[Influence of extreme weather conditions on the deployment volume of emergency medical services]. / Einfluss von Wetterextrema auf Einsatzzahlen im Notarztdienst.

BACKGROUND: Due to global warming a worldwide increase in the frequency and intensity of heat waves have been forecast. In the context of the overall increasing number of emergency service calls, weather-induced effects on the number of calls are highly relevant. We evaluated the influence of extreme temperatures on emergency medical services. MATERIALS AND METHODS: The study was conducted in Bochum, Germany. The authors examined the data from 16,767 emergency calls. In addition, the daily updated temperature data were collected for each emergency doctor call. Data were collected from 01 January 2014 until 31 December 2015. The primary question was the influence of extremes of the perceived temperature (PT; on the day of the call and the three previous days) on the diagnosis group of cardiovascular diseases. A secondary question was the influence of extremes of the temperature parameters (air temperature, PT, physiological equivalent temperature [PET]) on the day of call and the three previous days. RESULTS: A total of 16,767 calls were assessed. The threshold values (upper and lower 5%) were -8.7 and 32.5 °C for PT and -0.7 and 26.7 °C for air temperature. Examination of the PT indicated a significantly increased rate of calls for cold spells on the day of the call (RR = 1.14; p = 0.033) as well as a lag effect of 3 days (RR = 1.1; p = 0.049). CONCLUSION: The present study shows that during cold spells there is an increased rate of calls for cardiovascular diseases. This effect is not only observable on the extreme day itself but also 3 days later.

Use of automated external defibrillators for in-hospital cardiac arrest : Any time, any place?

BACKGROUND: Acute treatment of in-hospital cardiac arrest (IHCA) is challenging and overall survival rates are low. However, data on the use of public-access automated external defibrillators (AEDs) for IHCA remain controversial. The aim of our study was to evaluate characteristics of patients experiencing IHCA and feasibility of public-access AED use for resuscitation in a university hospital. METHODS: IHCA events outside the intensive care unit were analysed over a period of 21 months. Patients' characteristics, AED performance, return of spontaneous circulation (ROSC) and 24 h survival were evaluated. Outcomes following adequate and inadequate AED use were compared. RESULTS: During the study period, 59 IHCAs occurred. AED was used in 28 (47.5%) of the cases. However, AED was adequately used in only 42.8% of total AED cases. AED use was not associated with an increased survival rate (12.9 vs. 10.7%, p = 0.8) compared to non-AED use. However, adequate AED use was associated with a higher survival rate (25 vs. 0%, p = 0.034) compared to inadequate AED use. Time from emergency call to application of AED >3 min was the most important factor of inadequate AED use. Adequate AED use was more often observed between 7:30 and 13:30 and in the internal medicine department. CONCLUSION: AEDs were applied in less than 50% of the IHCA events. Furthermore, AED use was inadequate in the majority of the cases. Since adequate AED use is associated with improved survival, AEDs should be available in hospital areas with patients at high risk of shockable rhythm.

[Identification of common locations of out-of-hospital cardiac arrests in a German metropolis]. / Notfallortanalyse von Herz-Kreislauf-Stillständen in einer deutschen Großstadt.

BACKGROUND: Most patients who suffer a sudden cardiac arrest initially have a shockable rhythm. Fast defibrillation and correctly performed cardiopulmonary resuscitation (CPR) are key factors for patient survival. These can be carried out by bystanders if an automated external defibrillator (AED) is available even in the absence of emergency services. AIM: The place and time of CPRs in a German city were investigated and the strategic placement of emergency medical services and AEDs necessary were evaluated. METHODS: All prehospital resuscitation attempts by Bochum's emergency services in 2011 were retrospectively analyzed. The city was divided into a grid, according to the city map to describe the location of every resuscitation. The distribution of cases was correlated to the city grid and time of day. RESULTS: There were 299 cardiac arrests (mean age 74.2 ± 12.47 years; 59% of patients were male). Most resuscitations happened in a home environment between 8 am and 8 pm. There was a higher proportion of resuscitation attempts in grid squares with a high population density. Of the resuscitations in public places 16 of 47 (34%) happened in city district centers. In 72% of all cases, only a nonshockable rhythm could be documented as primary arrhythmia on the arrival of the emergency services. Of the 299 attempted resuscitations, a return of spontaneous circulation was achieved in 41%. CONCLUSIONS: The knowledge about increased frequency of resuscitations in city centers provides insight for strategic placement of emergency devices and services in those areas. This can possibly minimize the time until first response and enables early defibrillation with AED in a first-responder program. In addition, bystanders should obtain clear instructions for resuscitation by the dispatcher of the emergency services.

[Ten years of early defibrillation: "Bochum against sudden cardiac death". Acceptance and critical analysis of using automated external defibrillators]. / Zehn Jahre Frühdefibrillation: "Bochum gegen den plötzlichen Herztod". Akzeptanz und kritische Betrachtung des Einsatzes von automatisierten externen Defibrillatoren.

BACKGROUND: There is a comprehensive early defibrillation program in Bochum (Germany); since 2003 a total of 175 automated external defibrillators (AEDs) have been installed in urban areas by the city of Bochum and private companies. These were preferably installed in places with high foot traffic, e.g., public buildings, companies, and event/shopping centers. Approximately 15,000 laypeople who work in the vicinity of the AED locations were trained in the use of defibrillators and in basic resuscitation. In addition, rescue workers on fire trucks and medically trained personnel in physicians' medical practices were equipped as "first responders" with AEDs. RESULTS: After an initiation phase, all available information after each AED use since August 2004 has been collected by the project coordinator. During the period of data collection (August 2004 to August 2013), an AED was used in a total of 17 patients who had suffered sudden cardiac death (SCD) under the project in Bochum. Eleven patients had primary ventricular fibrillation (VF). Six of these survived without neurological deficit. In another 6 patients, a nondefibrillatable rhythm disorder was diagnosed. The AEDs are reliable and showed impeccable rhythm analysis before the instructions to provide any necessary shock. DISCUSSION: Compared to the number of existing units and an estimated number of 37-100 SCD/100,000, the use of the AEDs only 17 times appears relatively small. To improve the effectiveness of the AED program in Bochum, an analysis of the emergency service responses, which were necessary because of sudden circulatory collapse, is currently being performed. This will allow areas with an increased incidence of SCD to be identified and a plan for the strategic placement of AED and emergency services can be made.

The dromotropic pacemaker: system analysis and design considerations.

Patients suffering from chronotropic incompetence are generally treated with a rate-responsive pacemaker that stimulates the heart at a rate derived from a strain related sensor signal. The pacemaker concept described here uses a well-defined time interval in the electrogram as sensor parameter (AVCT: atrio-ventricular conduction time). AVCT is directly controlled by the autonomic nervous system. The design of the new algorithm was based on a thorough experimental analysis of AVCT subject to variations of the exercise rate and the pacing frequency. There it was demonstrated that AVCT is disturbed by the respiratory activity. The new rate-responsive algorithm which uses the internal model control principle explicitly takes into account the closed-loop nature of the underlying system. The major design objectives were: a) extended range of the individual heart rate, b) effective attenuation of the respiratory related disturbance and c) dynamic stability. Seven patients undergoing an incremental exercise test were paced with the new AVCT-based algorithm. When paced with this algorithm the paced heart rate was 126 +/- 12 min(-1) whereas the peak intrinsic heart rate was only 100 +/- 20 min(-1). The increase which was significant (26 +/- 13 min(-1); 15.53 min(-1)) clearly demonstrated the potential of this concept to restore chronotropic competence. A reanalysis of the experiments was undertaken in order to facilitate the individual parameterization in clinical practice. It could be demonstrated that a rather simple screening test is sufficient to gain the knowledge necessary for the individual parameterisation.

[Saving lives with dispatcher-assisted resuscitation: importance of effective telephone instruction]. / Leben retten durch leitstellengestützte Reanimation : Welche telefonische Anleitung ist sinnvoll?

BACKGROUND: Survival rates after sudden cardiac arrest could be increased if bystanders could be encouraged to perform CPR until emergency services arrive. This should be initiated by the dispatcher at the emergency control facility who receives the call. For the first time the ERC guidelines of 2010 included instructions to be given to untrained rescuers by the dispatcher. Rapid recognition of cardiac arrest and initiation of emergency measures is assured by means of specific training for the dispatchers. AIM: The aim of this investigation was to determine whether the time between an emergency call and beginning of cardiopulmonary resuscitation (CPR) could be shortened using a simple protocol and whether a relationship exists between the intensity of phone contact between dispatcher and caller and if this improves the results. MATERIALS AND METHODS: In known cases of unconsciousness, group 1 (45 persons) received short CPR instructions via the phone, where the dispatcher was on the phone for continuous advice until emergency services arrived. Group 2 (45 persons) received identical phone instructions like group 1, but the phone call was terminated by the dispatcher after the information was provided. Group 3 (29 persons) only received instructions to start CPR. RESULTS: On average, all test persons in group 1 started reanimation after 68.0 ± 33.5 s, in group 2 after 68.3 ± 25.2 s, and in group 3 after 64.9 ± 34.4 s. The compression frequency on average was 98.3/min in group 1, 84.8/min in group 2, and 85.2/min in group 3; therefore, all groups reached an average frequency of > 80/min. The correct compression depth was achieved by 47.8 % of test persons in group 1, by 44.2 % in group 2, and by 30.2 % in group 3. All volunteers felt well supported. Of the 90 people, 70 did not feel that they were missing instructions. DISCUSSION: There were no significant differences between the groups regarding the target variables. The results show that already extremely short instructions or advice by the dispatcher to start CPR is sufficient to encourage bystanders to give assistance in an emergency. Continuous support over the phone does not appear to be necessary.

[Stored electrograms in pacemakers and ICDs from Medtronic]. / Gespeicherte Elektrogramme in Schrittmachern und ICDs der Firma Medtronic.

Modern pacemakers and implantable defibrillators provide a multitude of technical algorithms and parameters, which can be programmed individually and can treat different forms of arrhythmias. Stored electrograms offer the possibility to obtain valuable information during follow-up (but also in real-time) about arrhythmias and device function or malfunction. This results in improved treatment of cardiac arrhythmias and heart disease. Due to constant innovation and development of these systems, it requires, however, profound biomedical and technical knowledge, since stored electrograms may display complex arrhythmias and device reactions that are not easy to interpret. Understanding of stored device information improves follow-up and facilitates individual care for the patient.