Fetal anaphylacxis
時間 － 在大多數致命性過敏反應病例中，從接觸過敏原到死亡的時間不到 60 分鐘[ 7,29 ]。大多數致命反應是單相的，爆發性出現，且進展迅速，儘管少數反應會經歷更為持久或雙相的病程，通常持續數小時以上[ 29,58,59 ]。
對英國 10 年間 202 起死亡事件的分析表明，接觸過敏原和出現症狀之間的間隔因過敏原類型和接觸途徑而異，如下所示 [ 5 ]：
●服藥後，住院患者平均 5 分鐘後出現症狀，而門診患者則平均 10 至 20 分鐘後出現症狀。
●被昆蟲叮咬後，症狀平均在 10 至 15 分鐘後出現。
●進食後，症狀在 25 至 35 分鐘後出現。
過敏原劑量 － 過敏原劑量越高，反應越迅速、越嚴重，這似乎是合乎邏輯的，儘管患者出現過敏反應的閾值水平可能有很大差異。
●據報道，各種劑量的過敏原都可能導致致命的食物過敏反應，從微量到超過 100 克的劑量。與堅果是特別強的過敏原的印像一致，一項評論發現，最常導致死亡的堅果劑量約為 1 克，而其他食物導致致命過敏反應的最常報告的劑量約為 10 克 [ 7 ]。
●大多數昆蟲蜇傷致死案例都是由一次蜇傷造成的 [ 52 ]。
●大多數藥物引起的死亡都是由正常劑量的致病藥物引起的[ 52 ]。
Timing — Less than 60 minutes elapses between allergen exposure and death in most cases of fatal anaphylaxis [7,29]. Most fatal reactions are uniphasic, present fulminantly, and progress rapidly, although a few follow a more protracted or biphasic course, typically over several hours [29,58,59].
An analysis of 202 fatalities over a 10-year period in the United Kingdom determined that the interval between exposure and the onset of symptoms varied with the type of allergen and route of exposure, as follows [5]:
●Following medications, symptoms appeared after a mean of 5 minutes in hospitalized patients and after 10 to 20 minutes in ambulatory patients.
●Following insect stings, symptoms appeared after a mean of 10 to 15 minutes.
●Following foods, symptoms appeared after 25 to 35 minutes.
Allergen dose — It seems logical that the higher the allergen dose, the more rapid and severe the reaction, although patients may have very different threshold levels beyond which they will experience anaphylaxis.
●Fatal food anaphylaxis has been reported in response to a wide range of allergen doses, from trace amounts to doses in excess of 100 grams. In keeping with the impression that nuts are especially potent allergens, one review found that the dose of nuts that was most frequently implicated in fatalities was approximately 1 gram, while the dose most often reported in fatal anaphylaxis from other foods was approximately 10 grams [7].
●Most insect sting fatalities result from a single sting [52].
●Most drug-induced fatalities occur in response to normal doses of the culprit medication [52].
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