ABSTRACT
INTRODUCTION: ICU admission occurs for active treatment (ventilation, vasopressors) and to monitor patients at risk. The Acute Physiology and Chronic Health Evaluation (APACHE) IVb defines Low Risk Monitor (LRM) as not actively treated on ICU day 1 and < 10% prospective risk of ever needing active treatment. LRM patients potentially fill ICU beds required by acutely ill patients. We investigated if unprecedented ICU demand during the COVID-19 pandemic decreased LRM admissions during COVID surges. METHOD(S): Retrospective analysis of hospitals tracking COVID-19 status and consistently contributing to the APACHE database March 23, 2020 to December 31, 2021. Baseline pre-pandemic data was also assessed. Patients with primary surgical and trauma diagnoses were removed to eliminate incidental COVID diagnoses. Pearson's correlation coefficient (r) assessed the weekly relationship between %COVID and LRM patients. RESULT(S): 117,004 patients were admitted to ICU at 43 hospitals. Baseline LRM averaged 28.6% pre-COVID. During successive COVID peaks in April, July and December 2020 and April, August and December 2021, there was high inverse correlation (r=-0.90) between COVID census and LRM percentage. For example, in September 2020 COVID% was 7.81 and LRM was 28.2%. In December 2020, COVID surged to 31.1% and LRM dropped to 21.3%. These percentages returned to COVID 9.5% and LRM 28.2% during the March 2021 trough. Hospital mortality was 10.9% pre-pandemic, and 14.69% actual/13.66 predicted (SMR=1.08) from April 2020 through December 2021. Mean ventilator days were 4.08 pre- and 5.58 pandemic. ICU LOS increased from 3.52 to 4.16 days (ratio 1.11). CONCLUSION(S): LRM admissions decreased dramatically during successive COVID-19 surges, demonstrating considerable elasticity in ICU triage decisions. Mortality, ventilator days and ICU LOS all increased during the pandemic compared to baseline. Consistent measurement of % LRM may be helpful in recognizing opportunities to reduce inappropriate ICU bed utilization and as a marker of strained capacity.