Amniotic fluid embolism:literature review and an integrated concept of pathomechanism

Literature concerning procoagulant activity of the amniotic fluid and pathomechanism of amniotic fluid embolism (AFE) was surveyed and a new concept of its pathogenesis, called the integrated concept of AFE, was presented. According to this concept, two components of the amniotic fluid are involved: (i) apoptosis-affected amniotic cells showing a special role in the initiation of disseminated intravascular coagulation (DIC) and (ii) leukotrienes (formerly called slow-reacting substances), inducing bronchial and pulmonary vascular smooth muscle contraction. Although each of these components initiates a different pathogenic pathway, they both lead to the formation of a mechanical barrier on blood flow through the lungs (amniotic debris + microemboli) and/or functional barrier (pulmonary vasoconstriction). An old dilemma, concerning indications for heparin therapy in AFE was recalled in the light of the new concept.

Heparin and other anticoagulants in amniotic fluid embolism(AFE):Literature review and concept of the therapy

Aim: The objective of this study is to review all the reported outcomes of heparin application in amniotic fluid embolism (AFE) so far and to find out why, when and how heparin or other anticoagulants should be used in AFE. Material and methods: We searched Medline (from 1969 to 2011), using two key words: 1) amniotic fluid embolism;2) amniotic fluid embolism and heparin. The search for the former produced 1127 replies, of which 208 were case reports of AFE. In response to the other key word, there were 94 articles. We looked through all the articles, selecting those relevant for our study. Results: In the years 1969-2011, 208 AFE cases were reported. Heparin (unfractionated heparin) or low molecular weight heparin (LMWH) was applied in 20 cases (9.6%), being the main drug in 11 cases (5.3%) and in 6 cases as a component of spectacular treatment of AFE (surgical treatment and extracorporal membrane oxygenation). In one of these cases anithrombin (AT) with LMWH was used. In one patient heparin therapy was considered to be unsuccessful and hence recombinant plasminogen activator (rt-PA) was instituted. All the patients survived. Conclusions: 1) The attempts to use heparin in AFE could be defined as promising, although the number of treated patients is too small for conclusion;2) The postulate to use heparin at the very onset of AFE (a bolus of 10,000 U followed by monitored intravenous infusion) has serious justification: one of the pathways of AFE is the target for heparin (coagulation pathway).

Amniotic Fluid Embolism (AFE): A Review of the Literature Orientated on Two Clinical Presentations--Typical and Atypical

Background/Aim: Recently, a comparative study on the incidence of AFE has highlighted rather confusing results, showing that the complication is more than three times higher in North America than that in some European countries. In this paper, we put forward the hypothesis that this discrepancy is due to inaccurate diagnosis of non-classical form of AFE (atypical AFE). We also provide an outline of symptoms that characterize this type of AFE based on the analysis of all available case reports. Material and Methods: We searched Medline from 1969 (its inception) to 2011, using the key words “amniotic fluid embolism”. The search produced 1127 articles, including 208 case reports of AFE and other publications identified as eligible for our study (11 review articles and 6 population-based studies of the last few years). Moreover, we looked through the articles from the period before “inception of Medline” to find 178 earlier case reports. Full texts were analyzed. Results and Conclusions: (i) Worldwide, 447 cases of AFE have been reported, including 70 cases of atypical AFE (15.7%). (ii) Typical AFE is characterized by three clinical phases (cardiopulmonary collapse, clotting disorders and hemorrhages, multiorgan disturbances), whereas the atypical one shows lack of cardiopulmonary collapse as the initial presentation—the first to appear is obstetric hemorrhage and/or pulmonary and renal dysfunction. (iii) Four subclasses of atypical AFE were distinguished on the basis of case reports: uterine hemorrhage-type of AFE, ARDS as the only presentation of atypical AFE, paradoxical AFE, and cesarean section-related atypical AFEs.

Effect of intraoperative cell rescue on bleeding related indexes after cesarean section

BACKGROUND Obstetric hemorrhage is the leading cause of maternal mortality globally,especially in China.The key to a successful rescue is immediate and rapid blood transfusion.Autotransfusion has become an integral part of clinical blood transfusion,with intraoperative cell salvage(IOCS)being the most widely used.AIM To investigate the application of IOCS in cesarean section.METHODS A total of 87 patients who underwent cesarean section and blood transfusion in our hospital from March 2015 to June 2020 were included in this prospective controlled study.They were divided into the observation(43 cases)and control(44 cases)groups using the random number table method.The patients in both groups underwent lower-segment cesarean section.The patients in the control group were treated with traditional allogeneic blood transfusion,whereas those in the observation group were treated with IOCS.Hemorheology[Red blood cell count,platelet volume,and fibrinogen(FIB)]and coagulation function(partial prothrombin time,prothrombin time(PT),platelet count,and activated coagulation time)were measured before and 24 h after transfusion.In the two groups,adverse reactions,such as choking and dyspnea,within 2 h after cesarean section were observed.RESULTS Before and after transfusion,no significant differences in hemorheology and coagulation function indices between the two groups were observed(P>0.05).About 24 h after transfusion,the erythrocyte count,platelet ratio,and FIB value significantly decreased in the two groups(P<0.05);the PLT value significantly decreased in the two groups;the activated partial thromboplastin time,PT,and activated clotting time significantly increased in the two groups(P<0.05);and no statistical differences were observed in hemorheology and coagulation function indices between the two groups(P>0.05).Furthermore,there was no significant difference in the incidence of adverse reactions between the two groups(P>0.05).CONCLUSION In patients undergoing cesarean section,intraoperative cell salvage has a minimum effect on hemorheology and coagulation function and does not increase the risk of amniotic fluid embolism.