TABLE 1.
Aerosol particle concentrations of different sizes during conventional nasal cannula therapy and high-flow nasal cannula (HFNC) therapy with and without a mask
Particle size | Conventional nasal cannula# versus HFNC (n=5) | HFNC with versus without a mask (n=6) | ||||||||||
Concentration at 1 foot¶ | Concentration at 3 feet¶ | Concentration at 1 foot¶ | Concentration at 3 feet¶ | |||||||||
Conventional cannula | HFNC | p-value | Conventional cannula | HFNC | p-value | No mask | Mask | p-value | No mask | Mask | p-value | |
≤0.3 µm | 710 212±622 173 | 581 273± 513 067 | 0.138 | 743 822±658 053 | 570 318± 490 647 | 0.043 | 706 247± 510 591 | 706 611± 531 585 | 0.753 | 653 710± 460 070 | 633 964± 439 677 | 0.249 |
0.3–0.5 µm | 29 598±25 464 | 22 914± 18 332 | 0.686 | 36 511±32 609 | 24 666± 20 414 | 0.08 | 23 020± 17 297 | 21 911± 17 796 | 0.046 | 23 275± 18 722 | 21 802± 17 307 | 0.173 |
0.5–1 µm | 2821±1464 | 2744±1317 | 0.50 | 3966±2758 | 2593±1243 | 0.043 | 2575±1124 | 1980±1083 | 0.028 | 2380±1118 | 2053±1082 | 0.173 |
1–3 µm | 913±368 | 876±436 | 0.345 | 943±499 | 732±316 | 0.043 | 758±348 | 544±274 | 0.028 | 647±295 | 501±252 | 0.028 |
3–5 µm | 436±166 | 418±242 | 0.50 | 423±200 | 355±179 | 0.08 | 386±225 | 266±117 | 0.028 | 319±171 | 254±124 | 0.116 |
5–10 µm | 205±77 | 194±127 | 0.50 | 152±86 | 142±80 | 0.225 | 197±177 | 129±65 | 0.173 | 135±114 | 107±58 | 0.753 |
Data are presented as mean±sd. #: conventional nasal cannula therapy was performed at 10–15 L·min−1; ¶: values are indicated in particles per cubic foot. 1 foot=30.5 cm.