ALTERED CARDIOVASCULAR PAIN REGULATORY RELATIONSHIPS IN CHRONIC PAIN

In healthy individuals, there is an inverse relationship between resti ng blood pressure (BP) and pain sensitivity. This study examined possi ble dysregulation of this adaptive relation in chronic pain patients, and tested whether the extent of this dysregulation is a function of p ain duration. Continuous resting BPs were assessed for 5 min after a 5 -min rest period in 121 chronic benign pain patients. Unlike the inver se relationship observed previously in normals, mean resting diastolic BPs during the assessment period were correlated positively with rati ngs of pain severity. A Pain Duration x Systolic BP interaction emerge d (p <.05) such that the magnitude of the BP-pain relation was greates t in patients with the longest duration of pain, r(38) =.50, p <.001. A hypothesized progressive alteration in endogenous pain regulatory sy stems in chronic pain patients was supported. A possible role of endog enous opioid dysfunction in accounting for these alterations is discus sed.