Does the number of emergency medical technicians affect the neurological outcome of patients with out-of-hospital cardiac arrest?

Effect of crew ratio of advanced life support-trained personnel on patients with out-of-hospital cardiac arrest: A systematic review and meta-analysis

BACKGROUND/PURPOSE

This review aimed to investigate the effect of crew ratios of on-scene advanced life support (ALS)-trained personnel on patients with out-of-hospital cardiac arrest (OHCA).

METHODS

We systematically searched PubMed, Ovid EMBASE, and the Cochrane Central Register of Controlled Trials databases from the inception date until September 30, 2022, for eligible studies. Two reviewers independently screened the studies for relevance, extracted data, and quality. We compared the effect of the ratio of on-scene ALS-trained personnel >50 % to those with a ratio ≤50 % among prehospital personnel on the clinical outcomes of OHCA patients. The primary outcome was survival-to-discharge and secondary outcomes were any return of spontaneous circulation (ROSC), sustained ROSC (≥2 h), and favourable neurological outcome at discharge (cerebral performance category scores: 1 or 2). Pooled odds ratios (ORs) were calculated, and the certainty of evidence was assessed.

RESULTS

From 10,864 references, we identified four non-randomised studies, including 16,475 patients. Two studies were performed in Japan and two in Taiwan. There were significant differences in survival-to-discharge (OR: 1.24, 95 % confidence interval [CI]: 1.07-1.44, I2: 7 %), any ROSC (OR:1.22, 95 % CI: 1.04-1.43, I2: 74 %) and sustained ROSC (OR: 1.39, 95 % CI: 1.16-1.65, I2: 40 %), but insignificant differences in favourable neurological outcome at discharge. The overall certainty of evidence was rated as very low for all outcomes.

CONCLUSION

Prehospital ALS care with a ratio of on-scene ALS-trained personnel >50 % could improve OHCA patient outcomes than crew ratios ≤50 %. Further studies are required to reach a robust conclusion.

Prehospital emergency medicine research by additional teams on scene - Concepts and lessons learned

While the initial minutes of acute emergencies significantly influence clinical outcomes, prehospital research often receives inadequate attention due to several challenges. Retrospective chart reviews carry the risk of incomplete and inaccurate data. Furthermore, prehospital intervention trials frequently encounter difficulties related to extensive training requirements, even during the planning phase. Consequently, we have implemented prospective research concepts involving additional paramedics and physicians directly at the scene during major emergency calls. Three concepts were used: (I) Paramedic field supervisor units, (II) a paramedic + physician field supervisor unit, (III) a special physician-based research car. This paper provides insights into our historical perspective, the current situation, and the lessons learned while overcoming certain barriers and using existing and novel facilitators. Our objective is to support other research groups with our experiences in their planning of upcoming prehospital trials.

The number and level of first-contact emergency medical services crew and clinical outcomes in out-of-hospital cardiac arrest with dual dispatch response

OBJECTIVE

This study aimed to evaluate the association between the number and level of emergency medical technicians (EMTs) in the first-contact emergency medical services (EMS) unit and the clinical outcomes of out-of-hospital cardiac arrest (OHCA) with a dual dispatch response.

METHODS

Adult nontraumatic EMS-treated OHCAs between 2015 and 2018 in a nationwide database, were enrolled. The main exposure was the number and certification level of first-contact EMS crew: three versus two members, proportion of EMT intermediate level (EMT-I) over 50% versus under or equal to 50%. Good neurologic recovery was selected as the primary outcome. Multilevel multivariable logistic regression analysis was conducted to calculate adjusted odds ratios and confidence intervals.

RESULTS

A total of 26,867 patients were enrolled and analyzed. Good neurologic recovery was different across the study groups: 5.4% in the two-member crews, 7.2% in the three-member crews, 5.9% in the low EMT-I proportion crews, and 6.8% in the high EMT-I proportion crews. In the main analysis, statistically significant differences for favorable outcomes were found between the three-member and two-member crews, and the high EMT-I proportion and low EMT-I proportion crews; for good neurologic recovery, adjusted odds ratios (95% confidence interval) were 1.23 (1.06-1.43) for three-member crews, and 1.28 (1.17-1.40) for a high EMT-I proportion.

CONCLUSION

The higher number and level of first-contact EMS crew was associated with better neurologic recovery in adult nontraumatic OHCA with a dual-dispatched EMS response.

Association between Paramedic Workforce and Survival Rate in Prehospital Advanced Life Support in Out-of-Hospital Cardiac Arrest Patients

The low survival rate of out-of-hospital cardiac arrest (OHCA) patients is a global public health challenge. We analyzed the relationship between the number of prehospital EMS personnel and survival admission, survival discharge, and good neurologic outcomes in OHCA patients. This was a retrospective observational study. Adult nontraumatic OHCA patients from January 1, 2015, to December 31, 2018, were included from 12 cities in the Gyeonggi province, a metropolitan area located in the suburbs of the capital of the Republic of Korea. By comparing the insufficient EMS team (four or five EMS personnel) and the sufficient EMS team (six EMS personnel), we showed the survival rate of each group. Using propensity score matching, we reduced the bias of the confounding variables. A total of 3,632 OHCA patients were included. After propensity score matching, survival to admission was higher in the sufficient EMS team than in the insufficient EMS team (odds ratio (OR): 1.38, 95% confidence interval (CI): 1.04–1.84, P=0.03). Survival-to-discharge was similar (OR: 1.70, CI: 1.20–2.40, P=0.03), but there was no significant outcome in good neurologic outcomes (OR: 0.88, CI: 0.57–1.36, P=0.58). Our findings suggest that a sufficient EMS team (six EMS personnel) could improve the survival admission and discharge of OHCA patients compared to an insufficient EMS team (four or five EMS personnel). However, there was no significant difference in neurologic outcomes according to the number of EMS personnel.

The Association Between the Number of Prehospital Providers On-Scene and Out-of-Hospital Cardiac Arrest Outcomes

Objective: The ideal number of emergency medical services (EMS) providers needed on-scene during an out-of-hospital cardiac arrest (OHCA) resuscitation is unknown. Our objective was to evaluate the association between the number of providers on-scene and OHCA outcomes. Methods: This was a secondary analysis of adults (≥18 years old) with non-traumatic OHCA from a 10-site North American prospective cardiac arrest registry (Resuscitation Outcomes Consortium) including a 2005-2011 cohort and a 2011-2015 cohort. The primary outcome was survival to hospital discharge. We calculated the median number of EMS providers on-scene during the first 10 minutes of the resuscitation and used multivariable logistic regression adjusting for age, sex, witness status, bystander CPR, arrest location, initial rhythm, and dispatch to EMS arrival time. Results: There were 30,613 and 41,946 patients with necessary variables in the 2005-2011 and 2011-2015 cohorts, respectively. Survival to hospital discharge (95% CI) was higher with 9 or more providers on-scene (17.2% [15.8-18.5] and 14.0% [12.6-15.4]) compared to 7-8 (14.1% [13.4-14.8] and 10.5% [9.9-11.1]), 5-6 (10.0% [9.5-10.5] and 8.5% [8.1-8.9]), 3-4 (10.5% [9.3-11.6] and 9.3% [8.5-10.1]), and 1-2 (8.6% [7.2-10.0] and 8.0% [7.1-9.0]) providers for the 2005-2011 and 2011-2015 cohorts, respectively. In multivariable logistic regressions, compared to 5-6 providers, there were no significant differences in survival to hospital discharge for 1-2 or 3-4 providers, while having 7-8 (adjusted odds ratios (aORs) 1.53 [1.39-1.67] and 1.31 [1.20-1.44]) and 9 or more (aORs 1.76 [1.56-1.98] and 1.63 [1.41-1.89]) providers were associated with improved survival in both the 2005-2011 and 2011-2015 cohorts, respectively. Conclusions: The presence of seven or more prehospital providers on-scene was associated with significantly greater adjusted odds of survival to hospital discharge after OHCA compared to fewer on-scene providers.

Association between case volume of ambulance stations and clinical outcomes of out-of-hospital cardiac arrest: A nationwide multilevel analysis

OBJECTIVES

The case volume effects of ambulance stations on the survival of out-of-hospital cardiac arrest (OHCA) patients are uncertain. This study was conducted to evaluate the association between the case volume of ambulance stations and clinical outcomes in OHCAs by the number of emergency medical services (EMS) providers at the scene.

METHODS

Adult cardiac EMS-treated OHCAs between 2015 and 2018 were enrolled. The main exposure was the annual OHCA case volumes of 204 ambulance stations in Korea, which were categorized into three groups; low-volume (<100), moderate-volume (100-159) and high-volume (≥160). The primary and secondary outcomes were good neurological recovery and survival to discharge. Multilevel multivariable logistic regression analysis was conducted to calculate adjusted odds ratios (AORs). Interaction analysis between the number of EMS providers at the scene and the exposure variable was performed.

RESULTS

A total of 92,534 patients were enrolled. OHCAs in the low-volume group tended to be arrest in a public place or a non-metropolitan area, less prehospital administration of an advanced airway and intravenous management. Significant differences were found the main analysis: AORs (95% CIs) compared to the low-volume group were 1.15 (1.03-1.29) and 1.14 (1.03-1.27) in the high-volume and moderate-volume groups for good neurological recovery and 1.19 (1.07-1.33) and 1.14 (1.04-1.25) in the high-volume and moderate-volume groups for survival to discharge. Significant interaction effects between the number of EMS providers at the scene and case volume on clinical outcomes were found.

CONCLUSION

OHCA case volumes of ambulance stations are associated with clinical outcomes after cardiac arrest.

Optimal paramedic numbers in resuscitation of patients with out-of-hospital cardiac arrest: A randomized controlled study in a simulation setting

Background

The effect of paramedic crew size in the resuscitation of patients with out-of-hospital cardiac arrest (OHCA) remains inconclusive. We hypothesised that teams with a larger crew size have better resuscitation performance including chest compression fraction (CCF), advanced life support (ALS), and teamwork performance than those with a smaller crew size.

Methods

We conducted a randomized controlled study in a simulation setting. A total of 140 paramedics from New Taipei City were obtained by stratified sampling and were randomly allocated to 35 teams with crew sizes of 2, 3, 4, 5, and 6 (i.e. 7 teams in every paramedic crew size). A scenario involving an OHCA patient who experienced ventricular fibrillation and was attached to a cardiopulmonary resuscitation (CPR) machine was simulated. The primary outcome was the overall CCF; the secondary outcomes were the CCF in manual CPR periods, time from the first dose of epinephrine until the accomplishment of intubation, and teamwork performance. Tasks affecting the hands-off time during CPR were also analysed.

Results

In all 35 teams with crew sizes of 2, 3, 4, 5, and 6, the overall CCFs were 65.1%, 64.4%, 70.7%, 72.8%, and 71.5%, respectively (P = 0.148). Teams with a crew size of 5 (58.4%, 61.8%, 68.9%, 72.4%, and 68.7%, P<0.05) had higher CCF in manual CPR periods and better team dynamics. Time to the first dose of epinephrine was significantly shorter in teams with 4 paramedics, while time to completion of intubation was shortest in teams with 6 paramedics. Troubleshooting of M-CPR machine decreased the hands-off time during resuscitation (39 s), with teams comprising 2 paramedics having the longest hands-off time (63s).

Conclusion

Larger paramedic crew size (≧4 paramedics) did not significantly increase the overall CCF in OHCA resuscitation but showed higher CCF in manual CPR period before the setup of the CPR machine. A crew size of ≧4 paramedics can also shorten the time of ALS interventions, while teams with 5 paramedics will have the best teamwork performance. Paramedic teams with a smaller crew size should focus more on the quality of manual CPR, teamwork, and training how to troubleshoot a M-CPR machine.

Improved outcomes for out-of-hospital cardiac arrest patients treated by emergency life-saving technicians compared with basic emergency medical technicians: A JCS-ReSS study report

BACKGROUND

Emergency life-saving technicians (ELSTs) are specially trained prehospital medical providers believed to provide better care than basic emergency medical technicians (BEMTs). ELSTs are certified to perform techniques such as administration of advanced airways or adrenaline and are considered to have more knowledge; nevertheless, ELSTs' effectiveness over BEMTs regarding out-of-hospital cardiac arrest (OHCA) remains unclear. We investigated whether the presence of an ELST improves OHCA patient outcomes.

METHODS

In a retrospective study of adult OHCA patients treated in Japan from 2011 to 2015, we compared two OHCA patient groups: patients transported with at least one ELST and patients transported by only BEMTs. The primary outcome measure was one-month favorable neurological outcomes, defined as Cerebral Performance Category ≤ 2. A multivariable logistic regression model was used to calculate odds ratios (ORs) and their confidence intervals (CIs) to evaluate the effect of ELSTs.

RESULTS

Included were 552,337 OHCA patients, with 538,222 patients in the ELST group and 14,115 in the BEMT group. The ELST group had a significantly higher odds of favorable neurological outcomes (2.5% vs. 2.1%, adjusted OR 1.39, 95% CI 1.17-1.66), one-month survival (4.9% vs. 4.1%, adjusted OR 1.37, 95% CI 1.22-1.54), and return of spontaneous circulation (8.1% vs. 5.1%, adjusted OR 1.90, 95% CI 1.72-2.11) compared with the BEMT group. However, ELSTs' limited procedure range (adrenaline administration or advanced airway management) did not promote favorable neurological outcomes.

CONCLUSIONS

Compared with the BEMT group, transport by the ELST group was associated with better neurological outcomes in OHCA.

Private residence as a location of cardiac arrest may have a deleterious effect on the outcomes of out-of-hospital cardiac arrest in patients with an initial non-shockable cardiac rhythm: A multicentre retrospective cohort study

AIM

We compared the outcomes between patients who experienced out-of-hospital cardiac arrest at private residences and public locations to investigate whether patient and bystander characteristics can explain the poorer outcomes of out-of-hospital cardiac arrests at private residences.

METHODS

Adult patients with intrinsic out-of-hospital cardiac arrest (n = 6,191, age ≥18 years) were selected from a prospectively collected Japanese database (January 2012 and March 2013). Patients were grouped according to arrest location into private-residence or control (e.g., public station or road, workplace, school, and other public locations) groups. The primary outcome was a favourable neurological outcome 1 month after out-of-hospital cardiac arrest.

RESULTS

The arrest location and initial cardiac rhythm had interaction effects on the outcome. After adjusting for patient and bystander characteristics and relative to the control group, a significantly poorer 1-month neurological outcome was observed in the private-residence group if the initial cardiac rhythm was non-shockable (odds ratio: 0.36, 95% confidence interval: 0.24-0.54), while it was not significant if the initial cardiac rhythm was shockable (odds ratio: 1.16, 95% confidence interval: 0.74-1.84).

CONCLUSIONS

Patients with out-of-hospital cardiac arrest at private residences had poorer outcomes than those with out-of-hospital cardiac arrest at public locations, even after adjusting for patient and bystander characteristics, if the initial cardiac rhythm was non-shockable. Our results suggest that poorer patient and bystander characteristics do not completely explain the poorer outcomes of out-of-hospital cardiac arrests; there may be unknown mechanisms through which the location of cardiac arrest affect the outcomes.

Impacts of Emergency Medical Technician Configurations on Outcomes of Patients with Out-of-Hospital Cardiac Arrest

Paramedics can provide advanced life support (ALS) for patients with out-of-hospital cardiac arrest (OHCA). However, the impact of emergency medical technician (EMT) configuration on their outcomes remains debated. A three-year cohort study consisted of non-traumatic OHCA adults transported by ALS teams was retrospectively conducted in Tainan City using an Utstein-style population database. The EMT-paramedic (EMT-P) ratio was defined as the EMT-P proportion out of all on-scene EMTs. Among the 1357 eligible cases, the median (interquartile range) number of on-scene EMTs and the EMT-P ratio were 2 (2–2) persons and 50% (50–100%), respectively. The multivariate analysis identified five independent predictors of sustained return of spontaneous circulation (ROSC): younger adults, witnessed cardiac arrest, prehospital ROSC, prehospital defibrillation, and comorbid diabetes mellitus. After adjustment, every 10% increase in the EMT-P ratio was on average associated with an 8% increased chance (adjusted odds ratio [aOR], 1.08; p < 0.01) of sustained ROSC and a 12% increase change (aOR, 1.12; p = 0.048) of favorable neurologic status at discharge. However, increased number of on-scene EMTs was not linked to better outcomes. For nontraumatic OHCA adults, an increase in the on-scene EMT-P ratio resulted in a higher proportion of improved patient outcomes.

Effect of Implementation of Cardiopulmonary Resuscitation-Targeted Multi-Tier Response System on Outcomes After Out-of-Hospital Cardiac Arrest: A Before-and-After Population-Based Study

Objective: A multi-tiered response (MTR) system has been controversial in terms of cost-effectiveness and outcome improvement. It remains uncertain whether a cardiopulmonary resuscitation (CPR)-targeted tiered response system is associated with better outcomes after out-of-hospital cardiac arrest (OHCA). This study aimed to investigate the effect of an MTR on OHCA outcomes. Methods: A natural experimental study was conducted for resuscitation-attempted adult OHCAs. The MTR system was implemented in Korea by the National Fire Agency in 2015 across the country where the single-tiered ambulance response system existed. The MTR program had the following 3 components: 1) detection of OHCA by dispatcher, 2) dispatch of ambulance or fire engine in addition to routine dispatch of ambulance, and 3) performance of team CPR. The study period of 2015-2016 was divided by 6 months (phases I [reference], II, III, and IV). The endpoints were prehospital defibrillation, prehospital return of spontaneous circulation (PROSC), survival to discharge and good neurological recovery. A multivariable logistic regression analysis was performed to evaluate the effect of the intervention, and adjusted odds ratios (AORs) with 95% confidence intervals (CIs) were calculated, adjusting for potential confounders. Results: A total of 32,663 eligible OHCA cases were evaluated during the study period. As the intervention program spread, the MTR with ambulance increased (from 7.0% in phase I to 53.7% in phase IV, p for trend < 0.01). During the study period, prehospital defibrillation increased from 23.6% in phase I to 26.9% in phase IV and the study outcome was improved from 7.4 to 12.6% for PROSC, from 6.7 to 9.1% for survival to discharge, and from 4.5 to 5.8% for good neurological outcome (p for trend < 0.01 for all). Compared with phase I, the AORs (95% CI) of phase IV were 1.16 (1.08-1.25) for prehospital defibrillation, 1.82 (1.63-2.04) for PROSC, 1.37 (1.21-1.56) for survival to discharge, and 1.23 (1.06-1.43) for good neurological outcome. Conclusion: The nationwide implementation of a multi-tiered response system for OHCA was associated with increased prehospital defibrillation and improved outcomes of OHCA patients.

The effect of the number and level of emergency medical technicians on patient outcomes following out of hospital cardiac arrest in Taipei

AIM

The effect of the number and level of on-scene emergency medical technicians (EMTs) on the outcomes of patients with out-of-hospital cardiac arrest (OHCA) remains unclear. We aimed to test the association between the number and level of EMTs and the outcomes of patients with OHCA.

METHODS

We analysed Utstein-based registry data on OHCA in Taipei from 2011 to 2015. The eligible patients were adults, aged ≥20 years, with non-traumatic OHCA who underwent resuscitation attempts. The exposures were the total number of EMTs or the EMT-Paramedic (EMT-P) ratio >50%. The outcome of interest was survival to discharge.

RESULTS

During study period, total 8262 OHCA cases were included, of which 1085 (13.1%) were approached by crews with an EMT-P ratio >50%. While an increase in the number of EMTs on-scene was not associated with better chances of survival (adjusted odds ratio [aOR] 0.98, 95% confidence interval [CI] 0.89-1.08), an EMT-P ratio >50% was significantly associated with improved outcome (aOR 1.36, 95% CI 1.06-1.76). Subgroup analyses showed that EMT-P >50% significantly benefited survival in witnessed OHCA cases with non-shockable rhythm (aOR 1.69, 95% CI 1.01-2.58). Survival was the highest among cases seen by four EMTs with an EMT-P ratio >50% (aOR 2.54, 95% CI 1.43-4.50).

CONCLUSION

An on-scene EMT-P ratio >50% was associated with improved survival to discharge of OHCA cases, especially in those with witnessed, non-shockable rhythm. The presence of four EMTs with an EMT-P ratio >50% at the scene of OHCA was associated with the best outcome.