Early defibrillation by emergency physicians or emergency medical technicians? A controlled, prospective multi-centre study

[Best practice-example of a paramedic competence system in the context of user and patient safety: the Reutlinger Weg]

The discussion about the competencies and responsibilities of paramedics has been going on for decades and is the subject of controversial legal debates and currently the focus of political attention due to the heterogeneous country-specific design. However, there are only a few published examples of a so-called competency system for the safe and effective use of prehospital emergency medicine interventions. The practical experience of a competence system is presented. Adequate education and training are crucial for development of competence. A physician-supported quality assurance system creates the opportunity to confirm the competencies of paramedics within the framework of competence checks, monitor the system by means of indicators, and detect weak points at an early stage. Safety culture must be exemplified. Standard operating procedures (SOPs) are the guideline for implementation. In a competence system, certified paramedics can be granted authorization and thus contribute to rapid and efficient patient care, while keeping emergency physicians available for indications requiring their competencies.

[Out-of-hospital emergency medicine in Germany, Austria and Switzerland : randomized prospective studies from 1990 to 2012]

BACKGROUND

Only randomized clinical trials can improve the outcome of life-threatening injuries or diseases but observations from England and North America suggest that the number of such randomized clinical trials is decreasing. In this study contributions from German speaking countries with regards to randomized clinical trials in emergency medicine over the last 22 years were investigated.

METHODS

The Medline database was searched from January 1990 to December 2012 for prospective randomized clinical trials in the prehospital setting using the criteria "cardiac arrest", "cardiopulmonary resuscitation", "multiple trauma", "hemorrhagic shock", "head trauma", "stroke" as well as myocardial infarction and emergency medical service. Only studies originating from Germany, Austria or Switzerland were included.

RESULTS

A total of 474 studies were found and 25 studies (5.3 %) fulfilled the inclusion criteria. In the last 22 years German speaking countries have published approximately one prospective, randomized, clinical trial per year on prehospital emergency medicine. The median number of patients included in the trials was 159 (minimum 16, maximum 1,219). Most (80 %) studies originated from Germany and most (64 %) studies were conducted by anesthesiology departments. Cardiac arrest was the most frequent subject of the investigated studies. Approximately 50 % of the studies had financial support from industrial companies.

CONCLUSION

A significant increase or decrease in the number of prospective randomized clinical trials in the out-of-hospital setting could not be found in German speaking countries despite the fact that the absolute numbers of studies had increased. Only about one prospective, randomized clinical trial with an emergency medicine core tracer diagnosis originated from Germany, Austria and Switzerland per year.

Brain tissue oxygen pressure and cerebral metabolism in an animal model of cardiac arrest and cardiopulmonary resuscitation

OBJECTIVE

Direct measurement of brain tissue oxygenation (PbtO2) is established during spontaneous circulation, but values of PbtO2 during and after cardiopulmonary resuscitation (CPR) are unknown. The purpose of this study was to investigate: (1) the time-course of PbtO2 in an established model of CPR, and (2) the changes of cerebral venous lactate and S-100B.

METHODS

In 12 pigs (12-16 weeks, 35-45 kg), ventricular fibrillation (VF) was induced electrically during general anaesthesia. After 4 min of untreated VF, all animals were subjected to CPR (chest compression rate 100/min, FiO2 1.0) with vasopressor therapy after 7, 12, and 17 min (vasopressin 0.4, 0.4, and 0.8 U/kg, respectively). Defibrillation was performed after 22 min of cardiac arrest. After return of spontaneous circulation (ROSC), the pigs were observed for 1h.

RESULTS

After initiation of VF, PbtO2 decreased compared to baseline (mean +/- SEM; 22 +/- 6 versus 2 +/- 1 mmHg after 4 min of VF; P < 0.05). During CPR, PbtO2 increased, and reached maximum values 8 min after start of CPR (25 +/- 7 mmHg; P < 0.05 versus no-flow). No further changes were seen until ROSC. Lactate, and S-100B increased during CPR compared to baseline (16 +/- 2 versus 85 +/- 8 mg/dl, and 0.46 +/- 0.05 versus 2.12 +/- 0.40 microg/l after 13 min of CPR, respectively; P < 0.001); lactate remained elevated, while S-100B returned to baseline after ROSC.

CONCLUSIONS

Though PbtO2 returned to pre-arrest values during CPR, PbtO2 and cerebral lactate were lower than during post-arrest reperfusion with 100% oxygen, which reflected the cerebral low-flow state during CPR. The transient increase of S-100B may indicate a disturbance of the blood-brain-barrier.

Survival after out-of-hospital cardiac arrests in Katowice (Poland): outcome report according to the “Utstein style”

The purpose of this study was to evaluate the outcome of out-of-hospital cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) in the city of Katowice, Poland, during a period of 1 year prior to the planned reorganization of the national emergency system. Data were collected prospectively according to a modified Utstein style. To ensure accurate data collection, a special method of reporting resuscitation events with the use of a tape-recorder was introduced. Patients were followed for a 1-year period. Between 1 July 2001 and 30 June 2002, out-of-hospital cardiac arrest was confirmed in 1153 patients. Cardiopulmonary resuscitation was attempted in 188 patients. Cardiac arrest of presumed cardiac aetiology (147) was bystander witnessed in 105 (71%) cases and lay-bystander basic life support was performed in 35 (24%). In the group of bystander witnessed arrest ventricular fibrillation (VF) or tachycardia was documented in 59, asystole in 40 and other non-perfusing rhythms in six patients. Of 147 patients with cardiac aetiology, return of spontaneous circulation (ROSC) was achieved in 64 (44%) patients, 15 (10%) were discharged alive and 9 (6%) were alive 1 year later. Most of these patients had a good neurological outcome. Time to first defibrillatory shock was significantly shorter for survivors (median 7 min) compared to non-survivors (median 10 min). The most important resuscitation and patient characteristics associated with survival were VF as initial rhythm, arrest witnessed, and lay-bystander CPR.

EMS defibrillation-first policy may not improve outcome in out-of-hospital cardiac arrest

OBJECTIVE

Early defibrillation using automated external defibrillators (AEDs) has been advocated to improve survival in witnessed out-of-hospital cardiac arrest (OHCA) due to pulseless ventricular tachycardia (VT) and ventricular fibrillation (VF). However, when VT/VF is untreated and prolonged for more than a few minutes, defibrillation using AEDs may fail.

METHODS

This retrospective study reviewed the charts from local emergency medical service (EMS) between the years 1993 to 2001 to evaluate the value of the AED after its introduction into our EMS. All witnessed OHCA due to VT/VF were analysed; cases of collapse witnessed by EMS were excluded. The primary endpoint was defined as survival to hospital discharge and at 1-year follow-up, and the secondary endpoint as survival without major neurological deficit. A total of 76 patients were treated for witnessed VT/VF before the implementation of the AED and 92 patients after its implementation.

RESULTS

Before the introduction of paramedic AED defibrillation, physician defibrillation was performed at 15.6 min (+/-5.5, S.D.). After the introduction of AED defibrillation, paramedic defibrillation was performed at 5.7 min (+/-2.4, S.D.); the mean response interval from the call to defibrillation was shortened significantly (P<0.001). At the same time, survival to hospital discharge decreased from 23.7% (18/76 patients) to 14.1% (13/92) (P=0.112) and at 1-year follow-up from 17.1% (13/76) to 9.8% (9/92) (P=0.161). Favourable neurological outcome at 1-year follow-up also decreased from 14.5% (11/76) to 8.7% (8/92) (P=0.239).

CONCLUSION

Implementation of the AED did not improve survival or a favourable neurological outcome in patients with OHCA due to VF/VT. However, with 5.7 min time to defibrillation, our EMS did not meet the criteria for early defibrillation. For prolonged periods of VT/VF, initial basic life support (BLS) may be superior to immediate AED. If response times of <4 min cannot be attained by the emergency systems, reconsidering of resuscitation algorithms seems to be advisable.

Multicenter, randomized, controlled trial of 150-J biphasic shocks compared with 200- to 360-J monophasic shocks in the resuscitation of out-of-hospital cardiac arrest victims. Optimized Response to Cardiac Arrest (ORCA) Investigators

BACKGROUND

In the present study, we compared an automatic external defibrillator (AED) that delivers 150-J biphasic shocks with traditional high-energy (200- to 360-J) monophasic AEDs.

METHODS AND RESULTS

AEDs were prospectively randomized according to defibrillation waveform on a daily basis in 4 emergency medical services systems. Defibrillation efficacy, survival to hospital admission and discharge, return of spontaneous circulation, and neurological status at discharge (cerebral performance category) were compared. Of 338 patients with out-of-hospital cardiac arrest, 115 had a cardiac etiology, presented with ventricular fibrillation, and were shocked with an AED. The time from the emergency call to the first shock was 8.9+/-3.0 (mean+/-SD) minutes.

CONCLUSIONS

The 150-J biphasic waveform defibrillated at higher rates, resulting in more patients who achieved a return of spontaneous circulation. Although survival rates to hospital admission and discharge did not differ, discharged patients who had been resuscitated with biphasic shocks were more likely to have good cerebral performance.

What are we doing in cardiopulmonary resuscitation training in Europe? An analysis of a survey

This study has analysed the status of cardiopulmonary resuscitation (CPR) training in Europe in medical schools, cities in the WHO European Healthy Cities network, and hospitals in the WHO European Health Promoting Hospitals network. Three questionnaires tested by a pilot study were sent in 1996-1997: one to medical school deans, one to the WHO Health Promoting Hospitals Network coordinators and one to the focal points of the WHO Healthy Cities Network. The glossary of terms was taken from the Utstein style guidelines. The 392 medical schools returned 168 questionnaires (43%): 167 teach CPR, 165 basic CPR, 136 advanced CPR and 114 both. The 310 hospitals returned 224 questionnaires and 202 were analysed (65%); 154 train physicians, 184 nurses and 110 nursing students. The 509 cities returned 67 questionnaires (13%); 28 train police officers and 36 fire fighters. A total of 120 institutions train paramedics and 82 lay people. The training hours in basic and advanced CPR vary between medical schools and various professional groups trained in hospitals and cities. More time is devoted to training in advanced CPR than in basic CPR and more in theory than practical training. This survey can be an important incentive for European Organisations to identify priorities in their educational efforts.

A rule for early outcome classification of out-of-hospital cardiac arrest patients presenting with ventricular fibrillation

The aim of the study was to develop a scoring system for outcome classification at the start of prehospital first tier resuscitation for patients with cardiac arrest from ventricular fibrillation (VF). We studied a consecutive sample of 100 out-of-hospital cardiac arrest patients, presenting with VF of presumed cardiac etiology on arrival of the first tier (in a two-tiered urban Emergency Medical Services system). The number of patients discharged was 29 ('survivors') and 71 died ('non-survivors'). The electrocardiography (ECG) tracings recorded during resuscitation using a semi-automatic defibrillator were retrospectively analysed. For each patient, VF amplitude in mV (VF_a) and the number of base-line crossings per second (VF_blc) were calculated. Fisher's linear discriminant analysis was applied to discriminate between survivors and non-survivors using the variables VF_a, VF_blc and age. Patients were classed as potential survivors or non-survivors using a survival index = 0.6*(VF_a) + 0.4*(VF_blc)-4.0. If for a given patient the survival index is < 0, he is classified in the non-survivor group, if the survival index is > 0, he is classified in the survivor group. Using this index 79% of the survivors and 70% of the non-survivors could be classified correctly. Adding age to the formula increased the correct classification of survivors to 86 and 73% for the non-survivors. The survival index provides a research tool for the discrimination between potential survivors and non-survivors, which opens the possibility for the development of alternative treatment protocols in cardiac arrest.

Quantifying the scanty science of prehospital emergency care

Research can produce false-positive results just as can diagnostic tests. Uncontrolled studies have a specificity of only 11%, versus 88% for randomized controlled trials (RCTs), which have been designed to minimize the bias of investigators toward a positive outcome. A search of all the scientific studies in Medicine since 1985 revealed 5,842 publications on prehospital EMS, but only 54 were RCTs (and therefore unlikely to produce false-positive results). By way of comparison, during the same time hundreds of RCTs have been conducted on major medical emergency conditions, and RCTs on even minor topics such as urticaria and constipation exceed the scientific database on all of EMS. Of the 54 EMS RCTs, 4 (7%) reported harm from the new therapy, and 74% reported no effect of the new therapy at all. Only 7 (13%) RCTs showing a positive outcome of the intervention were uncontradicted; of these only 1 examined a major outcome such as survival, and only 1 compared the intervention with a placebo and could therefore evaluate the efficacy of EMS itself. Because there is such a paucity of scientific support for EMS interventions and because monitoring of outcomes and adverse effects is so poor, a serious reexamination of EMS practice is indicated.

One-year survival after out-of-hospital cardiac arrest in Bonn city: outcome report according to the 'Utstein style'

Outcome after prehospital cardiac arrest was examined in the EMS system of Bonn, a midsized urban community, and presented according to the Utstein style. The data were collected from January 1st, 1989 to December 31st, 1992 by the Bonn-north ALS unit, which serves 240,000 residents. Fifty-six patients suffered from cardiac arrest of non-cardiac aetiology and were excluded; 464 patients were resuscitated after cardiac arrest of presumed cardiac aetiology (incidence of CPR attempts: 48.33 per year/100,000 population). The collapse was unwitnessed, bystander witnessed or EMS personnel witnessed in 178, 214 or 72 patients, respectively. In these subgroups discharge rates and 1-year survival accounted for 7.3% (4.5%), 22.9% (15.9%) and 16.7% (11.1%), respectively. Thirty-four patients were discharged without neurological deficits (cerebral performance category 1: CPC 1), 22 and nine patients scored CPC 2 or CPC 3, respectively. Nine patients were comatose (CPC 4) when they were discharged and remained in this state until they died. Of the 50 1-year survivors 35 lived without neurological deficit, eight demonstrated mild (CPC 2) and five severe (CPC 3) cerebral disability at 1-year after resuscitation, and, finally, two patients remained comatose for more than 1 year. The Utstein template recommends the selection of patients who were found in VF after bystander witnessed collapse. In our cohort 118 patients met these criteria. Of them 41 (35%) could be discharged from hospital and 28 (24%) lived more than 1 year. The comparison of our data with those from double-response EMS systems of other communities revealed that, in midsized urban and suburban communities the highest discharging rates could be achieved. Our study demonstrated that survival depends crucially on short response intervals and life support which will be performed by well-trained emergency technicians, paramedics and physicians.

Future directions for resuscitation research. III. External cardiopulmonary resuscitation advanced life support

This discussion about advanced cardiac life support (ACLS) reflects disappointment with the over 50% of out-of-hospital cardiopulmonary resuscitation (CPR) attempts that fail to achieve restoration of spontaneous circulation (ROSC). Hospital discharge rates are equally poor for in-hospital CPR attempts outside special care units. Early bystander CPR and early defibrillation (manual, semi-automatic or automatic) are the most effective methods for achieving ROSC from ventricular fibrillation (VF). Automated external defibrillation (AED), which is effective in the hands of first responders in the out-of-hospital setting, should also be used and evaluated in hospitals, inside and outside of special care units. The first countershock is most important. Biphasic waveforms seem to have advantages over monophasic ones. Tracheal intubation has obvious efficacy when the airway is threatened. Scientific documentation of specific types, doses, and timing of drug treatments (epinephrine, bicarbonate, lidocaine, bretylium) are weak. Clinical trials have failed so far to document anything statistically but a breakthrough effect. Interactions between catecholamines and buffers need further exploration. A major cause of unsuccessful attempts at ROSC is the underlying disease, which present ACLS guidelines do not consider adequately. Early thrombolysis and early coronary revascularization procedures should also be considered for selected victims of sudden cardiac death. Emergency cardiopulmonary bypass (CPB) could be a breakthrough measure, but cannot be initiated rapidly enough in the field due to technical limitations. Open-chest CPR by ambulance physicians deserves further trials. In searches for causes of VF, neurocardiology gives clues for new directions. Fibrillation and defibrillation thresholds are influenced by the peripheral sympathetic and parasympathetic nervous systems and impulses from the frontal cerebral cortex. CPR for cardiac arrest of the mother in advanced pregnancy requires modifications and outcome data. Until more recognizable critical factors for ROSC are identified, titrated sequencing of ACLS measures, based on physiologic rationale and sound judgement, rather than rigid standards, gives the best chance for achieving survival with good cerebral function.

Reporting approval by research ethics committees and subjects' consent in human resuscitation research

OBJECTIVE

To determine how frequently reports of research in human cardiopulmonary resuscitation mention approval by a research ethics committee and address subjects' consent.

METHODS

Retrospective review of published reports of interventional research in human cardiopulmonary resuscitation. Reports were retrieved from the MEDLINE database and selected according to pre-established criteria. Data were abstracted independently by the two authors with differences resolved by mutual agreement. Results were analyzed according to whether the research took place in the prehospital setting, the emergency department, or the hospital; whether it was conducted within or outside the United States; whether it received any funding from the US government; its randomization scheme; the year of publication; and whether the journal's instructions required mention of REC approval or subjects' consent.

RESULTS

Reports of 47 studies met our criteria for inclusion. Of these, 24 (51%) mentioned approval by a research ethics committee and 12 (26%) addressed subjects' consent. Significantly more studies reported ethics committee approval or addressed consent during more recent years. Authors were more likely to report consent, REC approval, or both when journal instructions required that REC approval be mentioned.

CONCLUSION

Reports of resuscitation research have not consistently mentioned approval from a research ethics committee or addressed subjects' consent for interventional studies using human subjects. However, they are doing so more frequently in recent years as journal requirements for reporting change. REC approval is now almost always being reported, but subjects' consent is often not addressed. Journal editors and reviewers should ensure that authors adhere to the journal's instructions about reporting ethical conduct of experiments.

Optimal defibrillation strategy and follow-up of out-of-hospital cardiac arrest. The Belgian CPCR Study Group

In the current climate of rising healthcare cost, resuscitation efforts performed outside the hospital are critically evaluated because of their limited success rate in some settings. As part of a quality assurance program between the 1st January 1991 and 31st December 1993, six centres of the Belgian CPCR study group prospectively registered cardiac arrest (CA) patients and their treatment according to the Ustein Style recommendations. In the group (n = 511) of patients initially found in ventricular fibrillation (VF) a significantly better survival rate was observed for those patients who received a 1st defibrillatory shock by the 1st tier (n = 142 (27.8%)) as compared to those defibrillated after arrival of the 2nd tier (n = 369 (72.2%)). Median time to delivery of the first shock was significantly shorter (5 min) in the 1st tier group. In a second part of the study we describe long-term management of the 28 surviving VF patients, treated by the single EMS system of Brugge between 1st January 1991 and 30th April 1995: only 6 patients eventually received an implantable cardioverter defibrillator (ICD), whereas coronary revascularization was performed in 9 patients, and 3 patients were discharged on amiodarone only. Satisfactory long-term survival after out-of-hospital VF can be achieved by an early shock followed by advanced life support and appropriate definitive treatment.