今長谷 尚史

IMPORTANCE: The optimal intensity of care for older patients (age ≥80 years) in intensive care units (ICUs) remains uncertain. Although institutional variation in critical care practice has been described, less is known about case-mix-adjusted variation in life-sustaining treatment use among older patients admitted to ICUs and whether greater institutional treatment intensity is associated with improved survival. OBJECTIVE: To quantify institutional variation in the use of life-sustaining treatments for older patients among ICUs and examine the association of treatment intensity with in-hospital mortality. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study used nationwide data from the Japanese Intensive Care Patient Database (JIPAD) for patients aged 80 years or older admitted to 127 ICUs at JIPAD-participating institutions in Japan between April 1, 2015, and March 31, 2023. EXPOSURES: Intensive care unit admission and age 80 years or older. MAIN OUTCOMES AND MEASURES: Institutional treatment intensity was quantified using standardized treatment ratio (STR), defined as the ratio of observed-to-expected life-sustaining treatment use after adjustment for patient-level characteristics. The association between STR category and in-hospital mortality was evaluated using both logistic regression and hierarchical bayesian multilevel logistic regression models. RESULTS: Among 60 713 patients (median age, 84 years [IQR, 82-87 years]; 32 302 male [53.2%]), the crude institutional rate of life-sustaining treatment use ranged from 4.8% (8 of 167 patients) to 38.0% (322 of 847 patients). After adjustment for patient case mix, the STR ranged from 0.24 (95% CI, 0.11-0.48) to 2.34 (95% CI, 1.91-2.85) across participating ICUs. In multilevel analyses adjusted for patient- and institution-level factors, higher institutional treatment intensity was not associated with in-hospital survival compared with intermediate treatment intensity (high STR category: odds ratio, 1.17; 95% credible interval, 0.91-1.39). CONCLUSIONS AND RELEVANCE: In this cohort study of older patients admitted to ICUs, institutional use of life-sustaining treatments varied substantially even after case-mix adjustment and higher institutional treatment intensity was not associated with better in-hospital survival. These findings suggest that increasing treatment intensity alone may not be associated with improved outcomes in this population and support the need for better approaches to identify patients most likely to benefit from intensive treatment.

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.