Electrical bioimpedance cardiography: an old technology with new hopes for the future.

HE POSITIVE IMPACT of early goal-directed hemodynamic therapy on postoperative outcome increasingly has been investigated over the last few years in high-risk patients undergoing noncardiac and cardiac surgeries. 1–4 However, these preemptive strategies require advanced hemodynamic monitoring to assess cardiac output and stroke volume. The classic available tools (intermittent pulmonary arterial or transpulmonary thermodilution or esophageal Doppler), either invasive or operator-dependent and necessitating a learning curve, are not convenient for routine practice. Therefore, they remain insufficiently used among North American and European anesthesiologists. 5 Besides, new mini-invasive cardiac output devices have been developed commercially over the last decade. 6 Less accurate but more convenient and easy to use, they potentially could help the practitioners in promoting advanced hemodynamic monitoring and early goal-directed therapy at the bedside in high-risk patients in an attempt to further improve postoperative outcome. Among these miniinvasive technologies, thoracic electrical bioimpedance (TEB) has major theoretical advantages and could be of great clinical utility in the settings of anesthesiology, cardiology, and perioperative medicine. Despite extensive literature published over the last 50 years, TEB remains scarcely used by practitioners. This review first describes the principles and limitations of the TEB before addressing the crucial problem of its clinical validation. Endotracheal electrical bioimpedance is a new approach in mechanically ventilated patients that could bring a decisive advantage in the coming years and allow a wide dissemination of the method in the operating room and intensive care units (ICUs). This new approach is detailed in the final section. In contrast, the bioreactance technology has been well-described in a recent review 6 and will not be discussed further.