feedback devices overestimate chest compression depth when performed on soft surfaces [108].
In addition to intubation equipment, airway management tools should include capnography and alternate airway devices such as the Combitube®, King LT® airway, or iGel®. In addition to standard intravenous catheters, EMS crews should also carry rapid‐access vascular tools such as intraosseous devices. Medical directors should provide regular training on the use of all equipment. Even in busy systems, many personnel may not perform important skills or use specific equipment for months at a time.
Optimizing System Design
EMS medical directors should play a key role in developing the system design for cardiac arrest care. One potential intervention is to optimize the positioning of EMS and other resources to match areas with the most cardiac arrests. Geographic mapping systems can play an important role, illustrating not only the distribution of cardiac arrest cases throughout a community, but also variables such as the preferred placement of AEDs [109, 110]. The OPALS study reduced cardiac arrest response and defibrillation times by moving first‐responders closer to areas with more cardiac arrests [70].
Some have touted the advantages of system status management, a formal system of continuously redeploying units based on current and anticipated use [111]. Others suggest that skill dilution occurs with too many ALS personnel. They recommend using fewer ALS personnel in a tiered response fashion [111,112].. A Scottish study reported on an initiative to better formalize the roles of senior EMS personnel, who are known to be able to contribute characteristics essential to high‐quality resuscitation, including non‐technical skills such as resuscitation team leadership, communication, and clinical decision making in a second tier, expert paramedic response to OHCA [113].
Hospital Liaison
There is growing awareness of the importance of post‐resuscitation care, which formally constitutes the final link in the chain of survival [114]. Care initiated in the field may prove fruitless if not continued in the hospital. The medical director should work closely with receiving hospitals to ensure continuity in cardiac arrest care, and targeted interventions and care algorithms initiated in the field should be continued in the hospital. For example, when determining the receiving hospital facility, EMS agencies that induce hypothermia after cardiac arrest in unconscious survivors should consider whether the receiving facility will continue this therapy [115–119].
Studies are currently being performed that use a system‐based approach in an attempt to integrate therapies that may have synergistic effects, and that are likely to show co‐dependence in outcome. These are typified by the CHEER study, designed to treat cardiac arrest patients with mechanical chest compressions and cool them to 33 degrees C in the prehospital setting, place them on an extracorporeal membrane oxygenator at the hospital, transport them to the interventional cardiac catheter laboratory for angioplasty, then maintain hypothermia for 24 hours [120].
Davis et al. demonstrated that diverting patients post‐arrest past the closest available hospital and to a tertiary care center did not worsen outcomes [121]. Future work should consider if regionalization of care and transfer of these patients to specialty facilities improves outcomes as it does for victims of major trauma [122–125]. Regional systems of care have improved both clinician experience and patient outcomes for those with ST‐elevation myocardial infarction and with life‐threatening traumatic injury. A Japanese cardiac arrest registry of 10,000 patients with OHCA transported to critical cardiac care hospitals showed improved 1‐month survival compared with those patients transported to hospitals without specialized cardiac facilities [126]. Compared with historical controls, survival to hospital discharge in the Take Heart America Program, a regionalized system of cardiac arrest care in Minnesota, improved from 8.5% to 19%. The difference was a dramatic improvement in survival after admission to intensive care from 24% to 51% [127]. This program seeks to optimize prehospital care, including EMS and community training, while establishing transport and treatment protocols with three dedicated cardiac arrest centers providing therapeutic hypothermia, interventional coronary artery evaluation and treatment, and electrophysiological evaluation. However, analysis of CARES data has not revealed a similar relationship between survival or neurological outcome and the presence of a coronary catheterization laboratory or the volume of patients received [128].
Quality Improvement Program
A prerequisite for improving cardiac arrest resuscitation quality is the collection of performance and quality data. EMS medical directors should implement quality inspection and assurance programs to ensure the delivery of high‐quality cardiac arrest care. Commonly collected cardiac arrest quality data include treatment intervals such as the activation interval, response interval, patient access interval, and call‐to‐first defibrillation interval. Another important measure is CPR performance. Monitors now permit the EMS medical director to evaluate the depth, rate, and interruptions of chest compressions delivered throughout the entire episode [129,130].
The Utstein style for reporting cardiac arrest data provides some common denominators for comparing resuscitation rates among various systems [131]. EMS services should adopt standardized data collection methods that allow for uniform reporting and benchmarking capability.
Summary
Improving survival from OHCA requires a comprehensive community systems approach. No single component, including EMS, can improve cardiac arrest survival independently. EMS agencies must assume a leadership role in promoting, developing, and implementing this systems‐based approach.
References
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