Assessment of the peripheral microcirculation using computer-assisted venous congestion plethysmography in post-traumatic complex regional pain syndrome type I

In complex regional pain syndrome type I (CRPS-I), edema of the affected li mb is a common finding. Therefore, the changes in macro- and microcirculato ry parameters were investigated to elucidate the underlying pathophysiology . Twenty-four patients with post-traumatic CRPS-I and 25 gender- and age-ma tched healthy subjects were examined by means of an advanced computer-assis ted venous congestion strain-gauge plethysmograph. The recording of the vol ume response of the forearm to a stepwise inflation of an occlusion cuff pl aced at the upper arm enabled the calculation of the arterial blood flow in to the arm (Q(a)), the vascular compliance (C), the peripheral venous press ure (P-v), the isovolumetric venous pressure (P-vi; = hydrostatic pressure needed to achieve net fluid filtration) and the capillary filtration capaci ty (CFC) - an index of microvascular permeability. The study revealed no di fference in any of the parameters between the right and left hand of health y subjects. In CRPS-I patients, however Qs, Pv, Pvi and CFC were significan tly (p < 0.01/0.001) elevated in the affected arm (Q(a) 11.2 +/- 7.0 ml min (-1) 100 ml(-1), P-v 20.2 +/- 8.1 mm Hg, P-vi 24.7 +/- 4.2 mm Hg, CFC 0.005 8 +/- 0.0015 ml min(-1) 100 ml(-1) mm Hg-1) compared to the unaffected arm (Q(a) 4.2 +/- 2.4 ml min(-1) 100 ml(-1), P-v 10.0 +/- 5.1 mm Hg, P-vi 13.2 +/- 3.7 mm Hg, CFC 0.0038 +/- 0.0005 ml min(-1) 100 ml(-1) mm Hg-1) and the values obtained in healthy controls (Q(a) 5.1 +/- 1.3 ml min(-1) 100 ml(-1 ), P-v 10.4 +/- 4.3 mm Hg, P-vi 15.7 +/- 3.3 mm Hg, CFC 0.0048 +/- 0.0012 m l min(-1) 100 ml(-1) mm Hg-1). Whereas the values in the unaffected arm of CRPS-I patients revealed no difference in Q(a), P-v and P-vi but a lower CF C (p < 0.01) compared to those from healthy controls. These results suggest profound changes in both macro- and microvascular perfusion in the affecte d arm of CRPS-I patients. The high CFC contributes to the edema formation, and combined with the elevated Pvi, they are in agreement with the hypothes is of an inflammatory origin of CRPS. Copyright (C) 2001 S. Karger AG, Base l.