鍵盤鄉民報到(快說我是網軍!!)
我是台大胸腔內科/重症科的第五年住院醫師。
網路上找不到正確的說法,就不小心認真了。
在論文第153頁,Patient and method的第一二段,寫道:
When a patient was accepted as a NHBD, the family consent was first obtained
after the explanation of the procedures to the family. The ECMO system (cat.
no. CB2505; Medtronic Inc., Anaheim, CA, USA), including centrifugal pump and
oxygenator, was primed with normal saline alone. The priming normal saline
was supplemented with CaCl2 up to a concentration of 1 mmol:L of calcium to
prevent acute hemodilution hypocalcemia after the donor was put on the ECMO
support. A temperature controller (11160 dual heater–cooler; Sarns:3M, Ann
Arbor, MI, USA) was connected to the ECMO to cool down the recirculating
priming solution in the ECMO circuit. The temperature set-point was 4°C.
Bilateral femoral areas were disinfected and well draped when the ECMO system
was being prepared.
After all were ready, we stopped all catecholamine infusion, and disconnected
the ventilator. Twenty-five thousand units of heparin and 10 mg of
phentolamine were injected intravenously. After the heart beats had stopped,
a strip of EKG was recorded for legal document of asystole. Then the right
femoral artery and vein were dissected and cannulated, and the cannulae were
connected to the ECMO system. [1]
這些病人,全部都是經過家屬同意,才撤除呼吸器及升壓劑的。呼吸器及升壓劑都是維生
裝置,是急救的一部份。導致病人死亡的是急救/維生裝置的撤除,或者說是導致他需要
急救/維生裝置背後的病因,讓病人死亡的。一個人拔管、拿掉升壓劑,血壓掉、心跳停
是必然。而用心跳停止來宣告病人死亡,也是我們對99.9%的病人做的事。只有死因有疑
慮或如器官移植等少數案例,才需要請檢察官前來。
心跳停止後,給予heparin(肝素)是葉克膜一定要用的抗凝血劑,作用是讓血液與人工物
品接觸的界面不要凝固。Phentolamine滴注是為了保護要取出的腎臟[2],改善他的血流
,不是降血壓用(雖然他的確可以降血壓)。雖然,若病人本身有出血,或他血壓已經不
穩定了,用這些藥的確會加速他的死亡。
然而,臨床上我們常給予拔管且不重插管,又要留一口氣回家的病人嗎啡滴注,讓病人比
較舒服一點。但嗎啡引起呼吸抑制,會讓病人早點走,這我們也都跟家屬充份解釋,家屬
也都能理解。難道這樣是我們殺了病人嗎?同理,病人既然要遺愛人間,捐出腎臟了,在
頻死前使用這些藥物來增加移植成功的機率,可以說是殺人嗎?
另外,文章開頭就說了,死亡判定有兩種,腦死或心跳停止。一般器官移植都是用腦死判
定,是因為可以在血流灌注正常的情況下等檢察官來判定,再摘取器官,讓器官在最好的
狀態。然而如果病人肺部受傷太厲害,則臨床上不允許進行腦死測試(否則會有生命危險
),則他就只能等到心跳停止,再請檢察官來判定,再進行器官移稙。但檢察官不可能隨
傳隨到,因此器官長時間曝露在沒有心流的環境中,造成不可逆的傷害。這篇文章說的是
如何從「心跳停止」到「等檢察官來判定」到「摘取器官」的過程,利用葉克膜來保護器
官有足夠的充氧血,避免受贈者好不容易等到器官了,也動了大手術移植了,後來卻因為
器官的不可逆傷害,很快就衰竭(graft failure)了。
結論:
一、「為了使心臟不跳動啦/他們先注射了酚妥拉明/讓血壓下降 降到心臟停止」?
錯,是先等心跳停止,才進行後續動作,增加成功率。死亡是撤除維生裝置導致,而非醫
療團隊導致病人死亡。
再說一次:
是先撤除維生裝置->等心跳停止->注射藥物->裝葉克膜
而非注射藥物->心跳停止->葉克膜
二、死亡判斷分為腦死及心跳停止。這篇文章討論的是如何在無法判定腦死的病人,在自
然心跳停止的病程中,減少器官心流不足的傷害,降低移植器官衰竭的機率,造福器官受
贈者。
1. Clin Transplant. 2000 Apr;14(2):152-6. Extracorporeal membrane oxygenation
support of donor abdominal organs in non-heart-beating donors. Ko WJ1, Chen
YS, Tsai PR, Lee PH.
2. Transplantation. 2000 Jan 15;69(1):184-6. Donor treatment with
phentolamine mesylate improves machine preservation dynamics and early renal
allograft function. Polyak MM1, Arrington BO, Kapur S, Stubenbord WT,
Kinkhabwala M.