indicate the monthly maximum amount of .45ns + .5:1 heparin patient 3369 has received until 02/20/2103.
select max(inputevents_cv.amount) from inputevents_cv where inputevents_cv.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 3369 ) ) and inputevents_cv.itemid in ( select d_items.itemid from d_items where d_items.label = '.45ns + .5:1 heparin' and d_items.linksto = 'inputevents_cv' ) and strftime('%y-%m-%d',inputevents_cv.charttime) <= '2103-02-20' group by strftime('%y-%m',inputevents_cv.charttime)