Five patients with immunopathologic renal disease, 12 with malignant paraproteinaemia and one with myasthenia gravis underwent a total of 179 plasma exchanges on a continuous flow cell separator. Replacement fluids devoid of coagulation factors were used in 160 exchanges while 19 exchanges were replaced with Fresh Frozen Plasma. Coagulation screening was done immediately before and 30 min after each plasma exchange. Plasma fibrinogen concentrations fell to a mean of 25% of initial levels during individual exchanges. Sequential reduction to 10.7% was observed after five consecutive daily exchanges and in one patient fell to 1.2% after 10 daily exchanges. Low levels of fibrinogen could be maintained with daily or alternate daily exchanges. Platelet counts fell to a mean of 50% of pre-exchange levels during individual exchanges. Consecutive daily exchanges resulted in mean reductions to 20.7% after 5 d, but further reductions were not observed with longer periods of exchange. Platelet counts recovered to pre-exchange values during exchange intervals of 2 or more days. Mild clinical bleeding episodes, probably related to low platelet counts, occurred in one exchange in each of three patients. Haemostasis was rapidly achieved in these patients by infusions of platelet concentrates. Coagulation screening, including prothrombin ratio, thrombin time, reptilase time and partial thromboplastin time with kaolin showed progressively greater abnormalities as the intervals between exchanges shortened. The low incidence of clinical haemorrhagic episodes, three of 179 exchanges (2.2%), despite markedly abnormal coagulation parameters, emphasize the safety of the procedure even in moribund patients. We conclude that the use of FFP in intensive exchange programmes solely for the prevention of spontaneous haemorrhagic phenoma is unjustified.

The effects of intensive plasma exchange on the circulating levels of coagulation factors I, 11, V, VII, VIII, IX, X and antithrombin 111 were determined.During courses of daily exchange marked cumulative reductions of coagulation factors may occur, particularly in the case of factors I, I1 and X, although usually remaining above the levels considered adequate for haemostasis. The extent of cumulative reduction and subsequent recovery differed for patients with different diseases. While antithrombin 111 levels were reduced during plasma exchange the results suggest that this may be partly due to consumption as well as physical removal.The very low incidence of haemorrhagic sequelae and absence of thrombotic events following plasma exchange at this Centre is explained by the maintenance of adequate levels of coagulation factors and of antithrombin 111 even during courses of daily plasma exchange.The effects of intensive plasma exchange with coagulation factor-free replacement fluids on the coagulation profile of patients have been described previously (Keller et al, 1979). Despite the frequent occurrence of grossly abnormal values for coagulation screening tests, fibrinogen and platelet count in such patients, a remarkably low incidence of haemorrhage was observed (2.2% of 179 exchanges). Previous workers have also documented the effects ofsingle plasma exchanges on the level of individual coagulation factors (Bayer et Flaum et at, 1979).In this study the effects of intensive plasma exchange on coagulation factors I (fibrinogen), 11, V, VII, VIII, IX, X and antithrombin 111 have been followed in a heterogenous group of patients. The cumulative effects of exchange every day or every other day on the level of coagulation factors after exchange were determined. In addition coagulator factor levels were determined serially up to 24 h after selected exchanges in all patients. By delineating the kinetics of removal and reappearance of coagulation factors during plasma exchange it was hoped to clarify how normal haemostasis is maintained in patients who, after plasma exchange, exhibit very abnormal coagulation profiles.

No abstract

We have previously reported the production of 3 murine monoclonal reagents for ABO typing (designated ES-9, ES-4 and ES-15). This study presents results of tests of stability of these 3 reagents, together with a fourth murine monoclonal antibody (LM103/107). In addition, data are also presented from a multi-centre evaluation of the performance of the murine monoclonal reagents in routine ABO typing of both donors and patients using a wide variety of techniques, both manual and automated. The potency and stability of the 4 monoclonal antibody based reagents is compared with a broad selection of monoclonal and polyclonal ABO typing reagents. The reagents used for comparison were produced by European and United States manufacturers in both the public and private sector and are widely used in routine ABO typing. The Scottish monoclonal reagents have been used successfully to ABO type over 500,000 blood samples in 7 centres within the UK, with no discrepant results.

SummaryVarious factor IX concentrates have been examined in a number of in vitro tests of thrombogenicity. The results suggest that some tests are superfluous as in concentrates with activity in any of these tests activation is revealed by a combination of the non-activated partial thromboplastin time, the thrombin (or Xa) generation time and factor VIII inhibitor bypassing activity tests. Assay of individual coagulant enzymes revealed that most concentrates contained more factor IXa than Xa. However only a small number of concentrates, chiefly those that had been purposefully activated, contained appreciable amounts of either enzyme.