Characteristics and potential hemodynamic benefits of proning on the right ventricle in intensive care patients with SARS-CoV-2 ARDS

Abstract Funding Acknowledgements Type of funding sources: None. Introduction One of the key challenges in treating COVID-19 ARDS patients is hemodynamic monitoring. Therapies proven to be effective in ARDS, such as protective ventilation, fluid restriction or high PEEP tend to alter right ventricular (RV) function and indicate a closer in-bed management, which is particularly difficult in prone position (PP) patients. Transthoracic echocardiography(TTE) enables a direct window for hemodynamic monitoring of RV performance. Objective To assess characteristics and potential hemodynamic benefits of proning on the RV in ICU patients with SARS-CoV-2 ARDS, using echocardiography. Methods This is an observational, cross-sectional study of SARS-CoV-2 ARDS in 11 patients hospitalized in a 12 bed ICU in Farhat Hached University hospital in December 2020. All patients were deeply sedated and curarized during the study. After a stabilization period (MAP ≥ 65mmHg), TTE was performed first in the supine position before putting the patient on PP. Same measures were repeated during a second scan 4 to 8 hours after PP setting. Norepinephrine infusion levels were not changed between the two scans. The average duration of a scan was 20 ± 10 minutes depending mostly on echogenicity. Several frequencies and harmonics were tested and we selected the ones that provided the best image quality. PP ventilation (PPV) was performed continuously for 12 hours using the "swimmer position" that enabled affordable TTE views. A quantitative study of the RV was performed using RV focused 4C view. A special view dedicated to the IVC was studied. Parameters measured were RV basal end diastolic diameter, S’ peak wave in TDI, tricuspid annular plane systolic excursion (TAPSE), fractional area change (FAC) and maximal trans tricuspid velocity (MTTV). Post hoc analysis was performed by two readers (one intensivist and one cardiologist). All parameters are expressed as a mean of two measurements. Results Twenty-four TTEs were performed in 11 patients respectively 40 ± 15mn before and 5.8 ± 1.1hrs after the PP setting. Patients were 71.0 ± 9.4yrs aged, 5(45%) obese, 7(63%) had diabetes mellitus, 4(36%) hypertension, 1(9%) coronary artery disease. All (100%) were on sinus rhythm. 7(63.6%) presented moderate ARDS and 3(27.3%) severe ARDS. None of the patients developed RV failure prior to the examination. The PPV achieved a non-statistically significant improvement in RV function as assessed by the increase of S′, TAPSE, a decrease in RV basal diameter and an increase in FAC. A statistically significant decrease in MTTV (mean 3.20 ± 0.49 m/s before PP vs mean 2.47 ± 0.77m/s (p = 0.01)) was objectified. Conclusions PPV improves hemodynamic parameters of the RV. TEE 4C view is sufficient in the assessment of RV function in PP. SPAP monitoring could be the key parameter to quickly and reliably assess RV response to PPV.