Assessment of Airway Inflammation in Real World Patients Undergoing Hyperbaric Oxygen Therapy

Abstract

Background: Patients undergoing hyperbaric oxygen therapy (HBOT) breathe 100% oxygen at a higher atmospheric pressure level (ATA) resulting in having O₂ molecules to dissolve into the plasma almost 15 times higher than normal. Thus patients should experience some degree of biochemical toxicity resulting in airway inflammation (AI) and having nitric oxide (NO) levels to be regarded as an indirect marker for up-regulation of AI. Previous studies assessed Fraction of Exhaled Nitric Oxide Levels (F_ENO) pre and post HBOT in either animal or healthy human studies. The purpose of this study is to assess the changes and trend values in F_ENO values among unhealthy patients undergoing HBOT in the clinical setting noninvasively. Methods: This study is approved by Loma Linda University Health Institutional Review Board. Inclusion criteria were any patients referred to HBOT for any indication, conscious and able to perform F_ENO test, and 18 years or older. Critically ill patients were excluded. Subjects who are referred to receive HBOT were recruited to the study. F_ENO levels were measured pre and post HBOT at baseline and every 5 treatment sessions (i.e. 1, 5, 10). HBOT total ordered sessions varied based on the indication. F_ENO was measured using NIOX VERO device by Circassia. Results: A total of 7 subjects were recruited into the study, 2 were excluded due to the inability to perform the F_ENO test. Mean age was 54.2 ± 18.8, 3, (60%) female. The mean ATA level was 2.3 ± 0.27 with 90 minutes of total treatment time. HBOT indications were soft tissue radiation necrosis (n = 2), hearing loss (n = 1), necrotizing soft tissue (n = 1), and osteomyelitis (n = 1). A total of 43 data points were collected. The mean and standard deviation (SD) of all F_ENO levels at baseline was (Pre = 23.6 ± 8.9; Post = 21.3 ± 14.5), table1. Significance were found in two subjects at treatment 15, and 25 (P < .001), between baseline to treatment 15 (n = 3; P = .058), between baseline to treatment 25 (n = 2; P < .001). Overall, no significant changes were seen in F_ENO levels pre and post HBOT sessions (P > .05) in all subjects from baseline to their last session. Conclusions: The results in this ongoing study shows that HBOT causes no significant changes in F_ENO level trends in real-world patients. Significant changes were only seen in some patients midway between baseline and treatment 15 and 25. More research having a higher sample size and data points should help us understand the trends in F_ENO levels more clearly.