###HUMAN: how many hours has it been since the first time patient 19428 stayed in careunit ccu in their current hospital visit., ###ASSISTANT: SELECT 24 * (STRFTIME('%j', CURRENT_TIME()) - STRFTIME('%j', transfers.intime)) FROM transfers WHERE transfers.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 19428 AND admissions.dischtime IS NULL) AND transfers.careunit = 'ccu' ORDER BY transfers.intime LIMIT 1