when was patient 67468 first diagnosed in 2105 with pressure ulcer, stage iv?
select diagnoses_icd.charttime from diagnoses_icd where diagnoses_icd.icd9_code = ( select d_icd_diagnoses.icd9_code from d_icd_diagnoses where d_icd_diagnoses.short_title = 'pressure ulcer, stage iv' ) and diagnoses_icd.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 67468 ) and strftime('%y',diagnoses_icd.charttime) = '2105' order by diagnoses_icd.charttime asc limit 1