Table 4.

Performance of SpO₂/FiO₂ and ultrasound interstitial syndrome (UIS) as a marker for with acute respiratory distress syndrome (ARDS) criteria when SpO₂ ≤ 97 %

		Number of observations (n = 33)		Test characteristic		95 % CI
Study physician		Oxygenation and radiographic criteria for ARDS
		Present	Absent	Sensitivity	83 %	52–98
SpO2/FiO2 ≤ 315 and UIS	Present	10	8	Specificity	62 %	38–82
	Absent	2	13	PPV	56 %	31–79
				NPV	87 %	60–98
		Oxygenation and radiographic criteria for moderate–severe ARDS
		Present	Absent	Sensitivity	64 %	31–89
SpO2/FiO2 ≤ 235 and UIS	Present	7	3	Specificity	86 %	65–97
	Absent	4	19	PPV	70 %	35–93
				NPV	83 %	61–95
Independent physician		Oxygenation and radiographic criteria for ARDS
		Present	Absent	Sensitivity	91 %	62–100
SpO2/FiO2 ≤ 315 and UIS	Present	11	11	Specificity	48 %	26–70
	Absent	1	10	PPV	50 %	28–72
				NPV	91 %	59–100
		Oxygenation and radiographic criteria for moderate–severe ARDS
		Present	Absent	Sensitivity	73 %	39–94
SpO2/FiO2 ≤ 235 and UIS	Present	8	5	Specificity	77 %	55–92
	Absent	3	17	PPV	62 %	32–86
				NPV	85 %	62–97

UIS defined as 3 or more B lines bilaterally and involving a minimum of three lung fields. CI confidence interval, FiO ₂ fraction of inspired oxygen, NPV negative predictive value, PaO ₂ partial pressure of oxygen, PPV positive predictive value, SpO ₂ pulse oximetric oxygen saturation