instruction: when did patient 1561 first receive a arterial bp [systolic] measurement a day before?
response: SELECT chartevents.charttime FROM chartevents WHERE chartevents.icustay_id IN (SELECT icustays.icustay_id FROM icustays WHERE icustays.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 1561)) AND chartevents.itemid IN (SELECT d_items.itemid FROM d_items WHERE d_items.label = 'arterial bp [systolic]' AND d_items.linksto = 'chartevents') AND DATETIME(chartevents.charttime, 'start of day') = DATETIME(CURRENT_TIME(), 'start of day', '-1 day') ORDER BY chartevents.charttime LIMIT 1