Article Figures & Data
Figures
- Fig. 1.
Raw data from gas sampling at the mouthpiece during quiet breathing (nasal cannula). Left column (A): fractional concentration of carbon dioxide plotted against fractional concentration of oxygen without supplemental oxygen (room air) and with supplemental oxygen (47%) at 4, 6, and 8 L/min. Right column (B): Examples of FO2 and FCO2 in real time from a patient breathing room air, and while breathing supplemental oxygen (47%) at 4, 6, and 8 L/min.
- Fig. 2.
The O2−CO2 diagram of Rahn and Fenn.6 To find the effective fraction of inspired oxygen (effective FIO2) we extrapolate along the gas line to the intersection on the X axis and convert PIO2 (partial pressure of inspired oxygen) to FIO2. I = inspired point. E′ = end-expired point. ̄E = mixed expired point. A = alveolar point. a = arterial point. v̄ = mixed venous point.
- Fig. 3.
Effective fraction of inspired oxygen (effective FIO2) measured at the mouthpiece versus in the trachea. There was excellent correlation, based on 59 paired measurements (r = 0.960, P < .001).
- Fig. 4.
Effective fraction of inspired oxygen (effective FIO2) versus oxygen flow rate with 2 different oxygen supply systems (membrane separator and molecular sieve) and 2 different oxygen delivery systems (nasal cannula and transtracheal catheter). Data are expressed as mean ± SEM.
- Fig. 5.
PaO2 versus oxygen flow. A: Data from all 10 subjects while receiving oxygen only via nasal cannula. B: Data from the 4 subjects who had transtracheal catheter, while they received oxygen only via nasal cannula, and while they received oxygen only via transtracheal catheter. Data are expressed as mean ± SEM.
