CHARACTERIZING THE FLOW OF SHORT-STAY PATIENTS IN THE INTENSIVE CARE UNIT

Purpose: Intensive care unit (ICU) volume continues to grow despite limited bed capacity, increasing the need for optimizing ICU patient flow.� We sought to characterize �short-stay� patients (those booked for transfer within 24 hours) by acuity and throughput out of the ICU.  

Methods: We obtained patient-level emergency department (ED) to Medical-ICU (MICU) admissions data from September 2010 to June 2011 for Yale-New Haven Hospital, which contains 40 MICU beds and 15 step-down unit (SDU) beds.� We also obtained MICU and Medicine Service (floor) census data, at four time points each day.� Patients were designated as �acute� if they met Society for Critical Care Medicine Guidelines for ICU Admission or received a critical care-level intervention, versus �sub-acute� if they met neither criterion.� Throughput data included ICU admission time, ICU service time, and ICU wait-time for transfer to the floor/SDU.� We performed a linear regression on ICU transfer wait-time and census levels, using ordinary least-squares, to investigate the impact of hospital crowding on patient throughput.�  

Results: � 970 patients were admitted from the ED to ICU over nine months, including 434 (37.5%) short-stay patients, of whom approximately 50% were classified as sub-acute.� Short-stay patients had an average ICU service time of 14.1 hours, followed by an average wait time of 10.0 hours for transfer to the floor/SDU (Table 1).� Although average ICU service time for non-short-stay patients exceeded three days, wait time for transfer was similar at 11.6 hours.� Overall wait-time for transfer out of the ICU decreased by 0.72 hours [SE: 0.12, p<0.0001] for each patient in the ICU census, and increased by 0.11 hours [SE: 0.02, p<0.0001] for each patient in the floor census, after controlling for time of day fixed-effects.�  

Conclusions: Empirical results indicate that patient crowding in the ICU and floor significantly impacts transfer wait-times out of the ICU, suggesting that the ICU is currently under strain.� Short-stay ICU patients spend a substantial proportion of their ICU length of stay waiting for transfer out of the ICU, resulting in bottlenecks for other critically-ill patients.� Half of these short-stay patients did not meet published admission guidelines nor receive critical care interventions, suggesting that they may not clinically warrant ICU stays.  Identifying and triaging sub-acute patients to alternate units may improve ICU bed availability and throughput.