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Correspondence  |   August 2012
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Author Affiliations & Notes
  • Barbara L. Leighton, M.D.
    *
  • *Washington University in St. Louis School of Medicine, St. Louis, Missouri.
Article Information
Correspondence
Correspondence   |   August 2012
In Reply
Anesthesiology 8 2012, Vol.117, 423-424. doi:10.1097/ALN.0b013e31825b936f
Anesthesiology 8 2012, Vol.117, 423-424. doi:10.1097/ALN.0b013e31825b936f
The United Kingdom Obstetric Surveillance System (UKOSS) report was published after we had finished collecting data and shortly before we submitted our manuscript to ANESTHESIOLOGY.1,2 We apologize for the oversight; we certainly would have contacted Knight had we been aware of UKOSS at that time. However, it is unclear how many of the cases in the UKOSS database would have qualified for our review. We employed the traditional definition of amniotic fluid embolism (AFE) used by the United Kingdom AFE register and the United States AFE registry.3,4 Patients had to have at least one major cardiac and one major pulmonary symptom (or cardiopulmonary arrest) plus consumptive coagulopathy to be diagnosed with AFE. In contrast, UKOSS used a much broader definition of AFE; for example, 38% of the UKOSS AFE patients did not have a coagulopathy.1 This is not a trivial distinction, for patients who do not meet the traditional definition of AFE seem to have better outcomes after receiving recombinant factor VIIa (rVIIa) than patients who do meet the definition, as seen in these case reports.5,6 We believe that the broader definition of AFE used by UKOSS permitted the enrollment of patients with similar but different diseases.
We also used a different measure of successful therapy than that used by UKOSS.1 UKOSS reported the number of patients who died after receiving rVIIa, but not the number with new permanent disability. Our primary outcome was intact survival versus  a negative outcome (new permanent disability or death).2 We don't consider surviving in a coma or with a stroke to be a successful outcome.
All of our AFE patients who received rVIIa also had surgery to control hemorrhage. We therefore chose AFE patients who had surgery to control hemorrhage but did not receive rVIIa as our comparison cohort. Patients who die very rapidly of AFE generally expire before surgical intervention or rVIIa treatment can be given.
We agree that identifying cases through a prospective, population-based reporting mechanism such as UKOSS is an excellent way to identify the incidence of complications. However, we are seriously concerned that the broad definition of AFE, including patients without coagulopathy, and the lack of information on morbidity weaken the ability of UKOSS to assess rVIIa complications in AFE patients.
Patients with AFE have high circulating levels of tissue factor, which is why rVIIa treatment is particularly risky both in theory and in practice.2 We urge UKOSS and the rest of the obstetric community to explore the use of potentially safer hemostatic alternatives, such as fibrinogen concentrate and tranexamic acid, rather than prematurely embracing rVIIa, the agent with the greatest potential for thrombotic complications.
References
Knight M, Tuffnell D, Brocklehurst P, Spark P, Kurinczuk JJ, UK Obstetric Surveillance System: Incidence and risk factors for amniotic-fluid embolism. Obstet Gynecol 2010; 115:910–7
Leighton BL, Wall MH, Lockhart EM, Phillips LE, Zatta AJ: Use of recombinant factor VIIa in patients with amniotic fluid embolism: A systematic review of case reports. ANESTHESIOLOGY 2011; 115:1201–8
Tuffnell DJ: United Kingdom amniotic fluid embolism register. BJOG 2005; 112:1625–9
Clark SL, Hankins GD, Dudley DA, Dildy GA, Porter TF: Amniotic fluid embolism: Analysis of the national registry. Am J Obstet Gynecol 1995; 172:1158–69
Lim Y, Loo CC, Chia V, Fun W: Recombinant factor VIIa after amniotic fluid embolism and disseminated intravascular coagulopathy. Int J Gynaecol Obstet 2004; 87:178–9
Prosper SC, Goudge CS, Lupo VR: Recombinant factor VIIa to successfully manage disseminated intravascular coagulation from amniotic fluid embolism. Obstet Gynecol 2007; 109:524–5