Episode #18 Coronavirus Resources: OR Ventilation

Hello and welcome back to the Anesthesia Patient Safety Podcast.  My name is Alli Bechtel and I am your host. Thank you for joining us for another show.

Today, we are going to return to the Novel Coronavirus (COVID-19) Anesthesia Resource Center. Don’t forget, we are constantly updating the information in the resource center so let’s look at one of the more recent articles.  Let’s let the anticipation build for a moment.

Before we dive into today’s episode, we’d like to recognize Masimo, a major corporate supporter of APSF. Masimo has generously provided unrestricted support as well as research and educational grants to further our vision that “no one shall be harmed by anesthesia care”. Thank you, Masimo – we wouldn’t be able to do all that we do without you!”

Today, we are going to stay positive on this show and talk about OR ventilation during the SARS COV-2 Pandemic. That’s right, we are going to review the article by Charles Cowles, published on September 5^th called “Recommendations for OR Ventilation during the SARS COV-2 Pandemic – Staying Positive.” You can follow along with us by clicking on the Patient Safety Resources Heading, 1^st one down is the, Coronavirus Resource Center. Then, just scroll down to the latest news and click on the first article. Don’t worry, I will include a link to the article in the show notes as well.  As we review this important topic, please keep in mind that we are making our best efforts to provide accurate information on this podcast and on our website, but this material is provided only for informational purposes and does not constitute medical or legal advice.

This is a Q and A article so let’s get started with a question: Has the APSF come up with definitive recommendations regarding negative pressure operating rooms for patients who are known or suspected to have SARS-COV-2 infection?

Cowles reminds us that positive pressure in the OR occurs when the pressure in the OR is greater than in the rooms just outside the OR and this is the usual way that ventilation occurs in the OR in an effort to prevent pathogens from finding their way into the OR and contaminating an open wound. Thus, for patients undergoing surgery, positive pressure in the OR helps to prevent infection. Negative pressure on the other hand is when the pressure in the OR is less than in the rooms just outside of the OR which can help to decrease the spread of airborne pathogens from the OR to the surrounding rooms. This is not the usual way we approach the ventilation system in the OR, but it has been used before the COVID-19 pandemic for patients with a known or suspected infection with an airborne pathogen such as tuberculosis. So, then what about a patient with COVID-19, what is the best OR ventilation strategy in order to protect the patient from wound contamination and decrease the risk to staff and other patients during aerosol generating procedures? This is a great question. We hope that you will be able to use this information to make an informed decision about the OR ventilation strategy that is optimal in your ORs and procedure rooms.

The next question is what are the current recommendations for ventilation in the operating rooms? Now, we are going to get technical since the American Institute of Architects recommends 15 air exchanges each hour in addition to 3 air exchanges with outside fresh air for operating rooms. Plus, the airflow should create positive pressure in the OR in order to decrease open wound contamination from outside the OR pathogens. These are the standard requirements for all patients who receive anesthesia care in the OR.

In light of the current pandemic, the next question asks “Should the operating room (OR) ventilation be converted to negative pressure to protect the staff from COVID-19 exposure when caring for known or suspected COVID-19 positive patient?” Well, the American Society of Healthcare Engineering offers recommendations for patients with COVID-19 that are similar for patients with other airborne infections including the following:

• Only medically necessary procedures should be scheduled “after hours.”
• Minimize staff, and all staff involved are to wear N95 or HEPA respirators.
• Door to room should be kept closed throughout the procedure.
• Recovery should be accomplished in an Airborne Infection Isolation Room (AIIR).
• Terminal Cleaning should be performed after sufficient number of air changes has removed potentially infectious particles.

But remember that in a negative pressure room, outside pathogens like Staph can enter the OR and contaminate an open wound. Perhaps the best choice for patients and environmental safety is to combine the approaches by performing aerosol generating procedures (like intubations) in an Airborne Infection Isolation Room that is separate from the OR and then performing surgical procedures in a positive pressure OR, if possible.

So, what is an Airborne Infection Isolation Room? Is this different from a negative pressure room? Here are the criteria for this special type of room from the American Institute of Architects:

1. at least 12 air exchanges per hour
2. inability to inadvertently change the ventilation modes from a negative mode to a positive mode
3. it is tightly sealed
4. self-closing doors
5. a permanent indicator of airflow that is visible when room is occupied and
6. a filtration system with at least 90% efficiency

Once these criteria are met, the Isolation Room can be positive pressure with a negative pressure ante room. If there is no ante room then the isolation room will need to be negative pressure compared to the surrounding area and a negative pressure room can be made with a return air system rate that is greater than the supply of air. In this way, it is possible to create Airborne Infection Isolation Rooms in the ICU, PACU, and other areas to help care for patients with COVID-19 using the above criteria.

What if your Operating Room is not negative pressure? How can we keep the staff and other patients safe? One possibility may be to create a temporary negative pressure ante room in the OR adjoining the patient entry door to the OR with a portable air handler to create the negative pressure environment which will help prevent the transmission of airborne particles from the positive pressure operating room into the hallway or another adjacent room. The ante room needs to be largest enough to move the patient bed through and the other doors to the OR should be sealed to airflow. There are a lot of considerations and the APSF and the American Society of Anesthesiologists offer further guidance. It is important to try to minimize environmental contamination and decrease the risk to the staff during any aerosol generating procedures. When intubation and extubation occur in the OR, one consideration may be to only have the staff necessary to safely secure the airway who are wearing appropriate PPE with the rest of the OR doors closed. Then, after the intubation or extubation, other staff should wait until enough time has passed to remove any airborne pathogens from the room before returning into the OR. The time it takes to clear the room is another important consideration. The CDC states that at 15 air exchanges each hour, 99% of the airborne pathogens can be cleared in about 14 minutes. It may not be quite as simple as that though since this is an estimate based on many different factors including laminar air-flow compared to turbulent air flow created by the anesthesia machine in the room, OR tables, and other pieces of equipment in the OR. In addition, the type of filer may change the required time. Operating rooms should have a filtration system with a minimum efficiency reporting value system of 14 or greater (remember, a higher number means that the filter is more efficient for small particles).

Do you still have questions about ventilation standards and recommendations during this COVID-19 pandemic? If so, we have some more resources for you especially because every operating room and hospital and healthcare system has different resources available for providing care for patients with Covid-19. I have included a list of these additional resources in the show notes. We hope that you will check it out.

Before we wrap up for today, we want to highlight the Society of Neuroanesthesiology and Critical care or SNACC, and APSF 2020 Patient Safety Award Winner. This is such a great award! The mission of the society of neuroanesthesiology and critical care is to further the art and science of patients with neurological impairment with education, training, and research in perioperative neuroscience. This mission is also represented by several of the APSF’s patient safety initiatives including perioperative delirium, cognitive dysfunction, and brain health. Each year at the SNACC meeting, young scientists present quality improvement and research projects that often display excellence in patient safety. And the winner of the award this year is Shilpa Rao for her project, “Prioritizing neurosurgical workflow during COVID-19 pandemic at two tertiary level hospitals” Congratulations and thank you for your excellent work in neuroanesthesiology and patient safety.

If you have any questions or comments from today’s show, please email us at [email protected].

Visit APSF.org for detailed information and check out the show notes for links to all the topics we discussed today.  Plus, you can find us on twitter and Instagram!  See the show notes for more details and we can’t wait for you to tag us in a patient safety related tweet or like our next post on Instagram!! Follow along with us for anesthesia patient safety pictures and stories!!

Until next time, stay vigilant so that no one shall be harmed by anesthesia care.

© 2020, The Anesthesia Patient Safety Foundation