Online monitoring of carbon dioxide and oxygen in exhaled mouse breath via substrate-integrated hollow waveguide Fourier-transform infrared-luminescence spectroscopy

Abstract

Exhaled breath offers monitoring bio markers, as well as diagnosing diseases and therapeutic interventions. In addition, vital functions may be non-invasively monitored online. Animal models are frequently used in research for determining novel therapeutic approaches and/or for investigating biological pathways. The exhaled carbon dioxide concentration, exhaled and inhaled oxygen concentration, and the subsequent respiratory quotient (RQ) offer insight into metabolic activity. One may adapt breath sampling systems and equipment designed for human applications to large animal studies. However, such adaptations are usually impossible for small animals due to their minuscule breath volume. Here, we present a system for the online monitoring of exhaled breath in a 'mouse intensive care unit' (MICU) based on a modified Fourier-transform infrared spectrometer equipped with a substrate-integrated hollow waveguide gas cell, and a luminescence-based oxygen flow-through sensor integrated into the respiratory equipment of the MICU. Thereby, per-minute resolution of O consumption and CO production was obtained, and the 95% confidence range of the determined RQ was ±0.04 or approximately ±5% of the nominal value. Changes in the RQ value caused by intervention in either the metabolic or respiratory system may therefore reliably be detected.

From Light Pipes to Substrate-Integrated Hollow Waveguides for Gas Sensing: A Review

“…The sample volume was calculated as 315 μL, and the sensor was applied for an online monitoring of exhaled mouse breath performed in 14 mechanically ventilated and instrumented mice (Figure 12). Seichter et al 54 demonstrated the usage of a compact FTIR-iHWG-based gas sensor to monitor 12 CO 2 / 13 CO 2 and oxygen by a luminescence-based flow-through sensor integrated into the respiratory equipment of the mouse intensive care unit (MICU). These systems are nowadays in routine use in MICU stations and for the first time provide real-time information on the physiological condition of small animals via a noninvasive exhaled breath analysis.…”

The future of basic science in orthopaedics and traumatology: Cassandra or Prometheus?

“…Therefore, multiple efforts have been undertaken to closer simulate the real world in trauma, burn and sepsis research [ 161 ] including international expert consensus initiatives to improve animal modelling [ 162 ] addressing among others the principle of “refinement”. Moreover, the use of a mouse- or pig intensive care unit seems to provide a higher degree of clinical simulation, validity and reliability [ 138 , 163 ]. Furthermore, the better definition of the inflicted injury on well-defined anatomical regions helps to standardize the injury pattern and thus provides a better if not superior comparison with specific human situations [ 164 ].…”

Hybrid Analytical Platform Based on Field-Asymmetric Ion Mobility Spectrometry, Infrared Sensing, and Luminescence-Based Oxygen Sensing for Exhaled Breath Analysis

“…The analysis of 12 CO 2 , 13 CO 2 , and O 2 concentrations, as well as the respiratory quotient (RQ) in mouse breath, has already been enabled by our research team via various analytical tools (i.e., iHWG-FTIR spectroscopy, interband cascade laser based tunable diode laser absorption spectroscopy (TDLAS), and LS) [46,47,48]. Besides these already quantifiable analytes in mouse breath, the detection of additional volatile compounds such as acetone and H 2 S is desirable for therapy monitoring and to aid in understanding the underlying metabolism of traumatized mice.…”