Table 2.

The factors related to CO elimination.

Field	Factor	Results	Experiment	Control	Reference
Environment	CO concentration increase	CO half-life longer	200.8 CO ppm for 60 min	51.6 CO ppm for 60 min	Peterson and Stewart (1970)
	Duration of exposure longer	CO half-life longer	1250 CO ppm for 40 min	10,000 CO ppm for 5 min	Bruce and Bruce (2006)
			(same CO dose in two groups)
	O2 concentration increase	CO half-life shorter	100% oxygen	-	Weaver et al. (2000)
			2.5 atm, 100% oxygen (HBO)	-	Pace et al. (1950)
Demography	Age increase	No difference	Range: 9–86 years old		Burney et al. (1982)
			>40 years old	<40 years old	Weaver et al. (2000)
		CO half-life shorter	4–12 years old	-	Klasner et al. (1998)
	Sex	No difference	Female	Male	Burney et al. (1982)
			Female	Male	Weaver et al. (2000)
		CO half-life shorter	Female	Male	Pace et al. (1950)
			Female	Male;	Zavorsky et al. (2014)
	Smoking	No difference	Smokers	Nonsmokers	Burney et al. (1982)
Physiology	Ventilation rate increase	CO half-life shorter	Range: 4–10 L/min		Coburn et al. (1965)
			15 and 30 L/min	3 and 6 L/min	Selvakumar et al. (1993)
			Range: 5–20 L/min		Kreck et al. (2001)
			Range: 4–40 L/min		Zavorsky et al. (2014)
	Chronic obstructive pulmonary disease (COPD)	No difference/CO half-life slightly longer	COPD patients	Normal subjects	Crowley et al. (1989)
	Blood volume increase	CO half-life shorter	-	-	Coburn et al. (1965)
			Range: 0.3–0.7 (Vb/VAwo)		Bruce and Bruce (2006)
	Haemoglobin mass increase	CO half-life longer	Male	Female	Zavorsky et al. (2014)
	Diffusion rate of CO flux from blood to muscle compartment increase	CO half-life shorter	Range: 0–2 mL/min/torr		Bruce et al. (2003)
	Muscle mass	Less important	-	-	Bruce and Bruce (2006)
	Anaemia	CO half-life shorter	Anaemia	Polycythaemia	Zavorsky et al. (2014)
Treatment	100% oxygen	CO half-life shorter	100% oxygen	-	Weaver et al. (2000)
	High-flow nasal cannula (HFNC)	No difference	100% oxygenwith high flow	100% oxygen	Kim et al. (2019)
	Continuous positive airway pressure (CPAP)	CO half-life shorter	100% oxygenwith positive pressure	100% oxygen	Bal et al. (2019)Caglar et al. (2019)
	Hyperbaric oxygen (HBO) therapy	CO half-life shorter	2.5 atm, 100% oxygen	-	Pace et al. (1950)
			3 atmosphere absolute (ATA), 100% oxygen	1 ATA, 100% oxygen	Peterson and Stewart (1970)
	Carbogen	CO half-life shorter	Hyperventilation(6% CO2 in O2)	Without isocapnia	Sein Anand et al. (2017)

Note: 1 torr = 1 mmHg, a unit of pressure based on an absolute scale.