The Science Journal of the American Association for Respiratory Care

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

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