Research

BioMedical Engineering OnLine

, 11:64

Open Access This content is freely available online to anyone, anywhere at any time.

Ventilation distribution in rats: Part I - The effect of gas composition as measured with electrical impedance tomography

  • Kimble R DunsterAffiliated withPaediatric Critical Care Research Group, Paediatric Intensive Care Unit, Mater Children’s HospitalCritical Care Research Group, The Prince Charles HospitalMedical Engineering, Queensland University of TechnologyPaediatric Intensive Care Unit, Mater Children’s Hospital Email author 
  • , Marlies FrieseAffiliated withCritical Care Research Group, The Prince Charles HospitalCentre for Advanced Imaging, The University of Queensland
  • , John F FraserAffiliated withPaediatric Critical Care Research Group, Paediatric Intensive Care Unit, Mater Children’s HospitalCritical Care Research Group, The Prince Charles HospitalMedical Engineering, Queensland University of Technology
  • , Gary J CowinAffiliated withCentre for Advanced Imaging, The University of Queensland
  • , Andreas SchiblerAffiliated withPaediatric Critical Care Research Group, Paediatric Intensive Care Unit, Mater Children’s HospitalCritical Care Research Group, The Prince Charles HospitalMedical Engineering, Queensland University of Technology

Abstract

The measurement of ventilation distribution is currently performed using inhaled tracer gases for multiple breath inhalation studies or imaging techniques to quantify spatial gas distribution. Most tracer gases used for these studies have properties different from that of air. The effect of gas density on regional ventilation distribution has not been studied. This study aimed to measure the effect of gas density on regional ventilation distribution.

Methods

Ventilation distribution was measured in seven rats using electrical impedance tomography (EIT) in supine, prone, left and right lateral positions while being mechanically ventilated with either air, heliox (30% oxygen, 70% helium) or sulfur hexafluoride (20% SF6, 20% oxygen, 60% air). The effect of gas density on regional ventilation distribution was assessed.

Results

Gas density did not impact on regional ventilation distribution. The non-dependent lung was better ventilated in all four body positions. Gas density had no further impact on regional filling characteristics. The filling characteristics followed an anatomical pattern with the anterior and left lung showing a greater impedance change during the initial phase of the inspiration.

Conclusion

It was shown that gas density did not impact on convection dependent ventilation distribution in rats measured with EIT.

Keywords

Electrical impedance tomography Ventilation distribution