Table 4. Summary of statistical distribution for arterial blood biochemistry values (t_2-7).

Parameters	Mean	SEM	Min.	Q1	Median	Q3	Max.	n	Friedman test p-value
pH	7.455	0.010	7.193	7.418	7.473	7.506	7.557	48	0.744
HCO3- (mmHg)	31.3	0.3	25.3	30.5	31.6	32.5	34.6	48	0.003
Lactate (mmol/l)	2.29	0.33	0.57	1.05	1.34	1.94	9.21	48	0.003
BEecf (mmol/l)	7.3	0.4	0	6	8	9	11	48	0.021
SaO2 (%)	99.5	0.3	88	100	100	100	100	48	0.335
PaO2 (mmHg)	203	7.7	69	164	204	247.5	290	48	0.014
PaCO2 (mmHg)	44.8	0.9	34.6	40.5	43.6	48.2	72.4	48	0.235
ETCO2	32.5	0.3	27	32	33	34	36	48	0.002

Descriptive statistics like mean, standard error of the mean (SEM), minimum (Min.), 25th percentile (Q₁), median, 75th percentile (Q₃), maximum (Max.), and number of observations (n) for each cardiopulmonary parameter measure over the six hours of mechanical ventilation with Masi (t_2-7) were summarized below. Significant differences when using the Friedman test to analyse differences among t_2-7 were established at p-value <0.05. pH: potential of hydrogen, HCO₃^-: bicarbonate ion, BEecf: base excess in the extracellular fluid compartment, SaO₂: arterial oxygen saturation, PaO₂: arterial oxygen pressure, PaCO₂: arterial carbon dioxide pressure, ETCO₂: end-tidal carbon dioxide.