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Impact of Building Height and Volume on Cardiac Arrest Response Time

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journal contribution
posted on 18.09.2015 by Anders B. Conway, Andrew McDavid, Jamie M. Emert, Peter J. Kudenchuk, Benjamin A. Stubbs, Thomas D. Rea, Lihua Yin, Michele Olsufka, Andrew M. McCoy, Michael R. Sayre

Emergency medical services (EMS) care may be delayed when out-of-hospital cardiac arrest (OHCA) occurs in tall or large buildings. We hypothesized that larger building height and volume were related to a longer curb-to-defibrillator activation interval. We retrospectively evaluated 3,065 EMS responses to OHCA in a large city between 2003–13 that occurred indoors, prior to EMS arrival, and without prior deployment of a defibrillator. The two-tiered EMS system uses automated external defibrillator-equipped basic life support firefighters followed by paramedics dispatched from a single call center. We calculated three time intervals obtained from the computerized dispatch report and time-synchronized defibrillators: initial 911 call to address curb arrival by first unit (call-to-curb), curb arrival to defibrillator power on (curb-to-defib on), and the combined call-to-defib on interval. Building height and surface area were measured with a validated program based on aerial photography. Buildings were categorized by height as short (<25 ft), medium (26–64 ft) and tall (>64 ft). Volume was categorized as small (<60,000 ft3), midsize (60,000–1,202,600 ft3) and large (>1,202,600 ft3). Intervals were compared using the two-tailed Mann-Whitney test. EMS responded to 1,673 OHCA events in short, 1,134 in medium, and 258 in tall buildings. There was a 1.14 minute increase in median curb-to-defib on interval from 1.97 in short to 3.11 minutes in tall buildings (p < 0.01). Taller buildings, however, had a shorter call-to-curb interval (4.73 for short vs 3.96 minutes for tall, p < 0.01), such that the difference in call-to-defib on interval was only 0.27 minutes: 6.87 for short and 7.14 for tall buildings. A similar relationship was observed for small-volume compared to large-volume building: longer curb-to-AED (1.90 vs. 3.01 minutes, p < 0.01), but shorter call-to-curb (4.87 vs. 4.05, p < 0.01); the difference in call-to-defib on was 0.18 minutes. Both taller and larger-volume buildings had longer curb-to-AED intervals but shorter 911 call-to-curb arrival intervals. As a consequence, building height and volume had a modest overall relationship with interval from call to defibrillator application. These results do not support the hypothesis that either taller or larger-volume buildings need cause poorer outcomes in urban environments.