Prostacyclin therapy of thrombotic thrombocytopenic purpura

Thrombocytopenia in the Intensive Care Unit Setting

Thrombocytopenia is a commonly encountered labora tory abnormality in the intensive care unit setting. Al though moderate degrees of thrombocytopenia may be dismissed as clinically trivial, severe thrombocytopenia can have catastrophic consequences. This review di vides the potential pathogenesis of thrombocytopenia into three pathophysiological categories: (1) produc tive, (2) consumptive, and (3) distributional. The im portant etiologies and appropriate therapies for throm bocytopenia in each of these categories are discussed. We have attempted to emphasize the underlying patho genic mechanisms as well as highlight the diagnostic dilemmas likely to be faced by intensive care unit physi cians. Although this review stresses those thrombocyto penic disorders most likely to be encountered in the intensive care unit, chronic etiologies of thrombocy topenia are also discussed because preexistent throm bocytopenia will further complicate the care of any acutely ill intensive care unit patient.

Successful treatment of hemolytic uremic syndrome and thrombotic thrombocytopenic purpura with fresh frozen plasma and plasma exchange

Four patients with hemolytic uremic syndrome (HUS) and seven with thrombotic thrombocytopenic purpura (TTP) were treated with infusions of fresh frozen plasma (FFP). In one patient with HUS and five patients with TTP this treatment was combined with plasma exchange (PE). The additional treatment varied; corticosteroids, antiplatelet drugs, heparin and blood exchange. All but one patient recovered completely in spite of severe illness with uremia, oliguria and/or cerebral symptoms during the acute phase. The results were surprisingly good in comparison with other published series. The success must in the first place be attributed to early diagnosis and to the infusions of FFP. PE seemed to potentiate the effect of FFP.

The management of idiopathic thrombotic microangiopathy. Changing trends

Thrombotic microangiopathy, including the two related syndromes thrombotic thrombocytopenic purpura and hemolytic-uremic syndrome, is a rare and severe multisystem disorder, due to widespread deposition of intravascular microthrombi consisting mainly of platelets, with subsequent consumption thrombocytopenia, microangiopathic hemolytic anemia, renal abnormalities, and neurologic disturbances. The epidemic, verotoxin-induced hemolytic-uremic syndrome, typically associated with prodromal diarrhea, mainly affects young children in small outbreaks. By contrast, idiopathic thrombotic microangiopathy generally affects adults in a sporadic form; it has a more devastating course and a less favourable outcome. Over 90% of the reported cases in the adult, when untreated, have progressed to death within three months of diagnosis. Since the introduction of plasma exchange, a dramatic change in the prognosis of the disease has taken place, although the mortality rate still remains considerable. Indeed, improved survival is the most striking feature of adult thrombotic microangiopathy compared to some decades ago. In the present article we will focus on the evolving concepts able to exert a considerable impact in the management of the adult idiopathic form of thrombotic microangiopathy.

Iloprost in the treatment of thrombotic microangiopathy: report of thirteen cases

Defective prostacyclin bioavailability seems to play a role in the pathogenesis of thrombotic microangiopathy, including thrombotic thrombocytopenic purpura and hemolytic uremic syndrome. Eight consecutive patients with a proven diagnosis of thrombotic microangiopathy were treated by Iloprost, a recently developed stable prostacyclin analogue; during follow-up, three of them relapsed and received further treatment. To our knowledge, this is the first report on a wide series of patients who received Iloprost for thrombotic microangiopathy. Soon after diagnosis, Iloprost was given by continuous intravenous infusion at a rate of 1.5-2 ng/kg/minute over 16-18 h/day for several days (mean 12 days; range 6-24) until the platelet count steadily increased. In addition, plasma exchange with fresh frozen plasma (average volume exchange 20-40 mL/kg for each session) was performed in 11 out of the 13 cases. No other antiplatelet agent was given. In all 13 cases, Iloprost administration coincided with achievement of remission. At present, all the patients are still maintaining remission. Our results indicate a useful role for Iloprost in the management of thrombotic microangiopathy.

Intravenous prostacyclin in thrombotic thrombocytopenic purpura: case report and review of the literature

The use of prostacyclin infusion in thrombotic thrombocytopenic purpura is consistent with the hypothesis that patients may lack a plasma factor stimulating prostacyclin production. However, prostacyclin therapy, alone or in combination with aspirin, dipyridamole, steroid and plasmapheresis, failed in many cases. We here describe the case of a patient who responded dramatically to a combination of prostacyclin and plasma infusions, after conventional therapy had failed (plasmapheresis, fresh frozen plasma infusions). Prostacyclin was infused intravenously initially for 120 h from 4 to 9 ng kg min-1 and then continuously for 48 h at 9 ng kg min-1. Despite the scarcity of case reports in the literature, we conclude that the failure of prostacyclin in thrombotic thrombocytopenic purpura appears to be related to insufficient doses and/or duration of therapy.

Platelet factor 4 and the response to plasma exchange in the treatment of thrombotic thrombocytopenic purpura

We report two patients with thrombotic thrombocytopenic purpura who were subjected to plasma exchange. In one case, the plasma levels of platelet factor 4, measured shortly after plasma exchange, increased significantly during plasma exchange. This was followed, however, by a failure to respond to therapy. Repeated plasmapheresis over 3 weeks gave no therapeutic benefit and reversible deep coma occurred. This patient recovered completely after treatment with vincristine. In the second patient, a decline in platelet factor 4 was observed after plasma exchange. This was accompanied by improvement of the patient's condition and a slow rise in platelet count. Plasma exchange was again carried out in this patient because of a recurrence of thrombotic thrombocytopenic purpura 3 years later; again decreased platelet factor 4 plasma levels were observed after plasma exchange and again a therapeutic response followed. Platelet factor 4, therefore, seems to be an effective and early index for the therapeutic benefit of plasma exchange in thrombotic thrombocytopenic purpura.

Plasma infusion for hemolytic-uremic syndrome in children: results of a multicenter controlled trial

The results of a controlled trial to ascertain the usefulness of plasma infusion for the treatment of hemolytic-uremic syndrome (HUS) are reported. Criteria for admission were (1) observation within 8 days from first symptoms, (2) dialysis treatment required, and (3) no special treatments and no more than 25 ml blood/kg previously received. Children were subdivided according to age (less than or more than 3 years) and then randomly assigned to treatment with plasma or symptomatic therapy. Thirty-two children ranging in age from 4 months to 6 years entered this study; 17 received plasma (P+ group) and 15 only symptomatic therapy (P- group). The mean follow-up period was 16 months in both groups. Surgical renal biopsy was performed 29 to 49 days after onset in 11 P+ and 11 P- children, and 33 histologic findings were semiquantitatively evaluated. No death occurred in either group. No differences were found in blood pressure, proteinuria, or hematuria at the end of the follow-up period; in no case were severe arteriolar lesions found. There were no significant differences for the scores of the individual histologic measurements; on electron microscopy, no vascular changes were observed in seven children of the P+ group, whereas in five of seven of the P- group, thickening of the lamina rara interna and arteriolar damage were present. The ability of plasma to stimulate prostacyclin (PGI2) production, measured as its stable derivative 6-keto-PGF1 alpha, was within the normal range for all patients. In our patients with predominant glomerular involvement who were treated in a very early phase of HUS, infusions of plasma did not significantly influence the short- and medium-term clinical outcome and were not effective in severe HUS when given later in the course of the disease. A longer follow-up is needed to ascertain whether the presence of endothelial damage, demonstrated by electron microscopy in children who were not given plasma, is of clinical relevance.

Thrombotic thrombocytopenic purpura: treatment with plasmapheresis

Twenty-one episodes of thrombotic thrombocytopenic purpura (TTP) were treated with plasmapheresis. Adjunctive agents included corticosteroids, aspirin, dipyridamole, and vincristine. There were 17 patients; 12 were female. The median age was 41 years. Most patients presented with neurologic symptoms. Thrombocytopenia was profound with a mean initial platelet count of 14,900/mm3. The mean hematocrit on presentation was 26.7% and the mean LDH 1300 IU/L. Eighteen episodes responded completely following plasmapheresis/plasma exchange (86%). Response was prompt, the initial rise in platelet count occurred after a mean of four exchanges, and complete response (a platelet count over 150,000/mm3) was obtained after a mean of nine exchanges. Four of the episodes treated were relapses that occurred in three patients. All responders are alive with a median duration of follow-up of 20 months. The three patients who failed to respond have died. This report extends recent observations that the addition of plasmapheresis/plasma exchange to the therapy of TTP has significantly improved the outlook for patients with this disorder.

[Thrombotic thrombocytopenic purpura]

Thrombotic thrombocytopenic purpura (TTP) is an uncommon disorder which usually occurs in young adults. It is characterized by a pentad of clinical findings: fever, neurological abnormalities, renal dysfunction, microangiopathic hemolytic anemia and thrombocytopenia. The histological hallmark is the presence of platelet thrombi occluding the microcirculation of multiple organs. The etiology and pathogenesis of disseminated platelet aggregation are uncertain and obviously not uniform in individual patients. Experimental findings suggest that microthrombi may result from intravascular platelet activation or form secondarily at sites of vessel wall damage. The differential diagnosis of TTP includes the hemolytic uremic syndrome in which the microangiopathic changes are exclusively found in the kidneys. When untreated, TTP invariably runs a progressive and fatal course. In recent years, prognosis has been improved by new forms of therapy such as plasmapheresis or infusions of fresh frozen plasma which may lead to recovery in about 80% of patients.

Nobel lecture. Adventures and excursions in bioassay--the stepping stones to prostacyclin

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Nobel lecture, 8th December 1982. Adventures and excursions in bioassay: the stepping stones to prostacyclin

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Thrombotic thrombocytopenic purpura: report of fourteen cases--occurrence during pregnancy and response to plasma exchange

Thrombotic thrombocytopenic purpura (TTP), a syndrome of diverse etiology probably related to factors regulating platelet-vessel wall interaction, is predominantly a disorder of women. We report our experience with 14 patients in an 11-year period. Thirteen were female and aged between 25-69 years. Four were postmenopausal, and of the nine premenopausal women three were pregnant, one was immediately postpartum, and three were taking estrogen-containing oral contraceptives. A review of the literature confirms the two to one female/male preponderance and that TTP is reported in 56 women who are pregnant or recently postpartum. While this association with possible hormonal events has been noted, it has previously received little comment. We stress the similarity between TTP and some occurrences of preeclamptic toxemia, and that this may suggest not only a common etiology but that therapeutic attempts should be similar. While no single therapeutic modality is universally successful, our experience is that plasma exchange is the most effective, with five of seven patients so-treated obtaining prolonged remission; four of five patients responded to splenectomy and corticosteroids, but one died of infection postoperatively. Five patients, including two treated exclusively with antiplatelet aggregating agents, died without achieving remission. The frequency of successful therapy is not changed by the concurrent pregnancy, but the fetal loss is high. There does seem to be an increased risk of recurrence of TTP in a subsequent pregnancy, and this might be considered when counseling premenopausal patients who have achieved remission of TTP.

Side effects occurring during administration of epoprostenol (prostacyclin, PGI2), in man

1 Fifty infusions of epoprostenol (PGI2) were made, usually increasing the infusion rate until adverse effects were encountered. The volunteers were appraised that they might experience headache and facial flushing. 2 Facial flushing, headache, tachycardia and decrease in diastolic blood pressure were seen in almost all subjects. Erythema over the venous infusing site was also encountered in 13 infusions. Less common effects were sudden bradycardia, pallor and sweating--the vagal reflex--(seven times) and chest pain (twice). Other complaints included restlessness, abdominal discomfort, nausea and drowsiness. 3 The literature on side effects reported during PGI2 infusion is reviewed and recommendations are made concerning administration of PGI2.