Cardiac arrest survival as a function of ambulance deployment strategy in a large urban emergency medical services system

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.

Evidence-Based Guideline for Prehospital Airway Management

Airway management is a cornerstone of emergency medical care. This project aimed to create evidence-based guidelines based on the systematic review recently conducted by the Agency for Healthcare Research and Quality (AHRQ). A technical expert panel was assembled to review the evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. The panel made specific recommendations on the different PICO (population, intervention, comparison, outcome) questions reviewed in the AHRQ review and created good practice statements that summarize and operationalize these recommendations. The recommendations address the use of ventilation with bag-valve mask ventilation alone vs. supraglottic airways vs. endotracheal intubation for adults and children with cardiac arrest, medical emergencies, and trauma. Additional recommendations address the use of video laryngoscopy and drug-assisted airway management. These recommendations, and the associated good practice statements, offer EMS agencies and clinicians an opportunity to review the available evidence and incorporate it into their airway management strategies.

Impact of an Extraglottic Device on Pediatric Airway Management in an Urban Prehospital System

Introduction

Prehospital pediatric endotracheal intubation has lower first-pass success rates compared to adult intubations and in general may not offer a survival benefit. Increasingly, emergency medical services (EMS) systems are deploying prehospital extraglottic airways (EGA) for primary pediatric airway management, yet little is known about their efficacy. We evaluated the impact of a pediatric prehospital airway management protocol change, inclusive of EGAs, on airway management and patient outcomes in children in cardiac arrest or respiratory failure.

Methods

Using data from a large, metropolitan, fire-based EMS service, we performed an observational study of pediatric patients with respiratory failure or cardiac arrest who were transported by EMS before and after implementation of an evidence-based airway management protocol inclusive of the addition of the EGA. The primary outcome was change in frequency of intubation attempts when paired with an initial EGA. Secondary outcomes included EGA and intubation success rates and patient survival to hospitalization and discharge.

Results

We included 265 patients age <16 years old, with 142 pre- and 123 post-protocol change. Patient demographics and event characteristics were similar between groups. Intubation attempts declined from 79.6% pre- to 44.7% (p<0.01) post-protocol change. In patients with an intubation attempt, overall intubation success declined from 81.4% to 63.6% (p<0.01). Post-protocol change, an EGA was attempted in 52.8% of patients with 95.4% success.

Conclusion

Implementation of an evidenced-based airway management algorithm for pediatric patients, inclusive of an EGA device for all age groups, was associated with fewer prehospital intubations. Intubation success may be negatively impacted due to decreases in procedural frequency.

Effectiveness of Prehospital Dual Sequential Defibrillation for Refractory Ventricular Fibrillation and Ventricular Tachycardia Cardiac Arrest

Objective: Dual sequential defibrillation (DSD) - successive defibrillations with two defibrillators - offers a novel approach to refractory ventricular fibrillation (RVF) and tachycardia (VF/VT). While associated with rescue shock success, the effect of DSD upon out-of-hospital cardiac arrest (OHCA) is unknown. We evaluated the association of DSD with survival after refractory VF/VT OHCA. Methods: We used data from a large metropolitan fire-based EMS service. We included all adult OHCA during 2013-2016 with ≥3 standard defibrillations. Physicians authorized subsequent DSD use by two separate defibrillators (PhysioControl LIFEPAK® 12/15) with pads placed anterior-lateral and anterior-posterior. Evaluated outcomes included return of spontaneous circulation (ROSC), survival to hospital admission, survival to 72 hours, and survival to hospital discharge. Using multivariable logistic regression, we evaluated the association between defibrillation type and OHCA outcomes, adjusting for patient demographics and event characteristics. Results: We included 310 patients in the analysis, 71 patients receiving DSD and 239 receiving conventional defibrillation. Patient demographics and event characteristics were similar between both groups. ROSC was lower for DSD than standard defibrillation: 39.4% vs. 60.3%, adjusted OR 0.46 (95% CI: 0.25-0.87). There were no differences in survival to hospital admission (35.2% vs. 49.2%, adjusted OR 0.57 [95% CI: 0.30-1.08]), survival to 72 hours (21.4% vs. 32.3%, adjusted OR 0.52 [95% CI: 0.26-1.10]), or survival to hospital discharge (14.3% vs. 20.9%, adjusted OR 0.63 [95% CI: 0.27-1.45]). Conclusions: Compared with conventional defibrillation, DSD was associated with lower odds of prehospital ROSC. Defibrillation type was not associated with other OHCA endpoints. DSD may not be beneficial in refractory VF/VT OHCA.

Can a Software-Based Metronome Tool Enhance Compression Rate in a Realistic 911 Call Scenario Without Adversely Impacting Compression Depth for Dispatcher-Assisted CPR?

IntroductionImplementation of high-quality, dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) is critical to improving survival from out-of-hospital cardiac arrest (OHCA). However, despite some studies demonstrating the use of a metronome in a stand-alone setting, no research has yet demonstrated the effectiveness of a metronome tool in improving DA-CPR in the context of a realistic 911 call or using instructions that have been tested in real-world emergency calls.HypothesisUse of the metronome tool will increase the proportion of callers able to perform CPR within the target rate without affecting depth.

METHODS

The prospective, randomized, controlled study involved simulated 911 cardiac arrest calls made by layperson-callers and handled by certified emergency medical dispatchers (EMDs) at four locations in Salt Lake City, Utah USA. Participants were randomized into two groups. In the experimental group, layperson-callers received CPR pre-arrival instructions with metronome assistance. In the control group, layperson-callers received only pre-arrival instructions. The primary outcome measures were correct compression rate (counts per minute [cpm]) and depth (mm).

RESULTS

A total of 148 layperson-callers (57.4% assigned to experimental group) participated in the study. There was a statistically significant association between the number of participants who achieved the target compression rate and experimental study group (P=.003), and the experimental group had a significantly higher median compression rate than the control group (100 cpm and 89 cpm, respectively; P=.013). Overall, there was no significant correlation between compression rate and depth.

CONCLUSION

An automated software metronome tool is effective in getting layperson-callers to achieve the target compression rate and compression depth in a realistic DA-CPR scenario.Scott G, Barron T, Gardett I, Broadbent M, Downs H, Devey L, Hinterman EJ, Clawson J, Olola C. Can a software-based metronome tool enhance compression rate in a realistic 911 call scenario without adversely impacting compression depth for dispatcher-assisted CPR? Prehosp Disaster Med. 2018;33(4):399-405.

The Effects of Public Access Defibrillation on Survival After Out-of-Hospital Cardiac Arrest: A Systematic Review of Observational Studies

BACKGROUND

Despite recent advances, the average survival after out-of-hospital cardiac arrest (OHCA) remains <10%. Early defibrillation by an automated external defibrillator is the most important intervention for patients with OHCA, showing survival proportions >50%. Accordingly, placement of automated external defibrillators in the community as part of a public access defibrillation program (PAD) is recommended by international guidelines. However, different strategies have been proposed on how exactly to increase and make use of publicly available automated external defibrillators. This systematic review aimed to evaluate the effect of PAD and the different PAD strategies on survival after OHCA.

METHODS

PubMed, Embase, and the Cochrane Library were systematically searched on August 31, 2015 for observational studies reporting survival to hospital discharge in OHCA patients where an automated external defibrillator had been used by nonemergency medical services. PAD was divided into 3 groups according to who applied the defibrillator: nondispatched lay first responders, professional first responders (firefighters/police) dispatched by the Emergency Medical Dispatch Center (EMDC), or lay first responders dispatched by the EMDC.

RESULTS

A total of 41 studies were included; 18 reported PAD by nondispatched lay first responders, 20 reported PAD by EMDC-dispatched professional first responders (firefighters/police), and 3 reported both. We identified no qualified studies reporting survival after PAD by EMDC-dispatched lay first responders. The overall survival to hospital discharge after OHCA treated with PAD showed a median survival of 40.0% (range, 9.1-83.3). Defibrillation by nondispatched lay first responders was associated with the highest survival with a median survival of 53.0% (range, 26.0-72.0), whereas defibrillation by EMDC-dispatched professional first responders (firefighters/police) was associated with a median survival of 28.6% (range, 9.0-76.0). A meta-analysis of the different survival outcomes could not be performed because of the large heterogeneity of the included studies.

CONCLUSIONS

This systematic review showed a median overall survival of 40% for patients with OHCA treated by PAD. Defibrillation by nondispatched lay first responders was found to correlate with the highest impact on survival in comparison with EMDC-dispatched professional first responders. PAD by EMDC-dispatched lay first responders could be a promising strategy, but evidence is lacking.

The Effect of Ambulance Staffing Models in a Metropolitan, Fire-Based EMS System

Introduction The staffing of ambulances with different levels of Emergency Medical Service (EMS) providers is a difficult decision with evidence being mixed on the benefit of each model. Hypothesis/Problem The objective of this study was to describe a pilot program evaluating alternative staffing on two ambulances utilizing the paramedic-basic (PB) model (staffed with one paramedic and one emergency medical technician[EMT]).

METHODS

This was a retrospective study conducted from September 17, 2013 through December 31, 2013. The PB ambulances were compared to geographically matched ambulances staffed with paramedic-paramedic (PP ambulances). One PP and one PB ambulance were based at Station A; one PP and one PB ambulance were based at Station B. The primary outcome was total on-scene time. Secondary outcomes included time-to-electrocardiogram (EKG), time-to-intravenous (IV) line insertion, IV-line success rate, and percentage of protocol violations. Inclusion criteria were all patients requesting prehospital services that were attended to by these teams. Patients were excluded if they were not attended to by the study ambulance vehicles. Descriptive statistics were reported as medians and interquartile ranges (IQR). Proportions were reported with 95% confidence intervals (CI). The Mann-Whitley U test was used for significance testing (P<.05).

RESULTS

Median on-scene times at Station A for the PP ambulance were shorter than the PB ambulance team (PP: 10.1 minutes, IQR 6.0-15; PB: 13.0 minutes, IQR 8.1-18; P=.01). This finding also was noted at Station B (PP: 13.5 minutes, IQR 8.5-19; PB: 14.3 minutes, IQR 9.9-20; P=.01). There were no differences between PP and PB ambulance teams at Station A or Station B in time-to-EKG, time-to-IV insertion, IV success rate, and protocol violation rates.

CONCLUSION

In the setting of a well-developed EMS system utilizing an all-Advanced Life Support (ALS) response, this study suggests that PB ambulance teams may function well when compared to PP ambulances. Though longer scene times were observed, differences in time to ALS interventions and protocol violation rates were not different. Hybrid ambulance teams may be an effective staffing alternative, but decisions to use this model must address clinical and operational concerns. Cortez EJ , Panchal AR , Davis JE , Keseg DP . The effect of ambulance staffing models in a metropolitan, fire-based EMS system. Prehosp Disaster Med. 2017;32(2):175-179.

Prehospital endotracheal intubation: elemental or detrimental?

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2015 and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/annualupdate2015. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Association between timing of epinephrine administration and intact neurologic survival following out-of-hospital cardiac arrest in Japan: a population-based prospective observational study

OBJECTIVES

This study aimed to investigate whether early epinephrine administration in out-of-hospital cardiopulmonary arrest (OHCA) patients was associated with improved outcomes and to address the selection bias inherent in observational studies (more severe cases are more likely to receive epinephrine).

METHODS

This was a retrospective analysis of prospectively collected population-based data of adult bystander-witnessed OHCA patients from a nationwide Japanese registry between January 2007 and December 2008. To address selection bias, those who attained early return of spontaneous circulation (ROSC) without epinephrine administration were excluded, leaving 49,165 patients in the analysis. The outcomes were intact neurologic survival, defined as survival with cerebral performance category score 1 or 2, and any survival at 1 month or at discharge (whichever was earlier). The primary predictor was the time from the start of cardiopulmonary resuscitation (CPR) by emergency medical services (EMS) to first epinephrine administration, with early epinephrine defined as within 10 minutes.

RESULTS

Multivariate logistic regression analysis showed that cardiac origin OHCA patients who received early epinephrine (≤ 10 minutes) had significantly higher rates of intact neurologic survival (odds ratio [OR]=1.39, 95% confidence interval [CI]=1.08 to 1.78) and any survival (OR=1.73, 95% CI=1.46 to 2.04) than those who did not receive early epinephrine, after adjusting for potential confounders. Results for noncardiac OHCA patients were similar.

CONCLUSIONS

Early epinephrine administration may be associated with higher rates of intact neurologic survival and any survival in adult bystander-witnessed OHCA patients. This article provides a potential method to address the selection bias inherent in observational studies that examine the effects of drug administration in OHCA patients.

Out-of-hospital endotracheal intubation experience and patient outcomes

STUDY OBJECTIVE

Previous studies suggest improved patient outcomes for providers who perform high volumes of complex medical procedures. Out-of-hospital tracheal intubation is a difficult procedure. We seek to determine the association between rescuer procedural experience and patient survival after out-of-hospital tracheal intubation.

METHODS

We analyzed probabilistically linked Pennsylvania statewide emergency medicine services, hospital discharge, and death data of patients receiving out-of-hospital tracheal intubation. We defined tracheal intubation experience as cumulative tracheal intubation during 2000 to 2005; low=1 to 10 tracheal intubations, medium=11 to 25 tracheal intubations, high=26 to 50 tracheal intubations, and very high=greater than 50 tracheal intubations. We identified survival on hospital discharge of patients intubated during 2003 to 2005. Using generalized estimating equations, we evaluated the association between patient survival and out-of-hospital rescuer cumulative tracheal intubation experience, adjusted for clinical covariates.

RESULTS

During 2003 to 2005, 4,846 rescuers performed tracheal intubation. These individuals performed tracheal intubation on 33,117 patients during 2003 to 2005 and 62,586 patients during 2000 to 2005. Among 21,753 cardiac arrests, adjusted odds of survival was higher for patients intubated by rescuers with very high tracheal intubation experience; adjusted odds ratio (OR) versus low tracheal intubation experience: very high 1.48 (95% confidence interval [CI] 1.15 to 1.89), high 1.13 (95% CI 0.98 to 1.31), and medium 1.02 (95% CI 0.91 to 1.15). Among 8,162 medical nonarrests, adjusted odds of survival were higher for patients intubated by rescuers with high and very high tracheal intubation experience; adjusted OR versus low tracheal intubation experience: very high 1.55 (95% CI 1.08 to 2.22), high 1.29 (95% CI 1.04 to 1.59), and medium 1.16 (95% CI 0.97 to 1.38). Among 3,202 trauma nonarrests, survival was not associated with rescuer tracheal intubation experience; adjusted OR versus low tracheal intubation experience: very high 1.84 (95% CI 0.89 to 3.81), high 1.25 (95% CI 0.85 to 1.85), and medium 0.92 (95% CI 0.67 to 1.26).

CONCLUSION

Rescuer procedural experience is associated with improved patient survival after out-of-hospital tracheal intubation of cardiac arrest and medical nonarrest patients. Rescuer procedural experience is not associated with patient survival after out-of-hospital tracheal intubation of trauma nonarrest patients.

Out-of-hospital cardiac arrest in denver, colorado: epidemiology and outcomes

OBJECTIVES

The annual incidence of out-of-hospital cardiac arrest (OOHCA) in the United States is approximately 6 per 10,000 population and survival remains low. Relatively little is known about the performance characteristics of a two-tiered emergency medical services (EMS) system split between fire-based basic life support (BLS) dispersed from fixed locations and hospital-based advanced life support (ALS) dispersed from nonfixed locations. The objectives of this study were to describe the incidence of OOHCA in Denver, Colorado, and to define the prevalence of survival with good neurologic function in the context of this particular EMS system.

METHODS

This was a retrospective cohort study using standardized abstraction methodology. A two-tiered hospital-based EMS system for the County of Denver and 10 receiving hospitals were studied. Consecutive adult patients who experienced nontraumatic OOHCA from January 1, 2003, through December 31, 2004, were enrolled. Demographic, prehospital arrest characteristics, treatment data, and survival data using the Utstein template were collected. Good neurologic survival was defined by a Cerebral Performance Categories (CPC) score of 1 or 2.

RESULTS

During the study period, 1,985 arrests occurred. Of these, 715 (36%) had attempted resuscitation by paramedics and constitute our study sample. The median age was 65 years (interquartile range = 52-78 years), 69% were male, 41% had witnessed arrest, 25% had bystander cardiopulmonary resuscitation (CPR) performed, and 30% had ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) as their initial rhythm. Of the 715 patients, 545 (76%) were transported to a hospital, 223 (31%) had return of spontaneous circulation (ROSC), 175 (25%) survived to hospital admission, 58 (8%) survived to hospital discharge, and 42 (6%, 95% confidence interval [CI] = 4% to 8%) had a good neurologic outcome.

CONCLUSIONS

Out-of-hospital cardiac arrest survival in Denver, Colorado, is similar to that of other United States communities. This finding provides the basis for future epidemiologic and health services research in the out-of-hospital and ED settings in our community.

The association between emergency medical services staffing patterns and out-of-hospital cardiac arrest survival

OBJECTIVE

To determine whether the number of advanced life support-trained personnel at the scene of an out-of-hospital cardiac arrest (OHCA) was associated with return of spontaneous circulation (ROSC) or survival to hospital discharge.

METHODS

A retrospective database review using Utstein-style reporting definitions was conducted in Milwaukee County. All adult (>or= 18 years of age) OHCA cases of presumed cardiac etiology from January 1993 through December 2005 were eligible for inclusion in the study. Cardiac arrests resulting from a drug overdose, suicide, drowning, hypoxia, exsanguination, stroke, or trauma were excluded from the study. Also excluded were cases in which no crew configuration or responding unit was available, cases in which no resuscitation effort was attempted, and cases in which no time data were available. Return of spontaneous circulation and survival to hospital discharge for OHCA patients treated by a crew with two paramedics were compared to those patients treated by crews with three or more paramedics. Multivariable logistic regression was used for the analysis and the results are reported as odds ratios (ORs).

RESULTS

During the study period, there were 10,298 OHCAs of cardiac etiology. Of those, 10,057 (98%) cases had sufficient data to be included in the analysis. There were 4,229 patients treated by two paramedics (9% survived to discharge), 4,459 patients treated by three paramedics (9% survived to discharge), and 1,369 patients treated by four or more paramedics (8% survived to discharge). In the multivariable analysis, when referenced against crews with two paramedics and controlled for factors that have a known correlation with cardiac arrest survival, patients treated by crews with three paramedics (0.83, 95% confidence interval [CI] 0.70 to 0.97, p = 0.02) and crews with four or more paramedics (0.66, 95% CI 0.52 to 0.83, p < 0.01) were associated with reduced survival to hospital discharge. Return of spontaneous circulation was not influenced by the number of paramedics present.

CONCLUSIONS

The presence of three or more paramedics at the scene of OHCA was not associated with improved survival to hospital discharge when compared to crews with two paramedics. Additional research is needed to determine the potential cause of this finding.

Lack of association between prehospital response times and patient outcomes

BACKGROUND

Limited data exist that examine the relationship between prehospital response times (RTs) and improved patient outcomes. Objective. We tested the hypothesis that patient outcomes do not differ substantially based on an explicitly chosen advanced life support (ALS) RT upper limit of 10 minutes 59 seconds (10:59 minutes).

METHODS

This case-control retrospective study was conducted in a metropolitan county with a population of 750,000 for the calendar year 2004. The emergency medical services (EMS) system is a single-tiered, ALS paramedic service that includes basic life support (BLS) first responders. The 90% fractile RT specification required by contractual agreement is 10:59 minutes or less for emergency, life-threatening (Priority 1) calls. Cases (study patients), defined as Priority 1 transports with RTs exceeding 10:59 minutes, were compared with controls, which comprised a random sample of Priority 1 calls with RTs of 10:59 minutes or less. Prehospital run reports and hospital outcomes were evaluated using explicit criteria by one observer for the primary outcome of in-hospital death and secondary outcomes of critical interventions performed in the field. We tested the hypothesis of equivalence using the 95% confidence intervals (CIs) for difference in proportions with alpha = 0.05 and beta = 0.2 to show Delta = +/- 5%.

RESULTS

Of the 3,270 emergency transports in 2004, we identified 373 study patients (RT > 10:59 min) and a random sample of 373 controls (RT < or = 10:59 min). Survival to hospital discharge was 80% (76% to 84%) for study patients vs. 82% (77% to 85%) for controls, yielding a 95% CI for the difference of -6 to +4%. ALS procedures were performed in 47.7% (95% CI: 43% to 53%) of study patients vs. 45.4% (40% to 51%) of controls (95% difference in proportions -10 to +5%). The most frequently performed procedures were administration of nitroglycerine and endotracheal intubation.

CONCLUSIONS

Compared with patients who wait 10:59 minutes or less for ALS response, Priority 1 patients who wait longer than 10:59 minutes could experience between a 6% increase and a 4% decrease in mortality, and do not have an increase in critical procedures performed in the field. Our data are most consistent with the inference that neither the mortality nor the frequency of critical procedural interventions varies substantially based on this prespecified ALS RT.

Using Geographic Information Systems to Evaluate Cardiac Arrest Survival

OBJECTIVE

To evaluate cardiac arrest survival using geographical information systems (GIS) methodology.

METHODS

Patient data were obtained from a fire district Utstein-style adult cardiac arrest registry that also included address data. All incident locations were geocoded and fire station first-due areas were mapped by using the new computer-aided dispatch geographic data. Retrospective assignment of first-due versus second-due fire response unit was done by using a GIS "point-in-polygon" algorithm Survival to hospital admission was the primary outcome measure for incidents responded to by first-due versus second-due apparatus controlling for other potential predictors of survival using logistic regression. Cluster analysis was also performed to evaluate potential areas of high or low rates of survival.

RESULTS

There were 461 eligible patients with an average age of 67+/-17 years, 63% were male, 53% had a witnessed arrest, bystander cardiopulmonary resuscitation was performed in 38%, bystander automatic external defibrillator (AED) Page: 1 was used in 0.01%, ventricular fibrillation or ventricular tachycardia were the presenting rhythms in 44%, the average response time was 5.5+/-2.1 minutes, and survival to hospital admission was 17%. There was no significant difference in response time between survivors (4.97 minutes) and non-survivors (5.52 minutes), (difference 0.55 minutes, 95%CI -0.08 to 1.18 min). The number of cardiac arrest calls varied from 1 to 49 for each station and the rate of second-due response varied from 0 to 19%. There was a nonsignificant association of survival to hospital admission for the first-due area cohort: odds ratio 0.70, 95% CI 0.38-1.29.

CONCLUSION

GIS is a new methodology for analyzing EMS incident data. It adds a spatial component of analysis to traditional statistical techniques. No spatial difference was found on patient survival in this analysis.

Prehospital Cardiac Arrest in a Paramedic First-responder System Using the Utstein Style

OBJECTIVES

To describe the characteristics of patients found to have cardiac arrest and to evaluate the characteristics predictive of survival after cardiac arrest in a paramedic first-responder model.

METHODS

All patients who suffered out-of-hospital cardiac arrest in the city of Reading, Ohio, from January 1998 to December 2003 were recorded in the Utstein style. The number and incidence rate of witnessed arrests, initial rhythms, rate of bystander cardiopulmonary resuscitation (CPR), and 30-day mortality rate were retrospectively collected. Demographics, time to hospital, and response times were evaluated as predictors of survival.

RESULTS

Of those patients initially found to be in cardiac arrest, 14.3% were discharged alive. Witnessed arrests were more likely to result in live discharge of the patient. Whether bystander CPR was performed was not found to affect survival, nor was initial rhythm, although no patients initially found in asystole were discharged alive. No demographic characteristics or response times were predictive of survival.

CONCLUSION

The rates of survival in this paramedic first-response system are favorable compared with basic emergency medical technician first-response systems. Further study using direct comparison methodology is warranted to confirm these findings.

Calling 911: Emergency Medical Services in Need of Human Factors

Emergency medical services (EMS) play an important role in community health care systems. Paramedics provide basic life support, deliver babies, and transport critical patients to the hospital, among other services. We observed EMS units in action to learn about their underlying human factors/ergonomics (HF/E) and found that equipment and organizational systems were often difficult to use or poorly suited to task demands. Although HF/E professionals have the knowledge and tools to improve patient safety and occupational health, HF/E research on EMS is scarce. Our observations provide a systems overview pointing to needed improvements in equipment, decision making, and organizational coordination.

Clinical trials in the out-of-hospital setting: rationale and strategies for successful implementation

Cardiopulmonary arrest and trauma are two of the major epidemics of our time. In most cases, the final outcome is altered, for better or for worse, by how interventions are provided in the prehospital setting, making that venue critical for lifesaving community research efforts. In certain venues, out-of-hospital emergency medical services personnel are highly skilled at managing resuscitations and routinely operate under strict, highly scrutinized protocols, resulting in extraordinary study compliance. Larger patient enrollment derived from population-based investigations can lead to faster study completion, less selection bias, higher-powered data, and enhanced subgroup analysis. Most importantly, the concomitant training, expert protocol development, and rigid scrutiny all lead to improved patient outcomes, regardless of study intervention. For successful implementation, emergency medical services personnel should be involved in study design, and utilize routine, automated data collection. Technologies should be provided that simplify tasks and diminish confounding variables. Considering that exception to informed consent is a critical component, prospective education and involvement of the medical community, community leaders, employee groups and the media, long before protocol implementation, is essential. Such efforts should be led by respected, academically authoritative, grassroots emergency medical services medical directors and trauma chiefs, preferably those based at the main trauma centers or public receiving facilities.

Association of delay to first intervention with return of spontaneous circulation in a swine model of cardiac arrest

OBJECTIVE

No single drug improves survival after cardiac arrest, despite success in animal studies. We sought to determine the duration of circulatory arrest after which maximal drug treatment and a rescue shock would fail to achieve return of spontaneous circulation (ROSC).

DESIGN/SUBJECTS

Retrospective analysis of 271 swine (20-30 kg) resuscitation attempts during ventricular fibrillation. Protocols were divided into five categories: immediate countershock, cardiopulmonary resuscitation (CPR) with standard-dose drugs, CPR alone, CPR and high-dose epinephrine (CPR+HDE) (0.1 mg/kg), and CPR with a drug cocktail (CPR+DC) of propanolol (1 mg), epinephrine (adrenaline) (0.1 mg/kg) and vasopressin (40IU). Time to first CPR, time to first drug administration, time to first shock, and protocol were examined as predictors of ROSC using logistic regression with Hosmer-Lemeshow test of fit. Probability of ROSC was calculated from logistic curves.

MAIN RESULTS

ROSC occurred in 119 of the 271 swine (44%). Time to first drug and the CPR+DC group were predictors of ROSC. Time to first CPR, the CPR+DC group, and the CPR+HDE group were also predictors of ROSC. Time to first rescue shock, the CPR+DC group, and the CPR+HDE groups were predictors of ROSC. In the CPR+DC group, 50% ROSC occurred at a first CPR time of 13.4 min, first drug time of 14.1 min and first rescue shock time of 17.5 min.

CONCLUSIONS

Pre-shock delivery of CPR+DC increases the likelihood of ROSC, and reaches 50% with a time of drug delivery of 14.1 min. ROSC rates of 50% may be achievable using an optimized resuscitation in experimental CPR.

Drug administration in animal studies of cardiac arrest does not reflect human clinical experience

INTRODUCTION

To date, there is no evidence showing a benefit from any advanced cardiac life support (ACLS) medication in out-of-hospital cardiac arrest (OOHCA), despite animal data to the contrary. One explanation may be a difference in the time to first drug administration. Our previous work has shown the mean time to first drug administration in clinical trials is 19.4min. We hypothesized that the average time to drug administration in large animal experiments occurs earlier than in OOHCA clinical trials.

METHODS

We conducted a literature review between 1990 and 2006 in MEDLINE using the following MeSH headings: swine, dogs, resuscitation, heart arrest, EMS, EMT, ambulance, ventricular fibrillation, drug therapy, epinephrine, vasopressin, amiodarone, lidocaine, magnesium, and sodium bicarbonate. We reviewed the abstracts of 331 studies and 197 full manuscripts. Exclusion criteria included: non-peer reviewed, all without primary animal data, and traumatic models. From these, we identified 119 papers that contained unique information on time to medication administration. The data are reported as mean, ranges, and 95% confidence intervals. Mean time to first drug administration in animal laboratory studies and clinical trials was compared with a t-test. Regression analysis was performed to determine if time to drug predicted ROSC.

RESULTS

Mean time to first drug administration in 2378 animals was 9.5min (range 3.0-28.0; 95% CI around mean 2.78, 16.22). This is less than the time reported in clinical trials (19.4min, p<0.001). Time to drug predicted ROSC (odds ratio 0.844; 95% CI 0.738, 0.966).

CONCLUSION

Shorter drug delivery time in animal models of cardiac arrest may be one reason for the failure of animal studies to translate successfully into the clinical arena.

Impact of advanced cardiac life support-skilled paramedics on survival from out-of-hospital cardiac arrest in a statewide emergency medical service

BACKGROUND

Prehospital research has found little evidence in support of advanced cardiac life support (ACLS) for out-of-hospital cardiac arrest. However, these studies generally examine city-based emergency medical services (EMS) systems. The training and experience of ACLS-skilled paramedics differs internationally, and this may also contribute to negative findings. Additionally, the frequency of negative outcome in out-of-hospital cardiac arrest suggests that it is difficult to establish sufficient numbers to detect an effect.

PURPOSE

To examine the effect of ACLS on cardiac arrest in Queensland, Australia. Queensland has a population of 3.8 million and an area of over 1.7 million km2, and is served by a statewide EMS system, which deploys resources using a two-tier model. Advanced treatments such as intubation and cardioactive drug administration are provided by extensively trained intensive care paramedics.

METHODS

An observational, retrospective design was used to examine all cases of cardiac arrest attended by the Queensland Ambulance Service from January 2000 to December 2002. Logistic regression was used to examine the effect of the presence of an intensive care paramedic on survival to hospital discharge, adjusting for age, sex, initial rhythm, the presence of a witness and bystander cardiopulmonary resuscitation.

RESULTS

The presence of an intensive care paramedic had a significant effect on survival (OR = 1.43, 95% CI = 1.02 to 1.99).

CONCLUSIONS

Highly trained ACLS-skilled paramedics provide added survival benefit in EMS systems not optimised for early defibrillation. The reasons for this benefit are multifactorial, but may be the result of greater skill level and more informed use of the full range of prehospital interventions.

Time to give the first medication during resuscitation in out-of-hospital cardiac arrest

OBJECTIVE

There is no evidence showing an impact from any advanced cardiac life support (ACLS) medications on patient survival following cardiac arrest. One potential reason for a lack of such benefit may be medication timing. We formed the hypothesis that medications are given late after rescuer arrival, limiting any benefit. We performed a meta-analysis to determine the time from emergency medical services (EMS) dispatch to first medication administration, regardless of route, during out-of-hospital cardiac arrest (OOHCA). Then, the mean time and ranges of reported study medication delivery in clinical trials where medication was the experimental intervention was determined.

METHODS

We conducted a comprehensive literature review between January 1990 and August 2005 in MEDLINE using the following MeSH headings: cardiopulmonary resuscitation, cardiac arrest, heart arrest, EMS, EMT, ambulance, and the names of all ACLS medications. We reviewed the abstracts of 632 studies and full manuscripts of 248 published papers. We eliminated the following articles from further analysis: non-peer reviewed; all without human primary data (includes review articles, guidelines or consensus manuscripts, editorials, or simulation studies); animal data; case reports. We used no language restriction. From this search, our independent reviewers found 17 papers that contained information on time to medication administration.

RESULTS

We analyzed reporting of drug delivery time to 7617 patients in 32 different emergency medical services systems. Time to first medication delivery by any route was a mean of 17.7 min (range 10.0-25.0; 95% CI around mean 10.6, 24.8). Time to intravenous experimental medication administration was a mean of 19.4 min (range 13.3-25.0; 95% CI around mean 12.8, 25.9).

CONCLUSIONS

Medications are given late during out-of-hospital cardiac arrest, even in cohorts where drug delivery is a key study intervention.

Out-of-hospital endotracheal intubation: where are we?

While remaining prominent in paramedic care and beneficial to some patients, out-of-hospital endotracheal intubation has not clearly improved survival or reduced morbidity from critical illness or injury when studied more broadly. Recent studies identify equivocal or unfavorable clinical effects, adverse events and errors, interaction with other important resuscitation interventions, and challenges in providing and maintaining procedural skill. We provide an overview of current data evaluating the overall effectiveness, safety, and feasibility of paramedic out-of-hospital endotracheal intubation. These studies highlight our limited understanding of out-of-hospital endotracheal intubation and the need for new strategies to improve airway support in the out-of-hospital setting.

The National EMS Research strategic plan

One of the eight major recommendations put forth by the National EMS Research Agenda Implementation Project in 2002 was the development of an emergency medical services (EMS) research strategic plan. Using a modified Delphi technique along with a consensus conference approach, a strategic plan for EMS research was created. The plan includes recommendations for concentrating efforts by EMS researchers, policy makers, and funding resources with the ultimate goal of improving clinical outcomes. Clinical issues targeted for additional research efforts include evaluation and treatment of patients with asthma, acute cardiac ischemia, circulatory shock, major injury, pain, acute stroke, and traumatic brain injury. The plan calls for developing, evaluating, and validating improved measurement tools and techniques. Additional research to improve the education of EMS personnel as well as system design and operation is also suggested. Implementation of the EMS research strategic plan will improve both the delivery of services and the care of individuals who access the emergency medical system.

Procedural experience with out-of-hospital endotracheal intubation

OBJECTIVE

Out-of-hospital rescuers likely need regular clinical experience to perform endotracheal intubation (ETI) in a safe and effective manner. We sought to determine the frequency of ETI performed by individual out-of-hospital rescuers.

DESIGN

Analysis of an administrative database of all emergency medical services (EMS) patient care reports in Pennsylvania.

SETTING

Commonwealth of Pennsylvania from January 1 to December 31, 2003.

SUBJECTS

EMS advanced life support rescuers (paramedics, prehospital nurses, and EMS physicians) who reported at least one patient contact during the study period.

INTERVENTIONS

None.

MEASUREMENTS

We calculated individual rescuer ETI frequency and opportunity. We evaluated relationships between ETI frequency and the number of patient contacts. We also examined the relationship with practice setting (air medical vs. ground rescuers and urban vs. rural rescuers).

MAIN RESULTS

In 1,544,791 patient care reports, 11,484 ETIs were reported by 5,245 out-of-hospital rescuers. The median ETI frequency was one (interquartile range, 0-3; range, 0-23). Of 5,245 rescuers, >67% (3,551) performed two or fewer ETIs, and >39% (2,054) rescuers did not perform any ETIs. The median number of ETI opportunities was three (interquartile range, 0-6; range, 0-76). ETI frequency was associated with patient volume (Spearman's rho = 0.67) and was higher for air medical (p = .006) and urban (p < .0001) rescuers. ETI frequency was not associated with response (Spearman's rho = -0.01) or transport (Spearman's rho = -0.06) times.

CONCLUSIONS

Out-of-hospital ETI, an important and difficult resuscitation intervention, is an uncommon event for most rescuers.