Changes in pulmonary oxygen content are detectable with laser absorption spectroscopy: proof of concept in newborn piglets

Abstract

BACKGROUND: Using an optical method based on tunable diode laser absorption spectroscopy, we previously assessed oxygen (O 2) and water vapor (H 2 O) content in a tissue phantom of the preterm infant lung. Here we applied this method on newborn piglets with induced lung complications. METHODS: Five mechanically ventilated piglets were subjected to stepwise increased and decreased fraction of inspired oxygen (FiO 2), to atelectasis using a balloon catheter in the right bronchus, and to pneumothorax by injecting air in the pleural cavity. Two diode lasers (764 nm for O 2 gas absorption and 820 nm for H 2 O absorption) were combined in a probe delivering light either externally, on the skin, or internally, through the esophagus. The detector probe was placed dermally. RESULTS: Calculated O 2 concentrations increased from 20% (IQR 17−23%) when ventilated with room air to 97% (88−108%) at FiO 2 1.0. H 2 O was only detectable with the internal light source. Specific light absorption and transmission patterns were identified in response to atelectasis and pneumothorax, respectively. CONCLUSIONS: The optical method detected FiO 2 variations and discriminated the two induced lung pathologies, providing a rationale for further development into a minimally invasive device for real-time monitoring gas changes in the lungs of sick newborn infants.

Gas in scattering media absorption spectroscopy on small and large scales: Toward the extension of lung spectroscopic monitoring to adults

“…We note that lung oxygen measurements in adults using GASMAS has so far not been possible, due to longer path‐lengths/larger geometries, leading to extremely low light intensities reaching the detector, as compared to the successful measurements on neonatal lungs, previously reported by our research group [31, 32]. The possibility to promptly identify severe lung complications, for example, pneumothorax (collapsed lung due to air leakage in the space between the lung and the chest wall) or atelectasis (collapsed lung due to deflated alveoli), using the GASMAS technique in an animal model has also been demonstrated [35]. The need for a noninvasive, harmless, continuous lung surveillance technique for preterm/ill infants is clear, and there is, of course, a corresponding need for adults, where many patients suffer from severe respiratory disorders, for example, pneumonia, chronic obstructive pulmonary disease, lung fibrosis and more recently the SARS‐CoV‐2 viral infection.…”

“…In scaling up lung monitoring from newborn to larger children or adults, internal light administration is clearly advantageous over light injection from the surface of the chest [33–35]. Internal fiber‐optical light administration would not present any major complication, since the patients mostly in need would anyway be intubated with an endotracheal tube, connected to a ventilator.…”

“…In addition, the specific gas absorption fraction of the total light received is enhanced, since all detected photons must have passed gas‐filled lung structures, and not only surrounding normal tissue. The advantages have recently been demonstrated in phantom work [34] and in a study on anesthetized piglets [35].…”

Initial non-invasive in vivo sensing of the lung using time domain diffuse optics

“…A larger study on 29 newborn infants demonstrated transcutaneous detection of oxygen in the lungs using GASMAS [20]. This approach was further validated also on a piglet animal model [21]. Yet, to the best of our knowledge, so far no non-invasive optical approach has been applied in vivo on the lungs in adults.…”

Highly Sensitive Trace Gas Detection Based on In-Plane Single-Quartz-Enhanced Dual Spectroscopy

“…Trace gas detection has numerous significant applications in various fields, such as biomedical analyses [1,2], combustion diagnosis [3][4][5], atmospheric environmental monitoring [6][7][8][9], as well as petroleum exploration [10,11]. Gas sensing technology based on laser absorption spectroscopy (LAS) has a number of advantages, including high sensitivity, rapid response time, high selectivity, et al [12].…”