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  很多凝血實(shí)驗(yàn)室都設(shè)置了項(xiàng)目危急值，這些危急值的設(shè)置有沒有依據(jù)？依據(jù)夠不夠可靠？本期以指南為主要依據(jù)，列出對凝血篩查項(xiàng)目危急值設(shè)置的建議，供參考。

APTT危急值的設(shè)置：

1.根據(jù)ACCP指南，使用各種治療劑量抗凝藥物時(shí)，APTT與正常對照的比值均應(yīng)在3.0以下，例如肝素（比值1.5~2.5）、阿加曲班（比值 1.5~3.0）。對應(yīng)的APTT上限一般在100秒左右。這成為APTT危急值設(shè)定的主要依據(jù)。[1]

2. 臨床研究表明使用肝素后抗Xa活性超過1U/mL的患者，比未超過者出血風(fēng)險(xiǎn)顯著增加[2, 3]，以抗Xa活性1U/mL對應(yīng)的APTT秒數(shù)作為危急值可能更為準(zhǔn)確，但需各實(shí)驗(yàn)室收集樣本檢測后自行確定。

因此依據(jù)相關(guān)指南及臨床研究，APTT危急值推薦設(shè)定為≥APTT正常均值的3倍，或應(yīng)用肝素后抗Xa活性1U/mL對應(yīng)的APTT均值秒數(shù)。

PT（INR）危急值的設(shè)置：

1.根據(jù)ACCP相關(guān)指南[4]，當(dāng)INR超出治療范圍但<5.0，且無明顯出血表現(xiàn)時(shí)，建議降低維K拮抗藥劑量并增加監(jiān)測頻次，不需要輸注逆轉(zhuǎn)藥等措施；而當(dāng)INR>5.0時(shí)，則要考慮應(yīng)用逆轉(zhuǎn)藥。這為INR危急值的設(shè)定提供了一個(gè)依據(jù)。

2. 根據(jù)ESC相關(guān)指南[5]，瓣膜性心臟病的華法林抗凝，最高危對應(yīng)的INR值不超過4.0。在一些INR與預(yù)后相關(guān)性的臨床研究中，INR值升高與死亡風(fēng)險(xiǎn)呈正相關(guān)[6]，4.0也被很多實(shí)驗(yàn)室確定為危急值。

因此依據(jù)相關(guān)指南及臨床研究，INR危急值推薦設(shè)定為≥4.0或5.0，PT危急值可據(jù)此換算。

FIB危急值的設(shè)置依據(jù)：

1.大部分DIC診斷與處置指南中[7, 8]，F(xiàn)IB<1.0g/L為積分項(xiàng)，且提示需給予FIB補(bǔ)充。

2.輸血相關(guān)指南中[9]，冷沉淀的應(yīng)用指征一般為FIB<1.0g/L。而在創(chuàng)傷出血、產(chǎn)后出血等需大量輸血的處置指南中，認(rèn)為FIB需維持在1.5~2.0 g/L[10, 11]。

  因此依據(jù)相關(guān)指南及臨床研究，FIB危急值推薦設(shè)定為≤1.0g/L。在溝通基礎(chǔ)上，特定科室（如產(chǎn)科）可考慮提高至≤1.5g/L或更高。沒有對FIB升高設(shè)置危急值的依據(jù)。

其他常規(guī)凝血項(xiàng)目如TT、D-dimer則沒有基于指南的危急值設(shè)置建議，上期本博也對為何不設(shè)置D-dimer危急值做了分析。

參考文獻(xiàn)

1. Hirsh J, Bauer KA, Donati MB, et al. Parenteral anticoagulants: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest. 2008; 133(6suppl):141S-159S.

2. Bates SM, Weitz JI, Johnston M,et al. Use of a fixed activated partial thromboplastin time ratio to establish a therapeutic range for unfractionated heparin. Arch Intern Med. 2001; 161:385-391.

3. van den Besselaar AM, Sturk A,Reijnierse GL. Monitoring of unfractionated heparin with the activated partial thromboplastintime: determination of therapeutic ranges. Thromb Res. 2002; 107:235-240.

4. Ansell J, Hirsh J, Hylek E, etal. Pharmacology and management of the vitamin K antagonists: American Collegeof Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest.2008; 133(6 suppl):160S-198S.

5. Baumgartner H, Falk V, Bax JJ, et al. 2017 ESC/EACTS Guidelines for the Management of Valvular Heart Disease. Rev EspCardiol (Engl Ed). 2018; 71(2):110.

6.Doering TA, Plapp F, Crawford JM. Establishing an Evidence Base for Critical Laboratory Value Thresholds. Am J Clin Pathol. 2014;142(5):617-28. 

7.Levi M, Toh CH, Thachil J, Watson HG. Guidelines for the diagnosis and management of disseminated intravascular coagulation. British Committee for Standards in Haematology. Br J Haematol. 2009; 145(1):24-33.

8. Taylor FB Jr, Toh CH, Hoots WK, et al.Towards definition, clinical and laboratory criteria, and a scoring system for disseminated intravascular coagulation. Thromb Haemost. 2001; 86(5):1327-30.

9. Blood Transfusion. NICE Guideline, No.24. National Clinical Guideline Centre (UK).London: National Institute forHealth and Care Excellence (UK); 2015 Nov.

10. Winearls J, Campbell D, Hurn C, et al. Fibrinogen in traumatic haemorrhage: A narrative review. Injury. 2017; 48(2):230-242.

11. Sentilhes L, Vayssière C, Deneux-Tharaux C, et al. Postpartum hemorrhage: guidelines for clinicalpractice from the French College of Gynaecologists and Obstetricians (CNGOF): in collaboration with the French Society of Anesthesiology and Intensive Care(SFAR). Eur J Obstet Gynecol Reprod Biol. 2016;198:12-21.