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

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. Impact Optical spectroscopy can detect pulmonary complications in an animal model. Oxygen concentrations can be evaluated in the lungs. Presents a novel minimally invasive method to detect lung oxygenation and complications. Potential to be developed into a lung monitoring method in newborn infants. Potential for bed-side detection of pulmonary complications in newborn infants.