how many days has it been since patient 25733 was last tested for bicarbonate during the current hospital visit?
select 1 * ( strftime('%j',current_time) - strftime('%j',labevents.charttime) ) from labevents where labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'bicarbonate' ) and labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 25733 and admissions.dischtime is null ) order by labevents.charttime desc limit 1