方山 真朱

OBJECTIVE: The aim of this study was to identify factors that predict admission to the intensive care unit (ICU) after activation of a rapid response system (RRS). METHODS: We conducted a retrospective observational study using data from 12,306 RRS activations recorded in the In-Hospital Emergency Registry in Japan database between November 2017 and September 2023. Patients aged under 18 years, noninpatients, and those who died or were transferred immediately after RRS activation were excluded. The primary outcome was ICU admission after RRS activation. Predictive factors were identified using multivariable logistic regression models: Model 1 included all available data, while model 2 was restricted to data available at the time of RRS activation. RESULTS: We analysed data from 8532 patients; 2298 (26.9%) were admitted to the ICU following RRS activation. Significant factors of ICU admission in model 1 included weekend activation (odds ratio [OR] = 1.17; 95% confidence interval [CI] = 1.02, 1.34), oxygen administration prior to activation (OR = 1.23; 95% CI = 1.08, 1.4), ICU discharge within 72 h before the index event (OR = 1.65; 95% CI = 1.28, 2.11), physician-initiated activation (OR = 2.16; 95% CI = 1.87, 2.50), and multiple abnormal vital signs. Model 2, which was limited to information available at the time of RRS activation, identified a similar pattern of associations. CONCLUSION: This study identified several important factors associated with ICU admission following RRS activation. These findings may support improved clinical decision-making regarding ICU transfers and provide a foundation for future work to develop and validate prediction models tailored to this setting.

RATIONALE: Positive end-expiratory pressure (PEEP) balances recruitment against over-inflation in ARDS. The early response to a PEEP step-down remains under-characterized. Four-dimensional computed tomography (4D-CT) can quantify within-breath mechanics with anatomy-specific resolution. OBJECTIVES: Using 4D-CT to characterize the early (3-5 min) effects of PEEP step-down (15 to 5 cmH2O) on tidal recruitment and over-inflation in ARDS patients. METHODS: In a prospective, single-center, physiological study, 40 patients with stabilized ARDS (77.5% with PaO2/FIO2 ≥ 150, median normalized respiratory system compliance 0.78 mL/cmH2O/kg) received lung-protective volume-controlled ventilation with median PEEP of 8 cmH2O. 4D-CT was obtained at PEEP 15 cmH2O and 3-5 min after a PEEP step-down to 5 cmH2O. We quantified tidal recruitment (-200 to + 100 HU) and over-inflation (-1000 to - 901 HU). MEASUREMENTS AND MAIN RESULTS: Tidal recruitment was low at high PEEP and minimally increased at low PEEP, from 1.15% to 1.84% of expiratory tissue weight (P < .001). End-inspiratory over-inflation decreased from 11.9% to 5.2% of end-inspiratory lung volume (P < .001), and tidal over-inflation decreased from 42.5% to 18.3% of tidal volume (P < .001). End-expiratory lung volume (EELV) substantially decreased (median -787 mL, 95% CI -952 mL to - 743 mL, P < .001) and the volume loss exceeded the passive elastic prediction, indicating substantial alveolar derecruitment. In exploratory analyses, the recruitment-to-inflation ratio did not modify the tidal recruitment response. CONCLUSIONS: At 3-5 minutes after a PEEP step-down from 15 to 5 cmH2O, 4D-CT showed large EELV loss, substantial alveolar derecruitment and reduced over-inflation, while tidal recruitment slightly increased and remained low. These results are compatible with a condition in which alveolar units prone to closure respond by closing and remaining closed.