Non-invasive radiation-free monitoring of regional lung ventilation in critically ill infants

Abstract

Objective: Established techniques used to examine lung function in critically ill infants cannot continuously follow regional aspects of lung ventilation although this information would be beneficial for proper therapy planning. We have studied the applicability and clinical relevance of a relatively new non-invasive radiation-free imaging method, electrical impedance tomography (EIT), in monitoring regional lung function in paediatric intensive care patients. Design: Prospective study. Setting: Neonatal and paediatric intensive care unit (ICU) at a university hospital. Patients: Eight infants (1 day-7 years old) suffering from miscellaneous diseases requiring intensive care therapy. Interventions: Adjustment of ventilator settings, surfactant administration, and postural changes. Measurements and results: Repeated EIT measurements were performed with the intention to monitor regional lung ventilation in mechanically ventilated and spontaneously breathing infants. The follow-up time ranged between 1 and 11 days. During individual EIT measurements of 100-s duration electrical voltages resulting from repetitive injection of small electrical currents were continuously measured on the thoracic circumference using conventional surface electrodes. Acquired data were used to generate functional cross-sectional thoracic images of regional lung ventilation. A total of 638 EIT measurements were performed. The redistribution of lung ventilation and changes in regional ventilation magnitude resulting from adjusted positive end-expiratory pressure, peak inspiratory pressure, inspiration-expiration ratio, surfactant instillation, and prone or supine positioning were identified. Conclusions: Provided that EIT hardware and software are further developed to guarantee stable and undisturbed measurements in the ICU and that practical handling is improved, this non-invasive method may become a useful bedside monitoring tool of regional lung ventilation in critically ill infants.