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Paramedic exposure to out-of-hospital cardiac arrest is rare and declining in Victoria, Australia
Resuscitation 89 (2015) 93–98
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Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Clinical Paper
Paramedic exposure to out-of-hospital cardiac arrest is rare and declining in Victoria, Australia夽 Kylie Dyson a,b,∗ , Janet Bray a,c,d,e , Karen Smith a,b,c , Stephen Bernard a,b,d , Lahn Straney a , Judith Finn a,c,e a
Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia Ambulance Victoria, Victoria, Australia c Discipline of Emergency Medicine, University of Western Australia, Perth, Australia d Alfred Hospital, Melbourne, Australia e School of Nursing and Midwifery, Curtin University, Perth, Australia b
a r t i c l e
i n f o
Article history: Received 10 October 2014 Accepted 21 January 2015 Keywords: Out-of-hospital cardiac arrest Resuscitation Workload Experience Exposure Clinical competence
a b s t r a c t Background and objective: Paramedic exposure to out-of-hospital cardiac arrest (OHCA) may be an important factor in skill maintenance and quality of care. We aimed to describe the annual exposure rates of paramedics in the state of Victoria, Australia. Methodology: We linked data from the Victorian Ambulance Cardiac Arrest Registry (VACAR) and Ambulance Victoria’s employment dataset for 2003–2012. Paramedics were ‘exposed’ to an OHCA if they attended a case where resuscitation was attempted. Individual rates were calculated for average annual exposure (number of OHCA exposures for each paramedic/years employed in study period) and the average number of days between exposures (total paramedic-days in study/total number of exposures in study). Results: Over 10-years, there were 49,116 OHCAs and 5673 paramedics employed. Resuscitation was attempted in 44% of OHCAs. The typical ‘exposure’ of paramedics was 1.4 (IQR = 0.0–3.0) OHCAs per year. Mean annual OHCA exposure declined from 2.8 in 2003 to 2.1 in 2012 (p = 0.007). Exposure was significantly less in those: employed part-time (p < 0.001); in rural areas (p < 0.001); and with lower qualifications (p < 0.001). Annual exposure to paediatric and traumatic OHCAs was particularly low. It would take paramedics an average of 163 days to be exposed to an OHCA and up to 12.5 years for paediatric OHCAs, which occur relatively rarely. Conclusions: Exposure of individual paramedics to resuscitation is low and has decreased over time. This highlights the importance of supplementing paramedic exposure with other methods, such as simulation, to maintain resuscitation skills particularly in those with low exposure and for rare case types. © 2015 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Out-of-hospital cardiac arrest (OHCA) is a leading cause of death worldwide.1 Commonly, survival from OHCA is less than 10%, without substantial improvement seen internationally in the last 30 years.2 The quality of resuscitation care provided by paramedics has
夽 A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2014.08.027. ∗ Corresponding author at: Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, Level 5, 99 Commercial Road, Melbourne, VIC 3004, Australia. E-mail address: [email protected] (K. Dyson). http://dx.doi.org/10.1016/j.resuscitation.2015.01.023 0300-9572/© 2015 Elsevier Ireland Ltd. All rights reserved.
been identified as one contributor to low survival.3–7 Poor resuscitation performance and low OHCA survival could be the result of paramedics not gaining enough exposure to OHCA to develop and maintain competency in their resuscitation skills. Current evidence suggests that paramedic exposure to OHCA is low; with median rates varying between 4 and 9 cases per year.8–11 However, many of these estimates are crudely calculated11–13 and may not accurately reflect the true exposure of paramedics to resuscitation. Furthermore, there is no evidence describing regional differences in exposure (e.g. metropolitan versus rural) nor exposure to subgroups of patients that require modified or specific skills (e.g. paediatrics and trauma). The primary aim of this study was to describe the average overall paramedic exposure to OHCA cases and in specific patient
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subgroups. A secondary aim was to determine if we could derive a crude estimate of paramedic exposure to OHCA using routinely collected data and determine whether this value accurately reflects actual exposure. 2. Methods This study is a retrospective analysis of prospectively collected, linked data from 2003 to 2012 from the Victorian Ambulance Cardiac Arrest Registry (VACAR)14 and Ambulance Victoria’s (AV) employment dataset. This study was approved by the Monash University Human Research Ethics Committee (project number: CF13/971 – 2013000471). 2.1. Setting The study was set in the Australian state of Victoria which covers an area of 227,000 km.15 Victoria has a population of 5.7 million, most (75%) of whom live in the capital city of Melbourne.15 The ageadjusted incidence of presumed cardiac aetiology OHCA in Victoria is 76.7 per 100,000 adults.16 AV is the sole provider of emergency medical services (EMS) in the state.14 AV delivers a primarily two-tiered EMS, with advanced life support (ALS) and intensive care paramedics. There are also basic life support (BLS) responders, the majority of whom operate on a voluntary basis in rural areas. Fire fighters also provide a first response in select areas of Melbourne and rural communities. Paramedics in Victoria are currently required to have a three year bachelor degree in paramedicine followed by a 12-month in field graduate year and intensive care paramedics have an additional postgraduate diploma in emergency health. There is no formalised ALS accreditation or mandatory recertification of resuscitation skills for AV paramedics after university training. Where available, two intensive care paramedics and two ALS paramedics are concurrently dispatched to each OHCA. OHCA patients are managed according to AV clinical practice guidelines,17 which are based on recommendations by the Australian Resuscitation Council.18 All ALS paramedics can administer intravenous adrenaline, perform manual defibrillation and insert supraglottic airways. In addition, intensive care paramedics are able to administer amiodarone, perform endotracheal intubation (ETI), insert intraosseous cannulae and provide advanced post resuscitation care (rapid sequence induction, sedation, therapeutic cooling and adrenaline infusion). AV paramedics can elect to withhold resuscitation where there is evidence of body decomposition, rigour mortis or injuries incompatible with life; or where the presenting rhythm is asystole and cardiac arrest duration is greater than 10 min. Resuscitation can be discontinued at the scene if ALS has been provided for at least 30 min, the patient is not in a shockable rhythm and there are currently no other signs of life present.17 2.2. Data sources The VACAR collects Utstein19 data elements for all OHCAs attended by EMS in Victoria. The aetiology of OHCA cases is presumed to be cardiac when no other cause is recorded on the patient care record (e.g. trauma). All OHCAs that occurred between 1 January 2003 and 31 December 2012 were included in this study. AV’s employment dataset contains information about the qualification held by paramedics, the duration of their employment and whether they are employed fulltime. The employment data captured was current as of the 31st of December 2012 or the paramedic’s last day of duty. We included all AV paramedics who were ‘operational’ (i.e. available to be exposed to OHCA cases) at some time during the study period. We classified paramedics as
working in a rural location if they treated OHCAs that occurred outside the city of Melbourne and, therefore, we were unable to determine the location of paramedics who did not attend an OHCA during the study period. Over 99% of all OHCA cases from VACAR where EMS resuscitation was attempted were linked to one or more paramedics in the AV employment dataset. 2.3. Definitions We considered paramedics to have ‘exposure’ to OHCA if they attended an OHCA case where EMS resuscitation was attempted (CPR and/or defibrillation). Given we were unable to determine which individual paramedic performed which resuscitation procedure, paramedics were considered to have ‘exposure’ to a procedure or skill if they were in attendance when it was performed and they were qualified to perform it (i.e. all intensive care paramedics at a case were considered to have been exposed to ETI if the patient was intubated). We measured experience from each paramedic’s first day of duty until their last day of duty or the last day of the study if they were still employed. To estimate the typical exposure of a paramedic to OHCA, we first calculated the annual average exposure for each paramedic by dividing the number of OHCAs they attended by the years that they were employed during the study period. To provide an estimate of the typical exposure we then took the median of those values. We calculated the average number of days between exposures to OHCA by dividing the total number of paramedic-days in the dataset by the number of exposures in the dataset. We defined paramedic-days as the number of days that paramedics were employed by AV during the study period. We also calculated a crude estimate of paramedic exposure to OHCA using information commonly available to EMS providers. We calculated the crude estimate by multiplying the total number of resuscitations attempted per year by the number of paramedics normally dispatched to OHCA (four in AV) and dividing this by the number of paramedics employed. 2.4. Statistical analysis We compared typical exposure between paramedic subgroups using the Mann–Whitney test and we used linear regression to analyse trends over the study period. We compared the crude estimate of paramedic exposure with mean exposure using concordance correlation20 and Pearson’s correlation. Statistical analyses were performed using Stata 12 (StataCorp, USA) and pvalues less than 0.05 were considered statistically significant. 3. Results 3.1. Characteristics of OHCA cases Paramedics in Victoria attended 49,116 OHCAs in the 10 year study period. Of these, 21,636 cases (44%) had paramedic attempted resuscitation. The characteristics of OHCA cases are provided in Table 1. A median of four paramedics (IQR 2–4) in two ambulances (IQR 1–2) attended cases that received an attempted resuscitation. The majority of attempted resuscitations (80%) had at least one intensive care paramedic on scene, however, they were only the first on scene 35% of the time. When an intensive care paramedic was not the first on scene, they typically arrived 5 min (IQR 1–10) after the first team. 3.2. Characteristics of paramedics There were a total of 5673 paramedics employed during the study period (Table 2). Paramedics had a median of 5.6 years of
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Table 1 Characteristics of all OHCAs attended by Ambulance Victoria, 2003–2012.
Number (%) Age (years; median [IQR]) Child (<18 years) (%) Female (%) Public location (%) Witnessed (%) Bystander Paramedic Bystander CPR (%) Primary suspected cause of arrest (%) Cardiac Trauma Terminal Overdose Hanging Respiratory Initial rhythm (%) Asystole PEA VF VT Unknown Rural location EMS response time (min; median [IQR])a Number of paramedics attending (median [IQR]) Number of teams attending (median [IQR]) Survival (%) Shockable
All OHCA
Resuscitation attempted
49,116 69 (52–80) 1082 (2) 16,619 (34) 9545 (19)
21,650 (44) 67 (52–79) 720 (3) 6812 (31) 5566 (26)
14,619 (30) 3663 (7) 11,725 (24)
10,666 (49) 3219 (15) 9261 (43)
3953 (14) 444 (2) 2464 (9)
34,540 (70) 3782 (8) 3062 (6) 2407 (5) 2102 (4) 1827 (4)
16,419 (76) 1014 (5) 861 (4) 776 (4) 404 (2) 1284 (6)
18,121 (66) 2768 (10) 2201 (8) 1631 (6) 1698 (6) 543 (2)
35,469 (72) 6120 (13) 6542 (13) 369 (1) 616 (1) 14,464 (29) 8 (6–12) 2 (2–4) 1 (1–2)
No resuscitation attempted 27,466 (56) 70 (51–82) 362 (1) 9807 (36) 3979 (14)
8863 (41) 5510 (25) 6483 (30) 350 (2) 444 (2) 5508 (25) 8 (6–11) 4 (2–4) 2 (1–2) 2481 (11) 1841 (27)
26,606 (97) 610 (2) 59 (0) 19 (0) 172 (1) 8956 (33) 8 (6–12) 2 (2–2) 1 (1–1)
IQR, inter quartile range; CPR, cardiopulmonary resuscitation; PEA, pulse-less electrical activity; VF, ventricular fibrillation; VT, ventricular tachycardia; EMS, emergency medical service. a Excludes EMS witnessed.
experience. The majority of paramedics were ALS qualified (59%) and employed fulltime (66%). Of those paramedics who attended an OHCA (n = 4274), 60% were employed in a metropolitan area. 3.3. Paramedic exposure to OHCA with attempted resuscitation The typical exposure of paramedics was 1.4 (IQR 0.0–3.0) OHCA cases per year (Table 3). During the study period, 28% of paramedics did not attempt resuscitation on any OHCA patients. On average, 42% of paramedics attended less than one OHCA per year and only 3% attended ten or more (Fig. 1). Across the entire
Table 2 Characteristics of operational Ambulance Victoria paramedics, 2003–2012.
a
Location unknown for paramedics with no OHCA exposures.
5673 (100) 3729 (66) 1934 (34) 2579 (45) 1695 (30) 1399 (25)a 595 (11) 3371 (59) 1521 (27) 186 (3) 5.6 (3–12) 14.0 (8–21) 5.0 (2–11) 4.5 (2–8) 5.0 (2–10) 5.0 (0–15) 1587 (28) 1399 (25)
45%
42%
40%
Percentage of paramedics
Number (%) Fulltime (%) Part-time/casual (%) Location (%) Metropolitan Rural Unknown Qualification (%) Intensive care ALS BLS Unknown Experience (years; median [IQR]) Intensive care ALS BLS Time in study (years, median [IQR]) OHCA exposure during study (median [IQR]) No exposure to OHCA with attempted resuscitation during study (%) No exposure to any OHCA during study (includes resuscitation not attempted [%])
paramedic cohort exposure to paediatric and traumatic OHCAs was particularly low (Table 3). The typical exposure to OHCA where defibrillation or post-arrest management were performed was less than one per year. OHCA exposure was significantly lower among those paramedics who (i) were based in a rural area, (ii) were not employed in fulltime positions or, (iii) held a lower qualification (Table 3). Metropolitan intensive care paramedics (n = 414) had the highest annual exposure; 7.5 (IQR 4.4–10.7) OHCA cases per year. However, rural intensive care paramedics (n = 169) had significantly lower exposure to OHCA, (2.8, IQR 1.5–4.3, p < 0.001) which was much closer to that of ALS paramedics (2.1, IQR 1.1–3.1). In addition, metropolitan intensive care paramedics had significantly higher exposure to OHCA ETI (6.1, IQR 3.7–8.9) than their rural intensive care counterparts (2.3, IQR 1.2–3.4, p < 0.001).
35% 30% 25% 20%
17%
16%
15%
10%
10%
6%
6% 3%
5% 0% <1
1<2
2<3
3<4
4<5
5<10
≥10
Average annual OHCA exposure Fig. 1. Distribution of the average annual paramedic exposure to OHCA with attempted resuscitation in Victoria, 2003–2012.
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Table 3 Paramedic exposure to resuscitation skills and OHCA with attempted resuscitation by paramedic and patient subgroups in Victoria, 2003–2012. Exposure
Median annual OHCA exposures (IQR)
All OHCA (n = 21,656) Paediatric (n = 720) Trauma (n = 1014) Paramedic witnessed (n = 3219) Treatment exposure First team Defibrillation ETI IV Adrenaline ROSC care
1.4 (0.0–3.0) 0.0 (0.0–0.1) 0.0 (0.0–0.1) 0.1 (0.0–0.4)
163 (0.4 years) 4566 (12.5 years) 3459 (9.5 years) 1099 (3.0 years)
0.9 (0.0–1.9) 0.6 (0.0–1.5) 4.5 (2.1–7.7) 1.6 (0.8–2.6) 0.4 (0.0–1.1)
314 (0.9 years) 325 (0.9 years) 73 (0.2 years) 163 (0.4 years) 406 (1.1 years)
Paramedic subgroups Employment locationa Metropolitan Rural Employment status Fulltime Part-time/casual Qualification Intensive care Advanced life support Basic life support
p-Value
Average days between OHCA exposures
2.8 (1.8–4.2) 1.2 (0.4–2.1)
ref <0.001
99 (0.3 years) 261 (0.7 years)
2.3 (1.2–3.7) 0.8 (0.3–1.8)
ref <0.001
124 (0.3 years) 603 (1.6 years)
5.6 (2.6–9.4) 2.1 (1.1–3.1) 0.0 (0.0–0.0)
ref <0.001 <0.001
59 (0.2 years) 172 (0.5 years) 2765 (7.6 years)
OHCA, out-of-hospital cardiac arrest; IQR, inter quartile range; ETI, endotracheal intubation; IV, intravenous; ROSC, return of spontaneous circulation. a Excludes paramedics with no exposure because location was unable to be determined.
3.4. Duration between paramedic exposures to OHCA with attempted resuscitation
3.6. Crude estimation of paramedic exposure to OHCA with attempted resuscitation
There were 11,400,602 paramedic-days in the study period and 69,913 exposures to OHCA with attempted resuscitation. On average, paramedics were exposed to one OHCA for every 163 days of employment (11,400,602/69,913); while it would take paramedics 12.5 years to be exposed to a paediatric OHCA (Table 3).
The crude estimate of paramedic exposure was 2.7 OHCAs per year, and generally overestimated mean exposure by approximately 0.5 cases per year (Fig. 3). There was moderate concordance between the estimated crude exposure and the calculated mean paramedic exposure (Fig. 3) (concordance = 0.47, 95% CI: 0.22–0.72). However the correlation was high (r = 0.97) suggesting that the differences were systematic and that a more accurate measure of the mean number of paramedics in attendance could improve this estimate.
3.5. Trends over the study period The mean number of OHCA cases that paramedics were exposed to, significantly declined from 2.8 in 2003 to 2.1 in 2012 (p = 0.007) (Fig. 2a). This was despite a significant increase in the rate of attempted resuscitations (41% in 2003 to 57% in 2012, p = 0.02). Over the same period, there were significant increases in the percentage of employees who were part-time (20% vs. 34%, p < 0.001) or BLS (14% vs. 20%, p = 0.002) and a significant decline in the percentage of intensive care paramedics who made up the workforce (18% vs. 10%, p < 0.001) (Fig. 2b).
Our results indicate that the typical paramedic was only exposed to 1.4 attempted resuscitations per year, and that this exposure has declined over time. This rate indicates that paramedics work an average of 163 days between cases. Exposure was particularly low for rare case types, specific skills, and across subgroups of paramedics.
b 3.1
40%
2.9
35%
Percentage of paramedics
Mean number of OHCA exposures
a
4. Discussion
2.7 2.5 2.3 2.1 1.9 1.7
25% 20% 15% 10% 5% 0% 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
1.5
2003
30%
2004
2005
2006
2007
2008 Year
2009
2010
2011
2012
Year Part-me p<0.001
BLS p=0.002
Intensive care p<0.001
Fig. 2. (a) Average annual paramedic exposure to OHCA with attempted resuscitation (with 95% CI) in Victoria, 2003–2012. (b) Temporal changes in the Victorian Paramedic workforce composition 2003–2012.
K. Dyson et al. / Resuscitation 89 (2015) 93–98
Number of OHCA exposures
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Year Mean paramedic exposure
Crude esmate of paramedic exposure
Fig. 3. Estimates of paramedic exposure to OHCA with attempted resuscitation in Victoria, 2003–2012.
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perform as ‘experts’, modifying the effect of widespread low exposure. Ideally a small number of cardiac arrest experts could respond to every OHCA, thereby increasing their exposure and competency. However, because OHCA occurs without warning, anywhere in the community, it would be difficult for an expert team to respond in a timely manner. In the Victorian system the ‘expert’ intensive care paramedics did not attend 20% of OHCA cases and typically arrived 5 min after other paramedics when they did respond. This highlights the need for simulation and/or education across the whole workforce, particularly in those with lower exposure. The importance of practitioner exposure to complex skills is illustrated by studies in other fields, such as surgery, which have shown that greater practitioner exposure to procedures is associated with a reduced rate of complications and improved patient survival.32 Although this volume-outcome relationship is yet to be validated in the prehospital setting,33 our findings highlight the need for such work. 4.1. Limitations
Previous reports of paramedic exposure to OHCA (median 4–9)8–11 are higher than in our study, even for our crudely calculated rate. This could, in part, be explained by differences in the rates of attempted resuscitation among these studies.8–10 Less than half of the patients in our study had attempted resuscitation (44%), and attempted resuscitation rates are known to be lower in Australia than in some parts of the world.1 We also saw significant temporal declines in exposure in this population. The average exposure was highest at the start of the study period (2.8 OHCA/year, 2003), however the rate significantly declined throughout the study period reaching 2.1 OHCA per year in 2012. This decline corresponds with changes across the workforce in this time, in which subgroups of paramedics with the lowest exposure (i.e. part-time and BLS) increased. In addition, a rising demand for EMS has resulted in an increase in the number of paramedics, while the incidence of OHCA has remained the same.21,22 This is one of the first studies to examine paramedic exposure to OHCA, and, to the best of our knowledge, the first to examine paramedic exposure to the less frequently encountered types of OHCA. We found that paramedic exposure to paediatric or traumatic OHCAs was exceptionally rare, with an average of 12.5 years and 9.5 years between cases, respectively. Given that these cases require additional and modified resuscitation skills, it is unlikely that paramedics would be able to maintain these specific skills though exposure alone. Our findings also have implications for general skill competency. Although it is unknown how much exposure is required to maintain resuscitation competency, resuscitation skills are known to deteriorate as early as 6 weeks after training.23 Paramedics are unlikely to be able to develop or maintain resuscitation competency when they are practicing these skills only every 163 days. Therefore, it is likely that paramedics would benefit from additional training or simulation to supplement their low exposure. Simulation has been proposed as an alternative to actual OHCA exposure for the development and maintenance of resuscitation skills. However, the controlled nature of simulation means it is unlikely to fully replicate actual prehospital exposure to skills. Despite the limitations of simulation, in the hospital setting it has been shown to improve resuscitation performance24–27 and there is some indication that it may improve patient survival.26,28 Therefore, further research is needed to investigate the effectiveness of simulation and education as substitutes for actual paramedic exposure. In Victoria, the two-tiered system resulted in a small group of intensive care paramedics with a relatively high rate of exposure to OHCA. Thus, a two-tier system may deliver improved resuscitation performance; where paramedics with higher exposure may
Although 99% of cardiac arrests were able to be linked with at least one paramedic, some paramedics may not have been recorded as having been in attendance at an OHCA. It is also probable that paramedic exposure to resuscitation procedures, such as defibrillation, was overestimated because we were unable to determine which paramedics performed each procedure resulting in each skill being assigned to every paramedic who was qualified and present. Given the number of paramedics on scene, active participation in resuscitation procedures is likely to be even lower than the numbers reported in our study. Because paramedic employment location was determined from their attendance at an OHCA outside of the capital city we were unable to determine if paramedics who had no exposure to OHCA during the study period worked in a rural or metropolitan area. 5. Conclusion Our study identified that paramedic exposure to resuscitation is low and has decreased over time. This highlights the importance of measuring paramedic exposure and supplementing it with other methods, such as simulation, to maintain resuscitation skills. This may be particularly important to paramedics with low exposure rates and for rare case types, such as paediatric OHCA. Conflict of interest statement KD, KS and SB are employed by Ambulance Victoria. All authors have no financial or personal conflicts of interest that could inappropriately influence (bias) their work to disclose. Funding KD is supported by a National Health and Medical Research Council (NHMRC) Public Health Postgraduate Research Scholarship (ID: 1075456) and a scholarship funded through the NHMRC Australian Resuscitation Outcomes Consortium (Aus-ROC) Centre of Research Excellence (CRE) (ID:1029983, https://www. ausroc.org.au). JB is supported by a co-funded NHMRC/National Heart Foundation Fellowship (#1069985/100136). JB, JF and LS receive salary support by the NHMRC Aus-ROC CRE. JF receives salary support from St John Ambulance Western Australia. Acknowledgement Ambulance Victoria for providing data.
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Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Clinical Paper
Paramedic exposure to out-of-hospital cardiac arrest is rare and declining in Victoria, Australia夽 Kylie Dyson a,b,∗ , Janet Bray a,c,d,e , Karen Smith a,b,c , Stephen Bernard a,b,d , Lahn Straney a , Judith Finn a,c,e a
Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia Ambulance Victoria, Victoria, Australia c Discipline of Emergency Medicine, University of Western Australia, Perth, Australia d Alfred Hospital, Melbourne, Australia e School of Nursing and Midwifery, Curtin University, Perth, Australia b
a r t i c l e
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Article history: Received 10 October 2014 Accepted 21 January 2015 Keywords: Out-of-hospital cardiac arrest Resuscitation Workload Experience Exposure Clinical competence
a b s t r a c t Background and objective: Paramedic exposure to out-of-hospital cardiac arrest (OHCA) may be an important factor in skill maintenance and quality of care. We aimed to describe the annual exposure rates of paramedics in the state of Victoria, Australia. Methodology: We linked data from the Victorian Ambulance Cardiac Arrest Registry (VACAR) and Ambulance Victoria’s employment dataset for 2003–2012. Paramedics were ‘exposed’ to an OHCA if they attended a case where resuscitation was attempted. Individual rates were calculated for average annual exposure (number of OHCA exposures for each paramedic/years employed in study period) and the average number of days between exposures (total paramedic-days in study/total number of exposures in study). Results: Over 10-years, there were 49,116 OHCAs and 5673 paramedics employed. Resuscitation was attempted in 44% of OHCAs. The typical ‘exposure’ of paramedics was 1.4 (IQR = 0.0–3.0) OHCAs per year. Mean annual OHCA exposure declined from 2.8 in 2003 to 2.1 in 2012 (p = 0.007). Exposure was significantly less in those: employed part-time (p < 0.001); in rural areas (p < 0.001); and with lower qualifications (p < 0.001). Annual exposure to paediatric and traumatic OHCAs was particularly low. It would take paramedics an average of 163 days to be exposed to an OHCA and up to 12.5 years for paediatric OHCAs, which occur relatively rarely. Conclusions: Exposure of individual paramedics to resuscitation is low and has decreased over time. This highlights the importance of supplementing paramedic exposure with other methods, such as simulation, to maintain resuscitation skills particularly in those with low exposure and for rare case types. © 2015 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Out-of-hospital cardiac arrest (OHCA) is a leading cause of death worldwide.1 Commonly, survival from OHCA is less than 10%, without substantial improvement seen internationally in the last 30 years.2 The quality of resuscitation care provided by paramedics has
夽 A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2014.08.027. ∗ Corresponding author at: Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, Level 5, 99 Commercial Road, Melbourne, VIC 3004, Australia. E-mail address: [email protected] (K. Dyson). http://dx.doi.org/10.1016/j.resuscitation.2015.01.023 0300-9572/© 2015 Elsevier Ireland Ltd. All rights reserved.
been identified as one contributor to low survival.3–7 Poor resuscitation performance and low OHCA survival could be the result of paramedics not gaining enough exposure to OHCA to develop and maintain competency in their resuscitation skills. Current evidence suggests that paramedic exposure to OHCA is low; with median rates varying between 4 and 9 cases per year.8–11 However, many of these estimates are crudely calculated11–13 and may not accurately reflect the true exposure of paramedics to resuscitation. Furthermore, there is no evidence describing regional differences in exposure (e.g. metropolitan versus rural) nor exposure to subgroups of patients that require modified or specific skills (e.g. paediatrics and trauma). The primary aim of this study was to describe the average overall paramedic exposure to OHCA cases and in specific patient
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subgroups. A secondary aim was to determine if we could derive a crude estimate of paramedic exposure to OHCA using routinely collected data and determine whether this value accurately reflects actual exposure. 2. Methods This study is a retrospective analysis of prospectively collected, linked data from 2003 to 2012 from the Victorian Ambulance Cardiac Arrest Registry (VACAR)14 and Ambulance Victoria’s (AV) employment dataset. This study was approved by the Monash University Human Research Ethics Committee (project number: CF13/971 – 2013000471). 2.1. Setting The study was set in the Australian state of Victoria which covers an area of 227,000 km.15 Victoria has a population of 5.7 million, most (75%) of whom live in the capital city of Melbourne.15 The ageadjusted incidence of presumed cardiac aetiology OHCA in Victoria is 76.7 per 100,000 adults.16 AV is the sole provider of emergency medical services (EMS) in the state.14 AV delivers a primarily two-tiered EMS, with advanced life support (ALS) and intensive care paramedics. There are also basic life support (BLS) responders, the majority of whom operate on a voluntary basis in rural areas. Fire fighters also provide a first response in select areas of Melbourne and rural communities. Paramedics in Victoria are currently required to have a three year bachelor degree in paramedicine followed by a 12-month in field graduate year and intensive care paramedics have an additional postgraduate diploma in emergency health. There is no formalised ALS accreditation or mandatory recertification of resuscitation skills for AV paramedics after university training. Where available, two intensive care paramedics and two ALS paramedics are concurrently dispatched to each OHCA. OHCA patients are managed according to AV clinical practice guidelines,17 which are based on recommendations by the Australian Resuscitation Council.18 All ALS paramedics can administer intravenous adrenaline, perform manual defibrillation and insert supraglottic airways. In addition, intensive care paramedics are able to administer amiodarone, perform endotracheal intubation (ETI), insert intraosseous cannulae and provide advanced post resuscitation care (rapid sequence induction, sedation, therapeutic cooling and adrenaline infusion). AV paramedics can elect to withhold resuscitation where there is evidence of body decomposition, rigour mortis or injuries incompatible with life; or where the presenting rhythm is asystole and cardiac arrest duration is greater than 10 min. Resuscitation can be discontinued at the scene if ALS has been provided for at least 30 min, the patient is not in a shockable rhythm and there are currently no other signs of life present.17 2.2. Data sources The VACAR collects Utstein19 data elements for all OHCAs attended by EMS in Victoria. The aetiology of OHCA cases is presumed to be cardiac when no other cause is recorded on the patient care record (e.g. trauma). All OHCAs that occurred between 1 January 2003 and 31 December 2012 were included in this study. AV’s employment dataset contains information about the qualification held by paramedics, the duration of their employment and whether they are employed fulltime. The employment data captured was current as of the 31st of December 2012 or the paramedic’s last day of duty. We included all AV paramedics who were ‘operational’ (i.e. available to be exposed to OHCA cases) at some time during the study period. We classified paramedics as
working in a rural location if they treated OHCAs that occurred outside the city of Melbourne and, therefore, we were unable to determine the location of paramedics who did not attend an OHCA during the study period. Over 99% of all OHCA cases from VACAR where EMS resuscitation was attempted were linked to one or more paramedics in the AV employment dataset. 2.3. Definitions We considered paramedics to have ‘exposure’ to OHCA if they attended an OHCA case where EMS resuscitation was attempted (CPR and/or defibrillation). Given we were unable to determine which individual paramedic performed which resuscitation procedure, paramedics were considered to have ‘exposure’ to a procedure or skill if they were in attendance when it was performed and they were qualified to perform it (i.e. all intensive care paramedics at a case were considered to have been exposed to ETI if the patient was intubated). We measured experience from each paramedic’s first day of duty until their last day of duty or the last day of the study if they were still employed. To estimate the typical exposure of a paramedic to OHCA, we first calculated the annual average exposure for each paramedic by dividing the number of OHCAs they attended by the years that they were employed during the study period. To provide an estimate of the typical exposure we then took the median of those values. We calculated the average number of days between exposures to OHCA by dividing the total number of paramedic-days in the dataset by the number of exposures in the dataset. We defined paramedic-days as the number of days that paramedics were employed by AV during the study period. We also calculated a crude estimate of paramedic exposure to OHCA using information commonly available to EMS providers. We calculated the crude estimate by multiplying the total number of resuscitations attempted per year by the number of paramedics normally dispatched to OHCA (four in AV) and dividing this by the number of paramedics employed. 2.4. Statistical analysis We compared typical exposure between paramedic subgroups using the Mann–Whitney test and we used linear regression to analyse trends over the study period. We compared the crude estimate of paramedic exposure with mean exposure using concordance correlation20 and Pearson’s correlation. Statistical analyses were performed using Stata 12 (StataCorp, USA) and pvalues less than 0.05 were considered statistically significant. 3. Results 3.1. Characteristics of OHCA cases Paramedics in Victoria attended 49,116 OHCAs in the 10 year study period. Of these, 21,636 cases (44%) had paramedic attempted resuscitation. The characteristics of OHCA cases are provided in Table 1. A median of four paramedics (IQR 2–4) in two ambulances (IQR 1–2) attended cases that received an attempted resuscitation. The majority of attempted resuscitations (80%) had at least one intensive care paramedic on scene, however, they were only the first on scene 35% of the time. When an intensive care paramedic was not the first on scene, they typically arrived 5 min (IQR 1–10) after the first team. 3.2. Characteristics of paramedics There were a total of 5673 paramedics employed during the study period (Table 2). Paramedics had a median of 5.6 years of
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Table 1 Characteristics of all OHCAs attended by Ambulance Victoria, 2003–2012.
Number (%) Age (years; median [IQR]) Child (<18 years) (%) Female (%) Public location (%) Witnessed (%) Bystander Paramedic Bystander CPR (%) Primary suspected cause of arrest (%) Cardiac Trauma Terminal Overdose Hanging Respiratory Initial rhythm (%) Asystole PEA VF VT Unknown Rural location EMS response time (min; median [IQR])a Number of paramedics attending (median [IQR]) Number of teams attending (median [IQR]) Survival (%) Shockable
All OHCA
Resuscitation attempted
49,116 69 (52–80) 1082 (2) 16,619 (34) 9545 (19)
21,650 (44) 67 (52–79) 720 (3) 6812 (31) 5566 (26)
14,619 (30) 3663 (7) 11,725 (24)
10,666 (49) 3219 (15) 9261 (43)
3953 (14) 444 (2) 2464 (9)
34,540 (70) 3782 (8) 3062 (6) 2407 (5) 2102 (4) 1827 (4)
16,419 (76) 1014 (5) 861 (4) 776 (4) 404 (2) 1284 (6)
18,121 (66) 2768 (10) 2201 (8) 1631 (6) 1698 (6) 543 (2)
35,469 (72) 6120 (13) 6542 (13) 369 (1) 616 (1) 14,464 (29) 8 (6–12) 2 (2–4) 1 (1–2)
No resuscitation attempted 27,466 (56) 70 (51–82) 362 (1) 9807 (36) 3979 (14)
8863 (41) 5510 (25) 6483 (30) 350 (2) 444 (2) 5508 (25) 8 (6–11) 4 (2–4) 2 (1–2) 2481 (11) 1841 (27)
26,606 (97) 610 (2) 59 (0) 19 (0) 172 (1) 8956 (33) 8 (6–12) 2 (2–2) 1 (1–1)
IQR, inter quartile range; CPR, cardiopulmonary resuscitation; PEA, pulse-less electrical activity; VF, ventricular fibrillation; VT, ventricular tachycardia; EMS, emergency medical service. a Excludes EMS witnessed.
experience. The majority of paramedics were ALS qualified (59%) and employed fulltime (66%). Of those paramedics who attended an OHCA (n = 4274), 60% were employed in a metropolitan area. 3.3. Paramedic exposure to OHCA with attempted resuscitation The typical exposure of paramedics was 1.4 (IQR 0.0–3.0) OHCA cases per year (Table 3). During the study period, 28% of paramedics did not attempt resuscitation on any OHCA patients. On average, 42% of paramedics attended less than one OHCA per year and only 3% attended ten or more (Fig. 1). Across the entire
Table 2 Characteristics of operational Ambulance Victoria paramedics, 2003–2012.
a
Location unknown for paramedics with no OHCA exposures.
5673 (100) 3729 (66) 1934 (34) 2579 (45) 1695 (30) 1399 (25)a 595 (11) 3371 (59) 1521 (27) 186 (3) 5.6 (3–12) 14.0 (8–21) 5.0 (2–11) 4.5 (2–8) 5.0 (2–10) 5.0 (0–15) 1587 (28) 1399 (25)
45%
42%
40%
Percentage of paramedics
Number (%) Fulltime (%) Part-time/casual (%) Location (%) Metropolitan Rural Unknown Qualification (%) Intensive care ALS BLS Unknown Experience (years; median [IQR]) Intensive care ALS BLS Time in study (years, median [IQR]) OHCA exposure during study (median [IQR]) No exposure to OHCA with attempted resuscitation during study (%) No exposure to any OHCA during study (includes resuscitation not attempted [%])
paramedic cohort exposure to paediatric and traumatic OHCAs was particularly low (Table 3). The typical exposure to OHCA where defibrillation or post-arrest management were performed was less than one per year. OHCA exposure was significantly lower among those paramedics who (i) were based in a rural area, (ii) were not employed in fulltime positions or, (iii) held a lower qualification (Table 3). Metropolitan intensive care paramedics (n = 414) had the highest annual exposure; 7.5 (IQR 4.4–10.7) OHCA cases per year. However, rural intensive care paramedics (n = 169) had significantly lower exposure to OHCA, (2.8, IQR 1.5–4.3, p < 0.001) which was much closer to that of ALS paramedics (2.1, IQR 1.1–3.1). In addition, metropolitan intensive care paramedics had significantly higher exposure to OHCA ETI (6.1, IQR 3.7–8.9) than their rural intensive care counterparts (2.3, IQR 1.2–3.4, p < 0.001).
35% 30% 25% 20%
17%
16%
15%
10%
10%
6%
6% 3%
5% 0% <1
1<2
2<3
3<4
4<5
5<10
≥10
Average annual OHCA exposure Fig. 1. Distribution of the average annual paramedic exposure to OHCA with attempted resuscitation in Victoria, 2003–2012.
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Table 3 Paramedic exposure to resuscitation skills and OHCA with attempted resuscitation by paramedic and patient subgroups in Victoria, 2003–2012. Exposure
Median annual OHCA exposures (IQR)
All OHCA (n = 21,656) Paediatric (n = 720) Trauma (n = 1014) Paramedic witnessed (n = 3219) Treatment exposure First team Defibrillation ETI IV Adrenaline ROSC care
1.4 (0.0–3.0) 0.0 (0.0–0.1) 0.0 (0.0–0.1) 0.1 (0.0–0.4)
163 (0.4 years) 4566 (12.5 years) 3459 (9.5 years) 1099 (3.0 years)
0.9 (0.0–1.9) 0.6 (0.0–1.5) 4.5 (2.1–7.7) 1.6 (0.8–2.6) 0.4 (0.0–1.1)
314 (0.9 years) 325 (0.9 years) 73 (0.2 years) 163 (0.4 years) 406 (1.1 years)
Paramedic subgroups Employment locationa Metropolitan Rural Employment status Fulltime Part-time/casual Qualification Intensive care Advanced life support Basic life support
p-Value
Average days between OHCA exposures
2.8 (1.8–4.2) 1.2 (0.4–2.1)
ref <0.001
99 (0.3 years) 261 (0.7 years)
2.3 (1.2–3.7) 0.8 (0.3–1.8)
ref <0.001
124 (0.3 years) 603 (1.6 years)
5.6 (2.6–9.4) 2.1 (1.1–3.1) 0.0 (0.0–0.0)
ref <0.001 <0.001
59 (0.2 years) 172 (0.5 years) 2765 (7.6 years)
OHCA, out-of-hospital cardiac arrest; IQR, inter quartile range; ETI, endotracheal intubation; IV, intravenous; ROSC, return of spontaneous circulation. a Excludes paramedics with no exposure because location was unable to be determined.
3.4. Duration between paramedic exposures to OHCA with attempted resuscitation
3.6. Crude estimation of paramedic exposure to OHCA with attempted resuscitation
There were 11,400,602 paramedic-days in the study period and 69,913 exposures to OHCA with attempted resuscitation. On average, paramedics were exposed to one OHCA for every 163 days of employment (11,400,602/69,913); while it would take paramedics 12.5 years to be exposed to a paediatric OHCA (Table 3).
The crude estimate of paramedic exposure was 2.7 OHCAs per year, and generally overestimated mean exposure by approximately 0.5 cases per year (Fig. 3). There was moderate concordance between the estimated crude exposure and the calculated mean paramedic exposure (Fig. 3) (concordance = 0.47, 95% CI: 0.22–0.72). However the correlation was high (r = 0.97) suggesting that the differences were systematic and that a more accurate measure of the mean number of paramedics in attendance could improve this estimate.
3.5. Trends over the study period The mean number of OHCA cases that paramedics were exposed to, significantly declined from 2.8 in 2003 to 2.1 in 2012 (p = 0.007) (Fig. 2a). This was despite a significant increase in the rate of attempted resuscitations (41% in 2003 to 57% in 2012, p = 0.02). Over the same period, there were significant increases in the percentage of employees who were part-time (20% vs. 34%, p < 0.001) or BLS (14% vs. 20%, p = 0.002) and a significant decline in the percentage of intensive care paramedics who made up the workforce (18% vs. 10%, p < 0.001) (Fig. 2b).
Our results indicate that the typical paramedic was only exposed to 1.4 attempted resuscitations per year, and that this exposure has declined over time. This rate indicates that paramedics work an average of 163 days between cases. Exposure was particularly low for rare case types, specific skills, and across subgroups of paramedics.
b 3.1
40%
2.9
35%
Percentage of paramedics
Mean number of OHCA exposures
a
4. Discussion
2.7 2.5 2.3 2.1 1.9 1.7
25% 20% 15% 10% 5% 0% 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
1.5
2003
30%
2004
2005
2006
2007
2008 Year
2009
2010
2011
2012
Year Part-me p<0.001
BLS p=0.002
Intensive care p<0.001
Fig. 2. (a) Average annual paramedic exposure to OHCA with attempted resuscitation (with 95% CI) in Victoria, 2003–2012. (b) Temporal changes in the Victorian Paramedic workforce composition 2003–2012.
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Number of OHCA exposures
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Year Mean paramedic exposure
Crude esmate of paramedic exposure
Fig. 3. Estimates of paramedic exposure to OHCA with attempted resuscitation in Victoria, 2003–2012.
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perform as ‘experts’, modifying the effect of widespread low exposure. Ideally a small number of cardiac arrest experts could respond to every OHCA, thereby increasing their exposure and competency. However, because OHCA occurs without warning, anywhere in the community, it would be difficult for an expert team to respond in a timely manner. In the Victorian system the ‘expert’ intensive care paramedics did not attend 20% of OHCA cases and typically arrived 5 min after other paramedics when they did respond. This highlights the need for simulation and/or education across the whole workforce, particularly in those with lower exposure. The importance of practitioner exposure to complex skills is illustrated by studies in other fields, such as surgery, which have shown that greater practitioner exposure to procedures is associated with a reduced rate of complications and improved patient survival.32 Although this volume-outcome relationship is yet to be validated in the prehospital setting,33 our findings highlight the need for such work. 4.1. Limitations
Previous reports of paramedic exposure to OHCA (median 4–9)8–11 are higher than in our study, even for our crudely calculated rate. This could, in part, be explained by differences in the rates of attempted resuscitation among these studies.8–10 Less than half of the patients in our study had attempted resuscitation (44%), and attempted resuscitation rates are known to be lower in Australia than in some parts of the world.1 We also saw significant temporal declines in exposure in this population. The average exposure was highest at the start of the study period (2.8 OHCA/year, 2003), however the rate significantly declined throughout the study period reaching 2.1 OHCA per year in 2012. This decline corresponds with changes across the workforce in this time, in which subgroups of paramedics with the lowest exposure (i.e. part-time and BLS) increased. In addition, a rising demand for EMS has resulted in an increase in the number of paramedics, while the incidence of OHCA has remained the same.21,22 This is one of the first studies to examine paramedic exposure to OHCA, and, to the best of our knowledge, the first to examine paramedic exposure to the less frequently encountered types of OHCA. We found that paramedic exposure to paediatric or traumatic OHCAs was exceptionally rare, with an average of 12.5 years and 9.5 years between cases, respectively. Given that these cases require additional and modified resuscitation skills, it is unlikely that paramedics would be able to maintain these specific skills though exposure alone. Our findings also have implications for general skill competency. Although it is unknown how much exposure is required to maintain resuscitation competency, resuscitation skills are known to deteriorate as early as 6 weeks after training.23 Paramedics are unlikely to be able to develop or maintain resuscitation competency when they are practicing these skills only every 163 days. Therefore, it is likely that paramedics would benefit from additional training or simulation to supplement their low exposure. Simulation has been proposed as an alternative to actual OHCA exposure for the development and maintenance of resuscitation skills. However, the controlled nature of simulation means it is unlikely to fully replicate actual prehospital exposure to skills. Despite the limitations of simulation, in the hospital setting it has been shown to improve resuscitation performance24–27 and there is some indication that it may improve patient survival.26,28 Therefore, further research is needed to investigate the effectiveness of simulation and education as substitutes for actual paramedic exposure. In Victoria, the two-tiered system resulted in a small group of intensive care paramedics with a relatively high rate of exposure to OHCA. Thus, a two-tier system may deliver improved resuscitation performance; where paramedics with higher exposure may
Although 99% of cardiac arrests were able to be linked with at least one paramedic, some paramedics may not have been recorded as having been in attendance at an OHCA. It is also probable that paramedic exposure to resuscitation procedures, such as defibrillation, was overestimated because we were unable to determine which paramedics performed each procedure resulting in each skill being assigned to every paramedic who was qualified and present. Given the number of paramedics on scene, active participation in resuscitation procedures is likely to be even lower than the numbers reported in our study. Because paramedic employment location was determined from their attendance at an OHCA outside of the capital city we were unable to determine if paramedics who had no exposure to OHCA during the study period worked in a rural or metropolitan area. 5. Conclusion Our study identified that paramedic exposure to resuscitation is low and has decreased over time. This highlights the importance of measuring paramedic exposure and supplementing it with other methods, such as simulation, to maintain resuscitation skills. This may be particularly important to paramedics with low exposure rates and for rare case types, such as paediatric OHCA. Conflict of interest statement KD, KS and SB are employed by Ambulance Victoria. All authors have no financial or personal conflicts of interest that could inappropriately influence (bias) their work to disclose. Funding KD is supported by a National Health and Medical Research Council (NHMRC) Public Health Postgraduate Research Scholarship (ID: 1075456) and a scholarship funded through the NHMRC Australian Resuscitation Outcomes Consortium (Aus-ROC) Centre of Research Excellence (CRE) (ID:1029983, https://www. ausroc.org.au). JB is supported by a co-funded NHMRC/National Heart Foundation Fellowship (#1069985/100136). JB, JF and LS receive salary support by the NHMRC Aus-ROC CRE. JF receives salary support from St John Ambulance Western Australia. Acknowledgement Ambulance Victoria for providing data.
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