Baseline parameters for non-activated rotational thromboelastometry tests with and without heparinase in healthy pregnant women at term gestation.

OBJECTIVE: To determine the normal values for non-activated thromboelastometry parameters among pregnant women. DESIGN: Prospective, observational study. SETTING: Tertiary care hospital. PATIENTS: Non-laboring women at term gestation without history of bleeding or clotting disorder or anticoagulation use. INTERVENTIONS: Venous blood samples were collected and ROTEM® was performed using NATEM and NaHEPTEM assays. MEASUREMENTS: Reference ranges were derived by calculating 2.5 and 97.5 percentiles for the following parameters: clotting time (CT), clot formation time (CFT), amplitude at 10 (A10) and 20 min (A20), alpha angle, maximum clot firmness (MCF), and lysis index at 30 (LI30) and 60 min (LI60). The NATEM/NaHEPTEM CT ratio was calculated to determine the baseline ratio in term pregnant women. MAIN RESULTS: 146 women were screened and 120 were enrolled. The median age was 34 years [31-36], median gestational age was 39.1 weeks [38.3-39.3], and median parity was 1 [0-2]. Median pre-delivery platelet and hematocrit levels were within the normal ranges. The reference ranges for NATEM parameters were: CT (232-759 (s)), CFT (69-243 (s)), alpha angle (50-77 (°)), A10 (44-69 (mm)), A20 (54-75 (mm)), MCF (57-77 (mm)), LI30 (100-100 (%)), LI60 (90-100 (%)). The reference ranges for NaHEPTEM parameters were: CT (224-717 (s)), CFT (66-210 (s)), alpha angle (53-77 (°)), A10 (44-67 (mm)), A20 (55-73 (mm)), MCF (58-74 (mm)), LI30 (99-100 (%)), LI60 (90-100 (%)). The NATEM to NaHEPTEM CT ratio reference range was 0.73-1.3. CONCLUSIONS: This study is the first to our knowledge to report reference ranges for non-activated ROTEM® tests with and without heparinase in non-laboring term pregnant women. These reference ranges may serve as a baseline comparison and may be useful for future research on anticoagulation management in pregnancy.

Barrier Devices, Intubation, and Aerosol Mitigation Strategies: Personal Protective Equipment in the Time of Coronavirus Disease 2019.

BACKGROUND: Numerous barrier devices have recently been developed and rapidly deployed worldwide in an effort to protect health care workers (HCWs) from exposure to coronavirus disease 2019 (COVID-19) during high-risk procedures. However, only a few studies have examined their impact on the dispersion of droplets and aerosols, which are both thought to be significant contributors to the spread of COVID-19. METHODS: Two commonly used barrier devices, an intubation box and a clear plastic intubation sheet, were evaluated using a physiologically accurate cough simulator. Aerosols were modeled using a commercially available fog machine, and droplets were modeled with fluorescein dye. Both particles were propelled by the cough simulator in a simulated intubation environment. Data were captured by high-speed flash photography, and aerosol and droplet dispersion were assessed qualitatively with and without a barrier in place. RESULTS: Droplet contamination after a simulated cough was seemingly contained by both barrier devices. Simulated aerosol escaped the barriers and flowed toward the head of the bed. During barrier removal, simulated aerosol trapped underneath was released and propelled toward the HCW at the head of the bed. Usage of the intubation sheet concentrated droplets onto a smaller area. If no barrier was used, positioning the patient in slight reverse Trendelenburg directed aerosols away from the HCW located at the head of the bed. CONCLUSIONS: Our observations imply that intubation boxes and sheets may reduce HCW exposure to droplets, but they both may merely redirect aerosolized particles, potentially resulting in increased exposure to aerosols in certain circumstances. Aerosols may remain within the barrier device after a cough, and manipulation of the box may release them. Patients should be positioned to facilitate intubation, but slight reverse Trendelenburg may direct infectious aerosols away from the HCW. Novel barrier devices should be used with caution, and further validation studies are necessary.