instruction: on the last hospital visit, how many times did patient 22973 visit the icu?
response: SELECT COUNT(DISTINCT icustays.icustay_id) FROM icustays WHERE icustays.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 22973 AND NOT admissions.dischtime IS NULL ORDER BY admissions.admittime DESC LIMIT 1)