Keywords ECMO-associated coagulopathy - extracorporeal membrane oxygenation - heparin-free
ECMO - microsurgical aneurysmal clipping - pulmonary neurogenic lung - subarachnoid
hemorrhage
Introduction
In the acute neurocritical care region, extracorporeal membrane oxygenation (ECMO)
has been thought to be of limited use due to the concomitant need for anticoagulation.[1 ]
[2 ]
[3 ] Thus, the accumulation of clinical evidence about ECMO management in the neurosurgical
intervention is essential. Here, we present a successful case of microsurgical aneurysmal
clipping during venovenous ECMO for World Federation of Neurological Societies (WFNS)
grade V subarachnoid hemorrhage (SAH) with severe neurogenic pulmonary edema (NPE).
Case Presentation
A 50-year-old man was admitted to our hospital due to sudden loss of consciousness.
His vital signs were as follows: blood pressure 80/58 mm Hg, heart rate 65 beats/min,
and oxygen saturation 85% under 10 L/min oxygen in a reservoir mask. A chest computed
tomography (CT; [Fig. 1a ]) and an echocardiography revealed an NPE and a stress-induced cardiomyopathy, and
the patient was intubated. Head CT and CT angiography ([Fig. 1b, c ]) showed SAH with multiple aneurysms. Because of poor clinical course at admission,
this patient was diagnosed as WFNS grade V SAH. Owing to the aneurysmal size, shape,
and location, microsurgical clipping was considered to be preferable to endovascular
treatment, which is the preferred treatment in serious systemic conditions. Repeated
arterial blood gas analyses showed severe hypoxemia refractory to conventional treatment.
Therefore, we initiated venovenous ECMO ([Fig. 2 ]). To avoid thrombosis inside the ECMO circuit despite no anticoagulants, a heparin-bonded
ECMO was maintained at a comparatively high flow rate (4.2 L/min). Gradually, low
blood pressure improved without vasopressor administration. On day 3, we decided to
perform a microsurgical clipping on ECMO. Intraoperatively we had difficulty in bleeding
control because of low platelet count, and a very bloody surgical field led to poor
vision of the microscope ([Fig. 3a ]). After the transfusion of 6 units red blood cells and 20 units platelets to correct
anemia and coagulopathy, we managed to apply clips for all the aneurysms ([Fig. 3b ]). Intraoperative blood loss was approximately 640 mL. Postoperatively ECMO weaning
was successful. The patient was doing well except for lenticulostriate artery (LSA)
infarction ([Fig. 3c ]). After 2 years from onset, his neurological examination showed only a slight hemiparesis.
His activities of daily life were independent (modified ranking scale 1).
Fig. 1 (A ) Chest computed tomography (CT) on admission shows neurogenic pulmonary edema in
both lungs. (B ) Head CT and (C ) CT angiography on admission show diffuse subarachnoid hemorrhage and an anterior
choroidal artery aneurysm and two middle cerebral artery aneurysms (red arrows ).
Fig. 2 Chest X-ray after the extracorporeal membrane oxygenation cannulation shows two single
lumen cannulas, draining from the inferior vena cava (IVC) and reinfusing into the
IVC/right atrium. The black arrow shows the tip of the draining venous cannula, and the two black arrowheads show the reinfusion cannula.
Fig. 3 (A ) An intraoperative photograph during the dissection of sylvian fissure shows very
bloody surgical field and poor vision of the microscope. (B ) The anteroposterior view of postoperative computed tomography angiography shows
complete neck clipping. (C ) A head computed tomography performed 1 month after the operation shows a right lenticulostriate
artery infarction.
Discussion
Although ECMO can be a last-resort treatment for patients with severe acute respiratory
failure, neurosurgical interventions are generally considered contraindications for
ECMO therapy because ECMO may increase additional neurological injuries such as intracranial
hemorrhage and ischemic stroke.[4 ]
[5 ]
[6 ] In particular, the use of systemic anticoagulation and impaired hemostasis due to
platelet consumption and its dysfunction during ECMO can increase intracranial hemorrhagic
complication. Thus, avoiding systemic anticoagulation and considering platelet transfusion
are desirable when neurosurgical interventions are performed for intracranial hemorrhagic
patients on ECMO.
The recent improvements in ECMO devices may make the use of heparin-free ECMO possible.[1 ]
[6 ]
[7 ] Arlt et al[8 ] reported that heparin-free ECMO could be a safe alternate rescue treatment in patients
with severe trauma and hemorrhagic shock. Faulkner et al[1 ] also reported the successful utilization of venovenous ECMO for severe respiratory
failure secondary to aneurysmal SAH after endovascular coiling. To reduce the risk
of clot formation in the oxygenator and venous thromboembolism even without any anticoagulants,
they used short lengths of heparin-bonded venovenous ECMO tubing and maintained the
venovenous ECMO pump speed at a slightly higher-than-normal speed for increased flow
throughout the ECMO circuit.[1 ] However, most of such successful reports about the utilization of ECMO in the acute
neurocritical care region were dominantly limited to macro-neurosurgical interventions
and postmicrosurgical management.[1 ]
[9 ]
[10 ] There was an extremely rare report of a successful microsurgical intervention under
ECMO.
According to our literature review, Hwang et al[11 ] were the first to report successful aneurysmal clipping under ECMO by using nafamostat
mesylate alternatively as a regional anticoagulant for an SAH patient with NPE. To
our knowledge, the present case is the first report of successful microsurgical clipping
for SAH during ECMO without any anticoagulants.
Preoperative management should begin with a critical evaluation of whether the patient
can be weaned from ECMO prior to the cerebral aneurysm surgery. If weaning from ECMO
is possible, careful attention to ECMO-associated coagulopathy is not needed and,
therefore, surgery can be performed under standard general anesthesia management for
cerebral aneurysmal clipping surgery. The next step is to determine the feasibility
of endovascular treatment. If ECMO weaning is not possible and the ruptured cerebral
aneurysm can be fully treatable with the endovascular treatment, this approach is
preferable to the direct surgery. In the cases where direct surgery is unavoidable,
it is crucial to plan a preoperative simulation so that the surgical procedures can
be conducted minimally invasively in the shortest possible time.
According to the Extracorporeal Life Support Organization (ELSO) guidelines,[12 ] relevant literature,[13 ] and our experience with this case, intraoperative management by anesthesiologists
should include red blood cell transfusion to maintain hemoglobin levels between 7
and 9 g/dL. Platelet transfusions should be administered based on the extent of intraoperative
bleeding; however, it is essential to maintain a platelet count above 100,000/µL to
avoid a bloody surgical field, especially during microscopic procedures. Fresh frozen
plasma transfusion is recommended to maintain fibrinogen levels between 250 and 300 mg/dL.
For neurosurgeons, the primary focus during surgery must be on meticulous bleeding
control. In the direct surgery for ruptured middle cerebral artery aneurysms like
the present case, a distal sylvian approach should be selected whenever possible,
because the extent of microsurgical dissection is minimally required. In addition,
proximal control should be achieved with minimal exposure of the M1 segment for the
application of a temporary clip. If the surgical field becomes bloody, timely replacement
of platelets and coagulation factors is essential, along with precise bipolar coagulation
and the use of suitable hemostatic agents. In the present case, the bipolar coagulation
in a bloody surgical field during M1 exposure may have contributed to LSA infarction.
Among hemostatic agents, a topical gelatin-thrombin hemostatic matrix such as FLOSEAL
appears to be particularly effective. Literature[14 ] supports FLOSEAL's efficacy in achieving hemostasis, especially in cases of diffuse
bleeding or when bleeding points are difficult to identify. FLOSEAL's effectiveness
has been demonstrated even in patients under heparinization.[15 ] Such a hemostatic agent is likely well suited for use in microsurgical procedures
for patients with bleeding tendencies on ECMO.
Conclusion
The use of a heparin-bonded ECMO tubing, maintenance of a slightly higher ECMO pump
speed, and preparation of enough platelet transfusion to correct coagulopathy are
essential to perform a safe and precise microsurgical procedure for SAH patients on
ECMO without any anticoagulants. This report demonstrated the possibility to extend
the range of application of microsurgical clipping for poor-grade SAH patients requiring
ECMO treatment.
