RESUMO
Objective:To explore the automated external defibrillator (AED) configuration optimization strategy in line with the characteristics of the rapidly developing cities by analyzing the actual coverage of AED in Bao'an District based on the real world data of out-of-hospital cardiac arrest (OHCA) in Bao'an District, Shenzhen City.Methods:The data of cardiac arrest database registered in Bao'an District of Shenzhen City from March 1, 2019 to February 29, 2020 were included in a retrospective observational study. The AED coverage of public and non-public areas was analyzed by calculating the minimum distance between the occurrence place of each OHCA event and the nearest AED. The minimum distance ≤100 m was set as AED coverage, and the minimum distance > 100 m was set as non-AED coverage. It was assumed that one AED was configured for each OHCA hotspot area, then the AED coverage changes were analyzed. Based on the actual situation that the AED in schools, governments, sports venues, subways, tourist attractions and parks of public areas in Bao'an District could not be obtained at any time within 24 hours, it was assumed that all AED in the public areas could be obtained at any time within 24 hours, the impact of AED available at any time on AED coverage was analyzed.Results:A total of 525 cases of OHCA were enrolled. The highest incidence of OHCA was found in residential and industrial areas [54.5% (286/525) and 14.3% (75/525), respectively]. There were 252 AED in Bao'an District, Shenzhen, and 115 OHCA events occurred within the coverage area of AED. Even if all AED met the ideal state that could be obtained at any time within 24 hours, the coverage rate was only 21.9% (115/525). The AED coverage rate of the public areas and non-public areas was 31.6% (37/117) and 19.1% (78/408) respectively, with uneven distribution, and the AED coverage rate of non-public areas was low. Assuming that the residential community and industrial zone with more than 2 OHCA cases were respectively equipped with one AED, the coverage rate of AED in the non-public areas increased from 19.1% (78/408) to 28.2% (115/408), basically meeting the requirement that AED could be obtained at any time when OHCA events occurred. Some AED in the public areas of Bao'an District were not available at any time within 24 hours. If the ideal state that all AED in the public area could be obtained at any time within 24 hours could be achieved, the AED coverage rate of all regions increased from 16.8% (88/525) to 21.9% (115/525), the AED coverage rate of the public areas increased from 29.1% (34/117) to 31.6% (37/117), the AED coverage rate of the non-public areas increased from 13.2% (54/408) to 19.1% (78/408).Conclusions:AED configuration in Bao'an District was unevenly distributed, and the coverage rate of AED in non-public areas was low. The allocation strategy for AED in fast-growing cities like Shenzhen should be as follows: on the premise of ensuring AED availability for 24 hours, priority should be given to covering the number of AED in the non-public areas including residential communities and industrial zones; AED is available in the public areas for 24 hours.
RESUMO
Objective To discuss the influence of two recombinant hemoglobin (rHb1.1 and rHb2.0) and human serum albumin (HSA) on oxygen supply and demand balance in rat with coronary heart disease (CHD). Methods Male Wistar rats were randomly divided into normal control group, CHD model group, HSA treatment group, rHb1.1 treatment group and rHb2.0 treatment group, 20 rats in each group. Rat model of CHD was established by high fat diet combined with pituitrin injection. The mean arterial pressure (MAP) decreased to 40 mmHg (1 mmHg = 0.133 kPa) after femoral arterial blood was drawn from the femoral arteries, and the rats were resuscitated with 13.4% HSA, rHb1.1 and rHb2.0, respectively, at the rate of 60 mL·kg-1·h-1 (20 mL/kg). The changes of electrocardiogram (ECG) ST-segment were calculated before model reproduction and at 12 hours after the last time injection of pituitrin. MAP, heart rate (HR), superior mesenteric artery blood flow (QSMA) and arterial blood gas analysis were recorded at 0, 30, 60, 90 and 120 minutes after the administration. The blood was collected after 12-hour fasting, and serum total cholesterol (TC) and triglyceride (TG) were determined by enzymatic method. The pathological changes in cardiac tissue were observed with light microscope. Results Compared with the normal control group, the changes of ECG ST-segment and TC, TG of model group were significantly increased. Compared with the model group, rHb can significantly reduce the value of ST segment changes, and HSA has no such effect; rHb short-term infusion has no significant effect on blood lipids, but can reduce myocardial pathological changes. Compared with the normal control group, the MAP of the model group decreased significantly, the HR was increased, the QSMA was slowed down, the pH value, the residual alkali (BE), the arterial carbon dioxide partial pressure (PaCO2) and HCO3- were decreased significantly. MAP in rHb1.1 group and rHb2.0 group were significantly higher than those in HSA group. Values of MAP were significantly higher in rHb2.0 group than those in rHb1.1 group at 90 minutes and 120 minutes (mmHg: 80.9±3.3 vs. 69.4±4.9, 79.2±4.0 vs. 69.1±3.7, both P < 0.05). The HR of HSA, rHb1.1 and rHb2.0 decreased to normal in 30 minutes after administration, significantly lower than those in the model group (bpm: 534±46, 518±28, 526±37 vs. 609±52, all P < 0.05). In the rHb2.0 group, the QSMA increased significantly at 60, 90 and 120 minutes compared with the model group (qv·mL-1·min-1: 5.6±0.4 vs. 3.9±0.6, 6.2±0.6 vs. 4.1±0.4, 6.9±0.7 vs. 4.0±0.3, all P < 0.05), but there was no significant difference between the HSA group and the rHb1.1 group. The pH, BE, PaCO2 did not return to the normal level after administration of HSA; pH, PaCO2 and HCO3- in the rHb1.1 group returned to normal level at 60 minutes after administration, and BE returned to normal level at 90 minutes after administration. Each index in rHb2.0 group can restore to normal levels 30 minutes ahead of. Conclusion Recombinant hemoglobin can significantly improve the oxygen supply and demand balance of rats with CHD model, can quickly and effectively correct the hypoxic state of blood metabolic acidosis, and rHb2.0 has better effect than rHb1.1.