instruction: give the number of patients whose diagnosis short title is status-post ptca and drug route is neb.
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN prescriptions ON demographic.hadm_id = prescriptions.hadm_id WHERE diagnoses.short_title = "Status-post ptca" AND prescriptions.route = "NEB"