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Amniotic Fluid Embolism (AFE)

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发表于 8-14-2017 14:34:54 | 显示全部楼层 |阅读模式
本帖最后由 choi 于 8-15-2017 12:01 编辑

Betsy McKay and Paul Overberg, The Dangers of Giving Birth in Rural US; Risk of fatality is higher than in cities, a switch; The fight for Whitney Brown. Wall Street Journal, Aug 12, 2017 (front page).
https://www.wsj.com/articles/rur ... ey-brown-1502462523
https://www.msn.com/en-us/money/ ... ey-brown/ar-AApSABh

My comment:
(a) The title and half of the text that discusses rural healthcare are distractions. AFE patients may die in cities, too.  
(b) "Ms Brown * * * grew up in McMinnville. The town of 13,761 residents was known locally as the 'Nursery Capital of the World' for the growers who supply shrubs and flowers across the US."

McMinnville, Tennessee
https://en.wikipedia.org/wiki/McMinnville,_Tennessee
(a city; was named for Governor Joseph McMinn [1758 – 1824]; 70 miles (110 km) northwest of Chattanooga)

(c)
(i) Pregnancy-Related Mortality. Child Health USA 2013. Maternal and Child Health Bureau (MCHB), Health Resources and Services Administration (HRSA), US Department of Health and Human Services (HHS), undated
https://mchb.hrsa.gov/chusa13/pe ... ated-mortality.html
(in US: "In 2006–2009, the latest years for which data are available, a total of 2,689 deaths were found to be pregnancy-related at a rate of 15.8 deaths per 100,000 live births")
(ii) Roth WH et al, Amniotic Fluid Embolism: an Interdisciplinary Challenge; Epidemiology, diagnosis and treatment. Deutsches Ärzteblatt International, 111: 126–132(2014)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3959223/
("it is the most common cause of maternal death in Australia and the second-most common in the USA and the UK")
(iii) Tamura N et al, Amniotic Fluid Embolism: Pathophysiology from the Perspective of Pathology. Journal of Obstetrics and Gynaecology Research, 43: 627-632 (2017)
onlinelibrary.wiley.com/doi/10.1111/jog.13284/full
("This clinical diagnosis is essentially exclusion based on clinical presentations that resemble both embolism and anaphylaxis. * * * lab test can not form the basis of diagnosis, because observation of fetal cells in maternal lung or uterine tissues are inconclusive:] fetal cells can be detected in 21 to 100 % of pregnant women without AFE")

(d) Caeiro AFC et al, Amniotic Fluid Embolism. Is a New Pregnancy Possible? Case Report. Revista Brasileira de Ginecologia e Obstetrícia, 39: 369-372 (2017).
https://www.ncbi.nlm.nih.gov/pubmed/28464190
(case report; abstract)

free full text: https://www.thieme-connect.com/p ... 1055/s-0037-1601428

(e)
(i) "The "team at the Erlanger hospital brought Ms Brown to an operating room, where they found 'massive amounts' of blood in her abdomen * * * They tried several ways to stop it.  The hospital eventually g[ave] Ms Brown more than three times her body's blood volume."
(A) A man's blood volume is about 5 liters.  A woman's is somewhat less, because she is, generally speaking, lighter in weight.
(B) "massive amounts of blood in her abdomen"

Joel L Moake, Disseminated Intravascular Coagulation (DIC). Merck Manual, undated (consumer version)
https://www.merckmanuals.com/hom ... lar-coagulation-dic
("Bleeding may occur [anywhere or everywhere, including] cavities of the body")

* The essence of DIC is coagulation first (inside blood vessels large and small in diameters), depleting coagulation factors the latter of which leads to widespread bleeding (hence "disseminated"). Usually DIC may result in deep vein thrombosis (veins deep in legs), causing leg swelling (edema); because blood can not easily return to heart, seeping out lymph). However, it is conceivable that blood had clotted throughout Ms Brown body, leading to generalized body swelling.
(ii) The fifth paragraph from the bottom states, "Ms Brown was swollen beyond recognition."  That likely was the first night (and hours after) Ms Brown arrived at big hospital.

(f)
(i) There is no animal model for AFE. So its cause and pathophysiology is hard to pin down.
(ii) About humans. During pregnancy, fetal cells enter the bloodstream of a mother. Certainly in the midst of childbirth, amniotic fluid and fetal blood enter the mother.  But in neither case, we know how much. Also most of the time, nothing bad happens to the mother.
(iii) The current thinking about AFE is as follows. Amniotic fluid that enters maternal bloodstream sometimes somehow triggers vasoconstriction (blood vessels contract in diameter) of blood vessels (hence patient feeling lack of air). The resulting pulmonary hypertension (high blood pressure in LUNGS, but not necessarily in the est of the body)  brings about right-sided heart failure (right ventricle unable to pump blood into lungs). Then left ventricle of the heart can not get blood, causing systemic hypotension. In the second phase, DIC sinks in.
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