Laminar air flow is a system for circulating filtered air in healthcare facilities. It is very relevant to the issue of Indoor Air Quality and the impact on potential spread of infections. This paper focuses on understanding how using Laminar Air Flow (LAF) can reduce the spread of hospital acquired infections in the context of Bone Marrow Transplant (BMT) patients. Infection can be a common occurrence during chemotherapy for cancer patients, particularly leukemia and BMT patients. Additionally, BMT patients are at higher risk for infection due to the use of T-cell depleted marrows and being subjected to high dose corticosteroids. A prime risk factor is inhalation of airborne fungal spores which may cause Pulmonary Aspergillosis. In this particular study the Westminster Children’s Hospital consisted of seven single cubicles in a naturally ventilated ward. One section was upgraded to install a five-bedded LAF unit incorporating HEPA filters. The study compares the impact on children undergoing transplantation before and after the installation.
To determine the impact of LAF isolation on outbreak of Invasive Pulmonary Aspergillosis (IPA)
Total of 38 children undergoing BMT were studied- 19 who had undergone transplantation in the 14 month prior to the opening of the LAF unit, and 19 transplanted in the 18 months following the installation. Risk factors for the development of Invasive Pulmonary Aspergillosis (IPA) were identified, and other transplant related risk factors were noted. Post-transplant complications were documented. Over an18 month period airborne fungal spores were collected from each room in the BMT unit, and a control ward on a different floor of the hospital. Samples of outside air were also taken.
32% of children undergoing BMT died of IPA in the pre-LAF group and accounted for all infection-related deaths. The patients’ stay coincided with the period of high fungal exposure. No documented cases of IPA were found in the children nursed in the LAF units.
Results of the study indicate that an appropriate air filtration system such as LAF can offer effective protection against airborne fungal infection.
The author of the study does not discuss any limitations. In the opinion of the reviewer, the study is old and the sample size is small. A similar study conducted longitudinally over a period of a few years would be more compelling. Air sampling is not synced completely with the patient outcomes. Also, the increase of asperigillus spores recovered during construction serves as a warning for how building work can cause nosocomial break. More detailed information on this would have been helpful.