Factors related to prolonged on-scene time during ambulance transportation for critical emergency patients in a big city in Japan: a population-based observational study

OBJECTIVES We aimed to investigate the factors related to prolonged on-scene times, which were defined as being over 30 min, during ambulance transportation for critical emergency patients in the context of a large Japanese city. DESIGN A population-based observational study. SETTING Kawasaki City, Japan's eighth largest city. PARTICIPANTS The participants in this study were all critical patients (age ≥ 15 years) who were transported by ambulance between April 2010 and March 2013 (N=11,585). OUTCOME MEASURES On-scene time during ambulance transportation for critical emergency patients. RESULTS The median on-scene time for all patients was 17 min (IQR 13-23). There was a strong correlation between on-scene time and the number of phone calls to hospitals from emergency medical service (EMS) personnel (p<0.001). In multivariable logistic regression, the number of phone calls to hospitals from EMS personnel, intoxication, minor disease and geographical area were associated with on-scene times over 30 min. Age, gender, day of the week and time of the day were not associated with on-scene times over 30 min. CONCLUSIONS To make on-scene time shorter, it is vital to redesign our emergency system and important to develop a system that accommodates critical patients with intoxication and minor disease, and furthermore to reduce the number of phone calls to hospitals from EMS personnel.