Related Experiment Video
Updated: Jun 23, 2026
Monitoring Lung Function with Electrical Impedance Tomography in the Intensive Care Unit
Published on: September 6, 2024
Assessing effects of PEEP and global expiratory lung volume on regional electrical impedance tomography
D G Markhorst1, A B J Groeneveld, R M Heethaar
1Paediatric intensive care unit, Free University Hospital, Amsterdam, The Netherlands. dg.markhorst@vumc.nl
Objective:
This study was performed to assess the value of electrical impedance tomography (EIT) as an indicator of tidal (V(T)) and end expiratory lung volume (EELV).
Methods:
EIT measurements were performed in seven healthy piglets during constant tidal volume ventilation at incremental and decremental positive end-expiratory pressure (PEEP) levels. Tidal impedance changes were calibrated to volume using V(T) calculated from flow at the airway opening. Simultaneously, calibrated respiratory inductive plethysmography was used to measure EELV changes, and used as a reference standard.
Results:
EIT systematically underestimated both V(T) and EELV changes when EELV deviated from the level at which it was calibrated. Calculated over the entire pressure-volume curve, EIT systematically underestimated V(T) by 28 ml, with a precision from -16 to 72 ml. EELV was systemically underestimated by 406 ml, with a precision of -38 to 849 ml. Nonlinear recruitment in the ventral regions of the lungs was the main cause of this underestimation.
Conclusions:
Tidal and end-expiratory changes in pulmonary impedance reflect corresponding changes in lung volume, but the increasing underestimation with increasing lung volume should be taken into account in the analysis of EIT data.
Related Concept Videos
01:20Assessment of Ventilation I: Respiratory Rate
A Ventilation assessment is critical for monitoring a patient's health status. Respiration, one of the most accessible vital signs, provides insights into the function of numerous body systems and can indicate serious health issues, such as brainstem injuries from head trauma.
Critical Guidelines for Assessing Ventilation:
01:29Assessment of Ventilation II: Respiratory Depth and Rhythm
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:
01:17Assessment of Diffusion and Perfusion
The Role of Diffusion in Respiration
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. In the respiratory system, this principle...
01:23Assessment of Respiration
Subjective Assessment: Nurses interview the patient to gather information directly during the subjective assessment. It includes questions about the individual's medical history, medications, and symptoms, focusing on past respiratory conditions like asthma or COPD,...
01:29Physical Assessment of the Respiratory Tract III: Percussion
Percussion in Respiratory Assessment
Percussion evaluates underlying tissue composition with audible and tactile vibrations,...