what time was the last time the arterial bp [diastolic] of patient 30671 was less than 38.0 since 1915 days ago?
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 = 30671 ) ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'arterial bp [diastolic]' and d_items.linksto = 'chartevents' ) and chartevents.valuenum < 38.0 and datetime(chartevents.charttime) >= datetime(current_time,'-1915 day') order by chartevents.charttime desc limit 1