Haemostatic changes caused by i.v. regional anaesthesia with lignocaine.

The various components of i.v. regional anaesthesia (IVRA), that is ischaemia, tourniquet compression and the presence of high concentrations of local anaesthetics in the blood vessels of the extremity, may affect haemostatic mechanisms. We performed a cross-over study in 10 healthy male volunteers to examine the role of lignocaine in IVRA on several haemostatic variables, and those indicating fibrinolysis and platelet function in particular. Venous blood samples were obtained from the test arm and the opposite arm before IVRA, at the time of tourniquet cuff deflation and 30 min thereafter. Metal needle punctures were used, and for the sample from the test arm at the time of cuff deflation, cuff pressure was reduced from 300 mm Hg to individual mean arterial pressure. The IVRA technique included exsanguination by arm elevation and axillary artery compression, inflation of the tourniquet cuff for 20 min and deflation of the cuff in one step (after obtaining the venous sample). Each subject received, in random order, either 0.5% lignocaine 3 mg kg-1 or the corresponding volume of saline i.v. All fibrinolysis markers, that is, D-dimer, tissue plasminogen activator antigen (t-PA antigen), tissue plasminogen activator activity (t-PA activity), plasminogen activator inhibitor activity (PAI) and protein C indicated enhanced fibrinolysis by IVRA, but only t-PA antigen and PAI showed greater changes in the lignocaine compared with the saline group in the exposed arm at the time of cuff deflation. Platelet function tests (ADP-induced platelet aggregation, beta-thromboglobulin and thrombelastogram (TEG)) indicated no differences between the lignocaine and saline groups. Although IVRA appeared to induce some platelet dysfunction, there was a small increase in TEG amplitude indicative of improved fibrin-platelet interaction in the lignocaine-exposed arm at the time of cuff deflation. We conclude that the presence of high i.v. lignocaine concentrations (median 144.4 micrograms ml-1 in cubital veins at the end of the tourniquet time) potentiated ischaemia-induced fibrinolysis activation during IVRA. Concomitant platelet dysfunction was not aggravated by lignocaine.

Physiological anticoagulants and activated protein C resistance in childhood stroke.

Immunological and functional protein S, protein C and antithrombin III levels and anticoagulant responses to activated protein C were measured in 24 patients with stroke in childhood. No hereditary deficiencies were found. The protein S levels in healthy controls of younger age did not differ from the adult levels. For optimal screening of protein S deficiency, measurements using functional as well as immunological assays are recommended. Appropriate criteria for the diagnosis of the deficiencies must be carefully applied if unnecessary anxiety and inappropriate treatment of children are to be avoided.

Hemostatic factors and replacement of major blood loss with plasma-poor red cell concentrates.

The purpose of this study was to assess the change of platelet and fibrinogen concentrations and the change of activities of prothrombin and factors V and VII when major surgical blood loss was replaced with plasma-poor red cell concentrates (RCCs) and colloid plasma substitutes. Sixty patients were studied. The average blood loss was 65% +/- 41% of the calculated blood volume (CBV). Blood loss was monitored carefully and replaced without delay to ensure stable blood volume. Blood samples were obtained at the induction of anesthesia and at the end of the recovery room period, or before the patient was given fresh frozen plasma. In addition, a platelet count was determined after each 20% blood loss. The results were converted to relative values, and simple linear regression with logarithmic transformation was applied. The initial platelet concentration was 257 +/- 89 x 10(3)/mm3 and the extrapolation of the regression line intercepted the critical level of 50 x 10(3)/mm3 at 230% (confidence interval 169%-294%) blood loss. The initial fibrinogen concentration was 3.7 +/- 1.1 g/L and the hemostatically significant level of 1.0 g/L was already reached at 142% (117%-169%) blood loss (r2 = 0.90). Activities of prothrombin and coagulation factors V and VII reached their critical levels at 201% (160%-244%), 229% (167%-300%), and 236% (198%-277%) blood loss, respectively. We conclude that deficiency of fibrinogen develops earlier than any other hemostatic abnormality when plasma-poor RCCs are used for the replacement of major blood loss.

Haemostatic factors and lipoprotein (a) in three geographical areas in Finland: the Finrisk Haemostasis Study.

BACKGROUND: An increasing volume of evidence suggests that haemostatic factors play a role in the risk of coronary heart disease. It is not known, however, whether between-population differences in haemostatic factors correspond with the differences in mortality related to coronary heart disease. We examined this question in Finland, where, in North Karelia (in the eastern part of the country), the mortality from coronary heart disease is 1.5-1.7 times higher than that in southwestern areas. METHODS: A random sample of 3000 people aged 45-64 years was drawn from the population registers of North Karelia, of the area surrounding Turku and Loimaa in southwestern Finland and of the Helsinki area in southern Finland. Of the 3000 people approached, 79.6% took part in the study. differences in coronary heart disease mortality and morbidity. RESULTS: Factor-VII coagulant activity was significantly higher in North Karelia than in the other areas (P = 0.0008). The fibrinogen level was also higher in North Karelia, although the difference was significant only among non-smokers (P = 0.02). Levels of factor-VII antigen, plasminogen and lipoprotein (a) did not differ between the areas. Within North Karelia, the levels of both factor-VII coagulant activity, and factor-VII antigen were higher in rural areas than in urban areas. Levels of factor-VII coagulant activity, factor-VII antigen and plasminogen were higher in women than in men and increased with age in women but not in men. The fibrinogen level increased with age in both sexes. CONCLUSION: These baseline findings of the Finrisk Haemostasis Study demonstrate that the geographical differences in levels of factor-VII coagulant activity and fibrinogen in Finland are consistent with the population

Fibrinolytic defect in chronic back pain. A controlled study of plasminogen activator activity in 20 patients.

We analyzed the fibrinolytic system in patients with chronic low back pain using a venous occlusion test to stimulate fibrinolysis, and we subsequently determined the levels of tissue plasminogen activator (TPA) and fast-acting inhibitor of TPA (PAI). There were 20 patients with a mean age of 50 years. Two thirds had radiographically spinal stenosis. Scar tissue around the spinal nerves was seen in 11 cases. Thirteen patients had undergone back surgery, whereas 21 healthy subjects served as controls. In the basal samples, TPA activity was decreased in the patients while TPA antigen level was increased compared with the controls. No clear explanation for this defective function of TPA in the patients was obtained, because no difference was seen in PAI level in basal samples. After the venous occlusion, no difference was observed in TPA activity between the two groups excluding the constitutionally defective fibrinolytic system in the patients. However, our results confirm low basal fibrinolytic activity in patients with chronic low back pain with manifest spinal pathology.