肾上腺素联合血管加压素在窒息家兔心肺复苏中的应用

【目的】观察心肺复苏（Cardiopulmonary resuscitation，CPR）时单独使用肾上腺素、血管加压素以及联合用药对冠脉灌注压（Coronary Perfusion Pressure，CPP）以及自主循环恢复（Restoration of Spontaneous Circulation，ROSC）的影响．比较不同血管升压药物对窒息型心跳停搏家兔心肺复苏的疗效。【方法】40只家兔均在呼气末夹闭气管8min．制作窒息型心跳停搏模型后，开始心肺复苏。家兔分为4组，分别予生理盐水、肾上腺素（45μg／kg）、血管加压素（0．8U／kg）和联合用药（肾上腺素45μg／kg＋血管加压素0．8U／kg）。【结果】ROSC家兔在复苏期间的CPP明显高于复苏失败组（P〈0．01）。联合用药组的CPP在DAI后各时点均显著高于另3组（P〈0．01）；ROSC率及2h生存率均显著高于对照组及血管加压素组（P〈0．05）。在存活家兔中．肾上腺素组自主循环恢复时间及使用的肾上腺素平均剂量均显著高于联合用药组（P〈0．05）。【结论】有效提高CPP对自主循环恢复意义重大。在窒息型心跳停搏家兔心肺复苏期间．联合使用肾上腺素与血管加压素能显著提高冠脉灌注压和复苏成功率；且有效减少肾上腺素的用量，缩短自主循环恢复时间。     

窒息家兔心肺复苏疗效与血浆内皮素变化的关系

目的探讨窒息家兔心肺复苏(cardiopulmonaryresuscitation,CPR)疗效与血浆内皮素(endothelin,ET)变化的关系。方法对62只家兔均在呼气末夹闭气管8min,造成窒息性心脏停搏模型后,开始人工胸外心脏按压及机械通气,期间不用任何药物,复苏5min内恢复自主循环(restorationof spontaneouscirculation,ROSC)的家兔定义为常规CPR成功;对5min内未能ROSC者再随机分为两组,分别给予肾上腺素(0.2mg kg)和加压素(0.8U kg)静脉注射,并继续行常规CPR。分别在窒息前和CPR15、60、120min采血测血浆ET浓度。结果常规CPR的家兔ROSC率为24.16%(1562),加用肾上腺素和加压素后总的ROSC率提高到48.39%(3062)。对常规CPR失败的家兔而言,肾上腺素疗效明显优于加压素(ROSC率分别为54.16%和8.70%,P=0.001)。但复苏成功组和复苏失败组家兔血浆ET的比较,差异无显著性。结论对窒息性心脏停搏的家兔CPR时应用肾上腺素或加压素可提高ROSC率,但肾上腺素疗效明显优于加压素。窒息家兔CPR疗效与血浆内皮素变化无明显相关关系。     

在心肺复苏中快速同步联用氨茶碱与肾上腺素的临床研究

[目的]探讨氨茶碱与肾上腺素快速同步联用在抢救心脏停搏病人心肺复苏中的应用效果及临床价值。[方法]将416例心脏停搏病人随机分为3组,即标准肾上腺素剂量组（SDE组）136例、大剂量肾上腺素组（HDE组）138例、氨茶碱与肾上腺素快速同步联用组（ADE组）142例。采用肘静脉通道应用肾上腺素和氨茶碱：SDE组采用1mg肾上腺素首次剂量、HDE组采用0．1mg／kg肾上腺素首次剂量、ADE组采用快速同步氨茶碱7mg／kg和肾上腺素1mg首次剂量静脉注射,若无效,每组均每间隔3min重复首次剂量快速静脉注射1次。同时监测心电图、平均动脉压、心率、自主循环恢复时间等,并进行复苏效果评价。[结果]ADE组和HDE组自主循环恢复率、24h存活率、存活出院率、格拉斯哥昏迷评分与SDE组比较均有统计学意义（P〈0．01）;ADE组与HDE组比较,ADE组用肾上腺素平均用量明显较HDE组少,但自主循环恢复率、24h存活率、存活出院率明显升高（P〈0．05）。[结论]氨茶碱和肾上腺素快速同步联用在抢救心脏停搏病人CPR流程中能明显提高心肺复苏自主循环恢复率、提升存活率并且能显著缩短自主循环复苏时间,是提高心肺脑复苏成功率的新方法。     

肾上腺素联合血管升压素氨茶碱在心肺复苏时的疗效观察

目的：研究心肺复苏时联合应用肾上腺素、血管升压素、氨茶碱的疗效。方法：60例心脏骤停的患者随机分为两组，肾上腺素标准剂量组（对照组）30例，联合应用肾上腺素、血管升压素、氨茶碱（治疗组）30例，各组分别观察自主循环恢复率、存活率及自主循环恢复时间。结果：对照组、治疗组自主循环恢复率分别为20.8％、67.9％，存活率分别为8．3％、42．9％。存活率明显高于对照组。同时治疗组的自主循环恢复时间明显短于对照组。结论：L心肺复苏期间，联合应用肾上腺素、血管升压素、氨茶碱比单独应用标准剂量的肾上腺亲能显著提高自主循环恢复率和存活率，缩短自主循环恢复时间。     

心肺复苏期间复苏药物联合应用的临床研究

目的:研究心肺复苏期间血管升压素与肾上腺素联合应用的复苏效果.方法:将符合入选标准的63例心脏停搏患者随机分为3组:大剂量肾上腺素组21例(A组),大剂量血管升压素组22例(B组),血管升压素+肾上腺素组20例(C组).分别观察3组自主循环恢复率、自主循环恢复时间、存活率.结果:A组、B组、C组自主循环恢复率分别为19.5%、36.4%、45.0%,C组高于A组、B组;C组存活率为30%,高于A组的4.8%、B组的13.6%;C组自主循环恢复时间短于A组、B组.结论:心肺复苏期间,联合应用血管升压素和肾上腺素比单独应用肾上腺素或血管升压素能显著提高自主循环恢复率和存活率,缩短自主循环恢复时间.     

心肺脑复苏中联合应用肾上腺素血管升压素氨茶碱的疗效

目的：评价心肺脑复苏时联合应用肾上腺素、血管升压素和氨茶碱的疗效。方法：57例心跳骤停患者随机分为两组，肾上腺素标准剂量组29例（对照组），联合应用肾上腺素、血管升压素、氨茶碱组28例（治疗组）。分别观察各组自主心律、循环、呼吸、意识恢复情况，并据此评价为显效、有效、无效。结果：对照组、治疗组总有效率分别为41．38％、71．4％；治疗组的心肺脑复苏成功率明显高于对照组，同时治疗组的自主循环恢复时间明显少于对照组。结论：联合应用肾上腺素、血管升压素、氨茶碱进行心肺脑复苏的成功率明显高于单独应用标准剂量的肾上腺素。     

氨茶碱和肾上腺素对大鼠心脏停搏的作用

目的探讨不同剂量氨茶碱和肾上腺素在大鼠窒息致心脏停搏模型中的疗效。方法呼气末夹闭气管8min,建立大鼠心脏停搏模型。48只大鼠随机分为氨茶碱和肾上腺素组,比较两组大鼠不同剂量的复苏疗效。结果心电活动恢复率氨茶碱组与肾上腺素组相比,差异无显著性(P>0.05);两组自主循环差异无显著性(P>0.05)。氨茶碱和肾上腺素复苏疗效均与剂量呈正相关。肾上腺素组心脏硬度记分显著高于氨茶碱组,且剂量越大,心脏硬度记分越高。结论在窒息致心脏停搏大鼠模型中,氨茶碱对心电活动和自主循环的恢复与肾上腺素疗效相近;氨茶碱和肾上腺素的复苏疗效与剂量相关;较高剂量肾上腺素容易致“石头心”的发生。     

肾上腺素联合血管升压素氨茶碱在心肺复苏时的应用研究

目的研究心肺复苏时联合应用肾上腺素、血管升压素、氨茶碱的疗效.方法52例心跳骤停的患者随机分为两组,肾上腺素标准剂量组(对照组)24例,联合应用肾上腺素、血管升压素、氨茶碱(治疗组)28例,各组分别观察自主循环恢复率、存活率及自主循环恢复时间.结果对照组、治疗组自主循环恢复率分别为20.8%、67.9%,存活率分别为8.3%、42.9%.存活率明显高于对照组.同时治疗组的自主循环恢复时间明显短于对照组.结论心肺复苏期间,联合应用肾上腺素、血管升压素、氨茶碱比单独应用标准剂量的肾上腺素能显著提高自主循环恢复率和存活率,缩短自主循环恢复时间.     

大剂量肾上腺素对复苏患者自主循环恢复时间的影响

大剂量肾上腺素对复苏患者自主循环恢复时间的影响欧世宁何伟生我们对２３例心室停搏患者复苏中使用常规剂量及大剂量肾上腺素，观察对患者自主循环恢复时间的影响。１病例和方法１．１病例：所有病例均经心电监护证实心室停搏。按现行心肺复苏标准进行抢救：施行胸外心脏...     

在心肺复苏中快速同步联用氨茶碱与肾上腺素的临床研究

[目的]探讨氨茶碱与肾上腺素快速同步联用在抢救心脏停搏病人心肺复苏中的应用效果及临床价值.[方法]将416例心脏停搏病人随机分为3组,即标准肾上腺素剂量组(SDE组)136例、大剂量肾上腺素组(HDE组)138例、氨荼碱与肾上腺素快速同步联用组(ADE组)142例.采用肘静脉通道应用肾上腺素和氨荼碱:SDE组采用1mg肾上腺素首次剂量、HDE组采用0.1 mg/kg肾上腺素首次剂量、ADE组采用快速同步氨茶碱7mg/kg和肾上腺素1 mg首次剂量静脉注射,若无效,每组均每间隔3min重复首次剂量快速静脉注射1次.同时监测心电图,平均动脉压、心率、自主循环恢复时间等,并进行复苏效果评价.[结果]ADE组和HDE组自主循环恢复率、24 h存活率、存活出院率、格拉斯哥昏迷评分与SDE组比较均有统计学意义(P<0.01);ADE组与HDE组比较,ADE组用肾上腺素平均用量明显较HDE组少,但自主循环恢复率、24 h存活率,存活出院率明显升高(P<0.05).[结论]氨茶碱和肾上腺素快速同步联用在抢救心脏停搏病人CPR流程中能明显提高心肺复苏自主循环恢复率、提升存活率并且能显著缩短自主循环复苏时间,是提高心肺脑复苏成功率的新方法.     

Epinephrine, but not vasopressin, improves survival rates in an adult rabbit model of asphyxia cardiac arrest

Although vasopressin has been reported to be more effective than epinephrine for cardiopulmonary resuscitation in ventricular fibrillation animal models, its efficacy in asphyxia model remains controversy. The purpose of this study was to investigate the effectiveness of vasopressin vs epinephrine on restoration of spontaneous circulation (ROSC) in a rabbit model of asphyxia cardiac arrest. Cardiac arrest was induced by clamping endotracheal tube. After 5 minutes of basic life-support cardiopulmonary resuscitation, animals who had no ROSC were randomly assigned to receive either epinephrine alone (epinephrine group; 200 microg/kg) or vasopressin alone (vasopressin group; 0.8 U/kg). The coronary perfusion pressure (CPP) was calculated as the difference between the minimal diastolic aortic and simultaneously recorded right atrial pressure. Restoration of spontaneous circulation was defined as an unassisted pulse with a systolic arterial pressure of 60 mm Hg or higher for 5 minutes or longer. We induced arrest in 62 rabbits, 15 of whom had ROSC before drug administration and were excluded from analysis. The remaining 47 rabbits were randomized to epinephrine group (n = 24) and vasopressin group (n = 23). Before and after drug administration, CPP in epinephrine group increased significantly (from -4 +/- 4 to 36 +/- 9 mm Hg at peak value, P = .000), whereas CPP in vasopressin group increased only slightly (from 9 +/- 5 to 18 +/- 6 mm Hg at peak value, P = .20). After drug administration, 13 of 24 epinephrine rabbit had ROSC, and only 2 of 23 vasopressin rabbit had ROSC (P < .01). Consequently, we conclude that epinephrine, but not vasopressin, increases survival rates in this adult rabbit asphyxia model.     

Dose-response of vasopressin in a rat model of asphyxial cardiac arrest

The advantage of vasopressin over epinephrine in the treatment of cardiac arrest (CA) is still being debated, and it is not clear whether a high dose of vasopressin is beneficial or detrimental during or after cardiopulmonary resuscitation (CPR) in a rat model of CA. In this study, asphyxial CA was induced in 40 male Sprague-Dawley rats. After 10 minutes of asphyxia, CPR was initiated; and the effects of different doses of vasopressin (low dose, 0.4 U/kg; medium dose, 0.8 U/kg; and high dose, 2.4 U/kg; intravenous; n = 10 in each group) and a saline control (isotonic sodium chloride solution, 1 mL, intravenous) were compared. Outcome measures included the rate of restoration of spontaneous circulation (ROSC) and changes of hemodynamic and respiratory variables after ROSC. The rates of ROSC were 1 of 10 in the saline group and 8 of 10 in each of the 3 vasopressin groups. There were no differences in mean aortic pressure or changes of respiratory function after CPR among the vasopressin groups. However, the heart rate was lower in the high-dose vasopressin group than in the low- and medium-dose groups. These findings indicate that different doses of vasopressin result in a similar outcome of CPR, with no additional benefits afforded by a high dose of vasopressin during or after CPR, in a rat model of asphyxial CA. The mechanism and physiologic significance of the relative bradycardia that occurred in the high-dose vasopressin group are currently unknown and require further investigation.     

加压素与肾上腺素在小鼠心肺复苏中的疗效比较

目的 比较加压素与肾上腺素在小鼠心肺复苏中的疗效.方法 30只雄性昆明小鼠经食道快速起搏心窒诱发室颤、建立心搏骤停模型,起搏开始后4 min将小鼠随机分成3组(n=10/组):对照组(Sal-gro)、加压素组(Vas-gro)、肾上腺素组(Epi-gro),分别经动脉注射药物(生理盐水、加压素0.4 U/kg和肾上腺素0.04mg/kg)1次,开始胸外心脏按压及机械通气,观察自主循环恢复情况,10min无效则放弃复苏.自主循环恢复的小鼠连续监测心电和血压60 min,观察血压、心率、呼吸恢复情况及生存时间.结果 加压素与肾上腺素组小鼠的自主循环恢复率均显著高于对照组(9/10,10/10和3/10,P＜0.05,P＜0.01).加压素与肾上腺素组组间比较差异无统计学意义(P＞0.05).肾上腺素组小鼠在自主循环恢复后全部出现自主呼吸,而加压素组小鼠只有4只出现自主呼吸(P＜0.05).肾上腺素组小鼠的生存时间明显长于加压素组和对照组小鼠(P＜0.05,P＜0.05).结论 加压素和肾上腺素均可显著提高心搏骤停小鼠的自主循环恢复率,但0.04 mg/kg的肾上腺素对自主循环恢复后小鼠呼吸功能及生存时间的影响明显优于0.4 U/k的加压素,其机制尚不清楚,还有待进一步研究.     

Vasopressin versus epinephrine during cardiopulmonary resuscitation: a randomized swine outcome study.

In animal models, vasopressin improves short-term outcome after cardiopulmonary resuscitation (CPR) for ventricular fibrillation compared to placebo, and improves myocardial and cerebral hemodynamics during CPR compared to epinephrine. This study was designed to test the hypothesis that vasopressin would improve 24-h neurologically intact survival compared to epinephrine. After a 2-min untreated ventricular fibrillation interval followed by 6 min of simulated bystander CPR, 35 domestic swine (weight, 25+/-1 kg) were randomly provided with a single dose of vasopressin (20 U or approximately 0.8 U kg(-1) intravenously) or with epinephrine (0.02 mg kg(-1) intravenously every 5 min). Ten minutes after initial medication administration (18 min after induction of ventricular fibrillation), standard advanced life support was provided, starting with defibrillation. Animals that were successfully resuscitated received 1 h of intensive care support and were observed for 24 h. Coronary perfusion pressures were higher in the vasopressin group 2 and 4 min after vasopressin administration (28+/-2 versus 18+/-1 mm Hg, P<0.01, and 26+/-3 versus 18+/-2 mm Hg, P<0.05, respectively). The vasopressin group tended to be successfully defibrillated on the first attempt more frequently (8/18 versus 3/17, P = 0.15). Return of spontaneous circulation (ROSC) was attained in 12/18 (67%) vasopressin-treated pigs versus 8/17 (47%) epinephrine-treated pigs, P = 0.24. Twenty-four hour neurologically normal survival occurred in 11/18 (61%) versus 7/17 (41%), respectively, P = 0.24. In conclusion, vasopressin administration during CPR improved coronary perfusion pressure, but did not result in statistically significant outcome improvement.     

Association of delay to first intervention with return of spontaneous circulation in a swine model of cardiac arrest

OBJECTIVE: No single drug improves survival after cardiac arrest, despite success in animal studies. We sought to determine the duration of circulatory arrest after which maximal drug treatment and a rescue shock would fail to achieve return of spontaneous circulation (ROSC). DESIGN/SUBJECTS: Retrospective analysis of 271 swine (20-30 kg) resuscitation attempts during ventricular fibrillation. Protocols were divided into five categories: immediate countershock, cardiopulmonary resuscitation (CPR) with standard-dose drugs, CPR alone, CPR and high-dose epinephrine (CPR+HDE) (0.1 mg/kg), and CPR with a drug cocktail (CPR+DC) of propanolol (1 mg), epinephrine (adrenaline) (0.1 mg/kg) and vasopressin (40IU). Time to first CPR, time to first drug administration, time to first shock, and protocol were examined as predictors of ROSC using logistic regression with Hosmer-Lemeshow test of fit. Probability of ROSC was calculated from logistic curves. MAIN RESULTS: ROSC occurred in 119 of the 271 swine (44%). Time to first drug and the CPR+DC group were predictors of ROSC. Time to first CPR, the CPR+DC group, and the CPR+HDE group were also predictors of ROSC. Time to first rescue shock, the CPR+DC group, and the CPR+HDE groups were predictors of ROSC. In the CPR+DC group, 50% ROSC occurred at a first CPR time of 13.4 min, first drug time of 14.1 min and first rescue shock time of 17.5 min. CONCLUSIONS: Pre-shock delivery of CPR+DC increases the likelihood of ROSC, and reaches 50% with a time of drug delivery of 14.1 min. ROSC rates of 50% may be achievable using an optimized resuscitation in experimental CPR.     

Effects of vasopressin and epinephrine on splanchnic blood flow and renal function during and after cardiopulmonary resuscitation in pigs

OBJECTIVE: To compare the effects of vasopressin versus epinephrine on splanchnic blood flow during and after cardiopulmonary resuscitation (CPR), and to evaluate the effects of these vasopressors on renal function in the postresuscitation phase. DESIGN: Prospective, randomized laboratory investigation using an established porcine CPR model with instrumentation for continuous measurement of splanchnic and renal blood flow. SETTING: University hospital experimental laboratory. SUBJECTS: A total of 12 anesthetized, 12- to 16-wk-old domestic pigs weighing 30-35 kg. INTERVENTIONS: After 4 mins of cardiac arrest, and 3 mins of CPR, 12 pigs were randomly assigned to receive either 0.4 units/kg vasopressin (n = 6) or 45 microg/kg epinephrine (n = 6). Defibrillation was performed 5 mins after drug administration; all animals were observed for 6 hrs after return of spontaneous circulation (ROSC). MEASUREMENTS AND MAIN RESULTS: Mean +/- SEM superior mesenteric artery blood flow was significantly (p < .05) lower after vasopressin compared with epinephrine at 90 secs after drug administration (13+/-3 vs. 129+/-33 mL/min); at 5 mins after drug administration (31+/-18 vs. 155+/-39 mL/min); at 5 mins after ROSC (332+/-47 vs. 1087+/-166 mL/min); and at 15 mins after ROSC (450+/-106 vs. 1130+/-222 mL/min); respectively. Mean +/- SEM left renal and hepatic artery blood flow after ROSC was comparable in both groups ranging between 120-290 mL/min (renal blood flow), and 150-360 mL/min (hepatic blood flow), respectively. Median urine output after ROSC showed no difference between groups, and highest values (180-220 mL/hr) were observed in the first 60 mins after ROSC. Median calculated glomerular filtration rate showed no difference between groups with values ranging between 30 and 80 mL/min in the postresuscitation phase. Calculated fractional sodium excretion and osmolar relationship between urea and plasma indicated no evidence for renal tubular dysfunction. CONCLUSIONS: In the early postresuscitation phase, superior mesenteric blood flow was temporarily impaired by vasopressin in comparison with epinephrine. With respect to renal blood flow and renal function after ROSC, there was no difference between either vasopressor given during CPR. Vasopressin given during CPR did not result in an antidiuretic state in the postresuscitation phase.     

Differences in the pharmacodynamics of epinephrine and vasopressin during and after experimental cardiopulmonary resuscitation

Vasopressin has been investigated as a possible alternative to epinephrine during cardiopulmonary resuscitation (CPR). We tested the hypothesis that vasopressin, in comparison with epinephrine, would improve cerebral blood flow and metabolism during CPR as well as after restoration of spontaneous circulation (ROSC). A total of 22 anaesthetised piglets were subjected to 5 min of ventricular fibrillation followed by 8 min of closed-chest CPR. The piglets were randomly allocated to receive repeated boluses of either 45 microg/kg epinephrine or 0.4 U/kg vasopressin IV. Haemodynamic parameters, cerebral cortical blood flow and cerebral tissue pH and PCO(2) were continuously monitored during CPR and up to 4 h after ROSC. Cerebral oxygen extraction ratio was calculated. Cerebral cortical blood flow increased transiently after each bolus of epinephrine, while only the first bolus of vasopressin resulted in a sustained increase. The peak in cerebral cortical blood flow was reached approximately 30 s later with vasopressin. During the initial 5 min following ROSC, cerebral cortical blood flow was greater in the vasopressin group. In conclusion, there is a difference between epinephrine and vasopressin in the time from injection to maximal clinical response and the duration of their effect, but their overall effects on blood pressures and cerebral perfusion do not differ significantly during CPR. In contrast, vasopressin results in a greater cerebral cortical blood flow during a transient period after ROSC.     

What is the optimal dose of epinephrine during cardiopulmonary resuscitation in a rat model?

Objective

Because different species may require different doses of drug to produce the same physiologic response, we were provoked to evaluate the dose-response of epinephrine during cardiopulmonary resuscitation (CPR) and identify what is the optimal dose of epinephrine in a rat cardiac arrest model.

Methods

Rat cardiac arrest was induced via asphyxia, and then the effects of different doses of epinephrine (0.04, 0.2, and 0.4 mg/kg IV, respectively) and saline on the outcome of CPR were compared (n = 10/each group). The primary outcome measure was restoration of spontaneous circulation (ROSC), and the secondary was the change of spontaneous respiration and hemodynamics after ROSC.

Results

Rates of ROSC were 9 of 10, 8 of 10, 7 of 10, and 1 of 10 in the low-dose, medium-dose, and high-dose epinephrine groups and saline group, respectively. The rates of withdrawal from the ventilator within 60 minutes in the low-dose (7 of 9) and medium-dose epinephrine groups (7 of 8) were higher than in the high-dose epinephrine group (1 of 7, P < .05). Mean arterial pressures were comparable, but the heart rate in the high-dose epinephrine group was the lowest among epinephrine groups after ROSC. These differences in part of time points reached statistical significance (P < .05).

Conclusion

Different doses of epinephrine produced the similar rate of ROSC, but high-dose epinephrine inhibited the recovery of spontaneous ventilation and caused relative bradycardia after CPR in an asphyxial rat model. Therefore, low and medium doses of epinephrine were more optimal for CPR in a rat asphyxial cardiac arrest model.     

Standard and Higher Doses of Atropine in a Canine Model of Pulse less Electrical Activity

Objective: To determine whether standard or increased doses of atropine improve the return of spontaneous circulation (ROSC) rate in a canine model of pulseless electrical activity (PEA).
Methods: A prospective, controlled, blinded laboratory investigation was performed using an asphyxial canine cardiac arrest model. After the production of asphyxial PEA, 75 dogs remained in untreated PEA for 10 minutes and then were randomized to receive placebo (group 1) or one of four doses of atropine (group 2, 0.04 mg/kg; group 3, 0.1 mg/kg; group 4, 0.2 mg/kg; group 5, 0.4 mg/kg). All the animals received mechanical external CPR and epinephrine (0.02 mg/kg every 3 minutes) throughout resuscitation.
Results: The ROSC rates were not significantly different between the groups (group 1, 73%; group 2, 67%; group 3. 40%; group 4, 47%; group 5, 27%; p = 0.06). The heart rates and hemodynamics during resuscitation were not significantly different between the groups.
Conclusion: In this canine model of asphyxial PEA cardiac arrest, standard-dose atropine did not improve ROSC rates, compared with placebo. Increasing doses of atropine tended to decrease ROSC rates, compared with placebo and standard-dose atropine.