2003 OPEN FORUM Abstracts
A Comparison of Oxygen Concentrations During Oral and Nasal Breathing Via Low Flow and High Flow Nasal Cannula
Richard B. Wettstein, BS, RRT; Claudia Cantu, BS, CRT; Lizzette Benavidez, BS, CRT; Janna Rodriguez, BS, CRT; David C. Shelledy, PhD, RRT; Jay I. Peters, MD. The University of Texas Health Science Center at San Antonio, Texas.
INTRODUCTION: Nasal Cannula (NC) are often used to deliver oxygen in the acute and chronic care settings. We compared the oxygen concentrations (OC) delivered by Adult NC (Salter Labs REF1600 @1-6 L/min and Salter Labs REF 1600HF @ 6-15 L/min) during oral and nasal breathing. We measured the pharyngeal OC in 10 normal subjects receiving O2 by these two devices consecutively.
METHOD: O2 by NC was initiated at 1 L, with the subjects at rest, breathing through their noses. Three gas samples were aspirated from a nasal catheter positioned with the tip in the nasopharynx. The same procedure was followed with the subject breathing through their mouth. This process was repeated at each L flow.
RESULTS: The mean (SD) and range for OC at prescribed flow rates were:
| Flow L/Min | Nasal | Oral | Significance | |||
| Mean (SD) | Range | Mean (SD) | Range | t-value | p | |
| Low Flow 1 | 23.8 (2.7) | 21-32 | 27.5 (6.2) | 20-45 | -3.04608 | 0.003485 |
| 2 | 29.8 (4.2) | 22-41 | 37.5 (8.5) | 24-53 | -4.48528 | 0.000035 |
| 3 | 35.2 (5.8) | 27-47 | 42.8 (11.0) | 29-69 | -3.36272 | 0.001372 |
| 4 | 39.7 (8.0) | 28-58 | 50.0 (10.9) | 31-74 | -4.17798 | 0.000100 |
| 5 | 45.0 (8.8) | 32-64 | 56.2 (13.2) | 33-83 | -3.86204 | 0.000286 |
| 6 | 47.9 (7.6) | 36-66 | 59.6 (11.7) | 40-86 | -4.60599 | 0.000023 |
| High Flow 6 | 46.6 (8.1) | 35-64 | 62.2 (12.3) | 37-89 | -5.78578 | 0.000000 |
| 7 | 51.1 (7.4) | 35-68 | 64.2 (14.0) | 42-85 | -4.54252 | 0.000029 |
| 8 | 50.0 (8.0) | 33-70 | 65.9 (13.5) | 39-87 | -5.55504 | 0.000001 |
| 9 | 55.8 (10.5) | 38-80 | 70.7 (12.0) | 44-89 | -5.12221 | 0.000004 |
| 10 | 58.7 (10.9) | 40-82 | 72.7 (10.7) | 51-88 | -5.04094 | 0.000005 |
| 11 | 60.1 (11.6) | 36-80 | 74.5 (13.7) | 41-91 | -4.38967 | 0.000049 |
| 12 | 61.9 (12.1) | 37-82 | 75.5 (12.4) | 41-93 | -4.33252 | 0.000059 |
| 13 | 64.4 (10.6) | 42-84 | 77.4 (13.3) | 47-96 | -4.16021 | 0.000106 |
| 14 | 67.8 (11.9) | 41-85 | 78.7 (10.7) | 47-89 | -3.73612 | 0.000429 |
| 15 | 69.8 (10.4) | 39-97 | 80.6 (13.3) | 49-98 | -3.49039 | 0.000929 |
CONCLUSION:
FIO2 delivered by NC varied widely between subjects. The evidence suggests that mouth breathers attain a statistically significant (p>0.05) higher FIO2 compared to nose breathers.
Departmental Funding