Table 1.

Summary of clinical studies evaluating the role of oxygen concentrations on outcome after cardiac arrest

Reference	Type	Patients (period)% of HO	OHCA	Definition HO	Evaluation	TH (% treated)	Cutoff a	Outcome	Main results
During CPR
Spindelboeck et al. [26]	R	145 (8 years) 14%	100%	>300 mm Hg	During CPR	NA	NR	In-hospital CPC	Higher rate of hospital admission in hyperoxemic patients
After ROSC
Kuisma et al. [27]	RCT	28 (NA) 50%	100%	1 hour of ventilation at FiO2 100%	24- and 48-hour	No (50%)	No	NSE and S100B	No difference in biomarkers of brain injury
Post-CA care (ICU stay)
Kilgannon et al. [28]	R/D	6,326 (5 years) 18%	43%	First ABG >300 mm Hg	24-hour	NR ≈ 6%	No	In-hospital death	Increased hospital mortality in hyperoxemic patients
								Neurological function
Kilgannon et al. [29]	R/D	4,459 (5 years) 18%	45%	First ABG	24-hour	NR ≈ 6%	No	In-hospital death	Increased hospital mortality for every 100 mm Hg increase in PaO2
								Neurological function
Bellomo et al. [31]	R/D	12,108 (10 years) 11%	68%	Worst (A-a) ΔO2 > 300 mm Hg	24-hour	NR ≈ 33%	No	In-hospital deathb	Hyperoxemia did not affect outcome when adjusted for several confounders.
Janz et al. [32]	R	170 (5 years) ≈ 25%	80%	Highest PaO2	24-hour	Yes	No	In-hospital death	Increased hospital mortality for every 100 mm Hg increase in PaO2
								In-hospital CPC
Ihle et al. [33]	R	584 (5 years) ≈ 6%	100%	Worst (A-a) ΔO2 > 300 mm Hg	24-hour	NR	No	In-hospital death	Hyperoxemia did not affect outcome.
Lee et al. [34]	R	213 (4 years) <3%	83%	Mean PaO2 value	24-hour	Yes	No	In-hospital death	V-shaped association between the mean PaO2 and poor neurologic outcome at hospital discharge
Vaahersalo et al. [35]	P	409 (1 year)	100%	Mean PaO2 value >300 mm Hg	24-hour	Yes (71%)	No	1-year CPC	PaO2 was not correlated to outcome

^aIdentification of an arterial oxygen pressure (PaO₂) threshold to accurately separate patients with good and poor outcome. ^bAfter adjustment on Acute Physiology and Chronic Health Evaluation III (APACHE III) score. (A-a)ΔO₂, alveolo-arterial oxygen difference; ABG, arterial blood gas (analysis); CA, cardiac arrest; CPC, Cerebral Performance Category; CPR, cardiopulmonary resuscitation; FiO₂, inspired oxygen fraction; HO, hyperoxemia; NA, not available; NR, not reported; NSE, neuron-specific enolase; OHCA, out-of-hospital cardiac arrest; P, prospective; R, retrospective; RCT, randomized clinical trial; R/D, retrospective analysis of database; ROSC, return of spontaneous circulation; S100B, protein S100B; TH, therapeutic hypothermia.