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Infection Prevention
The Hidden Pitfalls of HVAC Systems
Alex Stockdale
Publish Date: October 10, 2007   |  Tags:   Infection Prevention

During construction of two surgery centers in Tennessee, I endured the installation of an inadequate HVAC system not once, but twice. On both occasions, we spent more than $100,000 to retrofit the facilities with HVAC systems that would let my surgeons work in comfort during the dog days of summer or winter's deep freezes. I paid overtime rates for crews to make the changes on weekends so the ORs could remain open during the week. The thing is, I approved systems that matched the specs suggested by mechanical engineers. And yet neither turned out well. And therein lies the paradox: The problem with designing HVAC systems is that inadequacies arise only after the facility opens. Hopefully, you can learn from my mistakes.

HVAC is the place to splurge, not scrimp. Despite pressures to contain costs during new construction, don't try to shave money off the final bill at the expense of the HVAC system. Mechanical contractors will build to meet specs, but specs often don't correspond with reality. I recommend that you over-design the heating and cooling of your ORs by going way beyond the suggested numbers. If you want your rooms to be 60 degrees with 40 percent humidity, tell the mechanical engineers you want the system outfitted for 50 degrees at 30 percent humidity.

Call in the mechanical control company. Involve the mechanical control company that installs your HVAC system with the mechanical engineers and architects during the project's design. It's the mechanical engineer who designs your system's specs, but it's up to the mechanical control company to make the design work, and problems arise when the two parties don't communicate before installation begins.

One administrator who spoke up during the Q&A at a talk I gave on this very topic said that, during construction of his surgery center in Grand Rapids, Minn., mechanical engineers told him that the installation of humidifiers would be enough to combat the dry northern-Midwest winters. The design, therefore, did not include dehumidifiers. But when the summer climate added 80 percent humidity to warm outdoor temperatures, the environment in the Lakewood Surgery Center's ORs was nearly impossible to regulate.

"Our energy costs skyrocketed," he said. "Designers tell you that the specs will get your rooms to where they need to be, no matter the conditions outside, but the specs will get you to an un-ideal point. The mechanical control company may know the specs won't work, but they're hired to install the system a certain way and do only what the mechanical engineer designs," the administrator said. He knew his HVAC system was lacking but had to wait until the system's warranty expired before the mechanical control company would come back to make improvements.

Question everything. Even if specs are over-designed and mechanical control companies communicate with mechanical engineers, problems can still arise. As with the rounds you'll make when the center opens, don't hesitate to don a hard hat for a first-hand inspection of the construction site.

If something seems off to you - say, you notice the ductwork doesn't look right during a routine hard-hat tour of your facility - speak up. Another administrator's nightmare involved an HVAC contractor who was using the wrong materials. Luckily, she said something about it, found out the root of the problem and was able to bring in another firm to fix the mess, albeit at additional costs. The lesson: Make sure the installer is certified to do the work you hire him for and insist he show you documentation.

I can't stress enough the importance of staying on top of the project - and even then, unfortunately, you probably won't catch everything. It's small consolation, but you'll still likely avert at least some of the problems that would otherwise lie in wait for the future.

Why Is HVAC So Important?

We all know that effective heating, ventilating and air-conditioning units are essential to maintaining air quality and a sterile environment in your ORs. Here are six good reasons to ensure your HVAC system is up to speed and maintaining OR humidity in the 50 to 60 percent range:

  • In terms of simple human comfort, low humidity causes dehydration and high humidity causes bronchial and respiratory problems.
  • Low humidity can create an environment ripe for potential errant electrosurgical sparks and static discharges.
  • Low humidity makes fabrics dehydrate, joining surfaces shrink and liquids evaporate.
  • Excess dryness can be a serious problem in anesthesia administration. Patients benefit from breathing warm and humid gases during anesthesia because warm gases typically help maintain body temperature and help prevent airway and bronchial drying during intubation.
  • Humidity must be controlled for all forms of sterilization. Fabrics and devices need to be stabilized and pre-conditioned to a relative humidity of 50 percent for effective normal sterilization cycles.
  • High humidity doesn't cause problems unless it condenses into moisture, which then will carry any "bugs" it runs into. Condensation can form in high humidity for several reasons. For example, introducing something cold will cause condensation to form, and stagnant air (such as you might find in the corners of the room) can accumulate enough moisture that it eventually condenses. High humidity also causes doctors and nurses to sweat, which produces moisture. - Dan Mayworm

Mr. Mayworm ("[email protected]")) is the former publisher of The Journal of Healthcare Resource Management and Infection Control & Sterilization Technology.