生活小区火灾自动报警系统的设计 - 图文

兰州理工大学毕业设计

Background

In cardiac arrest the time to defibrillation is of major importance for survival. One way of achieving early defibrillation is by using Basic Life Support (BLS) responders: lay persons trained to perform BLS (chest compressions and mouth-to-mouth ventilation) and use an automatic external defibrillator (AED) (which is able to distinguish between shockable and non-shockable cardiac rhythms and advise the BLS responder to defibrillate or not) [1]. Guidelines 2000 for Cardiopulmonary Resuscitation [2,3] recommends the use of BLS responders such as fire fighters trained in BLS and the use of AED as a Class IIa recommendation

[1]. Studies show that the use of BLS responders is not always as successful as it might be expected to be [4-12]. Increase in survival among victims of out-of-hospital cardiac arrest (OCHA) has been found with the addition of BLS responders to the existing Emergency Medical Services (EMS) [4-9], while others find only modest or no improvements in cardiac arrest survival with the use of BLS responders [10,11]. One controlled clinical trial has shown a 21% relative increase in the proportion of cases reached within 8 minutes and a 33% relative increase in survival to hospital discharge after implementation of a BLS responder programme [6]. Another study, a controlled cohort trial, found an unchanged hospital discharge survival rate after implementation of a police-manned BLS responder system to the existing fire department-based BLS responders and EMS [11].

The lack of effect of BLS-responders might be due to weaknesses in organizational issues and implementation. Van Alem et al. observed in a prospective randomized trial of BLS responders in Amsterdam a median time interval between collapse and first shock of 668 seconds and that their intervention only caused a decrease in time to first defibrillation of 101 seconds [10]. This was partly

explained by delays in communication between the emergency medical system and first responder dispatch centres.The OPALS II study reported a mean response \receipt to vehicle stops with defibrillator\time of 318 seconds in the intervention phase.

As increasingly emphasised, these studies reflect that science alone is not enough. Training and implementation are crucial for gaining the benefit of science in cardiac arrest – expressed as \Denmark, BLS responders

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兰州理工大学毕业设计

are only scarcely used, and there are no published reports on successful resuscitation by out-of-hospital BLS responders, except a casuistic report from an airport [15]. The lack of experience in Denmark and the findings by van Alem et al. inspired to do a study with the focus on implementation of BLS responders. Our aim was to implement a system using BLS

responders to attend cardiac arrests and situations with a high risk of cardiac arrest in an urban area with relatively short EMS response time by focussing on the following elements of implementation: 1) minimizing dispatch time by short decision-making about activation of BLS responders 2) efficient and quick communication 3) area with appropriate driving distances to allow for defibrillation

within five minutes, 4) training of BLS responders and 5) feed-back to BLS responders. Success criteria for implementation was defined as arrival of the BLS responders before the EMS, attachment (and use) of the AED and successful defibrillation. Methods

This was a prospective observational study from September 1, 2005 to December 31, 2007 (28 months). Patient data (identity, symptoms, etc.) were only collected when the BLS responders arrived before the EMS. Setting

The city of Aarhus is mainly urban with 330,000 inhabitants. Using the definition of early defibrillation (\within 5 minutes from EMS call receipt\coverage of the BLS responders was defined to be an area within three kilometers driving distance from the main fire station (figure 1). The population in this area was approximately 81,500 throughout the study period. The central fire station is located in the center of Aarhus with road distances to the ambulance stations at 2.1, 3.8, and 7.8 kilometers (Figure 1). The EMS is a two tier system with ambulances manned with a paramedic and an emergency medical technician and a Mobile Emergency Care Unit (MECU) manned by an anaesthesiologist and a paramedic trained to assist the physician. The MECU is dispatched if life threatening situations are expected or if an ambulance needs assistance (rendez-vous with the ambulances) [16]. Response times (reception of dispatch message- to-arrival) for ambulances and the MECU averaged 6.7 and 9 minutes, respectively, in 2003 (most recent numbers prior to initiation of the study). Other statistical measures were not obtainable. Electronic dispatch messages were sent simultaneously to the relevant services (EMS, police, or fire department).

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