A Multivariable Index for Grading Exercise Gas Exchange Severity in Patients with Pulmonary Arterial Hypertension and Heart Failure

Table 1

Model showing individual variables (individual variable index, IVI) that make up the multivariable scoring system. Normal values from literature with delta representing a risk cutoff for each IVI. (MVI = CUM IVI/6).

	Rest PetCO2	ΔPetCO2	SaO2	OUES	𝑉𝐸/VCO2 slope	𝑃CAP
Normal value	40	3.6	94	1.6	26	400
Delta	5	1.8	4	0.24	7	40
Severity: IVI scores	Measured	Measured	Measured	Measured	Measured	Measured	CUM IVI
Normal: 0	40	3.6	94	1.6	26	360	0.00
Normal-mild: 1	35	1.8	90	1.36	33	320	6.00
Mild-moderate: 2	30	0	86	1.12	40	280	12.00
Moderate-severe: 3	25	−1.8	82	0.88	47	240	18.00
Severe-very severe: 4	20	−3.6	78	0.64	54	200	24.00