Strategies to improve survival outcomes of out-of-hospital cardiac arrest (OHCA) given a fixed budget: A simulation study.

BACKGROUND: Our study aimed to identify a strategy that maximizes survival upon hospital discharge or 30-days post out-of-hospital cardiac arrest (OHCA) in Singapore for fixed investments of S$1, S$5, or S$10 million. Four strategies were compared: (1) no additional investment; (2) reducing response time via leasing of more ambulances; (3) increasing number of people trained in cardiopulmonary resuscitation (CPR); and (4) automated external defibrillators (AED). METHODS: We estimated the effect of ambulance response time, bystander CPR and AED on survival based on Singapore's 2010-2015 OHCA registry data. We simulated the changes in ambulance response times and likelihood of (1) CPR and (2) AED usage as a function of their increased availability, which was then combined with the effect of each factor to determine the increase in survival for each strategy. RESULTS: Survival given no additional investment was 4.03% (95% CI: 3.96%, 4.10%). The investments in ambulances, CPR training and AEDs for a given budget of S$1M changed survival to 4.03% (95% CI: 3.96%, 4.10%), 4.04% (95% CI: 3.98%, 4.11%), and 4.44% (95% CI: 4.35%, 4.54%), respectively. This generated 0, 2 and 102 additional life years saved respectively. Given a budget of S$5M or S$10M, 509 or 886 additional life years could be saved, by investing in an additional 10,000 or 20,000 AEDs respectively. The strategies reached a saturation effect whereby improvement in survival was marginal when the budget was increased to ≥S$5M for investment in ambulances and CPR training. CONCLUSIONS: Investing in AEDs had the most gain in survival.

Effect of long-term fertilization on soil nitrate distribution.

A thirteen years long-term field fertilizer experiment was conducted to monitor the effect of different fertilization on soil nitrate distribution. The results showed: (1) Applying relative excessive N fertilizer could result large quantities of NO3- residue and NO3- movement downward in soil profiles; amending phosphate fertilizer or organic manure with nitrogen fertilizer together could significantly improve the status of NO3- leaching downward due to the balanced uptake of nutrients by crops. (2) Appropriate amounts of nitrogen fertilizer which was equal or smaller than the optimal fertilization rate could not result in more NO3- leaching in Northern China. (3) Precipitation influenced the amounts and depth of soil NO3- leaching: NO3- could move to 80 cm depth or below at autumn or at the next spring when rainfall was higher during the rainy season through July to September in North China.