Measurement of relative lung perfusion with electrical impedance and positron emission tomography: an experimental comparative study in pigs

Br J Anaesth. 2019 Aug;123(2):246-254. doi: 10.1016/j.bja.2019.04.056. Epub 2019 May 31.

Abstract

Background: Electrical impedance tomography (EIT) with indicator dilution may be clinically useful to measure relative lung perfusion, but there is limited information on the performance of this technique.

Methods: Thirteen pigs (50-66 kg) were anaesthetised and mechanically ventilated. Sequential changes in ventilation were made: (i) right-lung ventilation with left-lung collapse, (ii) two-lung ventilation with optimised PEEP, (iii) two-lung ventilation with zero PEEP after saline lung lavage, (iv) two-lung ventilation with maximum PEEP (20/25 cm H2O to achieve peak airway pressure 45 cm H2O), and (v) two-lung ventilation under unilateral pulmonary artery occlusion. Relative lung perfusion was assessed with EIT and central venous injection of saline 3%, 5%, and 10% (10 ml) during breath holds. Relative perfusion was determined by positron emission tomography (PET) using 68Gallium-labelled microspheres. EIT and PET were compared in eight regions of equal ventro-dorsal height (right, left, ventral, mid-ventral, mid-dorsal, and dorsal), and directional changes in regional perfusion were determined.

Results: Differences between methods were relatively small (95% of values differed by less than 8.7%, 8.9%, and 9.5% for saline 10%, 5%, and 3%, respectively). Compared with PET, EIT underestimated relative perfusion in dependent, and overestimated it in non-dependent, regions. EIT and PET detected the same direction of change in relative lung perfusion in 68.9-95.9% of measurements.

Conclusions: The agreement between EIT and PET for measuring and tracking changes of relative lung perfusion was satisfactory for clinical purposes. Indicator-based EIT may prove useful for measuring pulmonary perfusion at bedside.

Keywords: electrical impedance tomography; indicator dilution; positron emission tomography; regional pulmonary perfusion.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Disease Models, Animal
  • Electric Impedance
  • Lung / diagnostic imaging*
  • Lung / physiopathology*
  • Positron-Emission Tomography*
  • Pulmonary Ventilation / physiology*
  • Respiration, Artificial*
  • Swine