Effect of oxygen supplementation on cognitive performance among HEMS providers after acute exposure to altitude: the HEMS II randomized clinical trial

Falla, Marika; van Veelen, Michiel J.; Falk, Markus; Weiss, Elisabeth M.; Roveri, Giulia; Masè, Michela; Weber, Bernhard; Randi, Anna; Brugger, Hermann; Hüfner, Katharina; Strapazzon, Giacomo

doi:10.1186/s13049-024-01238-6

Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine

Table 2 Paired t-test of comparison between intervention and control trials

From: Effect of oxygen supplementation on cognitive performance among HEMS providers after acute exposure to altitude: the HEMS II randomized clinical trial

Parameter	Session	n	Intervention		Control		Corrected p-value
Parameter	Session	n	Mean	SD	Mean	SD	paired t-test
SpO₂ (%)	Baseline	36	98.2	1.2	98.2	1.2	0.992
	After 5 min	36	98.0	1.6	86.4	2.2	0.004
	After 30 min	36	97.8	1.5	85.6	2.6	0.004
	Mean	36	97.9	1.6	86.0	2.3	0.004
ScO₂ (%)	Baseline	36	70.0	5.1	70.1	5.1	0.962
	After 5 min	35	69.6	5.9	62.4	5.5	0.004
	After 30 min	34	69.8	5.6	61.4	4.9	0.004
	Mean	35	69.9	5.8	62.1	5.2	0.004
BR (bpm)^a	Baseline	36	17.3	3.0	17.3	3.0	0.950
	After 5 min	36	16.3	3.1	15.7	3.3	0.815
	After 30 min	36	15.9	2.9	15.0	2.9	0.116
	Mean	36	16.1	2.9	15.3	3.0	0.288
HR (bpm)^b	Baseline	36	72.7	10.8	72.2	9.3	0.700
	After 5 min	36	72.7	10.8	77.6	10.3	0.003
	After 30 min	36	70.6	10.8	75.4	10.0	0.003
	Mean	36	71.6	10.7	76.5	10.1	0.003
PVT mean RT (ms)	Baseline	36	279.4	17.6	282.0	17.6	0.230
	After 5 min	36	277.8	16.7	282.5	15.3	0.006
	After 30 min	36	276.9	17.7	280.7	15.0	0.054
	Mean	36	277.3	16.7	281.6	14.5	0.005
PVT performance score	Baseline	36	0.9	0.1	0.9	0.1	0.886
	After 5 min	36	0.9	0.1	0.9	0.1	0.897
	After 30 min	36	0.9	0.1	0.9	0.1	0.845
	Mean	36	0.9	0.1	0.9	0.1	0.867
PVT n of lapses	baseline	36	2.8	3.3	3.0	2.8	0.601
	After 5 min	36	2.2	3.1	2.6	4.7	0.556
	After 30 min	36	2.6	3.5	3.1	3.6	0.430
	Mean	36	2.4	3.1	2.9	3.9	0.413
DSST n of correct responses	Baseline	36	49.8	7.6	48.8	6.8	0.234
	After 5 min	36	50.4	6.1	49.3	6.6	0.096
	After 30 min	36	51.3	7.3	49.9	5.8	0.125
	Mean	36	50.8	6.5	49.6	5.8	0.035
DSST n of incorrect responses	Baseline	36	0.5	0.7	0.8	1.3	0.094
	after 5 min	36	0.7	1.1	0.9	15	0.401
	After 30 min	36	0.8	0.9	1.1	1.7	0.289
	Mean	36	0.7	0.8	1.0	1.2	0.152
2-BACK n of correct responses	Baseline	36	21.1	3.0	21.2	2.5	0.885
	After 5 min	32	21.7	3.1	21.7	2.2	0.924
	After 30 min	34	22.0	2.6	21.7	2.5	0.858
	Mean	35	21.8	2.6	21.7	2.1	0.894
2-BACK n of correct responses (1st part)	Baseline	35	10.5	2.6	10.1	2.5	0.535
	After 5 min	34	11.2	2.3	10.5	2.6	0.344
	After 30 min	33	11.1	2.3	10.7	2.4	0.518
	Mean	36	11.1	1.6	10.7	1.7	0.330
2-BACK n of correct responses (2nd part)	Baseline	35	10.3	2.9	10.6	2.3	0.810
	After 5 min	34	11.1	2.3	11.3	2.5	0.851
	After 30 min	33	10.9	2.1	10.8	2.8	0.875
	Mean	36	11.1	1.5	11.0	1.8	0.861
2-BACK n of missed responses	Baseline	36	2.9	3.0	2.8	2.5	0.585
	After 5 min	36	4.2	6.7	2.9	4.2	0.420
	After 30 min	36	3.3	5.7	2.4	2.5	0.451
	Mean	36	3.7	5.2	2.6	2.9	0.335
2-BACK n of incorrect responses	Baseline	36	1.3	1.8	1.3	1.1	0.833
	After 5 min	36	1.1	1.3	1.3	1.4	0.719
	After 30 min	36	1.5	2.0	1.1	1.3	0.669
	Mean	36	1.3	1.4	1.2	1.0	0.821
2-BACK correct RT mean (ms)	Baseline	36	0.6	0.2	0.6	0.2	0.976
	After 5 min	32	0.6	0.2	0.6	0.2	0.972
	After 30 min	34	0.6	0.2	0.6	0.2	0.966
	Mean	35	0.6	0.2	06	0.2	0.984
2-BACK correct mean RT (1st part) (ms)	Baseline	35	0.7	0.2	0.6	0.2	0.380
	After 5 min	34	0.6	0.2	0.6	0.2	0.980
	After 30 min	33	0.5	0.1	0.6	0.3	0.236
	Mean	36	0.5	0.1	0.6	0.1	0.376
2-BACK correct mean RT (2nd part) (ms)	Baseline	35	0.7	0.2	0.6	0.2	0.841
	After 5 min	34	0.6	0.2	0.6	0.2	0.928
	After 30 min	33	0.5	0.1	0.6	0.2	0.232
	Mean	36	0.5	0.1	0.6	0.1	0.464
2-BACK incorrect RT mean (ms)	Baseline	17	0.8	0.4	0.8	0.5	0.778
	After 5 min	15	0.8	0.3	0.8	0.4	0.709
	After 30 min	13	0.7	0.4	0.6	0.2	0.556
	Mean	25	0.7	0.3	0.7	0.3	0.790
PEGBOARD dominant hand (s)	Baseline	36	57.6	7.5	59.0	8.5	0.317
	After 5 min	36	57.1	6.1	58.3	9.6	0.342
	After 30 min	36	55.1	6.9	56.5	8.0	0.216
	Mean	36	56.1	6.0	57.4	8.2	0.201
VAS stress (range 0–100)	Baseline	36	26.4	18.7	33.8	25.0	0.059
	After 5 min	36	31.2	23.1	36.4	22.4	0.193
	After 30 min	36	30.0	22.9	36.9	24.3	0.062
	Mean	36	30.6	21.1	36.7	21.9	0.069
VAS performance (range 0–100)	Baseline	36	40.8	21.6	43.9	15.3	0.405
	After 5 min	36	34.8	17.0	44.7	19.7	0.021
	After 30 min	36	40.0	19.5	46.0	20.3	0.221
	Mean	36	37.4	17.0	45.3	18.6	0.060
PANAS-P (range 10–50)	Baseline	36	32.9	6.9	30.8	7.3	0.110
	After 5 min	36	31.9	8.0	29.7	9.0	0.141
	After 30 min	36	31.0	7.0	28.4	8.1	0.028
	Mean	36	31.4	7.3	29.1	8.2	0.063
PANAS-N (range 10–50)	Baseline	36	12.2	2.9	11.6	2.0	0.394
	After 5 min	36	11.2	1.3	11.7	2.0	0.238
	After 30 min	36	11.1	2.1	11.4	2.0	0.504
	Mean	36	11.2	1.6	11.5	1.8	0.323
NASA-TLX	Baseline	36	57.7	14.8	58.5	14.4	0.554
	After 5 min	36	57.7	14.8	58.5	14.4	0.554
	After 30 min	36	57.7	14.8	58.5	14.4	0.554
	Mean	36	57.7	14.8	58.5	14.4	0.554

Continuous variables are expressed as mean and standard deviation
p-values are given for each covariate effect on each variable. p-values have been corrected for multiple variable comparisons. p-values < 0.05 are in bold
2-BACK, 2-back Numerical task; bpm^a, beat per minute; bpm^b, breaths per minute; BR, breath rate; DSST, Digit Symbol Substitution Test; HR, heart rate; Mean, mean of values after 5 and 30 min; n, number; NASA-TLX, NASA Task Load Index; O₂, oxygen; PANAS, Positive (P) and Negative (N) Affect Schedule; PEGBOARD, Grooved Pegboard test; PVT, Psychomotor Vigilance Test; RT, reaction time; ScO₂, cerebral oxygenation saturation; SD, standard deviation; SpO₂, peripheral oxygen saturation; VAS, Visual Analogue Scale of subjective performance and stress

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