Increasing neurologically intact survival after out-of-hospital cardiac arrest among elderly: Singapore Experience

Objectives

With more elderly presenting with Out-of-Hospital Cardiac Arrests (OHCAs) globally, neurologically intact survival (NIS) should be the aim of resuscitation. We aimed to study the trend of OHCA amongst elderly in a large Asian registry to identify if age is independently associated with NIS and factors associated with NIS.

Methods

All adult OHCAs aged ≥18 years attended by emergency medical services (EMS) from April 2010 to December 2019 in Singapore was extracted from the Pan-Asian Resuscitation Outcomes Study (PAROS) registry. Cases pronounced dead at scene, non-EMS transported, traumatic OHCAs and OHCAs in ambulances were excluded. Patient characteristics and outcomes were compared across four age categories (18-64, 65-79, 80-89, ≥90). Multivariable logistic regression analysis determined the factors associated with NIS.

Results

19,519 eligible cases were analyzed. OHCA incidence increased with age almost doubling in octogenarians (from 312/100,000 in 2011 to 652/100,000 in 2019) and tripling in those ≥90 years (from 458/100,000 in 2011 to 1271/100,000 in 2019). The proportion of patients with NIS improved over time for the 18-64, 65-79- and 80-89-years age groups, with the greatest improvement in the youngest group. NIS decreased with each increasing year of age and minute of response time. NIS increased in the arrests of presumed cardiac etiology, witnessed and bystander CPR.

Conclusions

Survival with good outcomes has increased even amongst the elderly. Regardless of age, NIS is possible with good-quality CPR, highlighting its importance. End-of-life planning is a complex yet necessary decision that requires qualitative exploration with elderly, their families and care providers.

Improved interpretable machine learning emergency department triage tool addressing class imbalance

Objective

The Score for Emergency Risk Prediction (SERP) is a novel mortality risk prediction score which leverages machine learning in supporting triage decisions. In its derivation study, SERP-2d, SERP-7d and SERP-30d demonstrated good predictive performance for 2-day, 7-day and 30-day mortality. However, the dataset used had significant class imbalance. This study aimed to determine if addressing class imbalance can improve SERP's performance, ultimately improving triage accuracy.

Methods

The Singapore General Hospital (SGH) emergency department (ED) dataset was used, which contains 1,833,908 ED records between 2008 and 2020. Records between 2008 and 2017 were randomly split into a training set (80%) and validation set (20%). The 2019 and 2020 records were used as test sets. To address class imbalance, we used random oversampling and random undersampling in the AutoScore-Imbalance framework to develop SERP+-2d, SERP+-7d, and SERP+-30d scores. The performance of SERP+, SERP, and the commonly used triage risk scores was compared.

Results

The developed SERP+ scores had five to six variables. The AUC of SERP+ scores (0.874 to 0.905) was higher than that of the corresponding SERP scores (0.859 to 0.894) on both test sets. This superior performance was statistically significant for SERP+-7d (2019: Z = -5.843, p < 0.001, 2020: Z = -4.548, p < 0.001) and SERP+-30d (2019: Z = -3.063, p = 0.002, 2020: Z = -3.256, p = 0.001). SERP+ outperformed SERP marginally on sensitivity, specificity, balanced accuracy, and positive predictive value measures. Negative predictive value was the same for SERP+ and SERP. Additionally, SERP+ showed better performance compared to the commonly used triage risk scores.

Conclusions

Accounting for class imbalance during training improved score performance for SERP+. Better stratification of even a small number of patients can be meaningful in the context of the ED triage. Our findings reiterate the potential of machine learning-based scores like SERP+ in supporting accurate, data-driven triage decisions at the ED.

Technology activated community first responders in Singapore: Real-world care delivery & outcome trends

BACKGROUND

Community first responders (CFRs) strengthen the Chain of Survival for out-of-hospital cardiac arrest (OHCA) care. Considerable efforts have been invested in Singapore's CFR program, during the years 2016-2020, by developing an app-based activation system called myResponder. This paper reports on national CFR response indicators to evaluate the real-world impact of these efforts.

METHODS

We matched data from the Singapore Civil Defence Force's CFR registry with the Pan Asian Resuscitation Outcomes Study (PAROS) registry data to calculate performance indicators. These included the number of CFRs receiving and accepting an issued alert per OHCA event. Also calculated were the fraction of OHCA events where CFRs received an issued alert, or accepted the alert, and arrived at the scene either before or after EMS. We also present trends of these indicators and compare the prevalence of these fractions between the CFR-attended and CFR-unattended OHCA events.

RESULTS

Of 6577 alerted OHCA events, 42.7% accepted an alert, 50% of these arrived at the scene and 71% of them arrived before EMS. Almost all CFR response indicators improved over time even for the pandemic year (2020). The fraction of OHCA events where >2 CFRs received an alert increased from 62% to 96%; the same figure for accepting an alert did not change much but >2 CFRs arriving at the scene increased from 0% to 7.5%. The fraction of OHCA events with an automated external defibrillator applied and defibrillation performed by CFR increased from 4.2% to 10.3% and 1.6% to 3%, respectively. Statistically significant differences were observed in these indicators when CFR-attended and CFR-unattended OHCA events were compared.

CONCLUSION

This real-world study shows that activating CFRs using mobile technology can improve community response to OHCA and are bearing fruit in Singapore at a national level. Some targets for improvement and future research are highlighted in this report.

Impact of COVID-19 on barriers to dispatcher-assisted cardiopulmonary resuscitation in adult out-of-hospital cardiac arrests in Singapore

OBJECTIVE

Fewer out-of-hospital cardiac arrest (OHCA) patients received bystander cardiopulmonary resuscitation during the COVID-19 pandemic in Singapore. We investigated the impact of COVID-19 on barriers to dispatcher-assisted cardiopulmonary resuscitation (DA-CPR).

METHODS

We reviewed audio recordings of all calls to our national ambulance service call centre during the pandemic (January-June 2020) and pre-pandemic (January-June 2019) periods. Our primary outcome was the presence of barriers to DA-CPR. Multivariable logistic regression was used to assess the effect of COVID-19 on the likelihood of barriers to and performance of DA-CPR, adjusting for patient and event characteristics.

RESULTS

There were 1241 and 1118 OHCA who were eligible for DA-CPR during the pandemic (median age 74 years, 61.6 % males) and pre-pandemic (median age 73 years, 61.1 % males) periods, respectively. Compared to pre-pandemic, there were more residential and witnessed OHCA during the pandemic (87 % vs 84.9 % and 54 % vs 38.1 %, respectively); rates of DA-CPR were unchanged (57.3 % vs 61.1 %). COVID-19 increased the likelihood of barriers to DA-CPR (aOR 1.47, 95 % CI: 1.25-1.74) but not performance of DA-CPR (aOR 0.86, 95 % CI: 0.73 - 1.02). Barriers such as 'patient status changed' and 'caller not with patient' increased during COVID-19 pandemic. 'Afraid to do CPR' markedly decreased during the pandemic; fear of COVID-19 transmission made up 0.5 % of the barriers.

CONCLUSION

Barriers to DA-CPR were encountered more frequently during the COVID-19 pandemic but did not affect callers' willingness to perform DA-CPR. Distancing measures led to more residential arrests with increases in certain barriers, highlighting opportunities for public education and intervention.

Multifactorial influences underpinning a decision on COVID-19 vaccination among healthcare workers: a qualitative analysis

COVID-19 vaccination in healthcare workers (HCW) is essential for improved patient safety and resilience of health systems. Despite growing body of literature on the perceptions of COVID vaccines in HCWs, existing studies tend to focus on reasons for 'refusing' the vaccines, using surveys almost exclusively. To gain a more nuanced understanding, we explored multifactorial influences underpinning a decision on vaccination and suggestions for decision support to improve vaccine uptake among HCWs in the early phase of vaccination rollout. Semi-structured interviews were undertaken with thirty-three HCWs in Singapore. Transcribed data was thematically analyzed. Decisions to accept vaccines were underpinned by a desire to protect patients primarily driven by a sense of professional integrity, collective responsibility to protect others, confidence in health authorities and a desire to return to a pre-pandemic way of life. However, there were prevailing concerns with respect to the vaccines, including long-term benefits, safety and efficacy, that hampered a decision. Inadequate information and social media representation of vaccination appeared to add to negative beliefs, impeding a decision to accept while low perceived susceptibility played a moderate role in the decision to delay or decline vaccination. Participants made valuable suggestions to bolster vaccination. Our findings support an approach to improving vaccine uptake in HCWs that features routine tracking and transparent updates on vaccination status, use of institutional platforms for sharing of experience, assuring contingency management plans and tailored communications to emphasize the duty of care and positive outlook associated with vaccination.

An essential review of Singapore's response to out-of-hospital cardiac arrests: improvements over a ten-year period

Care for patients who experience out-of-hospital cardiac arrest (OHCA) has rapidly evolved in the past decade. Increased sophistication of care in the community, emergency medical services (EMS) and hospital setting is associated with improved patient-centred outcomes. Notably, Utstein survival doubled from 11.6% to 23.1% between 2011 and 2016. These achievements involved collaboration between policymakers, clinicians and researchers, and were made possible by a strategic interplay of policy, research and implementation. We review the development and current state of OHCA in Singapore using primary population-based data from the Pan-Asian Resuscitation Outcomes Study and an unstructured search of research databases. We discuss the roles of important milestones in policy, community, dispatch, EMS and hospital interventions. Finally, we relate these interventions to relevant processes and outcomes, such as the relationship between the strategic implementation of bystander cardiopulmonary resuscitation and placement of automated external defibrillator with return of spontaneous circulation, survival to discharge and survival with favourable neurological outcomes.

Nation-Wide Observational Study of Cardiac Arrests Occurring in Nursing Homes and Nursing Facilities in Singapore

Introduction: Nursing home (NH) residents with out-of-hospital cardiac arrests (OHCA) have unique resuscitation priorities. This study aimed to describe OHCA characteristics in NH residents and identify independent predictors of survival. Materials and Methods: OHCA cases between 2010–16 in the Pan-Asian Resuscitation Outcomes Study were retrospectively analysed. Patients aged <18 years old and non-emergency cases were excluded. Primary outcome was survival at discharge or 30 days. Good neurological outcome was defined as a cerebral performance score between 1–2. Results: A total of 12,112 cases were included. Of these, 449 (3.7%) were NH residents who were older (median age 79 years, range 69–87 years) and more likely to have a history of stroke, heart and respiratory diseases. Fewer NH OHCA had presumed cardiac aetiology (62% vs 70%, P <0.01) and initial shockable rhythm (8.9% vs 18%, P <0.01), but had higher incidence of bystander cardiopulmonary resuscitation (74% vs 43%, P <0.01) and defibrillator use (8.5% vs 2.8%, P <0.01). Non-NH (2.8%) residents had better neurological outcomes than NH (0.9%) residents (P <0.05). Factors associated with survival for cardiac aetiology included age <65 years old, witnessed arrest, bystander defibrillator use and initial shockable rhythm; for non-cardiac aetiology, these included witnessed arrest (adjusted odds ratio [AOR] 3.8, P <0.001) and initial shockable rhythm (AOR 5.7, P <0.001). Conclusion: Neurological outcomes were poorer in NH survivors of OHCA. These findings should inform health policies on termination of resuscitation, advance care directives and do-not-resuscitate orders in this population. Ann Acad Med Singapore 2020;49:285–93 Key words: Advance care directives, Do-not-resuscitate orders, Geriatrics, Out-of- hospital, Palliative care

Impact of Air Pollution and Trans-Boundary Haze on Nation-Wide Emergency Department Visits and Hospital Admissions in Singapore

Introduction: Air pollution is associated with adverse health outcomes. However, its impact on emergency health services is less well understood. We investigated the impact of air pollution on nation-wide emergency department (ED) visits and hospital admissions to public hospitals in Singapore. Materials and Methods: Anonymised administrative and clinical data of all ED visits to public hospitals in Singapore from January 2010 to December 2015 were retrieved and analysed. Primary and secondary outcomes were defined as ED visits and hospital admissions, respectively. Conditional Poisson regression was used to model the effect of Pollutant Standards Index (PSI) on each outcome. Both outcomes were stratified according to subgroups defined a priori based on age, diagnosis, gender, patient acuity and time of day. Results: There were 5,791,945 ED visits, of which 1,552,187 resulted in hospital admissions. No significant association between PSI and total ED visits (Relative risk [RR], 1.002; 99.2% confidence interval [CI], 0.995–1.008; P = 0.509) or hospital admissions (RR, 1.005; 99.2% CI, 0.996–1.014; P = 0.112) was found. However, for every 30-unit increase in PSI, significant increases in ED visits (RR, 1.023; 99.2% CI, 1.011–1.036; P = 1.24 × 10˗6) and hospital admissions (RR, 1.027; 99.2% CI, 1.010–1.043; P = 2.02 × 10˗5) for respiratory conditions were found. Conclusion: Increased PSI was not associated with increase in total ED visits and hospital admissions, but was associated with increased ED visits and hospital admissions for respiratory conditions in Singapore. Key words: Epidemiology, Healthcare utilisation, PSI, Public health, Time series

Factors Contributing to Inappropriate Visits of Frequent Attenders and Their Economic Effects at an Emergency Department in Singapore

OBJECTIVES

This study aimed to determine which factors contribute to frequent visits at the emergency department (ED) and what proportion were inappropriate in comparison with nonfrequent visits.

METHODS

This study was a retrospective, case-control study comparing a random sample of frequent attenders and nonfrequent attenders, with details of their ED visits recorded over a 12-month duration. Frequent attenders were defined as patients with four or more visits during the study period.

RESULTS

In comparison with nonfrequent attenders (median age = 45.0 years, interquartile range [IQR] = 28.0 to 61.0 years), frequent attenders were older (median = 57.5 years, IQR = 34.0 to 74.8 years; p = 0.0003). They were also found to have more comorbidities, where 53.3% of frequent attenders had three or more chronic illnesses compared to 14% of nonfrequent attenders (p < 0.0001), and were often triaged to higher priority (more severe) classes (frequent 52.2% vs. nonfrequent 37.6%, p = 0.0004). Social issues such as bad debts (12.7%), heavy drinking (3.3%), and substance abuse (2.7%) were very low in frequent attenders compared to Western studies. Frequent attenders had a similar rate of appropriate visits to the ED as nonfrequent attenders (55.2% vs. 48.1%, p = 0.0892), but were more often triaged to P1 priority triage class (6.7% vs. 3.2%, p = 0.0014) and were more often admitted for further management compared to nonfrequent attenders (47.5% vs. 29.6%, p < 0.001). The majority of frequent attender visits were appropriate (55.2%), and of these, 81.1% resulted in admission. For the same number of patients, total visits made by frequent attenders ($174,247.60) cost four times as much as for nonfrequent attenders ($40,912.40). This represents a significant economic burden on the health care system.

CONCLUSIONS

ED frequent attenders in Singapore were associated with higher age and presence of multiple comorbidities rather than with social causes of ED use. Even in integrated health systems, repeat ED visits are frequent and expensive, despite minimal social causes of acute care. EDs in aging populations must anticipate the influx of vulnerable, elderly patients and have in place interventional programs to care for them.

Effect of Location of Out-of-Hospital Cardiac Arrest on Survival Outcomes

Introduction: This study aims to study how the effect of the location of patient collapses from cardiac arrest, in the residential and non-residential areas within Singapore, relates to certain survival outcomes. Materials and Methods: A retrospective cohort study of data were done from the Cardiac Arrest and Resuscitation Epidemiology (CARE) project. Out-of-hospital cardiac arrest (OHCA) data from October 2001 to October 2004 (CARE) were used. All patients with OHCA as confirmed by the absence of a pulse, unresponsiveness and apnoea were included. All events had occurred in Singapore. Analysis was performed and expressed in terms of the odds ratio (OR) and the corresponding 95% confidence interval (CI). Results: A total of 2375 cases were used for this analysis. Outcomes for OHCA in residential areas were poorer than in non-residential areas—1638 (68.9%) patients collapsed in residential areas, and 14 (0.9%) survived to discharge. This was significantly less than the 2.7% of patients who survived after collapsing in a non-residential area (OR 0.31 [0.16 – 0.62]). Multivariate logistic regression analysis showed that location alone had no independent effect on survival (adjusted OR 1.13 [0.32 – 4.05]); instead, underlying factors such as bystander CPR (OR 3.67 [1.13 – 11.97]) and initial shockable rhythms (OR 6.78 [1.95 – 23.53]) gave rise to better outcomes. Conclusion: Efforts to improve survival from OHCA in residential areas should include increasing CPR by family members, and reducing ambulance response times. Key words: Emergency Medical Services, Non-residential, Prehospital, Residential

Recognition and Treatment of Out-of-Hospital Cardiac Arrests by Non-Emergency Ambulance Services in Singapore

Introduction: Prompt recognition of cardiac arrest and initiation of cardiopulmonary resuscitation (CPR) and defibrillation is necessary for good outcomes from out-of-hospital cardiac arrest (OHCA). This study aims to describe the recognition and treatment of OHCA in patients conveyed by non-emergency ambulance services (EAS) in Singapore. Materials and Methods: This is a multi-centre, retrospective chart review, of cases presenting to public emergency departments (EDs), conveyed by non-EAS and found to be in cardiac arrest upon ED arrival. The study was from October 2002 to August 2009. The following variables were examined: ability to recognise cardiac arrest, whether CPR was carried out by the ambulance crew and whether an automated external defibrillator (AED) was applied. Results: Eighty-six patients were conveyed by non-EAS and found to be in cardiac arrest upon ED arrival. Mean age was 63 years (SD 21.8), 70.9% were males. A total of 53.5% of arrests occurred in the ambulance while 70.9% were found to be asystolic upon ED arrival. Seven patients had a known terminal illness. Survival to discharge was 3.5%. Cardiac arrest went unrecognised by the ambulance crew in 38 patients (44.2%). CPR was performed in 35 patients (40.7%) of the 86 patients and AED was applied in only 10 patients (11.6%). Conclusion: We found inadequate recognition and delayed initiation of treatment for OHCA. Possible reasons include a lack of training in patient monitoring and detection of cardiac arrest, lack of CPR training, lack of confidence in performing CPR, lack of AEDs on ambulances and lack of training in their use. Key words: Automated external defibrillator (AED), Cardiopulmonary resuscitation (CPR), Emergency medical services, Prehospital

An Eight Year Review of Exercise-related Cardiac Arrests

Introduction: Exercise-related cardiac arrest is uncommon, however it is devastating when it occurs in otherwise healthy adults. This study aims to identify the characteristics of exercise-related cardiac arrest in the study population and estimate the overall survival rate. Materials and Methods: This is a retrospective observational study of exercise-related cardiac arrest in Singapore. Patients with exercise-related out of hospital cardiac arrest (OHCA) were selected from the Cardiac Arrest and Resuscitation Epidemiology (CARE) database, which is a prospective cardiac arrest registry, derived from ambulance records, emergency department and hospital discharge records. Patient characteristics, cardiac arrest circumstances and outcomes were studied. Results: Fifty-five cases of exercise-related cardiac arrests were identified from December 2001 to January 2008. Mean age was 50.9 years with a male predominance of 96.4%. Eighty percent of the exercise-related cardiac arrests were witnessed, however only 58.2% of the patients received bystander cardiopulmonary resuscitation (CPR). The first presenting rhythm was ventricular fibrillation (VF) in 40% of the patients, followed by asystole (38.2%). Of 96.2% of the patients who died from cardiac causes, coronary artery disease was the main etiology for 54%. The 30-day survival rate was 5.5%. Conclusion: We found that exercise-related cardiac arrest causes significant mortality in our community. Increased CPR training among the public, easy access to defibrillators and faster emergency medical service (EMS) response time could improve the outcome of exercise-related cardiac arrests. A comprehensive pre-participation screening for competitive exercises should be outlined for primary prevention of exercise-related cardiac arrest. A better reporting system for exercise-related cardiac arrest is needed. Key words: Sudden death, Survival

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

An Observational, Prospective Study to Determine the Ease of Vascular Access in Adults Using a Novel Intraosseous Access Device

Introduction: Intraosseous access is an alternative to conventional intravenous access when access is difficult or impossible in the adult population. The EZ-IOTM is a novel intraosseous access device designed for use in adults, utilising a powered driver. Materials and Methods: A prospective, observational study involving a convenience sample of 25 medical students, physicians and nursing staff recruited as study subjects to secure intraosseous access using the EZ-IOTM powered drill device, on a bone model. Results: Twenty-three (92%) of the 25 study subjects required only 1 attempt at placing the EZ-IOTM. There were 24 (96%) successful placements of the EZ-IOTM. The average time taken to place the EZ-IOTM was 13.9 seconds. Twenty (87%) of 23 participants reported easier placement with the EZ-IOTM than an intravenous cannula. The average time taken for the physicians, nursing staff and medical students was 3.71 (± SD 1.70) seconds, 7.88 (± SD 4.02) seconds and 33.7 (24.5), respectively. Overall mean difficulty of insertion score (VAS) was 3.1 (± SD 1.9). Conclusion: The intraosseous access device evaluated in this study appears to be easy to use with high success rates of insertion with inexperienced participants. There is potential for use in the Emergency Department. Key words: Emergency department, Intravascular infusion, Resuscitation, Shock

Observational Study to Determine Factors Associated with Blood Sample Haemolysis in the Emergency Department

Introduction: Haemolysis of blood samples is a common problem encountered in the Emergency department (ED). It leads to inaccurate blood results and has cost implications as blood samples very often have to be retaken. The purpose of our study was to determine which factors in blood sampling were associated with higher rates of haemolysis. Materials and Methods: An observational convenience sample of all patients presenting to the ED requiring blood urea and electrolyte (UE) analysis were eligible for our study. Questionnaires were distributed to the doctors and nurses conducting blood sampling to determine the method used and outcome data were collected after the samples were processed. Results: Out of 227 UE samples analysed, 45 (19.8%) were haemolysed. Various factors, including method (IV cannulation or venepuncture), system (syringe or vacutainer), operator, rate of blood flow, difficulty of cannulation/venepuncture and source of blood (arterial or venous), were analysed, but their effects on haemolysis were not statistically significant (P >0.05). However, the use of the vacutainer system was associated with the highest rates of haemolysis [adjusted odds ratio (OR), 6.0; 95% confidence interval (CI), 2.3 to 15.1]. Conclusion: We found blood sampling with the vacutainer system to have increased rates of haemolysis. This could potentially change attitudes towards equipment used for blood sampling in the ED. Key words: Chemistry testing, Emergency department, Sample haemolysis, Venepuncture, Venous cannulation