Table 3

Sensitivity, specificity, and positive predictivity of respiratory gas exchange results (the values while standing and the change from supine to standing) during the orthostatic tolerance test for the diagnosis of HVS

Parameter Cut off level Sensitivity (%) Specificity (%) Positive predictivity (%)
Fetco 2 <4%877782
ΔFetco 2 <–0.5%819293
e/V˙o 2 >3793100100
ΔV˙e/V˙o 2 >575100100
e/V˙co 2 >476910092
ΔV˙e/V˙co 2 >5699292
  • Fetco 2 = end expiratory tidal CO2 fraction;V˙e/V˙o 2,V˙e/V˙co 2 = ventilatory equivalents for O2 and CO2; sensitivity = true positives/(true positives + false negatives)%; specificity = true negatives/(true negatives + false positives)%; positive predictivity = true positives/(true positives + false positives)%.

  • Estimates are based on test result distributions of patients with HVS (n = 16) and healthy controls (n = 13).