Cardiovascular Effect of Cold Pressor Stimulation in Fibromyalgia

Objectives: The purpose of this study was to measure the cardiovascular response induced by a sympathetic activating stressor (cold pressor stimulation : CPS), in fibromyalgia syndrome (FMS) patients and controls. Methods: Ten female FMS subjects and 17 female control subjects were included in this study. The experiment was divided into a) 90-seconds of baseline before CPS, b) 30 seconds of CPS, and c) 240 seconds of recovery (post-CPS). During the CPS the subject's hand-forearm was immersed in 41 F water. A pulse oximeter attached to the ear lobe was used to continuously record heart rate, and intermittent blood pressures (systolic and diastolic) and heart rates were recorded every 60 seconds using an automatic vital signs monitoring device. A non-parametric Welch's ANOVA was performed on these data, since the data displayed unequal variance. Results: The peak of the response to CPS produced a change in baseline pulse of 6.75 and 10.74 bpm, respectively, for FMS and controls (p = 0.038). Group differences were not evident for the systolic or diastolic blood pressures. Conclusions: In summary, these data are clearly suggestive that FMS subjects exhibit a significantly diminished heart rate increase in response to the CPS when compared to the control subjects. These results also suggest that chronic FMS patients have a reduced cardiovascular responsivity to sympathetic stimulation, and this implies a possible desensitization of adrenergic receptors within the cardiovascular system.