-takers are trained to be alert to any qualification following a confirmation that the patient is breathing.

The linguistic and interactional factors impacting recognition and dispatch in emergency calls for out-of-hospital cardiac arrest: a mixed-method linguistic analysis study protocol.

INTRODUCTION: Emergency telephone calls placed by bystanders are crucial to the recognition of out-of-hospital cardiac arrest (OHCA), fast ambulance dispatch and initiation of early basic life support. Clear and efficient communication between caller and call-taker is essential to this time-critical emergency, yet few studies have investigated the impact that linguistic factors may have on the nature of the interaction and the resulting trajectory of the call. This research aims to provide a better understanding of communication factors impacting on the accuracy and timeliness of ambulance dispatch. METHODS AND ANALYSIS: A dataset of OHCA calls and their corresponding metadata will be analysed from an interdisciplinary perspective, combining linguistic analysis and health services research. The calls will be transcribed and coded for linguistic and interactional variables and then used to answer a series of research questions about the recognition of OHCA and the delivery of basic life-support instructions to bystanders. Linguistic analysis of calls will provide a deeper understanding of the interactional dynamics between caller and call-taker which may affect recognition and dispatch for OHCA. Findings from this research will translate into recommendations for modifications of the protocols for ambulance dispatch and provide directions for further research. ETHICS AND DISSEMINATION: The study has been approved by the Curtin University Human Research Ethics Committee (HR128/2013) and the St John Ambulance Western Australia Research Advisory Group. Findings will be published in peer-reviewed journals and communicated to key audiences, including ambulance dispatch professionals.

'Tell me exactly what's happened': When linguistic choices affect the efficiency of emergency calls for cardiac arrest.

BACKGROUND: Clear and efficient communication between emergency caller and call-taker is crucial to timely ambulance dispatch. We aimed to explore the impact of linguistic variation in the delivery of the prompt "okay, tell me exactly what happened" on the way callers describe the emergency in the Medical Priority Dispatch System®. METHODS: We analysed 188 emergency calls for cases of paramedic-confirmed out-of-hospital cardiac arrest. We investigated the linguistic features of the prompt "okay, tell me exactly what happened" in relation to the format (report vs. narrative) of the caller's response. In addition, we compared calls with report vs. narrative responses in the length of response and time to dispatch. RESULTS: Callers were more likely to respond with a report format when call-takers used the present perfect ("what's happened") rather than the simple past ("what happened") (Adjusted Odds Ratio [AOR] 4.07; 95% Confidence Interval [95%CI] 2.05-8.28, p<0.001). Reports were significantly shorter than narrative responses (9s vs. 18s, p<0.001), and were associated with less time to dispatch (50s vs. 58s, p=0.002). CONCLUSION: These results suggest that linguistic variations in the way the scripted sentences of a protocol are delivered can have an impact on the efficiency with which call-takers process emergency calls. A better understanding of interactional dynamics between caller and call-taker may translate into improvements of dispatch performance.

Association between ambulance dispatch priority and patient condition.

OBJECTIVE: To compare chief complaints of the Medical Priority Dispatch System in terms of the match between dispatch priority and patient condition. METHODS: This was a retrospective whole-of-population study of emergency ambulance dispatch in Perth, Western Australia, 1 January 2014 to 30 June 2015. Dispatch priority was categorised as either Priority 1 (high priority), or Priority 2 or 3. Patient condition was categorised as time-critical for patient(s) transported as Priority 1 to hospital or who died (and resuscitation was attempted by paramedics); else, patient condition was categorised as less time-critical. The χ2 statistic was used to compare chief complaints by false omission rate (percentage of Priority 2 or 3 dispatches that were time-critical) and positive predictive value (percentage of Priority 1 dispatches that were time-critical). We also reported sensitivity and specificity. RESULTS: There were 211 473 cases of dispatch. Of 99 988 cases with Priority 2 or 3 dispatch, 467 (0.5%) were time-critical. Convulsions/seizures and breathing problems were highlighted as having more false negatives (time-critical despite Priority 2 or 3 dispatch) than expected from the overall false omission rate. Of 111 485 cases with Priority 1 dispatch, 6520 (5.8%) were time-critical. Our analysis highlighted chest pain, heart problems/automatic implanted cardiac defibrillator, unknown problem/collapse, and headache as having fewer true positives (time-critical and Priority 1 dispatch) than expected from the overall positive predictive value. CONCLUSION: Scope for reducing under-triage and over-triage of ambulance dispatch varies between chief complaints of the Medical Priority Dispatch System. The highlighted chief complaints should be considered for future research into improving ambulance dispatch system performance.