instruction: provide the number of patients whose diagnosis icd9 code is v1254 and drug route is iv.
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.icd9_code = "V1254" AND prescriptions.route = "IV"