First-aid stations were divided randomly into 4 groups.Advanced airway for sudden cardiac arrest patients with laryngeal mask airway (LMA) was established in groups A and C while trachea cannula was inserted on spot of emergency medical service (EMS) or in ambulance in groups B and D.According to the results,the success rate of insertion and cardiopulmonary resuscitation (CPR) of groups A and C were higher than the other two groups (P ＜ 0.05).However,the required time was shorter (P ＜ 0.05).Due to a difficult catheterization environment,LMA is more effective and convenient than trachea cannula in EMS.

Objective To investigate the epidemiological features of out-of-hospital patients with ventricular fibrillation (VF) in Shanghai and to analysis factors associated with outcomes, and to provide evidence for improving the success rate of VF.Methods The data of patients with VF admitted to Shanghai Medical Emergency Center from January 2013 to December 2016 were analyzed retrospectively. All the data were recorded including the clinical data, medical service time, return of spontaneous circulation (ROSC) at scene/en route, survival to hospital discharge. Factors that associated with successful resuscitation were analyzed by Logistic regression.Results From 2013 to 2016, 21096 patients with suspected cardiac arrest were admitted to the Shanghai Medical Emergency Center. After excluding ventricular tachycardia (13 cases) and ventricular asystole (20995 cases), 88 patients with VF were enrolled, with 62 male and 26 female; the average age was (63.22±16.15) years old. While bystander cardiopulmonary resuscitation (CPR) was performed in only 21 cases (23.86％). Fifty-seven cases occurred during the day (08:00-20:00), while 31 cases occurred in the night. And the average emergency response time was (6.47±4.13) minutes; the average on-site time was (14.76±10.88) minutes; the average transport to hospital time was (5.95±4.00) minutes. There were no significant differences in response time, on-site time and transport to hospital time each year, and there were no significant differences in emergency medical service time between day and night either. From 2013 to 2016, prehospital successful resuscitation rate was decreased by years [95.65％ (22/23), 87.50％ (14/16), 83.33％ (20/24) vs. 80.00％(20/25), respectively,χ2 = 1.895,P = 0.595]. Survival to hospital discharge rate was increased by years [21.74％ (5/23), 31.25％ (5/16), 37.50％ (9/24), 40.00％ (10/25), respectively,χ2 = 2.862,P = 0.413]. The success rate of prehospital resuscitation for patients with 1, 2, ≥3 defibrillation was 35.23％ (31/88), 23.08％ (12/52), 89.19％ (33/37), respectively (χ2 = 42.811,P = 0.000). The on-site time in successful final resuscitation group was shorter than that in final resuscitation failure group (minutes: 10.85±8.83 vs. 16.79±11.36,t = 2.367,P = 0.020), the ROSC time in successful final resuscitation group was shorter than that of final resuscitation failure group (minutes: 3.24±3.17 vs. 7.43±6.64, t = 3.175,P = 0.002). It was shown by Logistic regression that long ROSC time was the risk factor for final resuscitation failure [odds ratio (OR) = 0.771,P = 0.024]. Gender, age, availability of witnesses CPR, call time, emergency response time, on-site time and transport to hospital time had no significant impact on the prehospital successful resuscitation and final successful resuscitation. In prehospital successful resuscitation group, there was significant difference in survival to hospital discharge rate among different defibrillation times group [48.39％ (15/31), 58.33％ (7/12) vs. 21.21％ (7/33),χ2 = 7.460,P = 0.024].Conclusions From 2013 to 2016, there were no significant changes in the emergency response time, prehospital successful resuscitation rate and survival to hospital discharge rate of patients with VF in Shanghai. Though, repeated defibrillation could significantly increased prehospital successful resuscitation rate, multiple defibrillation indicated decline of survival to hospital discharge rate in prehospital successful resuscitation group. Additionally, long on-site time and long ROSC time indicated poor prognosis.