how many times does patient 17667 have a bicarbonate test?
select count(*) 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 = 17667 )