PURPOSE: High flow, highly humidified air delivered to the nasal vestibule via a nasal cannula has been shown to be effective in the neonatal and pediatric age groups for respiratory assistance and appears to decrease work of breathing. Limited evidence has shown similar findings in adults with advanced lung disease. We sought to characterize the effect of this therapy further in patients with advanced COPD.
METHODS: 32 COPD patients were recruited from a VA hospital long-term oxygen therapy clinic. All patients were using either 1 or 2 LPM of nasal cannula oxygen and were clinically stable. After giving informed consent, subjects were given a 30 min washout period off oxygen then randomly assigned to 30 min of breathing their normal oxygen liter flow while sitting in a chair or breathing with the Vapotherm Flowrest at the highest liter flow tolerated between 15 and 35 LPM without supplemental oxygen added. A 30 min washout period was given at the crossover to the other condition. An ABG was drawn at the end of the baseline period and each condition. Other outcomes included continuous pulse-oximetry, average respiratory rate (RR) and heart rate over 2 min at the beginning and end of the baseline period and each condition measured by surface EKG and respiratory inductive plethysmography belts.
RESULTS: All subjects were male. The mean age was 69.4 ± 9.2 years. The mean FEV1 and FEV1/FVC ratio were: 1.16 ± 0.60 L and 45.5 ± 15.7%, respectively. Heart rate showed no change from baseline across conditions. Respiratory rate showed no change from baseline to the oxygen condition but slowed by 11% from baseline to the Flowrest condition (p < 0.0001) and by 13% from the oxygen to the flowrest condition (p < 0.0001). As expected, arterial PaO2 and SaO2 increased in the oxygen condition but did not change significantly from baseline in the Flowrest condition. The constant PaCO2 and PaO2, in spite of a significant decrease in RR, and no evidence suggesting a greater tidal volume, suggests that the Flowrest provided improved CO2 clearance and decreased work of breathing.
CONCLUSIONS: High flow highly humidified air delivered via nasal cannula may decrease work of breathing in advanced COPD patients.
CLINICAL IMPLICATIONS: This study did not assess outcomes but this should be considered for future studies. Longer term trials of Flowrest in advanced COPD are justified and should be conducted.
DISCLOSURE: Charles Atwood: Grant monies (from industry related sources): Vapotherm, Inc.
Thomas Miller: Employee: Vapotherm, Inc
Nicholas McMillan: Employee: Employee
The following authors have nothing to disclose: Kathryn Hartwig, Sharon Camhi, Hobart Schweikert
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