Directional air flow is used in many different work settings. In production facilities where absolute cleanliness is a must, directional HVAC is important for controlling the amount of contaminants in the air. If the clean room is designed to contain biohazards, a directional air flow system guarantees the safety of the workers in the room as well as the general public.
There’s one place where a high velocity directional air flow system is absolutely necessary. In the operating theater, the highest levels of air filtration are necessary to ensure that the patient on the operating table is protected from contamination by germs. Surgical success rates have never been higher, but the number one reason for complications remains infection of the wound. That has led to a concerted effort by hospitals to ensure that their operating theaters are served by the best directional air flow equipment.
Not all operations are the same. If you’re admitted to a hospital to have a minor surgical procedure, the amount of time you’re under the knife will be short, and the size and depth of your incision will probably be fairly small. In today’s healthcare climate, more and more procedures end with the patient being sent home the same day. That’s because the risk of wound infection is very low.
There are many surgical procedures that are much more invasive, and if they result in an infection, the ramifications can be quite serious. One good example is a hip replacement. During a hip replacement, the patient is subject to a very large, deep surgical incision, with a great deal of activity by a handful of doctors and assistants. Because of the nature of the work that must be done while the patient is in the operating theater, the chance of infection grows. The likelihood of infection isn’t the only consideration. The severity of the infection is likely to be much greater because it is so deep in the patient’s tissue. It’s common for an infection caused by a hip replacement to require the removal of the artificial hip.
General contamination of the wound by non-infectious agents is a real concern, but the heavy filtration of a typical directional air flow system is usually up to the task of supplying the operating theater with very clean air. Airborne bacteria are a much more serious problem, and hospitals are increasingly relying on a high velocity directional air flow system to protect patients during invasive surgery.
Benefits and Drawbacks
A high velocity directional air flow system is often referred to as a laminar system. It has been shown to reduce the number of microorganisms found in operating rooms. The efficiencies of the system come with some drawbacks, however. Air moves more rapidly through the operating theater, which can cause problems with ambient noise. These systems also cost more than conventional systems, and require more maintenance.
Horizontal or Vertical
A high velocity directional air flow system can work horizontally or vertically. A horizontal system costs less, and is less costly to operate as well. Horizontal systems have other benefits. Because the air is passing through the operating theater from side to side, it will draw contamination away from the surgical area naturally. Many surgeons favor horizontal systems because they allow them to position the overhead lights anywhere they choose without interfering with the laminar flow of air.
Vertical directional air flow system design is more complicated. It outperforms horizontal systems in some metrics, but it also has some notable drawbacks. In many very invasive surgeries like joint replacements, the surgeon and support team must work directly over the deep incision for long periods of time. This increases the chances of contamination from the face of the surgeon. With many bodies crowded around the patient, they can present the equivalent of a wall blocking out horizontal air flow, so a vertical directional air flow system is preferred for some procedures where a lot of activity is required by many people, like open heart surgery.
No matter which type of directional air flow system is used, hospitals must take as many precautions as possible to keep infection rates low. To reduce airborne bacteria in the operating theater, very thorough cleaning standards must be maintained. Another often-overlooked detail is the limiting of movement by personnel in the operating theater. No matter how clean an operating theater is, it’s better not to stir up the air in the room any more than is necessary. This is especially true of any movement that will draw contamination up from the floor and into the laminar air flow that passes by the patient at operating table height.
More Than Just an HVAC Problem
Hospitals have had good luck with limiting the number of people allowed in the operating theater, and also with training personnel to avoid moving quickly unless there’s an emergency. Hospitals have also instituted more stringent barrier rules, requiring 100 percent coverage of all hair and skin for any surgical procedure that lasts a long time or has a very deep incision. Double gloving and the use of absolutely impermeable gowns have also led to improvements in surgical infection rates.
More Information Is Needed
While the use of a high velocity directional air flow system in the operating theater has had a measurable effect on infection rates, more research is needed to determine whether vertical or horizontal flows are best. Hospitals are also increasing the use of antibiotics administered before any signs of infection are exhibited. This has also shown promise in the quest to bring post-surgical complication rates to as close to zero as possible.
Many hospitals are using only one approach to attack infections that result from very deep surgical incisions, but in the long run, it doesn’t matter if one method is slightly more effective than another. If any method improves surgical recovery rates at all, it should be used along with every other method that works. For the time being, high velocity directional air flow shows the most promise.