Case Description After completing a course in database management, you have been hired as...

Case Description

After completing a course in database management, you have been hired as a summer intern by Mountain View Community Hospital. Your first assignment is to work as part of a team of three people to develop a high-level E-R diagram for the hospital. You conduct interviews with a number of hospital administrators and staff to identify the key entity types for the hospital. You have also seen the preliminary enterprise-level diagram shown in MVCH Figure 1-3 and subsequent revisions. As a result, your team has identified the following entity types:

• Care Center—a treatment center within the hospital. Examples of care centers are maternity, emergency care, or multiple sclerosis center. Each care center has a care center ID (identifier) and a care center name.

• Patient—a person who is either admitted to the hospital or is registered as an outpatient. Each patient has an identifier, the medical record number (MRN), and a name.

• Physician—a member of the hospital medical staff who may admit patients to the hospital and who may administer medical treatments. Each physician has a physician ID (identifier) and name.

• Bed—a hospital bed that may be assigned to a patient who is admitted to the hospital. Each bed has a bed number (identifier), a room number, and a care center ID.

• Item—any medical or surgical item that may be used in treating a patient. Each item has an item number (identifier), description, and unit cost.

• Employee—any person employed as part of the hospital staff. Each employee has an employee number (identifier) and name.

• Diagnosis—a patient’s medical condition diagnosed by a physician. Each diagnosis has a diagnosis ID/code and diagnosis name. Mountain View Community Hospital is using the HIPAA-mandated ICD-9-CM Volume 1 diagnosis codes1 for patient conditions (e.g., 00.50, STAPH FOOD POISONING, 173.3, BASAL CELL CARCINOMA, 200.2, MALIGNANT MELANOMA, BURKITT’S TYPE, or 776.5. CONGENITAL ANEMIA).

• Treatment—any test or procedure ordered by and/or performed by a physician for a patient. Each treatment has a treatment ID/treatment code and treatment name using standard codes. HIPAA-mandated ICD-9-CM Volume 3 Procedure Codes are used for diagnostic and therapeutic procedures (e.g., 03.31, SPINAL TAP, 14.3, REPAIR OF RETINAL TEAR, 87.44, ROUTINE CHEST X-RAY, or 90.5, MICROSCOPIC EXAMINATION OF BLOOD).

• Order—any order issued by a physician for treatment and/or services such as diagnostic tests (radiology, laboratory) and therapeutic procedures (physical therapy, diet orders), or drugs and devices (prescriptions). Each order has an order ID, order date, and order time. The team next recorded the following information concerning relationships:

• Each hospital employee is assigned to work in one or more care centers. Each care center has at least one employee and may have any number of employees. The hospital records the number of hours per week that a given employee works in a particular care center.

• Each care center has exactly one employee who is designated nurse-in-charge for that care center.

• A given patient may or may not be assigned to a bed (since some patients are outpatients). Occupancy rates are seldom at 100 percent, so a bed may or may not be assigned to a patient.

• A patient may be referred to the hospital by exactly one physician. A physician may refer any number of patients or may not refer any patients.

• A patient must be admitted to the hospital by exactly one physician. A physician may admit any number of patients or may not admit any patients.

• Prior to a patient being seen by a physician, a nurse typically obtains and records relevant information about the patient. This includes the patient’s weight, blood pressure, pulse, and temperature. The nurse who assesses the vital signs also records the date and time. Finally, the reasons for the visit and any symptoms the patient describes are recorded.

• Physicians diagnose any number of conditions affecting a patient, and a diagnosis may apply to many patients. The hospital records the following information: date and time of diagnosis, diagnosis code, and description.

• Physicians may order and perform any number of services/ treatments for a patient or may not perform any treatment. A treatment or service may be performed on any number of patients, and a patient may have treatments performed or ordered by any number of physicians. For each treatment or service rendered, the hospital records the following information: physician ordering the treatment, treatment date, treatment time, and results.

• A patient may also consume any number of items. A given item may be consumed by one or more patients or may not be consumed. For each item consumed by a patient, the hospital records the following: date, time, quantity, and total cost (which can be computed by multiplying quantity times unit cost).

Reference figure1-3

When developing an E-R diagram for Mountain View Community Hospital, what is the significance of the business rule that states that some patients are assigned to a bed, but outpatients are not assigned to a bed?