Automation of sub-aortic velocity time integral measurements by transthoracic echocardiography: clinical evaluation of an artificial intelligence-enabled tool in critically ill patients.

Editor—Point-of-care ultrasound techniques are increasingly used for the bedside assessment of cardiac function and haemodynamics in critically ill patients. The sub-aortic or left ventricular outflow tract velocity time integral (VTI) can be measured using pulsed-Doppler ultrasonography from a transthoracic apical 5-chamber view. 1 Blanco P. Aguiar F.M. Blaivas M. Rapid ultrasound in shock (RUSH) velocity time integral. J Ultrasound Med. 2015; 34: 1691-1700 Crossref PubMed Scopus (52) Google Scholar Quantifying VTI is useful to discriminate between vasoplegic states (hypotension with normal/high VTI) and low flow states (low VTI). 1 Blanco P. Aguiar F.M. Blaivas M. Rapid ultrasound in shock (RUSH) velocity time integral. J Ultrasound Med. 2015; 34: 1691-1700 Crossref PubMed Scopus (52) Google Scholar ,2 Mercado P. Maizel J. Beyls C. et al. Transthoracic echocardiography: an accurate and precise method for estimating cardiac output in the critically ill patient. Crit Care. 2017; 21: 136 Crossref PubMed Scopus (88) Google Scholar Measuring VTI is also useful to predict fluid responsiveness, either by quantifying the respiratory swings in VTI when patients are mechanically ventilated, 3 Feissel M. Michard F. Mangin I. et al. Respiratory changes in aortic blood velocity as an indicator of fluid responsiveness in ventilated patients with septic shock. Chest. 2001; 119: 867-873 Abstract Full Text Full Text PDF PubMed Scopus (450) Google Scholar or by quantifying VTI changes during a passive leg raising manoeuvre or a fluid challenge. 4 Muller L. Toumi M. Bousquet P.J. et al. An increase in aortic blood flow after an infusion of 100 ml colloid over 1 minute can predict fluid responsiveness: the mini-fluid challenge study. Anesthesiology. 2011; 115: 541-547 Crossref PubMed Scopus (217) Google Scholar