A novel approach toward noninvasive monitoring of transcutaneous CO2

Abstract

The continuous monitoring of transcutaneous gases is an integral part of neonatal intensive care. Present monitors measure the equilibrating values of these gases by raising the skin temperature to 42°C or above. Because neonatal skin is very sensitive and delicate, this often leads to serious skin injuries. In this work, we present a new approach to the noninvasive measurement of transcutaneous partial pressure of carbon dioxide (tcpCO2) based on the initial pseudo steady state diffusion rates instead of the mass-transfer equilibrium. Because we are following initial diffusion rates, each measurement takes no more than a few minutes. Additionally, raising the surface temperature is not required, thus, skin irritation and burns are highly unlikely. A dual-chamber diffusion vessel with either porcine skin or dialysis membrane placed between the two chambers was used to mimic neonatal skin. LI-820 CO2 Analyzer was used to measure the CO2 diffusing through the membrane or skin. Initial experiments on adult human skin under varying physical activities, food intake and breathing patterns showed a strong influence of the various conditions on the amount of CO2 diffusing through skin. These initial findings suggest that this method can be used not only on neonates but to a wider population of patients.

Carbon Dioxide Sensing—Biomedical Applications to Human Subjects

“…The NDIR track was then dropped until the mid-2010s and the advent of rate-based approaches by the team of Chatterjee, Ge, Iitani et al [ 317 , 318 , 319 , 320 ] at first and by the team of Grangeat et al [ 321 , 322 ] in a second move. If the latter work is insufficiently detailed—especially the explanations concerning the sensing part itself—the former allows for a sound understanding of the rate-based approach.…”

“…Thus, NDIR sensing can be used instead of a dye-based thin film, with better lifetime, accuracy, and selectivity over the latter. These advantages made NDIR sensing the foremost choice of the authors who considered using a rate-based approach for transcutaneous CO sensing [ 317 , 318 , 319 , 321 , 322 ].…”

“…Further still, the recent work of Iitani et al [ 320 ] clearly illustrates the afore-mentioned inter-subject variability with a factor of more than ten between the exhalation rates of two subjects (S2 and S6 on their Figure 4-H). There may be an exception concerning neonates, however, whose exceedingly thin skin may be more homogeneous than that of adults, leading to less variability in their skin CO exhalation rate, and allowing Chatterjee et al [ 317 ] to demonstrate a significant correlation between skin CO exhalation rate and tcpCO .…”

Development and characterization of a point-of care rate-based transcutaneous respiratory status monitor

“…Its S/N was estimated to be 2.1 for CO 2 and 0.5 for O 2 when it is used for measurements on adults. So, although it has been successfully used for preterm neonates [15,16], it is too small for adults and the measurement results could be unreliable.…”

Noninvasive carbon dioxide monitoring in pediatric patients undergoing laparoscopic surgery: transcutaneous vs. end-tidal techniques

“…Therefore, the PtcCO 2 monitor needs further improvement to facilitate its use during the perioperative period. Some studies have reported that PtcCO 2 monitoring techniques are not based on electrochemical principles [ 34 – 36 ]. Because of the different monitoring mechanisms, the local heating on the skin is avoided, and the time required for calibration and stabilization is short, rendering the monitors convenient to use.…”