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Assessment of respiratory function using combined oximetry-cutaneous capnography has never been evaluated in patients with myasthenia gravis (MG). We investigated the effects of double filtration plasmapheresis (DFPP) on respiratory status in 18 MG patients. Results of combined oximetry and transcutaneous capnography, MG scores, and acetylcholine receptor antibody titers before and after DFPP treatment were compared. The respiratory monitoring was performed at three time periods (morning, afternoon, and sleep). Mean MG score was markedly lower after DFPP treatment (5.7) than before treatment (7.9). Before DFPP, the minimum pulse oximetric saturation (SpO2 ) level obtained during the night session was significantly lower (P = 0.0513 and P = 0.0199) than the levels obtained during the two daytime sessions. A similar phenomenon was noted for maximum transcutaneous carbon dioxide tension (PtcCO2 ). After DFPP treatment, the maximum and mean PtcCO2 levels were significantly higher (P = 0.0056) in the morning than in the afternoon. Of all the respiratory function parameters measured, only minimum SpO2 levels obtained during morning sessions before DFP treatment differed significantly from those obtained after DFPP treatment (P = 0.0322). Overall, however, minimum SpO2 levels as well as mean and maximum PtcCO2 levels improved significantly during sleep after DFPP. In conclusion, we found that respiratory function abnormalities were common in myasthenic patients without clinical respiratory symptoms. DFPP treatment resulted in minimal improvement of respiratory parameters.

Plasmapheresis not only removes circulating antibodies but also modulates cellular immunity, including lymphocyte subsets. To investigate the effect of double-filtration plasmapheresis (DFPP) on the ratio of lymphocyte subsets in patients with myasthenia gravis (MG), we examined the percentages of B-cells, T-cells, T helper (Th) cells, T suppressor (Ts) cells, natural killer (NK) cells, NKT cells, and Th/Ts ratio before and after a single DFPP session and after a course of DFPP. A total of 26 patients were recruited; their peripheral blood lymphocyte subsets were assayed using flow cytometry. After a single session of DFPP treatment, the percentages of T-cells (P = 0.0200), Th cells (P = 0.0178), and the Th/Ts ratio (P = 0.0309) decreased significantly, whereas the percentage of NK cells (P = 0.0007) increased significantly. More importantly, after one course of DFPP treatment, the reduced clinical quantitative MG (QMG) score was correlated with the decrease of the percentage of T-cells (r = 0.5005, P = 0.0092). Fourteen thymectomized MG patients had decreased percentages of T-cells (P = 0.0304) and Th cells (P = 0.0444), whereas they had increased NK cells (P = 0.0197) after a single DFPP session. Here, transiently decreased percentages of T-cells after the full DFPP course could enhance the effectiveness of plasmapheresis for MG patients.

The purpose of this study was to evaluate the influence of plasmapheresis on sleep in patients with generalized myasthenia gravis and no respiratory symptoms. Seven myasthenia gravis patients, four women and three men, aged 24-52 years, underwent plasmapheresis treatment because of recent worsening of clinical weakness and poor response to previous treatments. We prospectively recorded the myasthenia gravis score, measured acetylcholine-receptor antibody concentration, performed polysomnography, and checked the Epworth Sleepiness Scale at baseline and 1 day after completion of the last session of plasmapheresis. Myasthenic weakness was ameliorated following plasmapheresis in all patients with a median decrease in myasthenia gravis score of 2 points (P = 0.0002) and a median clearance of 43.3% of acetylcholine-receptor antibody. However, there was no significant change in polysomnographic parameters, except for a trend toward shorter duration of the longest apnea period (P = 0.0763) following the treatment. Plasmapheresis did not affect polysomnographic parameters despite improved clinical weakness along with decreased myasthenia gravis score and acetylcholine-receptor antibody concentration.

To evaluate the optimal session of double filtration plasmapheresis (DFP) in terms of the maximal clearance rates for various serum substances, the laboratory parameters of 152 consecutive patients treated with different sessions of DFP following a standard protocol on an alternate-day basis was studied. Immunoglobulin M (IgM) and lipoprotein cholesterol had the most effective clearance by a minimum of two sessions of DFP treatment, and the clearance rates remained relatively constant despite the increase in the number of treatment sessions, while the clearance rates for other serum proteins increased steadily with further treatments. Using the clearance rate of the 2-session group as reference, the highest slopes for clearance of albumin, globulin, and triglyceride were found in the 4-session group, while the slopes for IgA and IgG were highest in the 5-session group. In conclusion, for the clearance of IgM and lipoprotein cholesterol, two sessions of DFP treatment are adequate. However, the best clearance of IgG and other globulins cannot be achieved until the fourth session of DFP treatment. Therefore, a minimum of 4 sessions of DFP treatment at 2-day intervals is needed for most immunological diseases.

Hypotension is an uncommon complication of procedures involving extracorporeal circulation, including plasmapheresis. From November 1993 to March 1999, we treated 139 patients who underwent a total of 1,137 sessions of double filtration plasmapheresis (DFP). Hypotension was defined as a systolic blood pressure (BP) < 80 mm Hg or any decrease of systolic BP with systemic reactions. A total of 17 (1.5%) episodes of hypotension were documented in 15 patients during the study period. Hypotensive episodes occurred in 2.3% of patients with inflammatory neuropathy, 1.2% of patients with myasthenia gravis, and 1.2% of patients with all other medical diseases. Involvement of the autonomic nerve system (ANS) and a low baseline BP were associated with the occurrence of hypotension. Eight (47%) of 17 episodes were symptomatic and 2 were complicated with seizure. Patients with symptomatic hypotension had a higher level of systolic BP prior to DFP and a larger drop of systolic BP and pulse rate during hypotensive attacks compared to asymptomatic patients. Most hypotensive episodes were resolved briefly after intravenous infusion of saline within 30 min. Eight (47%) of the hypotensive episodes occurred during the first session of DFP treatment. Twelve (71%) of 17 episodes occurred during the last half period of treatment; 6 of them were noted during the terminating stage of DFP. In conclusion, in this series plasmapheresis-related hypotension occurred in 1.5% of DFP sessions and had a higher prevalence in patients with ANS instability and low BP. Extra caution in monitoring BP during DFP therapy is warranted in these vulnerable patients, especially during the termination phase of the first DFP session.

Assessment of respiratory function using combined oximetry-cutaneous capnography has never been evaluated in patients with myasthenia gravis (MG). We investigated the effects of double filtration plasmapheresis (DFPP) on respiratory status in 18 MG patients. Results of combined oximetry and transcutaneous capnography, MG scores, and acetylcholine receptor antibody titers before and after DFPP treatment were compared. The respiratory monitoring was performed at three time periods (morning, afternoon, and sleep). Mean MG score was markedly lower after DFPP treatment (5.7) than before treatment (7.9). Before DFPP, the minimum pulse oximetric saturation (SpO2 ) level obtained during the night session was significantly lower (P = 0.0513 and P = 0.0199) than the levels obtained during the two daytime sessions. A similar phenomenon was noted for maximum transcutaneous carbon dioxide tension (PtcCO2 ). After DFPP treatment, the maximum and mean PtcCO2 levels were significantly higher (P = 0.0056) in the morning than in the afternoon. Of all the respiratory function parameters measured, only minimum SpO2 levels obtained during morning sessions before DFP treatment differed significantly from those obtained after DFPP treatment (P = 0.0322). Overall, however, minimum SpO2 levels as well as mean and maximum PtcCO2 levels improved significantly during sleep after DFPP. In conclusion, we found that respiratory function abnormalities were common in myasthenic patients without clinical respiratory symptoms. DFPP treatment resulted in minimal improvement of respiratory parameters.

Plasmapheresis not only removes circulating antibodies but also modulates cellular immunity, including lymphocyte subsets. To investigate the effect of double-filtration plasmapheresis (DFPP) on the ratio of lymphocyte subsets in patients with myasthenia gravis (MG), we examined the percentages of B-cells, T-cells, T helper (Th) cells, T suppressor (Ts) cells, natural killer (NK) cells, NKT cells, and Th/Ts ratio before and after a single DFPP session and after a course of DFPP. A total of 26 patients were recruited; their peripheral blood lymphocyte subsets were assayed using flow cytometry. After a single session of DFPP treatment, the percentages of T-cells (P = 0.0200), Th cells (P = 0.0178), and the Th/Ts ratio (P = 0.0309) decreased significantly, whereas the percentage of NK cells (P = 0.0007) increased significantly. More importantly, after one course of DFPP treatment, the reduced clinical quantitative MG (QMG) score was correlated with the decrease of the percentage of T-cells (r = 0.5005, P = 0.0092). Fourteen thymectomized MG patients had decreased percentages of T-cells (P = 0.0304) and Th cells (P = 0.0444), whereas they had increased NK cells (P = 0.0197) after a single DFPP session. Here, transiently decreased percentages of T-cells after the full DFPP course could enhance the effectiveness of plasmapheresis for MG patients.

The purpose of this study was to evaluate the influence of plasmapheresis on sleep in patients with generalized myasthenia gravis and no respiratory symptoms. Seven myasthenia gravis patients, four women and three men, aged 24-52 years, underwent plasmapheresis treatment because of recent worsening of clinical weakness and poor response to previous treatments. We prospectively recorded the myasthenia gravis score, measured acetylcholine-receptor antibody concentration, performed polysomnography, and checked the Epworth Sleepiness Scale at baseline and 1 day after completion of the last session of plasmapheresis. Myasthenic weakness was ameliorated following plasmapheresis in all patients with a median decrease in myasthenia gravis score of 2 points (P = 0.0002) and a median clearance of 43.3% of acetylcholine-receptor antibody. However, there was no significant change in polysomnographic parameters, except for a trend toward shorter duration of the longest apnea period (P = 0.0763) following the treatment. Plasmapheresis did not affect polysomnographic parameters despite improved clinical weakness along with decreased myasthenia gravis score and acetylcholine-receptor antibody concentration.