how many days has it been since the first time potassium chloride was prescribed on this hospital visit to patient 27146?
select 1 * ( strftime('%j',current_time) - strftime('%j',prescriptions.startdate) ) from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 27146 and admissions.dischtime is null ) and prescriptions.drug = 'potassium chloride' order by prescriptions.startdate asc limit 1