Three-phase model of cardiac arrest: time-dependent benefit of bystander cardiopulmonary resuscitation

Evidence has suggested that the pathophysiology of ventricular fibrillation cardiac arrest may consist of 3 time-sensitive phases: electrical, circulatory, and metabolic. We performed a retrospective cohort study of adults in a metropolitan county who had had witnessed ventricular fibrillation arrest before emergency medical services were undertaken to investigate this 3-phase model with regard to bystander cardiopulmonary resuscitation (CPR). We hypothesized that the survival benefit from bystander CPR depends on the collapse-to-shock interval, with the highest benefit occurring during the circulatory phase. The collapse-to-shock interval was a priori grouped into 4 categories: 1 to 5, 6 to 7, 8 to 10, and > or = 11 minutes. We used logistic regression analysis to assess whether the association between CPR and survival to hospital discharge depended on the collapse-to-shock interval category. Of the 2,193 events meeting the inclusion criteria, 67.0% had received bystander CPR. The average collapse-to-shock interval was 8.2 +/- 2.8 minutes. The survival rate was 33.4%. A higher likelihood of survival was associated with bystander CPR (odds ratio [OR] 1.41, 95% confidence interval [CI] 1.15 to 1.73) and a shorter collapse-to-shock interval (OR -1.84, 95% CI 1.62 to 2.10, for each additional SD of 2.8 minutes less) after adjustment. The beneficial association of CPR increased as the collapse-to-shock interval increased (p = 0.05 for interaction). The bystander CPR was associated with an OR of survival of 0.96 (95% CI 0.64 to 1.46) for a 1- to 5-minute collapse-to shock interval, OR of 1.25 (95% CI 1.00 to 1.58) for a 6- to 7-minute interval, OR of 1.62 (95% CI 1.25 to 2.11) for an 8- to 10-minute interval, and OR of 2.11 (95% CI 1.32 to 3.37) for an > or = 11-minute interval. The results of this investigation support a phased model of ventricular fibrillation arrest. The findings suggest that the transition from the electrical to circulatory phase may occur at about 5 minutes, and the circulatory phase may extend to 15 minutes.     

Improved survival and reduced myocardial necrosis with cardiopulmonary bypass reperfusion in a canine model of coronary occlusion and cardiac arrest

STUDY QUESTION: Does cardiopulmonary bypass (CPB) improve resuscitation rates and limit infarct size after cardiac arrest and acute myocardial infarction? DESIGN: Controlled randomized trial with all animals undergoing left anterior descending coronary artery occlusion and subsequent ventricular fibrillation and resuscitation. All animals were supported for four hours after resuscitation in an intensive care setting. INTERVENTION: Group 1 (eight) was resuscitated with standard external CPR and advanced life support. Group 2 (eight) was resuscitated with CPB. MEASUREMENTS AND MAIN RESULTS: Group hemodynamic, resuscitation variables, number resuscitated, and number of four-hour survivors were compared. Ischemic and necrotic myocardial weights were determined with histochemical staining techniques in four-hour survivors. Infarct size was measured as the ratio of necrotic weight to ischemic weight. Significantly fewer dogs were resuscitated in group 1 (four of eight) than in group 2 (eight of eight) (P less than .05). Group 2 survivors required significantly less epinephrine and lidocaine than group 1 survivors (P less than .05) and higher aortic diastolic and coronary perfusion pressures after CPB (P less than .001). The ratio of myocardial necrotic weight to ischemic weight at four hours was 0.82 +/- 0.25 in group 1 and 0.22 +/- 0.25 in group 2 (P less than .05). However, collateral blood flow was not measured in this study. CONCLUSION: This pilot study further substantiates the improvement in resuscitation rates obtainable with CPB. CPB may also limit infarct size during the postresuscitation period and requires further study.     

Different forms of bystander cardiopulmonary resuscitation in out-of-hospital cardiac arrest

Out-of-hospital cardiac arrest (OHCA) is a major cause of death in the Western world with an estimated number of 275 000 treated with resuscitation attempts by the Emergency Medical Services (EMS) in Europe each year. Overall survival rates remain low, and most studies indicate that around 1 out 10 will survive to 30 days. Amongst the strongest factors associated with survival in OHCA is first recorded rhythm amendable to defibrillation, early defibrillation and prompt initiation of cardiopulmonary resuscitation (CPR). Overall, CPR started prior to EMS arrival has repeatedly been shown to be associated with survival rates 2–3 times higher compared with no such initiation. The primary goal of CPR is to generate sufficient blood flow to vital organs, mainly the brain and heart, until restoration of spontaneous circulation can be achieved. Barriers to the initiation of CPR by bystanders in OHCA include fear of being incapable, causing harm, and transmission of infectious diseases. Partly due to these barriers, and low rates of CPR, the concept of CPR with compression only was proposed as a simpler form of resuscitation with the aim to be more widely accepted by the public in the 1990s. But how reliable is the evidence supporting this simpler form of CPR, and are the outcomes after CO-CPR comparable to standard CPR?     

Two-year survival and neurological outcome of in-hospital cardiac arrest patients rescued by extracorporeal cardiopulmonary resuscitation

Background

The clinical benefit of extracorporeal cardiopulmonary resuscitation (E-CPR) has been proved in short-term follow-up studies. However, the benefit of E-CPR beyond 1 year has been not known. We investigated 2-year outcome of patients who received E-CPR or conventional CPR (C-CPR).

Methods

We analyzed a total of 406 adult in-hospital cardiac arrest victims who underwent CPR for more than 10 min from 2003 to 2009. The two-year survival and neurological outcome of E-CPR (n = 85) and C-CPR (n = 321) were compared using propensity score-matched analysis.

Results

The 2-year survival with minimal neurological impairment was 4-fold higher in the E-CPR group than the C-CPR group (23.5% versus 5.9%, hazard ratio (HR) = 0.57, 95% confidence interval (CI) = 0.43–0.75, p < 0.001) by unadjusted analysis. After propensity-score matching, it was still 4-fold higher in the E-CPR group than the C-CPR group (20.0% versus 5.0%, HR = 0.53, 95% CI = 0.36–0.80, p = 0.002). In the E-CPR group, the independent predictors associated with minimal neurological impairment were age ≤ 65 years (HR = 0.46; 95% CI = 0.26–0.81; p = 0.008), CPR duration ≤ 35 min (HR = 0.37; 95% CI = 0.18–0.76; p = 0.007), and subsequent cardiovascular intervention including coronary intervention or cardiac surgery (HR = 0.36; 95% CI = 0.18–0.68; p = 0.002).

Conclusions

The initial survival benefit of E-CPR for cardiac arrest patients persisted at 2 years.     

Acid-base balance in a canine model of cardiac arrest

Our study was performed to determine the pattern of arterial, venous, and cerebral spinal fluid (CSF) acidosis in a canine model of cardiac arrest and resuscitation; and the effect of bicarbonate treatment on arterial, venous, and CSF acidosis. Animals were instrumented to sample arterial blood, mixed venous blood, and CSF through a cisternal catheter. Following six minutes of ventricular fibrillation, manual CPR efforts were begun and continued for 30 minutes of cardiac arrest. Arterial, mixed venous, and CS fluids were sampled at baseline, six, 12, 18, 24, 27, and 30 minutes. Ten experimental dogs received sodium bicarbonate (2 mEq/kg) at 20 minutes of cardiac arrest, while ten animals in the control group received no alkali treatment. The experimental group showed a significantly higher arterial (7.79 +/- 0.20 vs 7.46 +/- 0.16 at 30 minutes) and venous pH (7.34 +/- 0.12 vs 7.19 +/- 0.10 at 24 minutes) following bicarbonate administration. This higher pH occurred despite a concomitant increase in arterial (31 +/- 10 vs 19 +/- 9 mm Hg at 27 minutes; 31 +/- 9 vs 10 +/- 8 at 30 minutes) and venous (104 +/- 30 vs 63 +/- 10 mm Hg at 24 minutes) pCO2. CSF analysis showed a gradually worsening acidosis. However, CSF pH (7.12 +/- 0.14 vs 7.16 +/- 0.23 at 30 minutes) and pCO2 were not significantly changed by the administration of bicarbonate.     

体外心肺复苏在成人心脏骤停中的应用

目的 总结体外心肺复苏(ECPR)在成人心脏骤停患者循环辅助中的临床经验.方法 收集2019-04～2020-12在该院EICU收住的进行ECPR救治的心脏骤停患者26例,回顾性分析患者的病历资料,对比生存组与死亡组的临床资料、实验室检查结果及各参数指标等.结果 26例患者中有9例成功从体外膜肺氧合(ECMO)撤机;6...     

心脏骤停患者心肺复苏程序的探讨

目的 探讨心脏骤停患者的心肺复苏的程序,以便为心肺复苏提供更多的复苏途径.方法 选择近年来心肺复苏成功的39例心脏骤停患者,根据不同情况采取相应的五种不同复苏程序:ABCD、D、C、CD、CABD.结果13例呼吸完全停止的患者采用传统ABCD复苏程序;26例呼吸尚存的患者,7例现场直接给予电除颤(D),其余19例现场不具备立即除颤的,立即给予胸外心脏按压,其中3例通过心脏按压直接复苏(C),9例心脏按压再电除颤后复苏(CD),7例心脏按压时间较长,呼吸逐渐停止,给予人工通气、复苏药物及电除颤最终复苏(CABD).结论对原发性心跳骤停的患者应视不同情况采取不同的复苏程序.     

Predictive indices of successful cardiac resuscitation after prolonged arrest and experimental cardiopulmonary resuscitation

To determine if clinically accessible hemodynamic and blood gas measurements are of value in predicting outcome of countershock after prolonged ventricular fibrillation (VF) and artificial cardiopulmonary support, 14 dogs were studied during 30 minutes of VF using two randomly assigned closed-chest techniques. Seven dogs underwent conventional CPR; the other seven were supported with a pneumatic thoracic vest and abdominal binder, which were inflated synchronously with the airway. Ascending aortic (Ao), right atrial (RA), and instantaneous coronary perfusion pressures (Ao - RA) were measured at five-minute intervals. Ao and RA blood samples were analyzed at 10, 20, 25 and 30 minutes for PO2, PCO2, and pH. After 25 minutes, 1 mg epinephrine was given intravenously, and five minutes later defibrillation was attempted. If unsuccessful, repeated countershocks, conventional pharmacologic therapy, and artificial support were continued. If a perfusing spontaneous cardiac rhythm did not result within an additional 30 minutes, the experiment was terminated. Six animals developed a perfusing cardiac rhythm after one or more countershocks (Group 1); eight failed to develop a perfusing rhythm after repeated countershocks and an additional 30 minutes of resuscitative effort (Group 2). Five Group 1 dogs received vest/binder artificial support. When measured values were averaged over the study period, Group 1 was found to have a significantly greater Ao end-diastolic pressure (AoEDP) and peak diastolic coronary perfusion pressure (CPP) when compared to Group 2 (23 +/- 6 vs 14 +/- 8 mm Hg, P less than .05; and 22 +/- 6 vs 5 +/- 10 mm Hg, P less than .01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Mechanical "cough" cardiopulmonary resuscitation during cardiac arrest in dogs

Hemodynamic findings during ventricular fibrillation (VF) and closed-chest cardiopulmonary resuscitation (CPR) are similar to those described during VF and vigorous coughing. Interventions during CPR that mimic the physiologic events of coughing (high intrathoracic pressure and high intraabdominal pressure) improve perfusion during VF and CPR. An external circulatory assist apparatus was devised to emulate cough physiology, i.e., simultaneous pulsatile increases in intrathoracic pressure (pneumatic vest), intraabdominal pressure (abdominal binder) and airway pressure (high-pressure airway inflation). In this study, vest/binder CPR was compared with conventional CPR during 30 minutes of VF and artificial support in 18 randomized dogs. Defibrillation and long-term (more than 24 hours) survival were chosen as end points. During VF and artificial support, aortic and right atrial (RA) pressures, the instantaneous aortic-RA pressure difference (coronary perfusion pressure) and blood gas levels were measured. After 30 minutes of VF and administration of 1 mg of epinephrine, countershock was attempted. Systolic aortic and RA pressures, mean aortic-RA pressure difference and blood gas levels were not significantly different between dogs that were successfully resuscitated and those that were not. However, peak diastolic coronary perfusion pressure (peak diastolic aortic-RA pressure) for survivors averaged 23 +/- 6 mm Hg, but only 6 +/- 10 mm Hg for nonsurvivors (p less than 0.001). A peak diastolic coronary perfusion pressure 16 mm Hg or greater had a positive and negative predictive value for a successful outcome of 1.00. Only 1 of 9 conventional CPR dogs survived 24 hours; 7 of 9 dogs supported with the vest/binder device were alive and neurologically normal at 24 hours (p = 0.007).(ABSTRACT TRUNCATED AT 250 WORDS)     

Vest inflation without simultaneous ventilation during cardiac arrest in dogs: improved survival from prolonged cardiopulmonary resuscitation

Myocardial and cerebral blood flow can be generated during cardiac arrest by techniques that manipulate intrathoracic pressure. Augmentation of intrathoracic pressure by high-pressure ventilation simultaneous with compression of the chest in dogs has been shown to produce higher flows to the heart and brain, but has limited usefulness because of the requirement for endotracheal intubation and complex devices. A system was developed that can produce high intrathoracic pressure without simultaneous ventilation by use of a pneumatically cycled vest placed around the thorax (vest cardiopulmonary resuscitation [CPR]). The system was first tested in a short-term study of the maximum achievable flows during arrest. Peak vest pressures up to 380 mm Hg were used on eight 21 to 30 kg dogs after induction of ventricular fibrillation and administration of epinephrine. Microsphere-determined myocardial blood flow was 108 +/- 17 ml/min/100 g (100 +/- 16% of prearrest flow) and cerebral flow was 51 +/- 12 ml/min/100 g (165 +/- 39% of prearrest). Severe lung or liver trauma was noted in three of eight dogs. If peak vest pressure was limited to 280 mm Hg, however, severe trauma was no longer observed. A study of the hemodynamics during and survival from prolonged resuscitation was then performed on three groups of seven dogs. Vest CPR was compared with manual CPR with either conventional (300 newtons) or high (430 newtons) sternal force. After induction of ventricular fibrillation, each technique was performed for 26 min. Defibrillation was then performed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Factors modifying the effect of bystander cardiopulmonary resuscitation on survival in out-of-hospital cardiac arrest patients in Sweden.

AIM: To describe possible factors modifying the effect of bystander cardiopulmonary resuscitation on survival among patients suffering an out-of-hospital cardiac arrest. PATIENTS: A national survey in Sweden among patients suffering out-of-hospital cardiac arrest and in whom resuscitative efforts were attempted. Sixty per cent of ambulance organizations were included. DESIGN: Prospective evaluation. Survival was defined as survival 1 month after cardiac arrest. RESULTS: In all, 14065 reports were included in the evaluation. Of these, resuscitation efforts were attempted in 10966 cases, of which 1089 were witnessed by ambulance crews. The report deals with the remaining 9877 patients, of whom bystander cardiopulmonary resuscitation was attempted in 36%. Survival to 1 month was 8.2% among patients who received bystander cardiopulmonary resuscitation vs 2.5% among patients who did not receive it (odds ratio 3.5, 95% confidence interval 2.9-4.3). The effect of bystander cardiopulmonary resuscitation on survival was related to: (1) the interval between collapse and the start of bystander cardiopulmonary resuscitation (effect more marked in patients who experienced a short delay); (2) the quality of bystander cardiopulmonary resuscitation (effect more marked if both chest compressions and ventilation were performed than if either of them was performed alone); (3) the category of bystander (effect more marked if bystander cardiopulmonary resuscitation was performed by a non-layperson); (4) interval between collapse and arrival of the ambulance (effect more marked if this interval was prolonged); (5) age (effect more marked in bystander cardiopulmonary resuscitation among the elderly); and (6) the location of the arrest (effect more marked if the arrest took place outside the home). CONCLUSION: The effect of bystander cardiopulmonary resuscitation on survival after an out-of-hospital cardiac arrest can be modified by various factors. Factors that were associated with the effect of bystander cardiopulmonary resuscitation were the interval between the collapse and the start of bystander cardiopulmonary resuscitation, the quality of bystander cardiopulmonary resuscitation, whether or not the bystander was a layperson, the interval between collapse and the arrival of the ambulance, age and the place of arrest.