Assessing Covid-19 Exposure Risk In Vascular Procedures: Exploring A Time:distance Score / Index.
Douglas L. Wooster, MD1, Elizabeth M. Wooster, M.Ed., PhD Candidate1, David M. Williams, MS2.
1Univ of Toronto, Toronto, ON, Canada, 2Medical Univ of South Carolina, Florence, SC, USA.
OBJECTIVES: The aims of this study were to 1. Define a Time:Distance Score (TDS) and Index (TDI) for the potential transmission of COVID. 2. Identify modifiers, such as mitigating factors (MF), disease burden (DB) and personal vulnerability (PV), 3. Apply TDS and TDI in practice and 4. Consider ranges of TDS and TDI in varying clinical exposure scenarios. METHODS: A literature review informed the TDS /TDI framework and supported the theoretical construct. Proof of concept data was obtained from vascular ultrasound practice (Carotid, Aorta, Leg artery, Leg veins). Sensitivity analysis was used to consider the effect of MF, DB and PV. RESULTS: Literature review re COVID-19 characteristics informed the theoretical construct - Time (min), Distance (m as Virtual = 0, > 2m = 1, 1-2 m = 2, 0.5-1 m = 3, <0.5 m = 4, contact = 5. Consider Disease Burden (DB) as 0 (may not exist), Low risk = 1, medium risk (exposure, suspected) = 2, high risk (positive dx) = 3 - applies as an overall modifier. Consider Mitigation Factor (MF) as none = 1.0, PPE = 0.10, Max PPE = 0.05. DB and PV are overall modifiers; MF can be applied to individual parameters. To calculate TDS = T x D x DB x MF x PV. The TDI = Procedure TDS / average bench mark TDS for procedure. Preliminary ‘proof of concept’ data supports the theoretical construct and sensitivity analysis allows for appropriate modification for scenarios. CONCLUSIONS: Time Distance Score and Time Distance Index can be successfully defined. Sensitivity analysis addresses varying clinical situations. Use of TDS and TDI should allow for recognition and modification of at-risk exposure.
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