The effect of high flow nasal cannula oxygen therapy on middle ear pressure

To investigate the effect of high flow nasal cannula oxygen therapy (HFOT) on middle ear pressure.

Ten patients (eight males and two females) with oxygen desaturations requiring HFOT were recruited with 19 ears available for our study. The study group was aged 29-90years (mean 65.3±16.5). All patients underwent a review of medical history, questioned about subjective hearing loss and underwent a standard otologic exam, with middle ear pressures measured with a GSI TympStar tympanometer.

The middle ear peak pressures in our study group ranged from 25 to -200daPa (mean -13.7±56.3daPa). Volume of HFOT was delivered at 20-40L (mean 30.5±9L) and fraction of inspired oxygen required was 30-70% (mean 58±13%). There was a positive correlation between liters of oxygen delivery and middle ear pressure with a Pearson coefficient (R) of 0.436, although lacking statistical significance (p=0.06).

Previous studies have shown that HFOT delivered in the range of 35-40L/min produces pharyngeal pressures at or above 5cm H2O. Since pharyngeal pressures of 5cm H2O produced via CPAP have shown to produce middle ear pressures above 40daPa, we expected HFOT to result in similar middle ear pressures of 35-40L/min. However, although our results show an increase in middle ear pressures with flow volume, HFOT did not produce significant increases in middle ear pressures. This may make HFOT an appropriate option of oxygen delivery to patients who require otologic procedures.