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ECMO Ở NGƯỜI HIẾN TẠNG TIỀM NĂNG

BS CKI. LÊ HẢI YẾN

BS CKII. TRẦN THANH LINH

KHOA HSCC – BV. CHỢ RẪY

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NỘI DUNG

1. Vai trò và đối tượng của ECMO ở người hiến tạng nhóm DBD và DCD.

2. Test ngưng thở ở người cho có ECMO.

3. Tưới máu vùng nhiệt độ bình thường người cho bằng ECMO.

4. Vấn đề đạo đức.

Từ khoá: Organ preservation ECMO, NRP, NRP- ECMO (N-ECMO).

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ECMO BẢO VỆ TẠNG� (ORGAN-PRESERVING ECMO (OP-ECMO)

Sử dụng ECMO nhằm mục đích bảo tồn cơ quan cho mục đích ghép tạng, không phải để cứu lấy mạng sống của bệnh nhân.
Áp dụng trên cả DBD và DCD.

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NGUỒN TẠNG

ECMO

However, even with optimal organ donor management, some consented organ donors are lost due to hemodynamic instability (up to 15% in the UK) (dalleave2016)

Extracorporeal membrane oxygenation can be used in the context of organ donation, where organ preserva- tion rather than saving the patient’s life is its primary role, which we call OP-ECMO. OP-ECMO can be used in the context of DCDD or DBDD programs.

Unlike donors under conditions of BD, organs in CAD undergo ischemic insult due to progressive hypotension and hypoxia from the LSTA until cardiac arrest (CA) plus the 5 min of observation required by the law before death is certified

They may be classified among four categories depending on events and conditions surrounding arrest: category I, dead on arrival (no attempt at resuscitation); category II, sudden cardiac arrest followed by unsuccessful resuscitation; category III, arrest following intentional withdrawal of life support in ventilated patient not meeting brain death criteria; and category IV, cardiac arrest while brain dead. Categories 1, 2 and 4 are classified as uncontrolled DCD (uDCD) and category 3 as controlled DCD (cDCD) [1]. In practice, category III cDCD and, to a lesser extent, category II uDCD donors comprise essentially all DCD donors that are used for transplantation globally.

The period of warm ischemia surrounding arrest, however, provokes organ injury, and DCD in general yields fewer organs per donor and ones of inferior quality when compared with donation after brain death (DBD) [2]. For this reason, there has been increasing interest in forgoing rapid cold preservation and recovery following the declaration of death (still the “gold standard” for DCD organ recovery in most transplant centers) and instead using normothermic regional perfusion (NRP) to temporarily restore oxygenated blood flow the abdominal and more recently thoracic organs prior to recovery.

https://www.intechopen.com/chapters/65892

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DBD VÀ DCD VỚI ECMO

Đối tượng:

DBD: (1) HATT < 90 mmHg với 2 loại vận mạch hoặc (2) SaO2 < 90% dù thở máy với PEEP cao và FiO2 > 80%

DCD: nhóm cDCD ( Maastricht III) liên quan đến bệnh nhân thở máy có suy 1 hoặc 2 cơ quan nghiêm trọng ( thường trên bệnh nhân có tổn thương não nặng hoặc NMCT kèm bệnh não thiếu oxy

Đối tượng:

DBD: CI < 2 L/m2/ph ,toan máu với BE < -5 trong 3 giờ, MAP < 60 mmHg, nước tiểu < 0,5 ml/kg/h với vận mạch liều cao (dopamine ≥20 µg/kg/min và/hoặc NE ≥0.3 µg/kg/min).
DBD: với FiO2>90%, PaO2/FiO2< 100, với Pplat > 30 cmH20 mà vẫn ứ CO2.

Hsieh2024-Using extracorporeal membrane oxygenation in donations after cardiac death or brain death _Asingle‐center experience and long‐term outcome

Fan2016-The organ preservation and enhancement of donation success ratio effect of extracorporeal membrane oxygenation in circulatory unstable brain death donor

Đối tượng thực hiện ECMO tuỳ nghiên cứu, tuỳ trung tâm

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ĐỐI TƯỢNG DBD VỚI ECMO

DBD

Đang ECMO --> chết não: ít lo ngại về đạo đức.

Khó khăn: test ngưng thở

DBD huyết động không ổn định/SHH nặng

CPR + phòng mổ

ECMO

Chưa chẩn đoán chết não hoặc chưa làm test chết não, Huyết động/HH không ổn

ECMO khi BN hoặc gia đình đã ký consent

Dalleave2016-The ethics of extracorporeal membrane oxygenation in brain-dead potential organ donors

-Tỉ lệ thấp

- Tổn thương nhiều cơ quan

CPR: This is depen- dent on whether the surgical retrieval team is immediately available, which is itself dependent on how far the organ donation process has advanced. In a brain-dead patient, this might result in a Maastricht Category IV DCDD.

it is estimated that 7 - 50% of patients on ECMO present with multiple conditions, including brain death (BD).(5,6) Data show that the latter occurs

in 21 - 28% of patients on ECMO with neurological complications.(5-7)

OP-ECMO in the not-yet brain-dead patient

The use of OP-ECMO before the declaration of brain death, as described in some case reports [23,24], is problematic. First, ECMO increases the potential risks of intracranial bleeding [7,12] and therefore could, in a not-yet brain-dead patient, hasten death. Second, in a severely brain-injured patient, the evolution toward brain death is difficult to predict and often remains uncertain. Implementing OP-ECMO before brain death (even after futility of ongoing treatment to save the life of the patient has been established) runs the risk of OP- ECMO being without benefit, if brain death never occurs. On the other hand, failing to use ECMO could lead to organ donation being impossible. Third, as the patient still has some brain activity the possibility of suffering cannot be excluded. Because of major risks of harm, we do not recom- mend the implementation of OP-ECMO before brain death has been established.

It is imperative in the not-yet brain-dead patient and the not-yet tested brain-dead patient that ECMO only be used for the direct clinical benefit of the patient and not for any organ-preserving properties the ECMO might confer. Clinicians should only implement ECMO in this situation if the therapeutic goal is to allow a diagnosis of brain death to be made not simply as a means of organ preservation

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ĐỐI TƯỢNG DCD VỚI ECMO

DCD

Maastricht III

Vấn đề đạo đức cho phép can thiệp trước hay sau khi tuyên bố chết

Maastricht IV

4A: uDCD: DBD ngưng tim đột ngột 🡪 CPR thất bại�🡪Vừa CPR + phòng mổ

4B: cDCD: DBD ngưng tim có kế hoạch ( rút các biện pháp duy trì sự sống WLST)

NRP - ECMO

The Maastricht category 4 DCD of cardiac arrest while awaiting brain death is different in Western and Eastern countries. In Western countries, most category 4 DCD donors are brain-dead organ donors with unexpected and uncontrolled cardiac arrest after unsuccessful resuscitation. They mostly occurr in the ICU during the preparation for DBD organ donation. Indeed the death of these donors is declared because of brain death and not of cardiocirculatory failure. This category does not require a “stand-off period.”

These donors may be urgently transported to the OR for organ procurement but their WI is usually long.

We propose to classify these DCD donors as category 4A to differentiate them from the Eastern countries category 4B DCD donors. In Eastern countries, such as Japan.79 and many Muslim nations, the concept of brain death is not widely accepted for culturaland/or religious reasons. Brain-dead donors may be transported to the OR for organ procurement after controlled

respiratory support withdrawal. These highly controlled DCD

donors may might be a potential source of all transplantable

organs. The category 4B DCD donation may also be (rarely)

performed in Western countries if the family does not rely on

the brain-death diagnosis and requests a controlled DCD

donation.20

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Khó khăn…

Thực hiện test ngưng thở chẩn đoán chết não ở bệnh nhân có ECMO?
ECMO ở bệnh nhân DBD và DCD có khác nhau?
Quy trình kĩ thuật
Vấn đề đạo đức

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Test ngưng thở/ ecmo

Khó khăn:

CO2 bị thải qua màng ECMO 🡪 phương pháp tăng CO2 đạt mục tiêu để kích thích trung tâm hô hấp ?
Cách làm test ngưng thở ở V-V và V-A không giống nhau???

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TEST NGƯNG THỞ Ở BN ECMO

- V-V ECMO:

Ngưng sweep gas → giảm oxy máu nghiêm trọng, gây rối loạn huyết động.
Duy trì sweep gas thì CO2 không đạt được mức kích thích hô hấp, test ngưng thở thất bại. Tuy nhiên:

🡪 Duy trì sweep gas ở mức thấp nhất: 0.5- 1 l/ph thường được lựa chọn ở nhiều trung tâm.

Nếu sweep gas ở mức tối thiểu nhưng CO2 vẫn chưa đạt đến ngưỡng kích thích hô hấp 🡪 thêm CO2 bên ngoài vào.

Sady2020_ Apnea test for brain death diagnosis in adults on extracorporeal membrane oxygenation: a review

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V –A ECMO:

Bán cầu não phải và trái có thể được cung cấp oxy từ những nguồn máu khác nhau, tuỳ thuộc vào dòng ECMO, chức năng tim hay tình trạng rối loạn hô hấp kèm theo. Do đó, nếu có sự khác biệt oxy hoá máu giữa 2 bán cầu đại não thì việc kích thích trung tâm hô hấp do CO2 cũng sẽ khác nhau.

Sady2020_ Apnea test for brain death diagnosis in adults on extracorporeal membrane oxygenation: a review

In this situation, the right cerebral hemisphere (or

both brain hemispheres, depending on the location

of the shunt point) would be perfused by anterograde

blood flow from the pulmonary circulation.(12) In the

case of preserved cardiac function associated with

significant respiratory dysfunction, these regions

would be exposed to hypoxia, while the left cerebral

hemisphere would be exposed to normoxic conditions

because it would be perfused with retrograde blood

flow from ECMO.(12)

However, because the exact determination of

this shunt point is difficult, the authors consider it

mandatory to collect blood samples from the circuit

after the ECMO oxygenator, in addition to a sample

from the arterial bed in the most peripheral path

(right radial artery for femoro-femoral cannulation

or femoral artery for axillary cannulation).(12) For this

reason, in a recent study, the authors recommend a

target oxygen saturation of > 88% in the two samples,

ensuring that both hemispheres are not exposed to

differential hypoxia.(12)

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🡪 Đảm bảo 2 bán cầu não đều không có sự tiếp xúc khác biệt với tình trạng nghèo oxy (differential hypoxia) : thử khí máu bệnh nhân ( ĐM quay phải) và khí máu sau màng ECMO đạt mục tiêu SaO2 > 88%.
🡪 Để chắc chắn thân não được kích thích bởi CO2 thì CO2 bệnh nhân và sau màng đều phải đạt mục tiêu ( > 60 mmHg).

Sady2020_ Apnea test for brain death diagnosis in adults on extracorporeal membrane oxygenation: a review

Finally, in cases of venoarterial ECMO, in addition

to preventing regional hypoxia, it should be ensured

that the brainstem, in fact, is exposed to the hypercapnia

stimulus.(12,26) For that, Ihle et al. recommend measuring

the blood gas tension of the native circulation, in the

peripheral arterial pathway, and of the extracorporeal

circulation by collecting samples in the ECMO circuit

after the oxygenator.(12) These authors also describe

a case whose test was invalidated because the partial

pressure of carbon dioxide (PaCO2) of the blood

sample collected after the ECMO oxygenator was lower

than the threshold required by legislation (60mmHg),

despite the tension of the sample obtained from the

native circulation being higher than the required

threshold.(12)

Therefore, a PaCO

2 above the threshold in both

samples would be unequivocal proof that both brain

hemispheres were exposed to this gas concentration and

that, therefore, in the absence of respiratory movement

(apnea), the test would be irrefutably compatible with

the condition of BD.(12)

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Sady2020_ Apnea test for brain death diagnosis in adults on extracorporeal membrane oxygenation: a review

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Biến chứng khi giảm sweep gas:�- Tụt oxy

- Tụt HA

Sady2020_ Apnea test for brain death diagnosis in adults on extracorporeal membrane oxygenation: a review

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THÊM CO2 VÀO ECMO

Beam2019-The Physiology of the Apnea Test for Brain Death Determination in ECMO_Arguments for Blending Carbon Dioxide

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THÊM CO2 VÀO ECMO

Champigneull2016-Efficiency and safety of apnea test process under extracorporeal membrane oxygenation- the most effective method remains questionable

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Beam2019-The Physiology of the Apnea Test for Brain Death Determination in ECMO_Arguments for Blending Carbon Dioxide

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22%

There was a high rate of nonconfirmatory ATs (22%) due to hemodynamic instability, severe hypoxia, and inadequate CO2 rise.

Pp truyền thống: Although previous studies of ATs in patients without ECMO report a failure rate of 10% to 24%,35,36 recent reports indicate a decline in complication rate with failure rates approaching 1%.

First, ancillary testing only evaluates the cerebral cortex, whereas the most common definition of brain death refers

to the absence of brainstem reflexes. Therefore, ancillary testing is not a substitute for assessing brainstem function.

Ở nước ngoài, nếu không làm được apnea test thì ngta cho phép dùng các cận lâm sàng để thay thế ( BN ECMO khác là không làm được MRA).

VN là phải làm đủ cả apnea test và cls.

Phương pháp giảm sweep gas flow dễ thực hiện nhưng cẩn thận gây tụt oxy, rối loạn huyết động.Thời gian thực hiện test ngưng thở từ 8-12ph để đạt mục tiêu CO2.

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TƯỚI MÁU VÙNG NHIỆT ĐỘ BÌNH THƯỜNG VỚI ECMO �( Normalthermic Regional Perfusion – ECMO)

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NORMOTHERMIC REGIONAL PERFUSION

NRP-ECMO: là phương pháp duy trì tưới máu tạng ở bệnh nhân DCD cho phép phục hồi lưu thông tưới máu cơ quan sau khi ngưng tuần hoàn, bằng cách thiết lập hệ thống V-A ECMO (tưới máu tạng ở nhiệt độ 37 độ C)
Mục đích:

- Phục hồi sau tình trạng tổn thương thiếu máu ấm ( warm ischemia time) và bổ sung dự trữ ATP.

- Đánh giá chức năng và chất lượng cơ quan

- Có thời gian cho tạng phục hồi và ekip nhận tạng.

Alamouti-fard 2022_Normothermic Regional Perfusion is an Emerging Cost Effective Alternative in Donation After Circulatory Death in Heart Transplantation

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KỸ THUẬT NRP-ECMO

Thời gian tưới máu # 2 giờ ( 1-4 giờ)

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ESOT Congress 2021 in Milan

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Oniscu2023-Improved Organ Utilization and Better Transplant Outcomes With In Situ Normothermic Regional Perfusion in Controlled Donation After Circulatory Death

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Mastrovangelis2024-Normothermic Regional Perfusion in Controlled Donation After Circulatory Death Liver Transplantation_A Systematic Review and Meta-Analysis

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THỰC HIỆN NRP -ECMO

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Thời điểm thực hiện ECMO

DCD:

uDCD: canula ECMO được đặt sau khi tuyên bố tử vong ( post – moterm)
cDCD:

Pre – moterm: trước khi WLST. Một số quốc gia không cho phép
Post – moterm: ít vấn đề y đức.

DBD:

V-A ECMO: CI < 2 L/m2/ph ,toan máu với BE < -5 trong 3 giờ, MAP < 60 mmHg, nước tiểu < 0,5 ml/kg/h với vận mạch liều cao (Dopa ≥20 µg/kg/min và/hoặc NE ≥0.3 µg/kg/min)
V-V ECMO: với FiO2>90%, PaO2/FiO2< 100, với Pplat > 30 cmH20 mà vẫn ứ CO2.

Fan2016-The organ preservation and enhancement of donation success ratio effect of extracorporeal membrane oxygenation in circulatory unstable brain death donor

BOOK of Guide to the quality and safety of organs for transplantation 7th Edition - 2018

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BOOK of Guide to the quality and safety of organs for transplantation 7th Edition - 2018

Bolus 5000 UI heparin

Đặt ECMO

(Post – moterm)

Đặt ECMO + Bóng

(pre – moterm)

(1) Agonal phase (Withdrawal time): thời gian từ lúc WLST đến lúc ngừng tim

(2) First WIT: Từ lúc ngừng tim đến lúc tạng được bảo quản lạnh in-situ. ( Gan: < 25 phút)

(3) Functional WIT (FWIT): từ lúc HA thấp có ý nghĩa ( định nghĩa tùy quốc gia) đến lúc tạng được bảo quản lạnh in-situ

Châu Âu: HATT < 50-60 mmHg

Mỹ: HATT <80 mmHg và/ hoặc SaO2 < 80%

(4) Donor WIT = total WIT = (1)+ (2)

Te outcome of transplantation with organs from cDCD donors is signifcantly inﬂuenced by the length of WIT. Following WLST, several time�periods have been defned (see Figure 12.6). Note that anastomosis time in the recipient is not included in�any of these defnitions:�a� Agonal phase (withdrawal time): the time from WLST to circulatory arrest.�First/primary WIT (asystolic or acirculatory time): the time from circulatory arrest to the start of in situ preservation.�Functional warm ischaemia time (FWIT):b� c� the time between frst episode of significant hypoperfusion (the start of which depends on national guidelines) and the start of in situ preservation �Donor WIT (DWIT): agonal phase (withdrawal time) + First WIT. Also referred to as�Total WIT.�Te moment that defnes the start of FWIT (signifcant hypoperfusion) is yet to be universally agreed upon, but in general a sustained fall in systolic blood�pressure ≤ 50 or 60 mmHg is accepted in Europe, while a fall in systolic blood pressure < 80 mmHg and/or O2 saturation < 80 % is accepted in the United�States [43, 100]. In addition, in the United States the term WIT refers to the total DWIT, as the time from�WLST to in situ preservation, whereas in the United�Kingdom it refers to the FWIT and in the Netherlands to the First WIT. Because of these varying defnitions being used to describe WIT it is essential to�verify the exact defnition when comparing literature.�Te acceptable FWIT varies for diﬀerent organs and ranges from 30 min for the liver and pancreas to 60 min for kidneys and lungs [101]. Tere is a lack of�evidence supporting these times, and several reports suggest that longer times yield transplantable organs, especially for kidneys [87, 102] and pancreas [103]. In liver transplantation it has been shown that every minute of extra ischaemia (First WIT) decreases graf survival, with a signifcantly higher chance of biliary complications [104], and care should be taken when First WIT exceeds 25 min [68]. Tese times are likely to change with the use of NRP �

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KỸ THUẬT

BOOK of Guide to the quality and safety of organs for transplantation 7th Edition - 2018

Reservoir (Bình chứa): thay thế thể tích bị mất trước đó, hoặc trong trường hợp liệt mạch nghiêm trọng ( thường dùng cho uDCD)

While NRP relies on extracorporeal membrane oxygenation (ECMO) technology, its clinical application is, in general, less complex than that of therapeutic ECMO.

An in-line reservoir may be included in the circuit, as well, to allow for replacement of volume prior to circuit failure in the event of volume loss or inadequate venous return due to severe vasoplegia (particularly relevant in the setting of uDCD). The precise positioning of occlusion balloon catheters or clamps used to exclude other vascular beds is what determines whether NRP is either thoracoabdominal or abdominal only.

Abdominal normothermic regional perfusion. Cannulae are placed in the femoral artery and vein in the groin region. A Fogarty balloon catheter is introduced through the contralateral femoral artery and positioned in the supraceliac abdominal or thoracic aorta.

At the least, clear and effective measures need to be put in place to ensure that cerebral reperfusion does not occur when NRP is established. Through the use of NRP, circulation is only restored to a limited region of the body, and a critical aspect of NRP in cDCD is ensuring lack of flow to the aortic arch vessels, thereby maintaining the permanence of circulatory arrest in the brain and brainstem.

BOOK

A traditional CPB system with an open reservoir would be less than ideal in this setting. An open reservoir system is designed to efficiently empty the heart

Cannulating the femoral vein and artery of one leg for the connection to an extracorporeal cir- culation system, which includes a membrane oxygenator and temperature exchanger. Introducing an endo-aortic balloon into the descending aorta, via the contralateral femoral artery, to restrict preservation to the abdom- inal cavity.

Simultaneously introducing the prime solution and premedication in the extracorporeal cir- culation pump. This should be finished before cannulation is completed.

Inflating the endo-aortic balloon before estab- lishing HRP or NRP, once the correct position of this catheter has been checked radiologically. The maximum duration of HRP or NRP in uDCD procedures has been established empir- ically at 240 min in most of the existing pro- grammes. If liver donation is planned, NRP rather than HRP should be established. If lung donation is planned, HRP is preferred, to avoid warming the thoracic cavity. Dual temperature – HRP for thoracic organs and NRP for abdom- inal organs – is feasible, allowing more organs to be recovered, but there is limited informa- tion on the results of lung and liver transplants using this strategy [36]. The available evidence suggests that kidneys can be recovered using both HRP or NRP.

In situ preservation manoeuvres based on HRP or NRP should be discontinued in the fol- lowing situations:

i. When the necessary consent and authorisation requirements for organ recovery have not been obtained.

ii. If after 240 min of HRP or NRP, the necessary requisites for organ recovery (e.g. consent and authorisation) have not been fulfilled

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First Scandinavian Protocol for Controlled Donation After Circulatory Death Using Normothermic Regional Perfusion

To avoid cardiac reanimation and cerebral reperfusion, the thoracic aorta was occluded with a double-lumen 7-Fr inflated balloon catheter which in addition allowed pressure measurements above the balloon to verify total occlusion of aorta

After consent for donation was granted, the NRP team was notified. Premortem patient management was conducted by the ICU team not affiliated with the organ donation service. The cDCD protocol used NRP support of abdominal organs by an ECMO circuit. After permission was granted, central lines were placed in the common femoral artery and vein. 5000 international units Heparin® was given intravenously at WLST. Preparations for abdominal NRP were performed bedside in the ICU but without cannulation for perfusion before declaration of death. After a minute of silence, life-support was withdrawn and symptomatic directed measures continued as needed. The patients were extubated and intravenous support and vasoactive medications were stopped. Upon wish, the next of kin could be present bedside during the agonal period.

After cardiac and respiratory arrest, and a 5-minute observation constituting a “no-touch period,” the primary responsible intensive care physician made the declaration of death. The next of kin left the room after the observation period. Using Seldinger percutaneous technique, cannulas were rapidly placed for the NRP circuit thereby providing an organ preservation flush line. To avoid cardiac reanimation and cerebral reperfusion, the thoracic aorta was occluded with a double-lumen 7-Fr inflated balloon catheter which in addition allowed pressure measurements above the balloon to verify total occlusion of aorta (Figure 1) when perfusion was initiated. A strategy to confirm correct balloon catheter placement by radiopaque contrast was introduced during the study period. Functional warm ischemic time (fWIT) for organs was defined as the time from mean blood pressure (BP) less than 50 mm Hg and/or oxygen saturation less than 80% (5 minute of “no-touch period” included) to NRP start.

Organs were accepted for transplantation according to EDQM guidelines¹⁹ with a maximum fWIT of 60 minutes for kidneys and 30 minutes for livers.

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Cổng luồn Guidewire (Distal port)

Bơm 30 ml Hepsal

Aortic endo-clamp (e.g. Cook 32/37mm, 120cm Coda LP balloon catheter)

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2022-Role of normothermic perfusion with ECMO in donation after controlled cardiac death in Spain

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Villares2017-Validation of a new proposal to avoid donor resuscitation in controlled donation after circulatory death with normothermic regional perfusion

Theo dõi 2 HA ĐMXL: động mạch quay (T) và động mạch đùi.

Theo dõi hoạt động não bằng Bispectral index trước và sau WLST

Heparin 500 – 600 UI/kg. Đặt canula ECMO trước WLST. Đặt bóng chẹn đm xuống.

Hình A

Trước WLST, bơm bóng đm chủ trong 4 giây 🡪 sóng đm đùi mất trong khi sóng động mạch quay vẫn còn --> mức áp lực đủ để ”blocked” đm chủ ngực. Ghi nhận thể tích tối thiểu để ”blocked”

Xả bóng.

X-quang ngực: xác định vị trí đúng của bóng.

Hình B

Sau khi tuyên bố tử vong và NRP bắt đầu: sóng đm quay (T) mất, trong khi sóng đm đùi vẫn duy trì với dạng ”sóng liên tục” ở mức HATB 60-65 mmHg

Nếu xuất hiện sóng ở đm quay, NRP được dừng lại ngay lập tức, xác định vị trí bóng cũng như bơm thêm bóng. Sau 5 phút ”no- touch”, mở lại NRP và theo dõi.

MỤC ĐÍCH: không xuất hiện sóng đm quay được xem tương đương như không có lưu lượng máu lên não.

Việc dùng X-quang xác định vị trí bóng giúp loại trừ bóng đi sai vị trí (các nhánh của động mạch chủ, qua động mạch đùi đối diện…),

Kinh nghiệm bên PTMM: đầu tip bóng ngang mức carina thì tương đương với bóng đang ở động mạch chủ ngực xuống.

A. Aortic occlusion catheter in the correct position with the balloon filled with radiopaque contrast. The femoral pulse taken in the ECMO cannula disappears when the balloon is filled while the radial pulse is maintained. The complete disappearance of the femoral pulse indicates the minimum filling balloon volume. B. If the aortic occlusion catheter is correctly positioned, the femoral cannula shows a non-pulsatile pressure while there is neither radial artery pressure nor oxygen saturation (right). If the balloon is not completely full or is too advanced, non-pulsatile pressure will be detected in both femoral and radial arteries (left).

Before WLST, the aortic occlusion bal- loon was filled for just 4 seconds, in order to confirm that pressure from the arterial femoral cannula disappeared while the left wrist line was maintained ensuring that the thoracic aorta was

adequately blocked. The balloon was then immediately emptied. The filling volume was recorded as the minimum volume to be used to block the aorta during nRP.An X-ray or fluoroscopy view was obtained before WLST to ensure the correct positioning of the catheter.

After death was certified and nRP was started, arterial pressure from the left radial artery disappeared with adequate blocking of the thoracic aorta, while the pressure from the femoral arterial cannula was maintained, but pressure was continuous rather than pulsatile because it was provided by the ECMO device (see Fig. 1B). A continuous pressure > 60–65 mmHg was maintained.

If flow was detected in radial line, nRP was immediately stopped and correct positioning or filling of the catheter was checked. The nRP was then reinitiated after a no-touch period of 5 min.

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THEO DÕI

Chỉ khởi động NRP khi kết nối hệ thống VÀ động mạch chủ ngực đã được kẹp hoặc chẹn bóng
Nhiệt độ máy: 37⁰C
Gas: 2 l/ph, FiO2 21%. Tránh cài FiO2 cao ( tạo ra các ROS, có thể gây tổn thương tạng do tái tưới máu đột ngột). Thay đổi Gas hoặc FiO2 dựa vào kết quả khí máu.
Thời gian chạy N-ECMO: ít nhất 1h và tối đa 4h cho phép phục hồi đầy đủ các cơ quan trong ổ bụng (đảo ngược quá trình thiếu máu) và phục hồi các chất năng lượng mà không gây tổn thương cho cơ quan nội tạng. Thường kéo dài 2h.
Heparin được lặp lại 150 UI/kg mỗi 90 phút.

2022-UK Protocol for Normothermic Regional Perfusion (NRP) in controlled Donation after Circulatory determination of Death

The pump must only be started once the circuit is completely connected, the thoracic aorta is cross-clamped/occluded and the aorta above the clamp is vented.
 The heater temperature should be 37°C.
 The air/O2 mixer should be set to deliver gas flow at 2 litres/minute with a starting FiO2 of 21% (air). High FiO2 should be avoided. Changes to the oxygen/air mixture may be required subsequently depending on the blood gas analysis. High oxygen concentrations may generate reactive oxygen species and can exacerbate reperfusion injury to the organs.

UK national NRP Protocol

The following parameters are suggested:

 Pump flow 2-3 litres/minute
 Temperature 35.5°C - 37.5°C
 Air / O2 to maintain a venous O2 saturation (SvO2) 60-80%
 Arterial pH 7.35-7.45
 Haematocrit > 20%
 Gas flow to maintain arterial pCO2 4.5 to 6.0 kPa.

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* Khí máu (động hoặc tĩnh mạch): đánh giá tưới máu và oxy hoá máu

* Lactate: nên giảm, tương ứng với chức năng gan. Bị ảnh hưởng bởi kẹp mạch máu, dung dịch Hartmann

* ALT: đánh giá chức năng gan ( > 3xULT hoặc > 4xULT cuối thời điểm NRP hoặc > 500 mmol/L là chống chỉ định tương đối của ghép gan...)

* Glucose: tăng liên quan đến chức năng gan, liên quan tuỵ…

…

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VẤN ĐỀ Y ĐỨC

Cần kí đồng thuận.
Vấn đề: Vi phạm “Dead donor rule”

Do tồn tại những vòng tuần hoàn song song, làm lưu lượng máu lên não
Do áp lực bơm bóng động mạch chủ không đủ lớn để ngăn máu từ dòng ECMO lên não.

Manara2017-Maintaining the permanence principle for death during in situ normothermic regional perfusion for donation after circulatory death organ recovery/ A UK and Canadian proposal

“The dead donor rule specifies that donors cannot be made dead in order to obtain their organs and that organ retrieval cannot cause death”

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NRP: ETHICAL CHALLENGES AND BENEFITS

NRP: có thể tái tưới máu não?
Mất hiệu lực của tuyên bố tử vong trước đó (Vi phạm Death Donor Rule).
Bóng chẹn đmc xuống chẹn hoàn toàn hay không?
Làm thế nào để xác định là đã chẹn hoàn toàn?
Thông khí phổi lại và tiếp tục lại hoạt động của tim (trong lấy tạng tim/phổi)?

NRP có được cân nhắc như một phương pháp chăm sóc cuối đời thường quy?
Can thiệp ante- moterm
Nơi WLST (ICU/phòng mổ)

Tối thiểu hoá những tổn thương do thiếu máu gây ra

Tăng số lượng và chất lượng mảnh ghép từ nhóm DCD�

Challenges

Benefits

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Xây dựng quy trình test ngưng thở ở người hiến tạng tiềm năng có ECMO (V-V, V-A)
NRP-ECMO giúp tăng số lượng tạng được lấy và được ghép. Cho phép có thời gian đánh gía tạng , cải thiện kết cục tạng ghép.
NRP-ECMO có thể thực hiện ở nhóm DBD và nhóm DCD, thời điểm thực hiện trước hoặc sau tuyên bố chết tuần hoàn.
Cần có thêm đồng thuận để tránh gây ra tranh cãi về mặt đạo đức trong hiến tạng.

KẾT LUẬN

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THANK YOU FOR LISTENING !