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

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

Ventilation distribution in rats: Part 2 – A comparison of electrical impedance tomography and hyperpolarised helium magnetic resonance imaging

“…[ 14 ] In a previous study using EIT we have shown, that measurement of regional ventilation distribution and ventilation in homogeneity was not affected by gas density. [ 6 ] This current study was a direct comparison between He3 MRI and EIT with inhalation gases of similar density.…”

“…Measurements were taken at 44 frames per second with a 100 kHz, 5mA pk-pk current. Data were processed as previously described [ 6 ].…”

Ventilation distribution in rats: Part 2 – A comparison of electrical impedance tomography and hyperpolarised helium magnetic resonance imaging

“…[ 14 ] In a previous study using EIT we have shown, that measurement of regional ventilation distribution and ventilation in homogeneity was not affected by gas density. [ 6 ] This current study was a direct comparison between He3 MRI and EIT with inhalation gases of similar density.…”

“…Measurements were taken at 44 frames per second with a 100 kHz, 5mA pk-pk current. Data were processed as previously described [ 6 ].…”

Deposition of Particles

“…The position in which rats are exposed may also influence the regional delivery and deposition of inhaled aerosols. In rats, the nondependent region of the lung has been reported to be better ventilated, whether positioned supine, prone, or on either side (Rooney et al, 2009;Dunster et al, 2012). In humans, ventilation patterns are affected by both body position and lung inflation.…”

Mesenchymal stromal cells and the acute respiratory distress syndrome (ARDS): challenges for clinical application

“…It is recognised that ventilation in rodents differs from humans14 15 and moreover genomic responses in mouse models correlate poorly with human inflammatory diseases 16. One approach to compliment and advance the data from small animal models is to use a large animal ovine model of ARDS, which most closely represents human pulmonary physiology 17…”

Ventilation distribution in rats: Part 2 – A comparison of electrical impedance tomography and hyperpolarised helium magnetic resonance imaging

“…[ 14 ] In a previous study using EIT we have shown, that measurement of regional ventilation distribution and ventilation in homogeneity was not affected by gas density. [ 6 ] This current study was a direct comparison between He3 MRI and EIT with inhalation gases of similar density.…”

“…Measurements were taken at 44 frames per second with a 100 kHz, 5mA pk-pk current. Data were processed as previously described [ 6 ].…”

Deposition of Particles

“…The position in which rats are exposed may also influence the regional delivery and deposition of inhaled aerosols. In rats, the nondependent region of the lung has been reported to be better ventilated, whether positioned supine, prone, or on either side (Rooney et al, 2009;Dunster et al, 2012). In humans, ventilation patterns are affected by both body position and lung inflation.…”

Mesenchymal stromal cells and the acute respiratory distress syndrome (ARDS): challenges for clinical application

“…It is recognised that ventilation in rodents differs from humans14 15 and moreover genomic responses in mouse models correlate poorly with human inflammatory diseases 16. One approach to compliment and advance the data from small animal models is to use a large animal ovine model of ARDS, which most closely represents human pulmonary physiology 17…”

Ventilation distribution in rats: Part 2 – A comparison of electrical impedance tomography and hyperpolarised helium magnetic resonance imaging

“…[ 14 ] In a previous study using EIT we have shown, that measurement of regional ventilation distribution and ventilation in homogeneity was not affected by gas density. [ 6 ] This current study was a direct comparison between He3 MRI and EIT with inhalation gases of similar density.…”

“…Measurements were taken at 44 frames per second with a 100 kHz, 5mA pk-pk current. Data were processed as previously described [ 6 ].…”

Deposition of Particles

“…The position in which rats are exposed may also influence the regional delivery and deposition of inhaled aerosols. In rats, the nondependent region of the lung has been reported to be better ventilated, whether positioned supine, prone, or on either side (Rooney et al, 2009;Dunster et al, 2012). In humans, ventilation patterns are affected by both body position and lung inflation.…”

Mesenchymal stromal cells and the acute respiratory distress syndrome (ARDS): challenges for clinical application

“…It is recognised that ventilation in rodents differs from humans14 15 and moreover genomic responses in mouse models correlate poorly with human inflammatory diseases 16. One approach to compliment and advance the data from small animal models is to use a large animal ovine model of ARDS, which most closely represents human pulmonary physiology 17…”