A simple breathing circuit allowing precise control of inspiratory gases for experimental respiratory manipulations

BMC Research Notes

Richard D Hoge¹  Isabelle Lajoie¹  Felipe B Tancredi¹ 

[1]Centre de recherche de l’institut universitaire de gériatrie de Montréal, 4545, Queen Mary, Montreal, QC H3W 1W5, Canada

关键词: Breathing circuit;    Hyperoxia;    Hypercapnia;    Functional MRI;    Respiratory manipulation;   

Others  :  1133751
DOI  :  10.1186/1756-0500-7-235

 received in 2013-10-22, accepted in 2014-04-09,  发布年份 2014

【 摘 要 】

Background

Respiratory manipulations modulating blood flow and oxygenation levels have become an important component of modern functional MRI applications. Manipulations often consist of temporarily switching inspired fractions of CO₂ and O₂; and have typically been performed using simple oxygen masks intended for applications in respiratory therapy. However, precise control of inspired gas composition is difficult using this type of mask due to entrainment of room air and resultant dilution of inspired gases. We aimed at developing a gas delivery apparatus allowing improved control over the fractional concentration of inspired gases, to be used in brain fMRI studies.

Findings

The breathing circuit we have conceived allowed well controlled step changes in FiO₂ and FiCO₂, at moderate flow rates achievable on standard clinical flow regulators. In a two run test inside the scanner we demonstrate that tightly controlled simple gas switching manipulations can afford good intra-subject reproducibility of induced hyperoxia/hypercapnia responses. Although our approach requires a non-vented mask fitting closely to the subject’s face, the circuit ensures a continuous supply of breathable air even if the supply of medical gases is interrupted, and is easily removable in case of an emergency. The apparatus we propose is also compact and MRI compatible, allowing subject placement in confined spaces such as an MRI scanner for brain examinations.

Conclusions

We have reported a new approach for the controlled administration of medical gases, and describe an implementation of the breathing circuit that is MRI compatible and uses commercially available parts. The resultant apparatus allows simple, safe and precise manipulations of FiO₂ and FiCO₂.

【 授权许可】

   
2014 Tancredi et al.; licensee BioMed Central Ltd.

【 图 表 】

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