Outpatient Practice Procedure Areas

Designing A Pulmonary Function Laboratory

Clinical laboratories are certified by CMS using the Clinical Laboratory Improvement Amendments (CLIA). Radiology departments are accredited by certification by the American College of Radiology. There are no certification or accreditation standards for pulmonary function laboratories currently so it falls to each hospital to design its own PFT lab. After being involved in the design of 4 PFT labs over the years, these are a few of the things about lab design that I have learned.

First decide what tests will be performed

The tests that the laboratory will perform will dictate the number of rooms and space required for the lab. The initial design of a pulmonary function lab should specify which types of tests will be performed in each room in order to ensure that each room is large enough for all of the equipment and supplies required for those tests.


The most common tests performed in a pulmonary function laboratory are spirometry, lung volumes, and diffusing capacity. These can all be done using an enclosed plethysmograph device that the patient sits inside of, sometimes called a “body box”. Each plethysmograph should be in a separate room. A small hospital or an outpatient physician group practice may only need 1 plethysmograph but most pulmonary function labs will need 2 to 4 plethysmographs, requiring 2 to 4 separate rooms. Spirometry can also be ordered as spirometry pre- and post-bronchodilator. The bronchodilator study does not require special space but usually does require a “Terminal Distributor of Dangerous Drugs License” from the state pharmacy board.

The next most common test is the 6-minute walk test. This is generally performed in a long, straight hallway with distances marked on the floor. The patient walks as fast as comfortable and the number of laps walked in 6 minutes are calculated along with the oxygen saturation during the test. The hallway should be wide enough to accommodate an oxygen tank on wheels and should should be lightly trafficked so that it can be blocked off during the duration the test. A related test is the oxygen titration study. In this test, a patient walks until their oxygen saturation drops below 89% and then supplemental oxygen is applied in increasing flow rates to determine the proper flow rate for that patient’s oxygen prescription. The oxygen titration study can be performed in the same hallway as the 6-minute walk test or can be performed on a treadmill.

The methacholine challenge test is a broncho-provocation test done by having the patient inhale increasing concentrations of methacholine, with spirometry performed after each concentration. In the past, an on-site pharmacy was generally required to perform dilutions of methacholine; however, pre-filled, pre-diluted testing kits are now commercially available, thus obviating the need for an on-site pharmacy. This test can be done in the same room used for one of the plethysmograph boxes. A related test is the eucapnic voluntary hyperventilation test that is used to diagnose exercise-induced bronchospasm.

The cardio-pulmonary exercise test is performed by having a patient ride a stationary bicycle (or sometimes by using a treadmill) while breathing into a metatabolic cart in order to measure values such as minute ventilation and oxygen uptake. This test is generally performed in separate room dedicated to exercise testing but can be performed in a room normally used for plethysmograph testing if the room is large enough to accommodate both the plethysmograph box and the exercise test equipment.

The high-altitude hypoxia simulation test is performed by measuring the patient’s oxygen saturation while breathing a 15% oxygen/85% nitrogen gas mixture from a large medical gas cylinder via a face mask. This test is used to determine if a patient requires supplemental oxygen when flying in a commercial aircraft. Because the only equipment required is the medical gas cylinder, this test can be performed in a room used for plethysmographic testing. However, it is preferable to perform this test in a room with a treadmill (or a stationary bicycle) so that the high-altitude hypoxia simulation test can be combined with an oxygen-titration test as a high altitude hypoxia exercise test in order to determine the oxygen flow rate required when a patient is walking at a high-altitude travel destination (such as Denver).

Arterial blood gases are performed by inserting a needle into the radial artery to withdraw arterial blood. This test is most commonly performed to get direct measurement of the amount of oxygen and carbon dioxide in the blood. Arterial blood gases can also be performed while the patient breaths 100% oxygen in the physiologic shunt study.

Get infection control involved early

Patients who get pulmonary function tests are vulnerable to contagious diseases due to their underlying respiratory compromise as well as due to frequenting taking immunosuppressive medications. In addition, these patients often have respiratory infections that can be transmitted to others. Your infection control department input is crucial to ensure that patients and staff are not at risk of acquiring infections from exposures in the lab.

One of the most important aspects of infection control of respiratory pathogens is the number of air changes in each room per hour. The more air changes per hour (ACH), the faster respiratory pathogens such as tuberculosis or the coronavirus causing COVID-19 are cleared from the breathable air.

The Centers for Disease Control has recommendations for the minimum ACH for each type of hospital room. This can range from a high of 15 ACH for an operating room to 2 ACH for certain storage rooms. An exam room or a hospital inpatient room is recommended to have 6 ACH and a bronchoscopy room is recommended to have 12 ACH. The CDC does not specify the ACH for a pulmonary function laboratory. However, the Veteran’s Administration recommends at least 8 ACH for a room used for plethysmographic testing and at least 10 ACH for a room used for cardiopulmonary exercise testing. In the era of COVID-19, the higher the ACH, the better. If the pulmonary function lab will also do sputum induction for suspected tuberculosis, then a negative airflow room is necessary.

In the past, pulmonary function testing utilized non-disposable mouthpieces, nose clips, and other equipment that required cleaning. This resulted in the requirement to have both a clean and a dirty utility room in the pulmonary function lab. Now, most labs use disposable mouthpieces, nose clips, and supplies so that there is no longer a need for a dirty utility room to avoid clean/dirty equipment conflicts.

The infection control department can also be helpful in room design. For example, selecting anti-microbial materials (such as copper) for door handles and other fixtures. Flooring should be made out of resilient tile with minimal seams. There should be hand washing sinks and wall-mounted hand sanitizer in each room used for diagnostic testing.

Efficiency and flexibility

Patients coming in for pulmonary function testing are often in wheelchairs and are often using supplemental oxygen. Doors to testing rooms need to be wide enough to accommodate the width of a bariatric wheelchair (48 inches). Similarly, diagnostic rooms need to contain bariatric-sized chairs. Because of the impaired mobility of many pulmonary patients, the lab should be located as close to building entrances and elevators as possible.

To optimize staff efficiency, a shared patient registration area that can serve multiple outpatient services is preferred for all but the largest pulmonary function labs. Shared waiting areas can optimize efficient use of building space; however, waiting areas should be designed so that staff can maintain line of sight observation of patients. Similarly, when possible, share resources for linen storage, housekeeping, general storage, waste storage, and staff support areas.

Most pulmonary function labs will require hemoglobin testing as part of the diffusing capacity test. Also, most pulmonary function labs will perform arterial blood gas testing. If these specimens must go to a central clinical chemistry lab, then the PFT lab should be close to that lab (at least within the same building). Most PFTs labs find it easier to perform point-of-care testing for arterial blood gases and finger-stick hemoglobin, however. Regardless of where these tests are run, sharps containers are needed in all diagnostic rooms.

Human needs

In addition to a close-by, adequately-sized waiting area, there needs to be restrooms and a staff break room near the lab (you don’t want your staff eating in the diagnostic area). The interior design should convey the appearance of a healthcare setting. There must be adequate lighting in all rooms and hallways. Be sure to have televisions in waiting areas and wifi access in all public areas. Artwork should be chosen carefully – for example, if there is a sizable Afghanistan war veteran patient population, avoid pictures of desert mountains. Similarly, pictures of happy people doing recreational activities can be depressing to patients confined to wheelchairs or oxygen tanks. Attention to privacy in door and window location can ensure that patients undergoing diagnostic testing cannot be easily seen from the hallway.

If there are exterior windows in the area of the building, it is preferable to locate rooms used for diagnostic testing where there are windows and then use windowless interior rooms for support purposes, break rooms, restrooms, staff offices, etc. Some patients get claustrophobic when enclosed in a plethysmographic box and having an exterior window in the room can lessen that claustrophobia. The plethysmograph box should be positioned so that the patient can see out the window when sitting in the box.

Room acoustics are frequently overlooked when designing the PFT lab. If you have ever stood outside of a room where spirometry is being performed, then you have inevitably heard a PFT technician shouting “Blow, blow, blow, as hard as you can…“. Performing PFTs is a loud process. Include acoustic ceiling tiles and adequately insulated walls in the initial design.

Physical layout

Rooms used for plethysmographic testing should ideally be at least 12 ft x 10 ft in size in order to accommodate the plethysmograph box, a workstation for the PFT technician, a chair, sink, equipment storage, trash can, sharps container, etc. Most plethysmographic boxes are about 7 feet tall so the ceiling height also needs to be considered. For hallway throughput safety, doors should open into the room rather than into the hallway. Data entry keyboards used by the staff should either be on mobile workstations-on-wheels or should be on swing-mounts on a wall but positioned so that the technician is facing the plethysmograph box and so that an opened door does not block the ability of the staff to see the patient in the plethysmograph box. Most plethysmograph boxes are 36 to 42 inches in diameter so having a 48 inch doorway is preferred to be sure you can get the box into the room.

Rooms used for exercise testing generally should be to be at least 12 ft x 20 ft in order to accommodate a treadmill and metabolic cart.

The hallway used for 6-minute walk testing should be adjacent to the diagnostic area. Wall-mounted medical gas outlets in the diagnostic rooms are convenient to support the needs of patients requiring supplemental oxygen but most labs can get by with re-fillable oxygen cylinders. Even if medical gas outlets are available in the diagnostic rooms, portable oxygen cylinders will still be required for tests such as oxygen titration studies; therefore a room dedicated to oxygen cylinder storage is required. Staff charting areas should ideally be in a location where staff can maintain visual observation of patients.

One of the most common mistakes in lab design is failing to plan for future growth. Most PFT labs have seen a steady increase in testing volume over the past 20 years. It is far easier (and less expensive) to expand an existing lab than to either build an entirely new larger lab or build a second satellite lab when the demand for services increases. Having adjacent space that can be readily re-purposed is wise. For example, staff offices adjacent to the lab can be relatively easily moved to a different location in the hospital or clinic building so that those offices can be converted into PFT lab expansion space in the future.

Patients who come in for pulmonary function testing are also frequently coming in to see their pulmonologist or coming in to do pulmonary rehabilitation. The best PFT labs are co-located with pulmonary physician offices and pulmonary rehab areas. Having a “one-stop-shop” for pulmonary patients can improve patient satisfaction and can give the clinic or hospital a competitive edge. Having close proximity to a physician or advance practice provider is also useful in the inevitable situations when patients develop medical conditions during pulmonary function testing or exercise testing.

Planning is key

Most people have a hard time conceptualizing what an architectural plan will look like in real-life. It is a good idea to find a large, open area and tape out the dimensions of the planned rooms on the floor. Then add taped out placements for all of the equipment and furniture as well as the door swing area. Then get input from the PFT technicians, an interior designer, the pulmonologist, and the infection control staff. It is far less expensive to get everything right the first time.

August 15, 2021

By James Allen, MD

I am a Professor Emeritus of Internal Medicine at the Ohio State University and former Medical Director of Ohio State University East Hospital