when was the last time the respiratory rate of patient 27409 was less than 19.0, on the first intensive care unit visit?
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 = 27409 ) and icustays.outtime is not null order by icustays.intime asc limit 1 ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'respiratory rate' and d_items.linksto = 'chartevents' ) and chartevents.valuenum < 19.0 order by chartevents.charttime desc limit 1