(P154) COVID-19 RISK IN THE CARDIAC CATHETERIZATION LABORATORY

Background: Infection Control Committees (IPC) have advised that droplet protocol protections are sufficient against COVID-19 unless Aerosol Generating Medical Procedures (AGMP) are being performed. AGMP do occur in the Cardiac Catheterization Lab (CCL) but are largely unpredictable. Recent analysis of superspreader events has provided evidence of significant aerosol spread. CO2 is exhaled by breathing subjects, and its measurement has been shown to be a reliable proxy for breathing activity, and thereby infectious risk, in indoor environments.

METHODS AND RESULTS: A portable CO2 monitor (AirQ AQ-200 or Aranet-4) was positioned at counter height in the periphery of CCL’s during diagnostic & coronary interventional (Cath), transcatheter aortic valve implantations (TAVI) and Mitraclip (MC) procedures. Procedure start and stop times were recorded. CCL ventilation parameters were provided by hospital building engineers. Usual personnel numbers were attributed to each type of case (no allowance was made for the emergency need of additional personnel). Data were inputted into a publicly available well-mixed room model coded in Python (https://indoor-covid-safety.herokuapp.com/) to obtain a safe maximum CO2 level for case and catheterization lab parameters. Procedural mean values were than compared to the safe maximum. Data were obtained from 278 cases, 246 Cath (mean duration 50 min, range 23-155), 27 TAVI (65 min, range 35-287) and 5 MC ( 247 min, range 178-371). Using surgical masks with average fit and transmissibility data from the Wild variant, Cath CO2 measurements were within safe range 98.8% of the time, TAVI 92.6% and MC 0%. Under Omicron variant conditions, this decreased to 17.5% (Cath) and no TAVI/MC cases. For cath cases, case duration was an important determinate of safety, and a safe duration depended greatly on the variant in circulation.
Increasing ventilation across a range of 6 ACH (air changes per hour) to 20 ACH led to marked improvement in risk from the Wild variant, but benefits were limited with the Delta and Omicron variants. Filtration had limited effect unless filters were MERV 15 or higher (HEPA).

Conclusion: COVID-19 risk in the CCL is significant even in the absence of AGMP. Increased CCL ventilation and filtration can reduce this risk, but are limited by constant production of infectious aerosols. Risk can be further reduced by complimentary strategies such as aerosol-grade PPE for CCL staff, pre-procedural COVID-19 testing of patients, and postponement of elective procedures expected to last above a duration threshold during periods of high community disease activity.