Vascular changes
PASP was found to be elevated in several studies, presumably due to
hypoxemia-mediated pulmonary vasoconstriction, pulmonary emboli and the
effects of positive pressure ventilation[18,22–25]. Notably, there
has also been a high incidence of deep venous thrombosis among COVID-19
patients. A recent meta-analysis highlighted an overall incidence of
20% which is disproportionately high when compared to patients admitted
for other medical conditions[34]. A recent study also described a
high rate of fluid responsiveness (82.9% of patients) based on an
inferior vena cava (IVC) distensibility index >18% at the
time of evaluation. This was thought to be due to third spacing of
fluids because of sepsis, reduction of venous return to the RV due to
high positive pressure ventilation and a natural tendency to maintain a
negative fluid balance in patients with ARDS[18].