Acute embolic lower limb ischaemia is associated with decreased red cell deformability

Red cell deformability is an important determinant of peripheral blood flow. In this study the red cell filtration rate (RFR) was measured in 17 patients admitted for acute embolic lower limb ischaemia. The severity of the limb ischaemia on admission was scored from 0 to 6 depending on the degree of pain, and loss of motor and sensibility functions in the ischaemic extremity. Patients who presented with very severe ischaemia on admission underwent early embolectomy whereas those with less severe ischaemia (range from 0 to approximately 3 in ischaemic score) initially were treated conservatively with heparin. Red cell filtration rate was assessed with a standard microfiltration method and expressed in microliters/sec. On admission the RFR averages 30 +/- 5 microliters/sec (mean +/- S.D.), significantly lower than the corresponding value in a normal population of similar age (50 +/- 5 microliters/sec). There was an inverse relationship (r = 0.74, P less than 0.001 by use of linear regression analysis) between the ischaemic score and the RFR on admission, with low RFR values being related to high ischaemic scores. Forty-eight hours after revascularisation, the RFR had improved significantly in the patients having undergone successful revascularisation, whereas it was unchanged in conservatively treated patients. It is concluded that patients with acute embolic lower limb ischaemia have an impaired red cell filtration rate suggesting decreased red cell deformability, the impairment being related to the severity of the ischaemia. A poor red cell filtration rate on admission is related to increased risk of postoperative gangrene and/or cardiac death. Successful revascularisation, but not conservative heparin treatment is associated with increasing deformability.