Résumé
Background: chronic elevation of arterial resistance due to cardiovascular risk factors could alter velocity profile of the middle cerebral artery (MCA) outside of any intracranial hypertension (ICHT). This could affect transcranial Doppler (TCD) of MCA velocities in critically ill patients.Methods: we conducted a prospective single-center cohort observational study involving 118 mechanically ventilated patients at three intensive care units (ICU) in Nîmes University Hospital, France, from April 2016 to November 2018. Patients with acute brain injury were excluded. All patients admitted in ICU had a systemic brain, lungs, and cardiac ultrasound exam at admission. The study population was divided into 2 groups: a cardiovascular risk group and a non-risk group. The primary objective was to compare the Doppler velocities of MCA between the 2 groups. The secondary objective was to compare the pulse wave velocity (PWV) and the proportion of patients with impaired PWV, which is a marker of chronic artery disease, to establish a link between altered PWV, and abnormalities of TCD velocities.Results: a total of 94 patients (median age 60 years, 25 (26.6%) were female) were included and assigned into 2 groups: 77 in the cardiovascular risk group and 17 in the non-risk group. Diastolic velocity (DV) was higher in the non-risk group (51 cm.s-¹ vs. 38 cm.s-¹, p=0.0174 for the right MCA, and 51 cm.s-¹ vs. 38 cm.s-¹, p=0.0330 for the left MCA). Pulsatility index (PI) was higher in the cardiovascular risk group (1.2 vs. 1.0, p=0.0063 for the right MCA and 1.2 vs. 1.0, p=0.0085 for the left MCA). The aortic PWV was higher in the cardiovascular risk group (10.4 m.s-¹ vs. 6.7 m.s-¹, p=0.0004). The number of patients with impaired aortic PWV was higher in the cardiovascular risk group (49.3% vs. 0.0%, p=0.0019). Conclusion: in ICU patients without acute brain injury, PI and DV recorded by TCD are significantly altered in patients with cardiovascular risk compared to patients without risk. Half of the patients with cardiovascular risk shows alterations of aortic PWV, reflecting a chronic artery disease whereas this was never observed in the non-risk group. This phenomenon may be a source of false diagnosis of ICHT in patients with cardiovascular risk.