instruction: is the sao2 in patient 739 last measured on the current intensive care unit visit less than second to last measured on the current intensive care unit visit?
response: SELECT (SELECT chartevents.valuenum 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 = 739) AND icustays.outtime IS NULL) AND chartevents.itemid IN (SELECT d_items.itemid FROM d_items WHERE d_items.label = 'sao2' AND d_items.linksto = 'chartevents') ORDER BY chartevents.charttime DESC LIMIT 1) < (SELECT chartevents.valuenum 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 = 739) AND icustays.outtime IS NULL) AND chartevents.itemid IN (SELECT d_items.itemid FROM d_items WHERE d_items.label = 'sao2' AND d_items.linksto = 'chartevents') ORDER BY chartevents.charttime DESC LIMIT 1 OFFSET 1)