In-airway molecular flow sensing: A new technology for continuous, noninvasive monitoring of oxygen consumption in critical care

Abstract

Laser absorption spectroscopy of respired gas offers new opportunities for monitoring critically ill patients.

ICL-based TDLAS sensor for real-time breath gas analysis of carbon monoxide isotopes

“…In accordance with the spectrometer sensitivity, the detection limit for 13 CO in case of a stable background signal was 9 ppbv. This means that, for healthy subjects, e 13 CO concentrations will be close to the detection limit, and e 12 C 18 O will not be measurable.…”

“…The upper curve (solid black line) represents mixed breath collected from a smoker during smoking, whereas the lower spectrum (inverted; solid red line) is from the undiluted 28.24 ppmv CO gas standard, both acquired with an integration time of 10 s. Here, mixed breath was exhaled into an aluminum sample bag directly after inhaling cigarette smoke. The sample contained 117.80 ppmv 12 CO, 1.38 ppmv 13 CO and 274 ppbv 12 C 18 O, which exemplifies the high CO levels in cigarette smoke. The gas standard sample contained 300 ppbv of 13 CO and 63 ppbv 12 C 18 O.…”

“…The sample contained 117.80 ppmv 12 CO, 1.38 ppmv 13 CO and 274 ppbv 12 C 18 O, which exemplifies the high CO levels in cigarette smoke. The gas standard sample contained 300 ppbv of 13 CO and 63 ppbv 12 C 18 O. The noisy baseline in the breath sample suggests residual absorption from unidentified breath or smoke constituents.…”

“…The noisy baseline in the breath sample suggests residual absorption from unidentified breath or smoke constituents. 13 CO in the gas standard diluted to 2 ppmv 12 CO, together with Voigt fit and residual. For both spectra, the sample pressure was 100 Torr.…”

“…This is in contrast to traditional offline sampling, where mixed or end-tidal breath is stored in sample containers for later analysis. Real-time BGA can be used to measure the response to exposure or interventions and extract physiological parameters [10][11][12][13], and to optimize breath sampling procedures. Another important, yet largely unexplored, feature is the possibility to obtain spatially resolved information about the respiratory tract.…”