Emergency Evacuation of Immunocompromised Patients From a Hematology Unit Following Flooding of High-Efficiency Particulate Air (HEPA) Filtration

To the Editor—To reduce the risk of developing nosocomial fungal infections, patients with hematological malignancies are placed in protected areas during intensive chemotherapy or during bone marrow transplant. ^{1 , 2} Patients admitted to these units often stay several weeks to be treated. Guidelines recommend placing high-risk patients in rooms with high-efficiency particulate air (HEPA) filtration systems. ³ The beds are located under laminar airflow and environmental samples (air and surface samples under laminar airflow and from the bathroom) are regularly taken from the patient rooms to detect air fungal contamination. ⁴

The hematopoietic stem cell transplantation center of Brest University Hospital has been accredited for the quality management system by the Joint Accreditation Committee of the International Society for Cellular Therapy (ISCT) and the European Society for Bone Marrow Transplantation (EBMT) known as JACIE since 2008. ^{5 , 6} JACIE is equivalent to its US counterpart, the Foundation for the Accreditation of Cellular Therapy, FACT, which is an ongoing quality management system that pertains to clinical, collection, and processing activities. The configuration of the Hematology Department of Brest University Hospital follows these guidelines and national recommendations: it is organized in 2 units of 7 rooms with independent air handlings. ³ The 2 units are separated by a corridor and equipped with 2 independent HEPA filtration systems. A third HEPA filtration system treats the air of the common parts of the service (Figure 1).

FIGURE 1 Ventilation system of the Hematology Department of Brest University Hospital.

In July 2016, a water pipe in the technical room located above the hematology unit broke, causing the HEPA filtration system number 1 to flood. The water flowed through the filters located in the ceiling and along the walls of the rooms. This incident caused the emergent evacuation of 7 patients.

We applied the JACIE evacuation disaster plan that first recommends triaging patients according to their level of risk of fungal infection. Patients treated by allogeneic hematopoietic stem cell transplantation are at high-risk for developing fungal infections and they must be relocated emergently to a protected area. ⁷ In this situation, 2 of these patients were relocated to available rooms in sector number 2, where the HEPA filtration system had not been flooded. Patients of sector number 2 who no longer needed to be located in a protected area were moved to standard hospital rooms in another department. However, there were not enough available rooms to harbor all patients from the flooded sector; we had to create a new protective environment using a mobile unit that recycled and distributed treated air through a plenum over an isolated zone. We used 2 Immunair Systems (AirInSpace, Montigny Le Bretonneux, France) to quickly convert 2 standard hospital rooms into areas that could be used to host immune-compromised patients. ^{8 – 10}

The flooded rooms were closed, and a slight negative pressure was created to extract humidity from the rooms and to prevent air fungal contamination of the corridors. These rooms had to be closed for 6 weeks, the time required to order and install 7 new custom HEPA filters and to monitor the effectiveness of the HEPA filtration system by collecting air and surface samples to detect an increase of air fungal contamination. During that time, the Hematology Department could care for only 9 patients instead of 14.

The HEPA filtration systems of sectors 1, 2, and 3 are located on the same ceiling. The broken water pipe seemed to have affected only the HEPA filtration system of sector 1, but we had to make sure that the HEPA filtration of sector 2 was still efficient. Therefore, we decided to sample the environments of all the patient rooms of sector number 2. A laboratory technician collected air samples from each room and its bathroom with a Microbiology Air Sampler-100 Bio Collector (Merck, Darmstadt, Germany) using Sabouraud chloramphenicol plates under the laminar airflow. We also collected air samples in the corridor of the department to assess fungal contamination where there was no HEPA filtration.

We collected 29 air samples during the period. Air samples from the flooded rooms showed a high level of air fungal contamination (27 colony forming units/m³). No fungal contamination was detected in air samples collected under laminar airflow of the rooms of sector 2. These rooms were controlled once a week to make sure HEPA filtration system was still efficient. Air samples collected in the corridors did not reveal any fungal contamination either. Negative pressures in the flooded sector seemed to have protected sector 2 and the corridors from fungal contamination.

The flooding of the unit was mainly due to the lack of waterproofing of the floor of the technical room; water flowed along the ventilation ducts that passed through the ceiling of the patients’ rooms. This incident revealed that this type of room should be isolated from both air and water. Therefore, the technical services of our hospital decided to seal the floor of the technical room above the rooms to avoid any further incidents of this kind.