To compare the hemodynamic and ventilatory responses to autonomic challenge evoked by upright tilt table testing in patients with chronic fatigue syndrome (CFS) to healthy individuals.
Thirty-two consecutive patients with CFS and 32 healthy volunteers were evaluated with the aid of the recently introduced capnography head-up tilt test (CHUTT). The main outcome measures were values of blood pressure (BP), heart rate (HR), respiratory rate (RR), and end-tidal pressure of co2 (ETPco2) recorded during recumbence and tilt. In addition, the end points of vasodepressor and cardioinhibitory reactions, hyperventilation (defined by ETPco2 <25 mm Hg) and the postural tachycardia syndrome, were recorded.
The BP, HR, RR, and ETPco2 recorded during recumbence were similar in both groups. During tilt, patients with CFS developed significantly lower systolic BP, diastolic BP, and ETPco2, and a significant rise in HR and RR (P<.01). In CFS patients, the postural tachycardia syndrome occurred in 44%, vasodepressor reaction in 41%, cardioinhibitory reaction in 13%, and hyperventilation in 31% of cases. One or more end points of the CHUTT were reached in 78% of patients with CFS but in none of the controls (P<.0001).
In most patients with CFS, a spectrum of abnormal homeostatic reactions is diagnosed with the aid of the CHUTT. Data provided by the CHUTT may reinforce the clinical diagnosis by adding objective and unbiased criteria to the subjective assessment of CFS.