Figure 1.

Plot of fraction of hemoglobin (red lines) and myoglobin (black lines) that is occupied by CO as a function of P_CO, for a fixed ${\mathrm{P}}_{{\mathrm{O}}_2}$ of 95 mmHg (solid lines), 50 mmHg (long-dashed lines), and 20 mmHg (dot-dashed lines). The black, horizontal dashed line indicates that for a fixed HbCO fraction of 0.2, the equilibrium P_CO is 0.112 mmHg for a ${\mathrm{P}}_{{\mathrm{O}}_2}$ of 95 mmHg, and decreases to a P_CO of 0.047 mmHg when the ${\mathrm{P}}_{{\mathrm{O}}_2}$ decreases to 20 mmHg.

Abbreviations: ${\mathrm{P}}_{{\mathrm{O}}_2}$, O₂ partial pressure; Hb, hemoglobin; HbCO, CO-bound Hb; P_CO, CO partial pressure.