what was the first time that patient 85010 had the maximum value of base excess in the previous month?
select labevents.charttime from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 85010 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'base excess' ) and datetime(labevents.charttime,'start of month') = datetime(current_time,'start of month','-1 month') order by labevents.valuenum desc, labevents.charttime asc limit 1