Surgical suite design has changed significantly over the past ten years and will continue to evolve over the next decade. Some of the key changes that have already had an impact include:

  • The shift from separate suites for Pre-op, PACU, and Stage 2 Recovery to more unified suites that can better accommodate shifts in population during the day, share staff, and most efficiently utilize space (see sidebar).

  • The increase in size of the Operating Room (OR) to the point that most surgical suites built now in hospitals have an average OR size of at least 600 square feet versus the former standard of 400 square feet.

  • Development of suites using smaller clusters of ORs versus larger groups of ORs organized around a sterile core. The cluster concept has often been developed to allow a more focused environment around surgical subspecialties.

Trends in the design of surgical suites that will continue to result in an evolution of these environments include:

  • The increased utilization of minimally invasive surgical (MIS) techniques, including robotics. This increase has helped to spur the need for larger ORs. As MIS technology evolves, especially toward smaller and more remote equipment, the OR environment will continue to evolve, potentially feeding a reduction in the size of the OR.

  • The development of special high-technology ORs, including intra-operative MRI rooms.

  • The integration of interventional and surgical environments is in its infancy, but will continue to feed the development of suites that are side-by-side departments sharing certain support spaces, including prep and recovery, and suites that are truly merged with side-by-side surgical and interventional rooms, as well as blended or hybrid rooms.

There are other developments that are affecting surgical techniques and procedures, including cryogenics and ultrasound, but these developments are not anticipated to have a direct impact on the design of the surgical suite or the operating room.

Operating room size

It is now uncommon for a surgical suite to be programmed with operating rooms of less than 600 square feet, unless the focus of the unit is purely outpatient procedures. Even in outpatient centers with increased use of MIS techniques, the need for larger ORs approaching 600 square feet is still present. Certainly the equipment is the same, but in an outpatient setting, the cases are typically less complicated and are more predictable and require smaller surgical teams. This often feeds into decisions to allow for slightly smaller ORs. In addition to the perception that outpatient facilities can be designed with smaller ORs, budget constraints are often involved in the decision to limit the size of outpatient ORs. Nonetheless, most outpatient suites are still being designed with ORs of over 500 square feet.

As the room becomes larger, the distance between the support and supply areas and the surgical field can become inefficient. Courtesy of KMD Architects

The major debate now in the design community is how large does an OR really need to be. At Memorial Sloan-Kettering Cancer Center (MSKCC) in New York City, the average OR was designed to be 600 square feet. This size has been working very well based on the first six months of operation.

Of particular interest, however, are six of the ORs at MSKCC, because they are not 600 square feet, but roughly 560 square feet. This was the result of these ORs being within an existing building; the existing columns would not accommodate a 600-square-foot OR. These six ORs are reported to be working as well as any of the other ORs.

The reason may be the shape of these six ORs; they are more rectangular than the typical OR at MSKCC. All of the ORs at MSKCC are designed to have the OR table oriented parallel to the corridor. These six ORs are roughly 27 feet long in the head-to-foot dimension, the dimension parallel to the corridor, but are only about 22 feet wide, perpendicular to the corridor. While there has not been any documented analysis for why these rooms are working effectively, the theory from the OR nurses is that the added length provides necessary clear floor area for the circulating staff to reach either side of the OR table and not disturb the staff in the surgical field. Also, there is adequate space for the anesthesia set-up, which is at the head end of the table and the room.

This theory has been reinforced at MSKCC by the shape of two other ORs, which were forced to be shorter in the head-to-foot direction because of special equipment and shielding. These two rooms are also 560 square feet, but are roughly two feet shorter than they are wide. As the staff has noted, the additional width has not helped, as the circulator still has to clear the surgical team and carts that are at the foot of the table, and the anesthesia set-up is squeezed at the head of the table. Clearly a square room may function well, but it appears that a more rectangular room may be best, especially if there is limited space and one dimension will be constrained.

Many in-hospital surgical suites designed recently have provided ORs that are larger than 600 square feet. In some cases, especially projects in California where heart ORs must have a minimum clear floor area of 650 square feet, the goal has been to provide a universal room size that can accommodate all procedures. This has led to a standard OR size in some facilities of 650 square feet. In addition, there has been a trend to design even larger ORs. At MSKCC four ORs were designed to be 750 square feet and were intended to accommodate special technologies, including intra-operative MRIs (IOMRI). At MSKCC, three of the four ORs were designed for IOMRIs, and one of these three rooms was fitted out with an MRI in the initial construction. In addition to the larger OR, adjacent spaces are provided for control rooms and dedicated electronics rooms. Designs accommodating these special ORs are becoming more common at larger specialty and tertiary hospitals.

Larger ORs are being designed not just for special technology such as MRIs or fixed X-ray equipment—which will be discussed in the second part of this article—but also to accommodate larger teams and more equipment. There is no clear evidence that indicates whether there is a minimum or a maximum functioning size for an OR. Theories exist that as the clear floor area greatly exceeds 800 square feet—up to 900 to 1000 square feet—that there are inefficiencies and a lack of return on the investment in the additional area. The success of the six 560-square-foot ORs at MSKCC indicates that building bigger is not necessarily the only answer.

The answer lies within the internal layout of the room. As the room becomes larger, the distance between the support and supply areas and the surgical field—which rarely changes significantly in size or shape—can become inefficient and require many more steps by the circulator or others to keep the surgery flowing smoothly (figure).

Also, these larger ORs potentially require additional staff to keep them operational, which carries a large added cost per case. There has also been some preliminary feedback from institutions with these larger ORs that extra equipment and supplies are accumulating in the open areas of the rooms, simply because the area is there. It has been shown that overstocking a procedure room or operating room is less efficient for the overall materials management supply of the department and results in waste.

Nevertheless, ORs in the 750- to 800-square-foot range meet a real need and can be justified, if for no other reason, because they can better accommodate a larger team and more equipment, such as those associated with procedures employing robotics equipment and mobile or fixed imaging equipment. HD

Part two of this article, to appear in the July 2007 issue of HEALTHCARE DESIGN, will continue the discussion of modern trends in surgery-suite design with a look at suite organization and how surgery suites incorporate IT.

Douglas Gordon, AIA, is director and senior medical planner at Kaplan McLaughlin Diaz (KMD) Architects in Portland, Oregon. He can be reached by e-mail at