Niemann James T, Rosborough John P, Kassabian Leo, Salami Bobak
Department of Emergency Medicine, Division of Cardiology, Harbor-UCLA Medical Center, Box 21, 1000 West Carson Street, Torrance, CA 90509, USA.
Resuscitation. 2006 May;69(2):295-301. doi: 10.1016/j.resuscitation.2005.07.025. Epub 2006 Feb 2.
Blood flow during conventional cardiopulmonary resuscitation (CPR) is usually less than adequate to sustain vital organ perfusion. A new chest compression device (LifeBelt) which compresses both the sternum and the lateral thoraces (compression and thoracic constraint) has been developed. The device is light weight, portable, manually powered and mechanically advantaged to minimize user fatigue. The purpose of this study was to evaluate the mechanism of blood flow with the device, determine the optimal compression force and compare the device to standard manual CPR in a swine arrest model.
Following anesthesia and instrumentation, intravascular contrast injections were performed in four animals and the performance characteristics of the device were evaluated in eight animals. In a comparative outcome study, 42 anesthetized and instrumented swine were randomized to receive LifeBelt or manual CPR. Ventricular fibrillation (VF) was induced electrically and was untreated for 7.5 min. After 7.5 min, countershocks were administered and chest compressions initiated. Pulseless electrical activity (PEA) was observed after one to three shocks in all animals. CPR was continued until restoration of spontaneous circulation (ROSC) or for 10 min after the first shock. If ROSC had not occurred within 5 min of beginning CPR, 0.01 mg/kg of epinephrine (adrenaline) was administered. During CPR, peak systolic aortic pressure (Ao), diastolic coronary perfusion pressure (CPP-diastolic aortic minus diastolic right pressure) and end-tidal CO(2) were measured.
Angiographic studies demonstrated cardiac compression as the mechanism of blood flow. Optimal performance, determined by coronary perfusion pressure, was observed at a sternal force of 100-130 lb (45-59 kg). In the comparative trial, significant differences in the measured CPP were observed between LifeBelt and manual CPR both at 1 min (15+/-8 mmHg versus 10+/-6 mmHg, p<0.05) and 5 min (17+/-4 mmHg versus 13+/-7 mmHg, p<0.02) of chest compression. A greater (p<0.05) ETCO(2), a marker of cardiac output and systemic perfusion, was observed with LifeBelt CPR (20+/-7 mmHg) than with manual CPR (15+/-5 mmHg) at 1 min. Peak Ao pressures were not different between methods. With the device, 86% of animals were resuscitated compared to 76% in the manual group.
Blood flow with the LifeBelt device is primarily the result of cardiac compression. At a sternal force of 100-130 lb (45-59 kg), the device produces greater CPP than well-performed manual CPR during resuscitation from prolonged VF.
传统心肺复苏（CPR）期间的血流量通常不足以维持重要器官的灌注。一种新型胸外按压装置（LifeBelt）已被研发出来，该装置可同时按压胸骨和胸廓外侧（按压与胸廓约束）。该装置重量轻、便于携带、手动驱动且具有机械优势，可最大程度减少使用者疲劳。本研究的目的是评估该装置的血流机制，确定最佳按压力量，并在猪心脏骤停模型中将该装置与标准徒手CPR进行比较。
在麻醉和仪器植入后，对4只动物进行血管内造影剂注射，并对8只动物评估该装置的性能特征。在一项比较性结局研究中，42只麻醉并植入仪器的猪被随机分组，分别接受LifeBelt或徒手CPR。通过电刺激诱发心室颤动（VF），并持续7.5分钟不予处理。7.5分钟后，进行电击除颤并开始胸外按压。所有动物在1至3次电击后均出现无脉电活动（PEA）。持续进行CPR，直至恢复自主循环（ROSC）或首次电击后10分钟。如果在开始CPR后5分钟内未出现ROSC，则给予0.01mg/kg肾上腺素。在CPR期间，测量收缩期主动脉压峰值（Ao）、舒张期冠状动脉灌注压（CPP，舒张期主动脉压减去舒张期右房压）和呼气末二氧化碳（EtCO₂）。
血管造影研究表明心脏按压是血流产生的机制。根据冠状动脉灌注压确定，在胸骨按压力为100 - 130磅（45 - 59千克）时观察到最佳性能。在比较试验中，LifeBelt和徒手CPR在胸外按压1分钟（15±8mmHg对10±6mmHg，p<0.05）和5分钟（17±4mmHg对13±7mmHg，p<0.02）时，测量的CPP存在显著差异。在1分钟时，作为心输出量和全身灌注指标的EtCO₂，LifeBelt CPR（20±7mmHg）比徒手CPR（15±5mmHg）更高（p<0.05）。两种方法的Ao峰值压力没有差异。使用该装置时，86%的动物被复苏，而徒手组为76%。
LifeBelt装置产生的血流主要是心脏按压的结果。在胸骨按压力为100 - 130磅（45 - 59千克）时，该装置在长时间VF复苏期间产生的CPP比熟练的徒手CPR更大。
