Oxygen With Cold Bubble Humidification Is No Better Than Dry Oxygen in Preventing Mucus Dehydration, Decreased Mucociliary Clearance, and Decline in Pulmonary Function.

BACKGROUND: Little is known about the effects of long-term nasal low-flow oxygen (NLFO) on mucus and symptoms and how this variable is affected by dry or cold humidified gas. The aim of this study was to investigate the effects of dry-NLFO and cold bubble humidified-NLFO on nasal mucociliary clearance (MCC), mucus properties, inflammation, and symptoms in subjects with chronic hypoxemia requiring long-term domiciliary oxygen therapy. METHODS: Eighteen subjects (mean age, 68 years; 7 male; 66% with COPD) initiating NLFO were randomized to receive dry-NLFO (n = 10) or humidified-NLFO (n = 8). Subjects were assessed at baseline, 12 h, 7 days, 30 days, 12 months, and 24 months by measuring nasal MCC using the saccharin transit test, mucus contact angle (surface tension), inflammation (cells and cytokine concentration in nasal lavage), and symptoms according to the Sino-Nasal Outcome Test-20. RESULTS: Nasal MCC decreased significantly (40% longer saccharin transit times) and similarly in both groups over the study period. There was a significant association between impaired nasal MCC and decline in lung function. Nasal lavage revealed an increased proportion of macrophages, interleukin-8, and epidermal growth factor concentrations with decreased interleukin-10 during the study. No changes in the proportion of ciliated cells or contact angle were observed. Coughing and sleep symptoms decreased similarly in both groups. There were no outcome differences comparing dry vs cold bubble humidified NLFO. CONCLUSIONS: In subjects receiving chronic NLFO, cold bubble humidification does not adequately humidify inspired oxygen to prevent deterioration of MCC, mucus hydration, and pulmonary function. The unheated bubble humidification performed no better than no humidification. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT02515786; URL: www.clinicaltrials.gov.

Mucociliary clearance is impaired in acutely ill patients.

OBJECTIVE: This study aimed to investigate nasal mucociliary clearance in acutely ill patients who were clinically stable and had no airway manipulation. DESIGN: Prospective clinical study. SETTING: Medical ICU. PATIENTS AND PARTICIPANTS: Sixteen medical patients admitted to the ICU and 16 healthy subjects were studied. Patients who were receiving airway manipulation, including tracheal suctioning, nasogastric or enteral tubes, noninvasive and invasive mechanical ventilation, were excluded. INTERVENTIONS: Mucociliary clearance was evaluated by saccharine transit time (STT) measurements at ICU admission (admission) and 90 days after hospital discharge (recovery). Healthy subjects were also subjected to two measurements 90 days apart. MEASUREMENTS AND RESULTS: The STT of patients was 26.4 +/- 11.3 min and 17.9 +/- 8.6 min at admission and recovery (p = 0.002) [mean +/- SD] but did not change along the 90-day interval in healthy subjects (17.2 +/- 10.2 min and 16.7 +/- 10.3 min), respectively. Smokers (patients and healthy subjects) presented prolonged STT when compared to nonsmokers (p = 0.026). STT at admission correlated positively with heart rate (r = 0.560; p = 0.024) and hospital stay (r = 0.634; p = 0.008). CONCLUSION: Mucociliary clearance is impaired in stable acutely ill patients with no airway manipulation and correlates with simple markers of underlying disease severity. Mucociliary dysfunction may help to explain the increased susceptibility of hospital-acquired respiratory infection in critically ill patients.