tell me the amount of total drain out #2 jackson pratt that patient 6440 had since 03/10/2100.
select sum(outputevents.value) from outputevents where outputevents.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 6440 ) ) and outputevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'drain out #2 jackson pratt' and d_items.linksto = 'outputevents' ) and strftime('%y-%m-%d',outputevents.charttime) >= '2100-03-10'