The effect of emergency department crowding on paramedic ambulance availability.

STUDY OBJECTIVE We determine the effect of emergency department (ED) crowding on paramedic ambulance availability. METHODS This was a prospective longitudinal study from April 2001 through March 2002 in Los Angeles, CA. All incidents in which a Los Angeles Fire Department ambulance was out of service for more than 15 minutes while waiting to transfer a patient because of the lack of open ED beds were captured and analyzed. Data included the total time each ambulance was out of service and the hospital where paramedics were waiting for an open gurney. Analysis was performed to determine weekly and seasonal variations and preponderance at various hospitals. RESULTS There were a total of 21,240 incidents in which ambulances were out of service while waiting to transfer their patients to an open ED gurney, which accounted for 1 of every 8 transports. Of these, 8.4% were in excess of 1 hour. The median waiting time per incident was 27 minutes, with an interquartile range of 20 to 40. There was a statistically significant difference in the monthly number of out-of-service incidents during the study (P<.0001), with the highest levels during the winter (January through March). CONCLUSION ED crowding has resulted in delays for paramedics waiting to transfer patients. This decrease in ambulance availability may have a significant effect on emergency medical services systems' abilities to provide timely response.