Coagulation Disorders Secondary to Two Plasmapheresis Techniques (Double Filtration Plasmapheresis vs. PFS). Descriptive Pilot Study.

Therapeutic plasmapheresis causes changes in haemostasis by purifying many of the circulating factors involved. Few reliable data are available on these changes and most studies are limited to coagulation factor assays before and after the session, with little data documenting the kinetics of regeneration of these factors. It is recognized that haemostasis disorders caused by therapeutic apheresis must be corrected in cases of active bleeding. However the methods of correcting these disorders are debatable. Finally, it is unclear when changes in haemostasis associated with coagulation factor deficiency should be corrected. Haemostasis is probably not based solely on the level of blood fibrinogen, but it is most often its threshold that is used to trigger replacement therapy to prevent a supposed risk of haemorrhage. No studies are available on the kinetics of haemostasis disorders and the risk of haemorrhage following a therapeutic plasmapheresis session, according to session type and fibrinogen level at the end of the session. The hypothesis of this research is that the link between fibrinogen level and thrombin generation capacity, post therapeutic plasmapheresis, will enable us to better assess the risk of haemorrhage and propose preventive measures.

Therapeutic plasmapheresis causes changes in haemostasis by purifying many of the circulating factors involved. Some data are available on changes in circulating haemostasis factors with the Single Plasma Exchange technique and the Double Filtration Plasmapheresis; however, most often these studies are carried out in specific clinical situations where other haemostasis disorders may be present, such as severe renal failure. Furthermore, in these studies, assessment of changes in haemostasis is often limited to coagulation factor assays before and after the session, with little data documenting the kinetics of regeneration of these factors, whose molecular weight and half-life vary widely. To date, there is no clear consensus/recommendation on the management of haemostasis disorders secondary to therapeutic apheresis. The need to correct haemostasis disorders caused by therapeutic apheresis also appears to be consensual in cases of active bleeding.The methods of correcting haemostasis disorders can also be discussed between infusion of coagulation factor and fresh frozen plasma. Finally, apart from these clinical situations, it is not clear when changes in haemostasis associated with coagulation factor deficiency should be corrected. There are no studies available on the kinetics of haemostasis disorders and the risk of haemorrhage following a therapeutic plasmapheresis session, depending on the type of session and the fibrinogen level at the end of the session. The hypothesis of our research is that the existence of a link between fibrinogen level and thrombin generation capacity, post therapeutic plasmapheresis, will enable us to better assess the risk of haemorrhage and to propose preventive measures.

Eligibility Criteria:
Inclusion Criteria:

* Patients without renal failure treated with chronic therapeutic plasmapheresis with a minimum treatment interval of 10 days and who can be treated with single plasma exchange (SPE) or double filtration plasmapheresis (DFPP) in accordance with the international recommendations.
* Therapeutic plasmapheresis with regional citrate anticoagulation.
* Patients over 18 years of age.
* Patient affiliated to or benefiting from a social security scheme.
* Free, informed and written consent, signed by the participant and the investigator (at the latest on the day of inclusion and before any examination required by the research).

Exclusion Criteria:

* Patients treated with oral anticoagulants or anti-platelet agents.
* Patients treated for hypercholesterolaemia or hypertriglyceridaemia; hyperviscosity, acquired haemophilia or nephrotic syndrome.
* Indication for substitution with fresh frozen plasma (FFP) for the treatment of the disease.
* Patient in an exclusion period determined by another study.
* Patient under court protection, guardianship or curatorship.
* Patient unable to give consent.
* Patient for whom it is impossible to give informed information.
* Pregnant or breast-feeding patients.