The advised regimen of plasma exchange removes a total of 200 to 250 mL/kg of plasma in 4 to 6 treatments on alternate days, or over a shorter period if there is no coagulopathy. The replacement fluid is saline combined with 5 percent albumin. The need for large-bore venous access usually requires the insertion of a double-lumen subclavian or internal jugular catheters and this may be the main source of complications (pneumothorax, infection, hemorrhage). In some patients, treatment can be instituted, and sometimes the entire course completed, through the antecubital veins. During and after the procedure, hypotension, hypoprothrombinemia with bleeding and cardiac arrhythmias may occur. Some units measure the level of fibrinogen, which is greatly reduced by exchanges, before the next exchange to gauge to the risk of potential hemorrhage. Reactions to the citrate that is used to prevent blood from clotting in the plasma exchange machine are common but can be obviated by the cautious addition of calcium to the intravenous return line. Hepatitis and HIV are not risks if plasma is replaced with albumin and saline rather than with pooled plasma.
As effective as plasma exchange is, IVIg (0.4 g/kg per day for 5 consecutive days) is easier to administer and probably safer because there is no need for large intravenous access. The results of the first trial conducted by van der Meché and colleagues were corroborated in an international study led by Hughes, in which we participated (see Plasma Exchange/Sandoglobulin Guillain-Barré Syndrome Trial Group). That trial compared plasma exchange to IVIg and also evaluated their use sequentially. There was a tenuous trend toward a better outcome in patients who received plasma exchange and results were perhaps slightly better in a group who were treated with plasma exchange followed immediately by 5 days of immune globulin infusions; in both instances, however, the differences failed to attain statistical significance and the three modes of treatment were said to be equivalent. Renal failure, proteinuria, and aseptic meningitis, manifested most often by severe headache, are infrequent complications of IVIg. The only serious reactions we have encountered have been in a very few patients who congenitally lacked IgA and in whom pooled gamma globulin caused anaphylaxis, and a few cases of inflammatory local venous thrombosis in the region of the infusion site. The pharmacokinetics of IVIg are highly variable among individuals and some groups have found an association between a high rate of clearance of agent and poorer clinical outcome (see Kuitwaard and colleagues). This group has suggested that patients who show only a small increment in serum IgG levels might benefit from higher doses or a second course of IVIg.
After the use of either plasma exchange or IVIg, 5 to 10 percent of patients who initially improve will have a relapse that becomes apparent several days or up to 3 weeks after completion of treatment. If there had been a response to the initial therapy, the same treatment may be repeated or the alternative treatment may be tried; either can be successful. A few such patients relapse repeatedly and have the course of chronic inflammatory demyelinating polyneuropathy (see further on). In some patients under our care, this form of the disease stabilized after several months in response to the administration of corticosteroids, with very gradual tapering of the dose over several months, or in combination with repeated courses of IVIg or plasma exchanges.