instruction: when was patient 23475's arterial bp [diastolic] measured for the first time on the first icu visit?
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 = 23475) AND NOT icustays.outtime IS NULL ORDER BY icustays.intime LIMIT 1) AND chartevents.itemid IN (SELECT d_items.itemid FROM d_items WHERE d_items.label = 'arterial bp [diastolic]' AND d_items.linksto = 'chartevents') ORDER BY chartevents.charttime LIMIT 1