Intersession repeatability of a novel nasal lavage technique

Pharyngeal Inflammation on Positron Emission Tomography/Magnetic Resonance Imaging Before and After Obstructive Sleep Apnea Treatment

Rationale: There is upper airway inflammation in patients with obstructive sleep apnea (OSA), which reduces with continuous positive airway pressure (CPAP) therapy. Objectives: Validate the use of positron emission tomography (PET)/magnetic resonance imaging (MRI) to quantify metabolic activity within the pharyngeal mucosa of patients with OSA against nasal lavage proteomics and assess the impact of CPAP therapy. Methods: Adults with OSA underwent [18F]-Fluoro-2-deoxy-D-glucose PET/MRI of the neck before and 3 months after initiating CPAP. Nasal lavage samples were collected. Inflammatory protein expression from samples was analyzed using the Olink platform. Upper airway imaging segmentation was performed. Target-to-background ratio (TBRmax) was calculated from target pharyngeal maximum standard uptake values (SUV) and personalized background mean SUV. Most-diseased segment TBRmax was identified per participant at locations with the highest PET avidity. Correlation analysis was performed between baseline TBRmax and nasal lavage proteomics. TBRmax was compared before and after CPAP using linear mixed-effect models. Results: Among 38 participants, the baseline mean age was 46.3 years (standard deviation [SD], 12.5), 21% were female, the mean body mass index was 30.9 kg/m2 (SD, 4.6), and the mean respiratory disturbance index measured by peripheral arterial tonometry was 31 events/h (SD, 16.4). There was a significant positive correlation between pharyngeal mucosa most-diseased segment TBRmax and nasal lavage proteomic inflammation (r = 0.41 [P < 0.001, false discovery rate = 0.002]). Primary analysis revealed a reduction in the most-diseased segment TBRmax after a median of 2.91 months of CPAP therapy (-0.86 [standard error (SE) ± 0.30; P = 0.007]). Stratified analysis by smoking status revealed a significantly decreased most-diseased segment TBRmax after CPAP therapy among never-smokers but not among ever-smokers (-1.01 [SE ± 0.39; P = 0.015] vs. -0.64 [SE ± 0.49; P = 0.201]). Conclusions: CPAP therapy reduces metabolic activity measured by PET/MRI within the upper airway of adults with OSA. Furthermore, PET/MRI measures of upper airway metabolic activity correlate with a noninvasive marker of inflammation (i.e., nasal lavage inflammatory protein expression).

Effect of humidified versus nonhumidified CPAP on inflammatory response and nasopharyngeal symptoms in healthy participants

Introduction

Continuous positive airway pressure (CPAP) may induce nasal inflammation because of mucosal compression or dryness. This study examined the impact of humidified versus nonhumidified CPAP on nasal inflammation and upper airway symptoms.

Methods

Seventeen healthy male subjects with no previous or current history of nasal symptoms were recruited. All subjects underwent 3 hours of nonhumidified CPAP at 12.5 cmH₂O via nasal mask. Among the 17 studied subjects, seven returned to receive a humidified CPAP at 12.5 cmH₂O via nasal mask. The nasal wash leukocyte count was assessed at baseline and after each CPAP setting. The white blood cell (WBC) count and levels of WBCs that are mononuclear cells (including lymphocytes and monocytes) were monitored. A six-point nasal score was also assessed before and after the CPAP intervention.

Results

The nasal wash WBC count (10³/µL) and mononuclear cell level (10³/µL) at baseline, on 12.5 cmH₂O humidified CPAP, and on 12.5 cmH₂O nonhumidified CPAP were significantly different (p = 0.016; p = 0.003). Changes in nasopharyngeal symptoms occurred in 12 of 17 subjects (70.5%) in the nonhumidified group. Participants experienced at least one nasal symptom after application of nonhumidified CPAP at 12.5 cmH₂O.

Conclusion

The present investigation suggests that humidified CPAP was not associated with early nasal inflammation and there were fewer nasopharyngeal symptoms. Further study is required to confirm the results and evaluate the impact of adding heat to the humidified CPAP system.