Objective To observe the effect of mild hypothermia on myocardial β-adrenergic receptor (β-AR) signal pathway after cardiopulmonary resuscitation (CPR) in pigs with cardiac arrest (CA) and explore the mechanism of myocardial protection. Methods Healthy male Landraces were collected for reproducing the CA-CPR model (after 8-minute untreated ventricular fibrillation, CPR was implemented). The animals were divided into two groups according to random number table (n = 8). In the mild hypothermia group, the blood temperature of the animals was induced to 33 ℃ and maintained for 6 hours within 20 minutes after return of spontaneous circulation (ROSC) by using a hypothermia therapeutic apparatus. In the control group, the body temperature of the animals was maintained at (38.0±0.5)℃ with cold and warm blankets. The heart rate (HR), mean arterial pressure (MAP), the maximum rate of increase or decrease in left rentricular pressure (+dp/dt max)were measured during the course of the experiment. The cardiac output (CO) was measured by heat dilution methods before CA (baseline), and 0.5, 1, 3, 6 hours after ROSC respectively, the venous blood was collected to detect the concentration of cTnI. Left ventricular ejection fraction (LVEF) was measured with cardiac ultrasound before CA and 6 hours after ROSC. Animals were sacrificed at 6 hours after ROSC and the myocardial tissue was harvested quickly, the mRNA expression of β1-AR in myocardium was detected by reverse transcription-polymerase chain reaction (RT-PCR), the contents of adenylate cyclase (AC) and cyclic adenosine monophosphate (cAMP) were detected by enzyme linked immunosorbent assay (ELISA), the protein content of G protein-coupled receptor kinase 2 (GRK2) was detected by Western Blot. Results After successful resuscitation, the HR of both groups were significantly higher than the baseline values, CO, ±dp/dt max were significantly decreased, MAP were not significantly changed, serum cTnI levels were significantly increased. Compared with the control group, HR at 0.5, 1, 3 hours after ROSC were significantly decreased in mild hypothermia group (bpm: 142.80±12.83 vs. 176.88±15.14, 115.80±11.48 vs. 147.88±18.53, 112.60±7.40 vs. 138.50±12.02, all 1 < 0.01), CO was significantly increased at 1 hours and 3 hours after ROSC (L/min: 3.97±0.40 vs. 3.02±0.32, 4.00±0.11 vs. 3.11±0.59, both 1 < 0.01), +dp/dt max at 3 hours and 6 hours was also significantly increased after ROSC [+dp/dt max (mmHg/s): 3 402.5±612.7 vs. 2 130.0±450.6, 3 857.5±510.4 vs. 2 562.5±633.9; -dp/dt max (mmHg/s): 2 935.0±753.2 vs. 1 732.5±513.6, 3 520.0±563.6 vs. 2 510.0±554.3, all 1 < 0.05], the cTnI was significantly decreased at 3 hours and 6 hours afher ROSC (μg/L: 1.39±0.40 vs. 3.24±0.78, 1.46±0.35 vs. 3.78±0.93, both 1 < 0.01). The left at 6 hours after ROSC in both groups was decreased as compared with that before CA. The LVEF in the mild hypothermia group was higher than that in the control group (0.52±0.04 vs. 0.40±0.05, 1 < 0.05). The mRNA expression of β1-AR, and concentrations of AC and cAMP in hypothermia group were significantly higher than those in control group [β1-AR mRNA (2-ΔΔCT): 1.18±0.39 vs. 0.55±0.17, AC (ng/L):197.0±10.5 vs. 162.0±6.3, cAMP (nmol/L): 1 310.58±48.82 vs. 891.25±64.95, all 1 < 0.05], GRK2 was lower than that in the control group (GRK2/GAPDH: 0.45±0.05 vs. 0.80±0.08, 1 < 0.05). Conclusion Mild hypothermia can reduce the degree of cardiac function injury after CPR, and its mechanism may be related to the reduction of impaired myocardial β-AR signaling after CPR.

Objective:To find effective methods to improve the distribution and usage efficiency of pre-hospital epidemic emergency care resource (PEECR) by analyzing the PEECR allocation and usage in Jinan City during the coronavirus disease 2019 (COVID-19) epidemic.Methods:Correlation significance test between the COVID-19 epidemiology sample and the PEECR allocation sample was conducted to estimate whether they came from the same population in Jinan from January 24 to June 30, 2020. The data used in empirical analysis were collected from the Health Commission of Shandong Province's daily epidemic information announcement (definite case increment, suspected case increment, suspected case stock, medical observation stock, close contact increment) and interview with some epidemic branch centers in Jinan City (vehicle using increment). Experiential analysis was used to analyze the waste of PEECR usage.Results:All the 5 COVID-19 epidemiology samples and the PEECR allocation sample came from different population. There was no correlation between the vehicle using increment and definite case increment, suspected case increment, suspected case stock, close contact increment (all P < 0.05), there was a weak correlation between the vehicle using increment and medical observation stock [the correlation coefficient was 0.048, ∈ (0.0, 0.2), P = 0.550]. There was systematic difference between PEECR indicator and COVID-19 epidemiology indicator. The waste in practice was also amplified by improper usage such as unsophisticated allocation, low effectiveness in primary units and unvalid emergency calling. Conclusions:① A primary screening system should be established in control center to decrease the waste of efficiency. ② Communities and units should improve overall epidemic dealing ability to assist emergency system. ③ The medical treatment ability and protection resource should be increased in normal pre-hospital care.