持续胸外按压自主呼吸恢复的临床意义

胸外按压是抢救心搏骤停(cardiac arrest,CA)的有效治疗措施,持续胸外按压能显著提高复苏成功率[1].在心肺复苏(cardiopulmonary resuscitation,CPR)过程中,人们始终把关注点集中在自主循环恢复(return of spontaneous circulation,ROSC)及脑功能的恢复上,而对自主循环未恢复情况下自主呼吸首先恢复的现象鲜有报道.     

不同胸外心脏按压方式对老年患者心肺复苏效果的影响

目的探讨心肺复苏机持续机械胸外心脏按压模式对心搏呼吸骤停(CPA)老年患者心肺复苏(CPR)效果的影响。方法依据CPR时采用胸外心脏按压方式的不同将150例院内发生的CPA老年患者分为两组,76例采用心肺复苏机持续机械胸外心脏按压的为机械组,74例采用多人次人工徒手胸外心脏按压的为人工组,两组使用气管插管、电除颤、药物复苏等抢救措施相同,比较两组患者恢复自主循环(ROSC)所需时间及比例。结果机械组患者ROSC所需时间优于人工组[(17.5±5.2)min比(26.8±7.3)min,P0.05],机械组ROSC例数高于人工组(42例比28例,P0.05)。结论心肺复苏机持续机械胸外心脏按压模式在缩短CPA老年患者ROSC时间、提高ROSC比例及CPR有效率方面均优于人工徒手胸外心脏按压。     

CCP与ICP用于成人心搏骤停患者院前急救对生存预后的影响对比

目的:对比连续胸外按压(CCP)与间断胸外按压(ICP)在成人心搏骤停患者院前急救中的应用效果及对患者生存预后的影响。方法:选取124例行院前急救心肺复苏(CPR)的心搏骤停患者作为研究对象,根据院前急救胸外按压方式的不同分为两组:连续组(58例)实施CCP,间断组(66例)实施ICP。对两组患者的院前急救情况、临床资料等进行回顾性对照分析。结果:连续组的初期ROSC率、初期复苏成功率均显著高于间断组(P0.05)。连续组与间断组的CPR持续时间、CPR启动时间、气管插管时间比较,均差异无统计学意义(P0.05);连续组的ROSC平均时间显著短于间断组(P0.05)。连续组的24 h存活率、出院存活率、出院后1个月存活率、出院后6个月存活率均显著高于间断组(P0.05)。多因素分析显示CPR启动时间、ROSC时间、胸外心脏按压方式均是心搏骤停患者生存预后的影响因素(P0.05)。结论:在心搏骤停患者的院前急救中,实施CCP进行CPR的效果优于ICP,其能有效提高CPR成功率,心搏骤停到CPR实施时间间隔、CPR到ROSC时间间隔、胸外按压方式是心搏骤停患者生存预后的主要影响因素。     

经腹呼吸支持方法的研究进展

1960年在马里兰医学组织会议上,胸外心脏按压和人工呼吸被正式推荐[1],这也是现代心肺复苏(CPR)的开端.经过50年的探索实践,院内CPR的自主循环恢复(ROSC)率和出院率有了明显的改善,但患者的生存出院率却很不理想,完善CPR的任务仍很艰巨[2].《2010美国心脏协会心肺复苏及心血管急救指南》中,建议将成人、儿童和婴儿(不包括新生儿)的基础生命支持程序从A-B-C(开放气道-人工呼吸-胸外按压)更改为C-A-B(胸外按压-开放气道-人工呼吸),更加强调胸外按压的重要性[3].心搏骤停分为原发性和继发性两种,其中继发性心搏骤停仍然强调呼吸支持的重要性,及时有效的呼吸支持也是CPR成功的关键所在.呼吸支持的方法很多,本文仅就经腹呼吸支持方法作一综述.     

腹部提压心肺复苏专家共识

现代心肺复苏(cardiopulmonary resuscitation,CPR)历经50余年的实践,自主循环恢复(restoration of spontaneous circulation,ROSC) 率虽有提高,但生存出院率仍不理想[1-2].完善和发掘CPR的适宜技术与方法,以求提高CPR患者的生存率,是心肺复苏工作者的重要使命.中国腹部提压心肺复苏协作组从临床CPR实际需求出发,弥补传统胸外按压心肺复苏的缺陷,达成了经腹部提压进行CPR的共识.     

开辟经腹心肺复苏新途径

1960年胸外心脏按压和人工呼吸的提出,标志着现代心肺复苏(CPR)的开始,经过50余年的探索实践,院内CPR的自主循环恢复(ROSC)率虽有提高,但患者的生存率却不理想[1].因此,需要人们解放思想、更新观念,紧跟现代医学的前沿技术,立足于临床CPR工作中的实际需求,不断开辟CPR的新途径,完善和发掘CPR适宜技术与方法,进一步提高CPR患者的生存率,可谓是我们急救医学工作者所面临的艰巨任务.     

心肺复苏质量对心博骤停猪血流动力学及氧代谢的影响

目的 应用O-CPR技术控制心肺复苏(CPR)质量,以观察在心脏骤停动物模型实施不同质量的CPR对复苏期间血流动力学和氧代谢的影响.方法 18头体质量为(30±1)kg的北京长白猪麻醉后,右侧股静脉送入Swan-Ganz导管并连接爱德华VigianceⅡ连续心排血量监测仪,左侧颈内静脉置管并放置电极到右心室,并分别行主动脉、右心房置管,连续记录血流动力学各指标,然后使用医用程控刺激仪电击致动物心博骤停,在室颤4 min后,将实验猪随机分为2组,标准CPR组和不标准CPR组,利用飞利浦HeartStart MRx监护仪/除颤器的O-CPR进行质量控制,监测胸外按压的深度、频率和回弹等.其中标准CPR组在复苏时进行标准胸外按压,频率为100次/min,按压通气比为30:2,按压深度为38～51 mm,胸廓充分回弹;不标准CPR组按压频率和按压通气比不变,但是按压深度为标准按压的60%～70%,每次胸廓回弹均不完全.在按压和通气9 min后开始电除颤.在各个时间点监测心排血量(CO)、平均主动脉压(MAP)等,计算冠脉灌注压(CPP),监测动静脉血气并计算氧输送量(DO2)和氧耗量(VO2)等,记录复苏成功的实验猪头数.数据处理采用SPSS 11.5统计软件进行y2检验和两个样本的t检验.结果 标准CPR组的自主循环恢复(ROSC)的成功率达90.9%,明显高于不标准者的28.6%(P=0.013),标准CPR组主要血流动力学指标CPP、CO、MAP高(P<0.05),全身血液氧合程度好,D02和VO2高于对照组(P<0.05).结论 在室颤心脏骤停猪模型中,应用规范化标准心肺复苏较不标准者能够明显提高CPP和CO2改善复苏期间的血流动力学,并可以提高DO2和VO2,对氧代谢的改善产生积极作用,因此ROSC成功率明显提高.     

细化心肺复苏流程对胸外按压中断时间的影响

目的探讨细化心肺复苏（ CPR）流程,对CPR的除颤期及气管插管期胸外按压中断时间的影响。方法依据2010 CPR指南,制定细化CPR的除颤期及气管插管期的CPR流程,缩短CPR过程中胸外按压中断时间。选择2012-08～2013-11间124例心脏骤停患者为试验组,实施细化的除颤期及气管插管期CPR流程。选择2011-04～2012-07间122例心脏骤停患者为对照组,实施常规CPR流程。对两组患者CPR胸外按压中断时间、自主循环恢复时间、自主循环恢复率、72 h生存率及28 d生存率、28 d神经功能预后CPC评分进行回顾性对比分析。结果两组患者CPR的除颤期胸外按压中断时间及气管插管期胸外按压中断时间、自主循环恢复时间、自主循环恢复率、28 d生存率及28 d神经功能预后CPC评分各项指标比较均差异有统计学意义（P＜0.05）。两组患者72 h生存率比较差异无统计学意义（P＞0．05）。结论细化CPR流程,可缩短CPR的除颤期及气管插管期胸外按压中断时间,有效提高CPR成功率。     

心肺复苏仪胸外心脏按压对心肺复苏成功的影响

目的:探讨心肺复苏仪胸外心脏按压对心肺复苏成功的影响。方法:将42例心跳呼吸骤停患者随机分为徒手胸外心脏按压组(A组)和心肺复苏仪胸外心脏按压组(B组)。二组均进行无创动脉血压、心电、经皮氧饱和度sPO2等监测。结果:B组的自主循环恢复率和24小时存活率均明显高于A组(P<0.05和P<0.01),但二组的出院存活率无显著性差异。B组的经皮氧饱和度明显高于A组(P<0.05),而自主循环恢复时间则明显短于后者(P<0.01);二组的平均动脉压无显著性差异。结论:心肺复苏仪胸外心脏按压在提高自主循环率,缩短自主循环恢复时间,改善患者生存机会等方面明显优于徒手胸外心脏按压。     

心肺复苏装置研究与应用现状

心搏骤停(cardiac arrest,CA)是威胁人类生命的严峻问题,而心肺复苏术( cardiopulmonary resuscitation,CPR)是抢救心搏骤停患者的重要措施.1960年Kouwenhoven等[1]首先报道了应用胸外心脏按压压迫胸骨和脊柱间的心脏而泵血救治心搏骤停成功.此后,标准CPR (STD-CPR)在国际上一直备受推崇.经大量的研究证明,在心肺复苏时,心脑需要充足的灌注来恢复自主循环(restoration of spontaneous circulation,ROSC),并提高无神经损害的生存率.但长期以来,标准CPR下的患者血流灌注并不理想,即使由受过培训的医务人员操作,脑组织中的血流也会减少至正常血供的30％ ～ 40％,在心脏则会减少至10％ ～ 20％[2].如果人工胸外按压不恰当,就会使重要器官的血流量进一步减少.在实际操作中,由于人工CPR操作者容易疲劳,所以需要2名以上操作者合作,这就不可避免地会中断按压,降低复苏效果,同时也会受操作熟练程度等人为因素的干扰,使标准CPR的有效性受到影响.借助仪器监测人工胸外按压的频率和深度发现,目前临床中存在着诸如胸壁回弹不够、频繁中断、按压深度太浅、按压间隙太长及过度通气等诸多问题.     

Comparison of shock-first strategy and cardiopulmonary resuscitation-first strategy in a porcine model of prolonged cardiac arrest

Objective

The choice of a shock-first or a cardiopulmonary resuscitation (CPR)-first strategy in the treatment of prolonged cardiac arrest (CA) is still controversial. The purpose of this study was to compare the effects of these strategies on oxygen metabolism and resuscitation outcomes in a porcine model of 8 min CA.

Methods

Ventricular fibrillation (VF) was electrically induced. After 8 min of untreated VF, 24 male inbred Wu-Zhi-Shan miniature pigs were randomized to receive either defibrillation first (ID group) or chest compression first (IC group). In the ID group, a shock was delivered immediately. If the defibrillation attempt failed to attain restoration of spontaneous circulation (ROSC), manual chest compressions were rapidly initiated at a rate of 100 compressions min⁻¹, and the compression-to-ventilation ratio was 30:2. If VF persisted after five cycles of CPR, a second defibrillation attempt was made. In the IC group, chest compressions were delivered first, followed by a shock.

Results

Hemodynamic variables, the VF waveform and blood gas analysis outcomes were recorded. Oxygen metabolism parameters and the amplitude spectrum area (AMSA) of the VF waveform were computed. There were no significant differences in the rate of ROSC and 24 h survival between two groups. The ID group had lower lactic acid levels, higher cardiac output, better oxygen consumption and better oxygen extraction ratio at 4 and 6 h after ROSC than the IC group.

Conclusions

In a porcine model of prolonged CA, the choice of a shock-first or CPR-first strategy did not affect the rate of ROSC and 24 h survival, but the shock-first strategy might result in better hemodynamic status and better oxygen metabolism than the CPR-first strategy at the first 6 h after ROSC.     

Transthoracic impedance for the monitoring of quality of manual chest compression during cardiopulmonary resuscitation

Objective

The quality of cardiopulmonary resuscitation (CPR), especially adequate compression depth, is associated with return of spontaneous circulation (ROSC) and is therefore recommended to be measured routinely. In the current study, we investigated the relationship between changes of transthoracic impedance (TTI) measured through the defibrillation electrodes, chest compression depth and coronary perfusion pressure (CPP) in a porcine model of cardiac arrest.

Methods

In 14 male pigs weighing between 28 and 34 kg, ventricular fibrillation (VF) was electrically induced and untreated for 6 min. Animals were randomized to either optimal or suboptimal chest compression group. Optimal depth of manual compression in 7 pigs was defined as a decrease of 25% (50 mm) in anterior posterior diameter of the chest, while suboptimal compression was defined as 70% of the optimal depth (35 mm). After 2 min of chest compression, defibrillation was attempted with a 120-J rectilinear biphasic shock.

Results

There were no differences in baseline measurements between groups. All animals had ROSC after optimal compressions; this contrasted with suboptimal compressions, after which only 2 of the animals had ROSC (100% vs. 28.57%, p = 0.021). The correlation coefficient was 0.89 between TTI amplitude and compression depth (p < 0.001), 0.83 between TTI amplitude and CPP (p < 0.001).

Conclusion

Amplitude change of TTI was correlated with compression depth and CPP in this porcine model of cardiac arrest. The TTI measured from defibrillator electrodes, therefore has the potential to serve as an indicator to monitor the quality of chest compression and estimate CPP during CPR.     

Detection of a spontaneous pulse in photoplethysmograms during automated cardiopulmonary resuscitation in a porcine model

Introduction

Reliable, non-invasive detection of return of spontaneous circulation (ROSC) with minimal interruptions to chest compressions would be valuable for high-quality cardiopulmonary resuscitation (CPR). We investigated the potential of photoplethysmography (PPG) to detect the presence of a spontaneous pulse during automated CPR in an animal study.

Methods

Twelve anesthetized pigs were instrumented to monitor circulatory and respiratory parameters. Here we present the simultaneously recorded PPG and arterial blood pressure (ABP) signals. Ventricular fibrillation was induced, followed by 20 min of automated CPR and subsequent defibrillation. After defibrillation, pediatric-guidelines-style life support was given in cycles of 2 min. PPG and ABP waveforms were recorded during all stages of the protocol. Raw PPG waveforms were acquired with a custom-built photoplethysmograph controlling a commercial reflectance pulse oximetry probe attached to the nose. ABP was measured in the aorta.

Results

In nine animals ROSC was achieved. Throughout the protocol, PPG and ABP frequency content showed strong resemblance. We demonstrate that (1) the PPG waveform allows for the detection of a spontaneous pulse during ventilation pauses, and that (2) frequency analysis of the PPG waveform allows for the detection of a spontaneous pulse and the determination of the pulse rate, even during ongoing chest compressions, if the pulse and compression rates are sufficiently distinct.

Conclusions

These results demonstrate the potential of PPG as a non-invasive means to detect pulse presence or absence, as well as pulse rate during CPR.     

Increased cortical cerebral blood flow with LUCAS; a new device for mechanical chest compressions compared to standard external compressions during experimental cardiopulmonary resuscitation

OBJECTIVE: LUCAS is a new device for mechanical compression and decompression of the chest during cardiopulmonary resuscitation (CPR). The aim of this study was to compare the efficacy of this new device with standard manual external chest compressions using cerebral cortical blood flow, cerebral oxygen extraction, and end-tidal CO2 for indirect measurement of cardiac output. Drug therapy, with adrenaline (epinephrine) was eliminated in order to evaluate the effects of chest compressions alone. METHODS: Ventricular fibrillation (VF) was induced in 14 anaesthetized pigs. After 8 min non-intervention interval, the animals were randomized into two groups. One group received external chest compressions using a new mechanical device, LUCAS. The other group received standard manual external chest compressions. The compression rate was 100 min(-1) and mechanical ventilation was resumed with 100% oxygen during CPR in both groups. No adrenaline was given. After 15 min of CPR, external defibrillatory shocks were applied to achieve restoration of spontaneous circulation (ROSC). Cortical cerebral blood flow was measured continuously using Laser-Doppler flowmetry. End-tidal CO2 was measured using mainstream capnography. RESULTS: During CPR, the cortical cerebral blood flow was significantly higher in the group treated with LUCAS (p = 0.041). There was no difference in oxygen extraction between the groups. End-tidal CO2, an indirect measurement of the achieved cardiac output during CPR, was significantly higher in the group treated with the LUCAS device (p = 0.009). Restoration of spontaneous circulation was achieved in two animals, one from each group. CONCLUSIONS: Chest compressions with the LUCAS device during experimental cardiopulmonary resuscitation resulted in higher cerebral blood flow and cardiac output than standard manual external chest compressions. These results strongly support prospective randomised studies in patients to evaluate this new device.     

Continuous chest compressions with asynchronous ventilation improve survival in a neonatal swine model of asphyxial cardiac arrest

BackgroundGuidelines for neonatal resuscitation recommend a 3:1 compression to ventilation ratio. However, this recommendation is based on expert opinion and consensus rather than strong scientific evidence. Our primary aim was to assess whether continuous chest compressions with asynchronous ventilations would increase return of spontaneous circulation (ROSC) rate and survival compared to the 3:1 chest compression to ventilation ratio.MethodsThis was a prospective, randomized, laboratory study. Twenty male Landrace-Large White pigs, aged 1–4 days with an average weight 1.650 ± 228.3 g were asphyxiated and left untreated until heart rate was less than 60 bpm or mean arterial pressure was below 15 mmHg. Animals were then randomly assigned to receive either continuous chest compressions with asynchronous ventilations (n = 10), or standard (3:1) chest compression to ventilation ratio (n = 10). Heart rate and arterial pressure were assessed every 30 s during cardiopulmonary resuscitation (CPR) until ROSC or asystole. All animals with ROSC were monitored for 4 h.ResultsCoronary perfusion pressure (CPP) at 30 s of CPR was significantly higher in the experimental group (45.7 ± 16.9 vs. 21.8 ± 6 mmHg, p < 0.001) and remained significantly elevated throughout the experiment. End-tidal carbon dioxide (ETCO₂) was also significantly higher in the experimental group throughout the experiment (23.4 ± 5.6 vs. 14.7 ± 5.9 mmHg, p < 0.001). ROSC was observed in six (60%) animals treated with 3:1 compression to ventilation ratio and nine (90%) animals treated with continuous chest compressions and asynchronous ventilation (p = 0.30). Time to ROSC was significantly lower in the experimental group (30 (30−30) vs. 60 (60–60) sec, p = 0.021). Of note, 7 (77.8%) animals in the experimental group and 1 (16.7%) animal in the control group achieved ROSC after 30 s (0.02). At 4 h, 2 (20%) animals survived in the control group compared to 7 (70%) animals in the experimental group (p = 0.022).ConclusionContinuous chest compressions with asynchronous ventilations significantly improved CPP, ETCO₂, time to ROSC, ROSC at 30 s and survival in a porcine model of neonatal resuscitation.     

Poor chest compression quality with mechanical compressions in simulated cardiopulmonary resuscitation: a randomized, cross-over manikin study

Introduction

Mechanical chest compression devices are being implemented as an aid in cardiopulmonary resuscitation (CPR), despite lack of evidence of improved outcome. This manikin study evaluates the CPR-performance of ambulance crews, who had a mechanical chest compression device implemented in their routine clinical practice 8 months previously. The objectives were to evaluate time to first defibrillation, no-flow time, and estimate the quality of compressions.

Methods

The performance of 21 ambulance crews (ambulance nurse and emergency medical technician) with the authorization to perform advanced life support was studied in an experimental, randomized cross-over study in a manikin setup. Each crew performed two identical CPR scenarios, with and without the aid of the mechanical compression device LUCAS. A computerized manikin was used for data sampling.

Results

There were no substantial differences in time to first defibrillation or no-flow time until first defibrillation. However, the fraction of adequate compressions in relation to total compressions was remarkably low in LUCAS-CPR (58%) compared to manual CPR (88%) (95% confidence interval for the difference: 13–50%). Only 12 out of the 21 ambulance crews (57%) applied the mandatory stabilization strap on the LUCAS device.

Conclusions

The use of a mechanical compression aid was not associated with substantial differences in time to first defibrillation or no-flow time in the early phase of CPR. However, constant but poor chest compressions due to failure in recognizing and correcting a malposition of the device may counteract a potential benefit of mechanical chest compressions.     

Cardiopulmonary resuscitation for cardiac arrest: the importance of uninterrupted chest compressions in cardiac arrest resuscitation

Over the last decade, the importance of delivering high-quality cardiopulmonary resuscitation (CPR) for cardiac arrest patients has become increasingly emphasized. Many experts are in agreement concerning the appropriate compression rate, depth, and amount of chest recoil necessary for high-quality CPR. In addition to these factors, there is a growing body of evidence supporting continuous or uninterrupted chest compressions as an equally important aspect of high-quality CPR. An innovative resuscitation protocol, called cardiocerebral resuscitation, emphasizes uninterrupted chest compressions and has been associated with superior rates of survival when compared with traditional CPR with standard advanced life support. Interruptions in chest compressions during CPR can negatively impact outcome in cardiac arrest; these interruptions occur for a range of reasons, including pulse determinations, cardiac rhythm analysis, electrical defibrillation, airway management, and vascular access. In addition to comparing cardiocerebral resuscitation to CPR, this review article also discusses possibilities to reduce interruptions in chest compressions without sacrificing the benefit of these interventions.     

A randomized comparison of manual, mechanical and high-impulse chest compression in a porcine model of prolonged ventricular fibrillation

BACKGROUND: Elevated coronary perfusion pressure (CPP) during CPR is associated with return of spontaneous circulation (ROSC). We compared CPP achieved with three methods of chest compression: manual (MAN), mechanical (MECH) and high-impulse mechanical (HI) in a porcine model of prolonged ventricular fibrillation (VF). We hypothesized that HI (very rapid acceleration of the down-stroke) would produce greater CPPs than MAN or MECH, and that HI would also produce a higher rate of ROSC. METHODS: Twenty-eight domestic swine (mean 27.8 kg) were randomly assigned to three methods of chest compression. Animals were instrumented under anesthesia, and VF was induced and untreated for 8 min. After 2 min of CPR, epinephrine (adrenaline) (0. 1 mg/kg), vasopressin (40 U) and propranolol (1.0 mg) were administered. CPR continued for three more minutes, after which up to three rescue shocks were delivered. CPP was determined in an automated fashion by measuring the difference between aortic and right atrial pressures 0.1s prior to the down-stroke of each compression (i.e. end-relaxation). ROSC was defined as a systolic pressure greater than 80 mmHg sustained for at least 1 min. We analyzed CPP and ROSC using repeated measures ANOVA and Fisher's exact test. RESULTS: Over the 5 min of CPR, CPP increased more with HI compression than with MAN compression (p=0.017). ROSC was attained in 4/9 MAN, 6/9 MECH and 10/10 HI (HI versus MAN p=0.01). CONCLUSIONS: Over the course of CPR, HI compression increased CPP more than MAN compression. HI compression produced a significantly higher rate of ROSC than MAN, but not MECH compression.     

Oxygen delivery and return of spontaneous circulation with ventilation:compression ratio 2:30 versus chest compressions only CPR in pigs

The need for rescue breathing during the initial management of sudden cardiac arrest is currently being debated and reevaluated. The present study was designed to compare cerebral oxygen delivery during basic life support (BLS) by chest compressions only with chest compressions plus ventilation in pigs with an obstructed airway mimicked by a valve hindering passive inhalation. Resuscitability was then studied during the subsequent advanced life support (ALS) period. After 3 min of untreated ventricular fibrillation (VF) BLS was started. The animals were randomised into two groups. One group received chest compressions only. The other group received ventilations and chest compressions with a ratio of 2:30. A gas mixture of 17% oxygen and 4% carbon dioxide was used for ventilation during BLS. After 10 min of BLS, ALS was provided. All six pigs ventilated during BLS attained a return of spontaneous circulation (ROSC) within the first 2 min of advanced cardiopulmonary resuscitation (CPR) compared with only one of six compressions-only pigs. While all except one compressions-only animal achieved ROSC before the experiment was terminated, the median time to ROSC was shorter in the ventilated group. With a ventilation:compression ratio of 2:30 the arterial oxygen content stayed at 2/3 of normal, but with compressions-only, the arterial blood was virtually desaturated with no arterio-venous oxygen difference within 1.5–2 min. Haemodynamic data did not differ between the groups. In this model of very ideal BLS, ventilation improved arterial oxygenation and the median time to ROSC was shorter. We believe that in cardiac arrest with an obstructed airway, pulmonary ventilation should still be strongly recommended.