Out-of-hospital cardiac arrest (OHCA) is a global health concern. It is estimated that OHCA events occur in 235 000–325 000 people in the United States (US) every year (Zive et al, 2011). OHCA events have a low survival rate and there is considerable variation between US locations (Zive et al, 2011). As a result of poor prognosis and outcome variability, several cardiac arrest registries, such as the National Emergency Medical Service (EMS) Information System (NEMSIS), Resuscitation Outcomes Consortium-Epistary (ROC), and Cardiac Arrest Registry to Enhance Survival (CARES), have been created to compile data regarding OHCA incidence, EMS response, and patient outcomes. Standardised data allow researchers to devise the most effective means to increase chances of survival. Registries assist researchers to identify areas of concern, generate hypotheses, and drive policy and protocol changes using evidence-based criteria (Neumar et al, 2011).
American Medical Response (AMR), the largest EMS provider in the US, contracts EMS services for Multnomah and Clackamas Counties in Oregon, and Clark County in Washington State (Neumar et al, 2011). These counties are part of the Portland metropolitan area. While the Portland metropolitan area has been a part of several aggregate studies, there are little data evaluating OHCA events specific to Portland. The goal of the current study was to investigate any differences in the outcomes of OHCA for people being treated by AMR in the three Portland counties.
Along with the latest consensus on cardiac arrest treatment, which reinforces the cardiac chain of survival and the primary importance of early activation, high-quality cardiopulmonary resuscitation (CPR), and early defibrillation, there is a need for future research. One area of focus for this future research should be increasing the amount of data describing OHCA characteristics in geographical regions that have been underreported.
The current study was conducted to describe OHCA calls in the counties serviced by AMR, evaluate differences in outcomes, and determine the proportion of patients who achieved a return of spontaneous circulation (ROSC) from EMS treatment and survived to hospital admission (SHA).
Cardiac arrest
Cardiac arrest exhibits wide variations in incidence, response, and outcome across regions as a result of its multifactorial nature (Nichol et al, 2008; Kleinman et al, 2018). Several factors that may play a role in these variations are discussed in the current article. To further understand such variation and to improve survival rates, research continues on these OHCA variables. These continuing efforts help to establish policy and guide evidence-based changes in EMS conduct (Neumar et al, 2011).
Community-based OHCA response
The most important community contributors to OHCA survival are early recognition of a cardiac arrest, EMS activation, early implementation of high-quality CPR, and early defibrillation (Neumar et al, 2011). After EMS activation, the best response from bystanders is the administration of high-quality chest compressions until an automated external defibrillator (AED) arrives. High-quality CPR for adults is defined as a chest compression fraction over 80%, between 100−120 compressions per minute, at a depth of greater than 50 mm or over two inches in adults (allowing for full chest recoil), and a ventilation rate of fewer than 12 breaths per minute (Kleinman et al, 2018). After EMS activation and starting CPR, the next component is early defibrillation (Nichol et al, 2008; Kleinman et al, 2018).
EMS-based response
The major contribution from EMS providers in OHCA care is continuing CPR to ensure high-quality compressions continue, rapid AED or other defibrillator use, access to advanced drug intervention, and advanced airway administration. (Hess and White, 2010; Kleinman et al, 2018). A key aspect from EMS services is time to arrival, time on scene, and transport time to an emergency department (ED) (Nichol et al, 2008). For reasons that are not well understood, there is also wide variability in all of these components across regional EMS providers (Zive et al, 2011). However, the recognition and analysis of these variations will help to devise protocols to increase OHCA survival rates (Meaney et al, 2013).
Another major component of EMS care has traditionally been advanced cardiac life-saving (ACLS) techniques from EMS providers. This includes early defibrillation, advanced airway placement, establishing intravenous or interosseous lines, and the administration of cardiac medications (Glover et al, 2012; Kleinman et al, 2018). However, research has been mixed about the effectiveness of airway placement and drug administration. While studies have shown that ACLS care improves SHA, they have shown no improvement in survival-to-discharge or improvement in neurological outcome (Glover et al, 2012; Kleinman et al, 2018).
Variability in OHCA incidence, response, and outcome
There are multifactorial differences in OHCA incidence, response, and outcomes seen in patients and EMS protocols. Specifically, these include: whether an OHCA was witnessed; variations in CPR quality and when defibrillation occurred; what cardiac drugs were administered, other ACLS care provided; and transport time (Hess et al, 2010; Glover et al, 2012).
Bystander intervention
Bystander response has an important effect on OHCA survival. Research by Nehme et al (2014) found that when bystanders do not call EMS first, but call a doctor or family member, chances of OHCA survival significantly drop. The authors found that when groups other than EMS were called first, this group had a significantly higher rate of resuscitation efforts ceasing at the scene (62.2% vs. 78.8%). EMS being called first was associated with finding a shockable rhythm (13.7% vs. 8.1%) and chances of ROSC was greatly improved (Nehme et al, 2014).
A study by Wissenberg et al (2013) found a public education programme to increase awareness regarding bystander response and CPR administration led to increased public intervention and increased survival. Rates of bystander CPR in Denmark increased from 19.4% in 2001 to 43.3% in 2010. SHA increased from 6.5% to 19.1% and 30-day survival increased from 2.8% to 8.6% over the study period (Nehme et al, 2014).
Further research by Haukoos et al (2010) also found a significant increase in SHA for patients in OHCA coinciding with increased bystander response in Denver, Colorado. However, while rates of bystander-provided CPR were improving, their study found that bystander-provided CPR only occurred in 25% of cases, which was comparable to national rates of 27% (Haukoos et al, 2010).
CPR quality
The biggest factor determining OHCA survival is the quality of chest compressions (Nichol et al, 2008; Kleinman et al, 2018). The 2010 American Heart Association (AHA) Consensus Statement (Kleinman et al, 2018) and the 2015 AHA Guidelines Update (Meaney et al, 2013) both emphasise high-quality CPR as the critical component in OHCA treatment. Factors that contribute to high-quality CPR include minimising interruptions; an adequate compression rate; adequate chest compression depth; allowing full chest recoil; and avoiding excessive ventilations (Meaney et al, 2013).
To minimise interruptions in CPR and optimise perfusion, a chest compression fraction (CCF) of over 80% is desired. CCF reflects the amount of time that compressions are being performed during a cardiac arrest. A CCF below 80% is associated with lower ROSC and SHA rates (Meaney et al, 2013).
A chest compression rate of 100–120 compressions per minute has been found to be the optimal range for OHCA survival. CPR rates above or below this range reduce chances for SHA (Meaney et al, 2013).
Vadeboncoeur et al (2014) investigated the effect of chest compression depth on survival. When professional rescuers perform CPR, the administration of chest compressions of greater than 51 mm is significantly associated with ROSC and increased odds of survival.
When the rescuer leans into the patient while performing CPR, the chest wall is prevented from fully expanding and decreases venous return and cardiac output. To maximise perfusion, responders should avoid leaning into the patient to allow full chest recoil (Meaney et al, 2013).
Current AHA recommendations are for a ventilation rate of less than 12 breaths per minute with minimal chest rise (Meaney et al, 2013). In fact, excessive ventilation reduces CCF during synchronous ventilation while breaths are administered. Therefore, current recommendations are for untrained responders to provide hands-only CPR during an OHCA event until trained responders arrive so that CCF is maximised (Meaney et al, 2013; Kleinman et al, 2018).
Administration of cardiac drugs
Many drugs are administered by EMS services during cardiac arrest, including:
However, the 2010 position stand by AHA and International Liaison Committee on Resuscitation (ILCOR) considers drug administration of secondary importance. The most important factors are early EMS activation and high-quality chest compressions with rapid defibrillation (Meaney et al, 2013).
Variations in time to transport
Prior research has found wide variations in OHCA incidence and outcomes in North America (Nichol et al, 2008). While some variations were thought to be a result of underlying regional risk factors for heart disease, the authors speculated that some variation may be the result of how different EMS agencies operate (Nichol et al, 2008). This study was conducted through the ROC-Epistry and all cardiac arrest data were standardised. However, each individual EMS agency operates under individual OHCA response protocols owing to differences in local, county, and state guidelines and practices (Nichol et al, 2008).
An investigation by Zive et al (2011) found wide regional variation in transport practices and OHCA survival. The study focused on the specific termination of resuscitation (TOR) protocols established by individual EMS agencies. The agencies that provided CPR and defibrillation to achieve ROSC, prior to transport, had longer on-scene and transport times, but higher ROSC and SHA rates. Patients who had initial rhythms of ventricular fibrillation (VF), pulseless ventricular tachycardia (pVT), or AED use made up the largest patient group transported after ROSC was achieved. Of this group, 45.5% survived (Zive et al, 2011).
EMS agencies that transported to the ED prior to achieving ROSC had shorter times overall, but significantly worse outcomes. Of the group with VF/pVT/AED use that were transported prior to documented ROSC, only 9.1% survived (Zive et al, 2011). The authors also found a higher likelihood of transport prior to achieving ROSC if a basic life-saving (BLS) unit was responding, as most BLS units are not granted authority to pronounce deaths on scene (Zive et al, 2011).
Increasing OHCA survival
Since the 2010 position on OHCA response and treatment, there has been improvement in OHCA outcomes in the literature (Zive et al, 2011; Wissenberg et al, 2013; Kleinman et al, 2018). Although survival rates remain low and varied, the goal of increasing OHCA survival persists (Zive et al, 2011; van Diepen et al, 2013; Kleinmen et al, 2018).
Through the use of standardised criteria to define OHCA data points and the use of cardiac arrest registries (Neumar et al, 2011), current knowledge regarding OHCA treatment may be expanded to improve cardiac arrest survival rates. Therefore, this study was conducted to describe differences in outcomes to OHCA for patients treated by AMR in Portland. The goal was to describe the incidence of OHCA, evaluate any differences in response between the three counties, and determine what proportion of patients achieved ROSC from EMS treatment and SHA.
Methods
This study used a retrospective cohort design and previously collected data from the Multiple-EMS Data Systems (MEDS) database which is utilised by all AMR ambulance crews, found in the AMR IT Department in Roseville, California. The study period was from 1 January 2013—31 December 2014. Data had all identifiers removed by AMR IT personnel. The study used secondary data from OHCA databases. Therefore, a waiver for informed consent and International Review Board approval was obtained from the A.T. Still University Institutional Review Board. All descriptive data were analysed using statistical software (IBM SPSS v.22). All statistical tests used an alpha of p<0.05 for significance and were two-tailed.
Inclusion criteria for this study were:
Exclusion criteria were patients under the age of 18 or a cardiac arrest caused by traumatic injury. Once data were collected and OHCA incidences calculated, all patients who were pronounced dead on scene or were not treated by paramedics were excluded from further data analysis.
Measured variables included patient sex, age, bystander-witnessed event, CPR administration, defibrillation performed, epinephrine use, ROSC achieved, and SHA achieved. Additional variables included EMS time to scene from dispatch in minutes, time spent on scene in minutes, and transport time to ED in minutes.
Descriptive statistics were used to analyse all data. Interval/ratio data were assessed for normality using means, medians, and standard deviation. Interval/ratio data were also examined for skewness and kurtosis. Nominal data were expressed as frequencies and percentages. OHCA incidences were expressed as part of the overall AMR service area and broken into individual counties of service. Rates were expressed as OHCA events per 10 000 population. Population estimates were based on US Census Bureau demographics (2016a; 2016b; 2016c).
The interval/ratio data of time from dispatch to scene, time on scene, and transport time to hospital were analysed using an ANOVA. The Kruskal-Wallis test was used for interval/ratio data that displayed a non-normal distribution. Significant differences were further tested using Tukey's honest significant difference as a post hoc test.
The nominal variables of sex, bystander-witnessed OHCA, CPR performed, defibrillation performed, and epinephrine use was examined using bivariate tests of association. The odds ratios and 95% confidence intervals were calculated against the two outcome measures of ROSC and SHA.
Chi-square tests assessed bivariate relationships between the counties and the outcome measures of return of ROSC and SHA. Cross-wise comparisons were performed between the counties and ROSC and SHA. Cramer's V coefficient was used to test the level of association between all significant results. The methodology of this study is similar to previous research in OHCA epidemiology (Haukoos et al, 2010).
Results
Cardiac arrest incidence
There were 2029 cardiac arrest events that AMR responded to during the study period. Thirteen patients were excluded from the study owing to the cause of their cardiac arrest: eight from drowning, two from electrocution, and three from trauma. These exclusions resulted in a sample of 2016 non-traumatic cardiac arrest incidents.
The total incidence rate for OHCA for the AMR service area in 2013 was 6.36 per 10 000 population. The 2013 OHCA incidence by county was 4.7 per 10 000 for Clackamas, 6.44 per 10 000 for Multnomah, and 7.67 per 10 000 for Clark. The total 2014 OHCA incidence rate for the AMR service area was 6.16 per 10 000 population. The 2014 OHCA incidence rate by county was 4.5 per 10 000 for Clackamas; 6.6 per 10 000 for Multnomah; and 6.85 for Clark.
Response comparisons
There were 1123 (55%) cardiac arrest cases paramedics attempted treatment on out of 2016 OHCA incidents during the study period. The other 893 cases (45%) were pronounced at the scene. These 1123 patients comprise the treatment population sample used to determine survival odds. Table 1 details the descriptive analyses of the OHCA variables for the three counties for all patients. Four outliers were removed that had treatment time in over 100 minutes. The mean response time for Clackamas was 8.11 minutes (SD=4.37); for Multnomah, 6.17 minutes (SD=3.18); and for Clark, 6.86 minutes (SD=2.75). The mean treatment time for Clackamas was 21.87 minutes (SD=9.03); for Multnomah, 4.24 minutes (SD=9.08); and for Clark, 24.11 minutes (SD=8.32). The mean transport time for Clackamas was 10.87 minutes (SD=7.34); for Multnomah, 9.11 minutes (SD=6.26); and for Clark, 10.70 minutes (SD=5.43).
| County | Variable | Time from dispatch to scene arrival | Time EMS spent on treatment | Time to transport to hospital or medical care |
|---|---|---|---|---|
| Clackamas | n | 230 | 230 | 229 |
| Mean | 8.11 | 21.87 | 10.87 | |
| Median | 7.00 | 21.00 | 9.00 | |
| Std Dev | 4.37 | 9.04 | 7.34 | |
| Multnomah | n | 649 | 642 | 642 |
| Mean | 6.17 | 24.24 | 9.11 | |
| Median | 6.00 | 24.00 | 8.00 | |
| Std Dev | 3.18 | 9.08 | 6.26 | |
| Clark | n | 243 | 239 | 239 |
| Mean | 6.86 | 24.11 | 10.70 | |
| Median | 7.00 | 23.00 | 10.00 | |
| Std Dev | 2.75 | 8.32 | 5.43 | |
| Total AMR | n | 1,122 | 1,111 | 1,110 |
| Mean | 6.72 | 23.72 | 9.82 | |
| Median | 6.00 | 23.00 | 9.00 | |
| SD | 3.45 | 8.96 | 6.38 |
n=number of patients. SD=Standard Deviation. AMR=American Medical Response. EMS=emergency medical services. Different n for each county indicates missing data or treatment cessation.
Table 2 lists the Kruskall-Wallis test results and any differences between the counties in response, treatment, and transport times. There were significant differences in the Chi-square and Mann-Whitney tests for response times between all counties in the AMR service area. The Chi-square and Mann-Whitney tests were significant for treatment times between Clackamas and Multnomah, and between Clackamas and Clark. The Chi-square and Mann-Whitney analyses were also significant in transport times between Clackamas and Multnomah, and between Multnomah and Clark. There was no significant difference in treatment time between Multnomah and Clark. There was also no significant difference in transport time between Clackamas and Clark.
| Response time | Treatment time | Transport time | |
|---|---|---|---|
| Chi-Square | 57.86 | 19.93 | 27.57 |
| p<0.05 | 0.000* | 0.000* | 0.000* |
| Clackamas vs. Multnomah | |||
| Mann-Whitney | 51 389.5 | 59 602.0 | 62 645.5 |
| Z Score | -7.082 | -4.345 | -3.332 |
| p<0.05 | 0.000* | 0.000* | 0.001* |
| Clackamas vs. Clark | |||
| Mann-Whitney | 24 013.5 | 22 389.50 | 25 962.0 |
| Z Score | -2.664 | -3.476 | -.961 |
| p<0.05 | 0.008* | 0.001* | 0.336 |
| Multnomah vs. Clark | |||
| Mann-Whitney | 63 795.0 | 76 319.0 | 60 552.5 |
| Z Score | -4.434 | -0.119 | -4.825 |
| p<0.05 | 0.000* | 0.905 | 0.000* |
p<0.05 is significance level for all tests.
Outcome comparisons
Table 3 details the patient data with bivariate associations with ROSC for the three counties studied. Table 4 lists the bivariate associations for the cohort's ROSC and SHA by county. Table 5 lists the odds ratios and confidence intervals for ROSC and SHA. ROSC is highly associated with SHA. Clark had no cases of a cardiac arrest patient surviving without achieving ROSC. Additionally, Clackamas had an odds ratio (OR) of 25.43 (confidence interval (CI)=9.62–67.23) of not surviving to admission if ROSC is not achieved. Multnomah had an OR of 26.47 (CI=14.29–49.0) against survival if ROSC is not achieved.
| Return of Spontaneous Circulation (ROSC) | ||||||
|---|---|---|---|---|---|---|
| No | Yes | No | Yes | No | Yes | |
| County | Clackamas | Multnomah | Clark | |||
| Variable | ||||||
| Male | 49 (62.8%) | 108 (70.6%) | 134 (65.7%) | 293 (65.8%) | 41 (36.4%) | 109 (59.2%) |
| Female | 29 (37.2%) | 45 (29.4%) | 70 (34.3%) | 152 (34.2%) | 18 (22.6%) | 75 (40.8%) |
| Witnessed | ||||||
| Yes | 42 (53.8%) | 102 (66.7%) | 122 (59.8%) | 282 (63.4%) | 36 (61.0%) | 111 (60.3%) |
| No | 36 (46.2%) | 51 (33.3%) | 82 (40.2%) | 163 (36.6%) | 23 (39.0%) | 73 (39.7%) |
| CPR | ||||||
| Yes | 70 (89.7%) | 152 (99.3%) | 193 (94.6%) | 439 (98.7%) | 54 (91.5%) | 182 (98.9%) |
| No | 8 (10.3%) | 1 (0.7%) | 11 (5.4%) | 11 (5.3%) | 5 (8.5%) | 2 (5.3%) |
| Defibrillation | ||||||
| Yes | 38 (48.7%) | 80 (52.3%) | 104 (51.0%) | 196 (44.0%) | 25 (42.4%) | 72 (39.1%) |
| No | 40 (51.3%) | 73 (47.7%) | 100 (49.0%) | 249 (56.0%) | 34 (57.6%) | 112 (60.9%) |
| Epinephrine | ||||||
| Yes | 67 (85.9%) | 105 (68.6%) | 171 (83.8%) | 304 (68.3%) | 51 (86.4%) | 150 (81.5%) |
| No | 11 (14.1%) | 48 (31.4%) | 33 (16.2%) | 141 (31.7%) | 8 (13.6%) | 34 (18.5%) |
Counts indicate numbers within each cohort. The brackets indicate percentages within each cohort.
| Survival to Hospital Admission (SHA) | ||||||
|---|---|---|---|---|---|---|
| No | Yes | No | Yes | No | Yes | |
| County | Clackamas | Multnomah | Clark | |||
| ROSC | ||||||
| Yes | 20 (23.5%) | 129 (97.0%) | 73 (28.9%) | 362 (97.3%) | 25 (30.5%) | 153 (100.0%) |
| No | 65 (76.5%) | 4 (3.0%) | 180 (71.1%) | 10 (2.7%) | 57 (69.5%) | 0 (0.0%) |
Counts indicate numbers within each cohort. The brackets indicate percentages within each cohort.
ROSC=Return of spontaneous circulation.
| Survival to Hospital Admission (SHA) | ||||
|---|---|---|---|---|
| County | Clackamas | Multnomah | Clark | Total |
| Variable | OR 95% CI | OR 95% CI | OR 95% CI | OR 95% CI |
| ROSC | ||||
| Yes | 0.24 (0.17, 0.36) | 0.30 (0.24, 0.36) | 0.31 (0.22, 0.42) | 0.29 (0.27, 0.34) |
| No | 25.43 (9.62, 67.23) | 26.47 (14.29,49.0) | 0.00 (0.00)* | 33.8 (20.06, 57.0) |
OR=odds ratio. CI=confidence Interval. ROSC=return of spontaneous circulation.
Across the county-by-county Chi-Square comparison for ROSC and the Chi-Square test for SHA, there were no significant differences in either ROSC or SHA between the three counties studied.
The study found that over half (55%) of all OHCA cases were treated by paramedics. There was considerable variation between the response times, treatment times, and transport times for the three counties studied. In total, there were 2016 cardiac arrests in the study period, with 153 patients who survived to hospital admission [SHA]. The OHCA SHA rate was therefore 7.5%. The most noteworthy finding for this study was the large effect that CPR administration had on both ROSC and SHA. Furthermore, despite variations between the response times, there were no significant differences in the achievement of ROSC or survival to an ED.
Discussion
Cardiac arrest is a serious event with generally unsatisfactory outcomes (Nichol et al, 2008; Neumar et al, 2011; Zive et al, 2011) The findings in response time variation, the importance of CPR to achieving ROSC and SHA, and the link between ROSC and SHA in this study reflected the findings of previous studies. The survival rate of 7.5% in this study is also comparable to previous findings. (Haukoos et al, 2010; Neumar et al, 2011; Zive et al, 2011; van Diepen et al, 2013; Kleinman et al, 2018).
While similar to prior research (Haukoos et al, 2010) in the overall incidence of OHCA between Portland and Denver, the OHCA incidence on a county-wide basis was much lower in the three counties studied than Denver. The 2003 Denver incidence rate of 18.5 per 10 000 population and 2004 Denver incidence rate of 17.2 per 10 000 population far exceeds the highest rate seen in this study; 7.67 OHCA incidences per 10 000 population for Clark in 2013. The reason for this wide disparity is unknown but well-documented (Nichol et al, 2008).
The three counties studied demonstrated how regional differences can change the response, treatment, and transport times. There were significant differences for all counties, with the post hoc tests detailing that only the Multnomah vs. Clark test for treatment time and the Clackamas vs. Clark test for transport time were not significantly different. Clark encompasses urban and rural areas of Washington State which likely affected response and treatment times. Although there were variations in times for response, treatment, and transport between the three counties, there were no significant differences in ROSC and SHA. The percentage of patients in OHCA who were treated by paramedics, at 55%, is similar to previous findings with respect to cases pronounced at the scene (45%) and cases treated by EMS (55%) (Neumar et al, 2011; Zive et al, 2011).
The most noteworthy finding of this study was the importance of high-quality CPR. While sex, bystander-witnessed OHCA, defibrillation, and epinephrine administration variables all affected the odds ratios and the chances of ROSC and SHA, no other factor had as large of an effect as CPR. Clackamas had the largest demonstrable effect of CPR on ROSC. Patients who did not receive CPR had a 15-fold likelihood of not achieving ROSC. Clark patients had a 7.8-fold chance of not achieving ROSC without CPR; and Multnomah had a 4-fold chance of no ROSC occurring. The overall odds for all counties were 6.12 for achieving ROSC. Those who did not receive CPR had a 6-fold chance of not achieving ROSC and dying.
This study further demonstrated the relationship between ROSC and SHA. Patients who achieved ROSC were more likely to live long enough to reach a hospital ED as shown by the high odds ratios in Table 4 and Table 5. Clark had no cases of SHA without ROSC, reflecting the importance of ROSC to OHCA survival.
Limitations
This study had some limitations. First, it uses previously collected data. This fact means there is no way to correct for missing or mis-keyed data. Therefore, no explanation was possible for the three outliers observed with over 100 minutes of treatment time, leading to their exclusion from the study. The descriptive nature of the study reduces the noteworthiness of its findings. While it does add to knowledge regarding cardiac arrest, the lack of controlled, clinical interventions yields little new clinical information.
Another limitation using previously collected data is that no explanation may be made for data that seems incongruous. For example, Table 3 shows that 14 patients did not receive CPR, yet ROSC was achieved; and Table 4 shows that 14 patients survived to hospital admission without ROSC. The fact that with cardiac arrest these patients are for all purposes dead, but still survived to hospital admission without receiving CPR or achieving ROSC is confounding. Whether the data were entered incorrectly on-scene or after transport, the original condition was misdiagnosed, or these patients were defibrillated and did not require CPR is unknown and cannot be elucidated from the data.
Also, this study represents data collected only from AMR calls. A sizeable amount of OHCA data are unaccounted for from other EMS agencies. This lack of data prevents a robust description of the actual cardiac arrest profile for Portland. Future research in Portland should focus on incorporating more service agencies to provide greater detail and add to cardiac arrest registries.
Conclusion
Cardiac arrest is a severe global health concern. The current study describes the features of OHCA in the Portland metropolitan area and adds to the information regarding OHCA incidence, response by EMS providers, and survival outcomes. While it provides new information regarding the specific Portland area, it also reinforces the importance of high-quality CPR to patient survival and the prominence that the ROSC has on SHA. This information adds to expanding registries in North America and globally to help derive new research avenues for OHCA treatment. Continuing research is crucial to help increase OHCA survival odds and guide EMS systems on the best treatment.