Transcranial Doppler in Acute COVID-19 Infection Unexpected Associations

Background and Purpose: Stroke may complicate coronavirus disease 2019 (COVID-19) infection based on clinical hypercoagulability. We investigated whether transcranial Doppler ultrasound has utility for identifying microemboli and clinically relevant cerebral blood flow velocities (CBFVs) in COVID-19. Methods: We performed transcranial Doppler for a consecutive series of patients with confirmed or suspected COVID-19 infection admitted to 2 intensive care units at a large academic center including evaluation for microembolic signals. Variables specific to hypercoagulability and blood flow including transthoracic echocardiography were analyzed as a part of routine care. Results: Twenty-six patients were included in this analysis, 16 with confirmed COVID-19 infection. Of those, 2 had acute ischemic stroke secondary to large vessel occlusion. Ten non-COVID stroke patients were included for comparison. Two COVID-negative patients had severe acute respiratory distress syndrome and stroke due to large vessel occlusion. In patients with COVID-19, relatively low CBFVs were observed diffusely at median hospital day 4 (interquartile range, 3-9) despite low hematocrit (29.5% [25.7%-31.6%]); CBFVs in comparable COVID-negative stroke patients were significantly higher compared with COVID-positive stroke patients. Microembolic signals were not detected in any patient. Median left ventricular ejection fraction was 60% (interquartile range, 60%-65%). CBFVs were correlated with arterial oxygen content, and C-reactive protein (Spearman rho=0.28 [P=0.04]; 0.58 [P<0.001], respectively) but not with left ventricular ejection fraction (rho=-0.18; P=0.42). Conclusions: In this cohort of critically ill patients with COVID-19 infection, we observed lower than expected CBFVs in setting of low arterial oxygen content and low hematocrit but not associated with suppression of cardiac output.

Automated summary

In critically ill patients with COVID-19 infection, lower than expected cerebral blood flow velocities were observed despite low arterial oxygen content and hematocrit, not associated with suppression of cardiac output. Higher levels of C-reactive protein were positively correlated with blood flow velocities.