EIT may allow advanced respiratory and cardiovascular monitoring in critically ill patients
– ICM, May 2019.
STUDY STRENGTHS & LIMITATIONS
Electrical impedance tomography (EIT) is a recently developed technique based on the application of alternate micro currents spinning at 20–50 Hz along a set of electrodes positioned around the patient’s chest.
EIT is a non-invasive, radiation-free and bedside lung imaging technique that allows a continuous and dynamic monitoring of regional gas distribution inside the lung. EIT may be used in in critically ill patients for physiological evaluation and clinical application. In patients with Acute Respiratory Distress Syndrome (ARDS), EIT provides a dynamic breath-by-breath evaluation of alveolar recruitment and over-distension. In this manner, EIT may support the choice of the most appropriate PEEP for ARDS patients.
EIT may be also used for respiratory and hemodynamic monitoring. In spontaneous breathing situation, EIT, by checking the homogeneity or inhomogeneity of lung ventilation, guides the clinical decisions on mechanical ventilation and weaning phase.
An innovative use of EIT is the assessment of central and pulmonary hemodynamics. EIT can dynamically quantify regional changes of lung blood content from which regional blood flow can be derived. However, this application is evaluated in experimental model and should be further validated in clinical setting.
EIT also has some limitations: 1) It allows the evaluation of a slice of the lungs, assuming that the remaining lung regions have the same characteristics, 2) it reflects only a relative impedance change, 3) it does not differentiate the anatomical borders between lung and non-aerated tissues.
TAKE HOME MESSAGE
EIT is a promising technique that may allow an advanced respiratory and cardiovascular monitoring in critically ill patients. However, it needs to be further improved.
This article review was prepared and submitted by Professor Maria Vargas, Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples (Italy), on behalf of the ESICM Journal Review Club.
1) Mauri T, Eronia N, Turrini C, Battistini M, Grasselli G, Rona R, Volta CA, Bellani G, Pesenti A (2016), Bedside assessment of the effects of positive end-expiratory pressure on lung inflation and recruitment by the helium dilution technique and electrical impedance tomography, Intensive Care