Correspondence
Extracorporeal Membrane Oxygenation for ARDS in Adults
N Engl J Med 2012; 366:575-576February 9, 2012
- Article
To the Editor:
While summarizing the use of extracorporeal membrane oxygenation (ECMO) in the acute respiratory distress syndrome (ARDS), Brodie and Bacchetta (Nov. 17 issue)1 suggest venoarterial ECMO as an alternative approach to standard venovenous ECMO when hemodynamic support is needed.
In our experience, this practice is associated with considerable risk. First, because of the arterial cannula, the perfusion to the affected limb is compromised and limb ischemia can occur in up to 21% of patients.2 Second, because of the considerably reduced blood flow through the pulmonary circulation, thrombus formation is possible.3 Finally and most importantly, the blood supply to the systemic circulation in this situation is dual: oxygenated blood enters the descending aorta from the ECMO circuit while (unlike with cardiopulmonary bypass) poorly oxygenated blood continues to be ejected by the left ventricle. As a result, more cranial organs such as the brain and myocardium receive poorly oxygenated blood as compared with the caudal organs supplied by the descending aorta, which receive well-oxygenated blood.4,5 We therefore recommend that venoarterial ECMO is best avoided in ARDS.
Hergen Buscher, F.C.I.C.M.
Priya Nair, F.C.I.C.M.
St. Vincent's Hospital, Sydney, NSW, Australia
hergenbuscher@yahoo.de No potential conflict of interest relevant to this letter was reported.
5 References1
Brodie D ,Bacchetta M . Extracorporeal membrane oxygenation for ARDS in adults. N Engl J Med 2011;365:1905-1914
Full Text | Web of Science | Medline2
Foley PJ ,Morris RJ ,Woo EY , et al. Limb ischemia during femoral cannulation for cardiopulmonary support. J Vasc Surg 2010;52:850-853
CrossRef | Web of Science | Medline3
Muehrcke DD ,McCarthy PM ,Stewart RW , et al. Complications of extracorporeal life support systems using heparin-bound surfaces: the risk of intracardiac clot formation. J Thorac Cardiovasc Surg 1995;110:843-851
CrossRef | Web of Science | Medline4
Nair P ,Davies AR ,Beca J , et al. Extracorporeal membrane oxygenation for severe ARDS in pregnant and postpartum women during the 2009 H1N1 pandemic. Intensive Care Med 2011;37:648-654
CrossRef | Web of Science | Medline5
Kitamura M ,Shibuya M ,Kurihara H ,Akimoto T ,Endo M ,Koyanagi H . Effective cross-circulation technique of venoarterial bypass for differential hypoxia condition. Artif Organs 1997;21:786-788
CrossRef | Web of Science | Medline
To the Editor:
We respectfully disagree with the assertion by Brodie and Bacchetta that emphasis on disease management mandates that patients with ARDS be treated in the medical intensive care unit (ICU). ECMO circuit design is complex and best accomplished with expert advice. Management of large-bore cannulae may not be straightforward; insertion and removal may be safest in the operating room or angiography suite. Nursing and respiratory care of patients receiving ECMO is specialized. We believe no other form of critical care requires such wide-based expertise. We suggest a collaborative-care model in which multiple groups, each bringing specialized expertise, care for the patient in the location where the expertise is most concentrated. In some institutions, this location may be the pediatric ICU, because ECMO is more widely used in children than in adults. In other institutions, it may be the surgical ICU. Institutions undertaking ECMO for patients with ARDS should take into account their own local expertise when designing a collaborative-care model.
Michael Hutchens, M.D.
Howard Song, M.D., Ph.D.
Laura Ibsen, M.D.
Oregon Health and Science University, Portland, OR
hutchenm@ohsu.edu No potential conflict of interest relevant to this letter was reported.
To the Editor:
As clinical ethicists, we would add that ECMO's scientific advance necessitates a correlative reexamination of the meaning of resuscitation and the framing of end-of-life discussions. When resuscitation consisted of just chest compressions and mechanical ventilation, the do-not-resuscitate (DNR) order sufficed to withhold these techniques.1,2 But ECMO, which provides continual resuscitation through ongoing perfusion and oxygenation, places the DNR construct under severe conceptual strain.
What would a DNR designation mean for a patient receiving ECMO? Would it represent the withholding of cardiopulmonary resuscitation, which paradoxically is less efficacious than ECMO itself? Or would it mean the discontinuation of ECMO, which is properly understood as a withdrawal of life-sustaining therapy?
These questions are more than academic. Decisions to de-escalate care are generally initiated with a DNR order. ECMO complicates this trajectory and reveals the limitations of the DNR construct as it is currently understood. Ethicists and intensivists need to revitalize the language of resuscitation to respond to these conceptual challenges.
Ellen C. Meltzer, M.D.
Joseph J. Fins, M.D.
Weill Cornell Medical College, New York, NY
elc9076@med.cornell. edu No potential conflict of interest relevant to this letter was reported.
2 References1
Burns JP ,Edwards J ,Johnson J ,Cassem NH ,Truog RD . Do-not-resuscitate order after 25 years. Crit Care Med 2003;31:1543-1550
CrossRef | Web of Science | Medline2
Ewanchuk M ,Brindley PG . Perioperative do-not-resuscitate orders -- doing `nothing' when `something' can be done. Crit Care 2006;10:219-219
CrossRef | Web of Science | Medline
Author/Editor Response
We thank Buscher and Nair for elaborating on the use of venoarterial ECMO in ARDS and agree with their conclusion that it is best avoided when possible. The need for venoarterial ECMO to provide substantial hemodynamic support in patients with ARDS — as in patients with concomitant cardiogenic shock — is an uncommon occurrence. However, when such a need arises, the issues raised by Buscher and Nair must be addressed.
Limb ischemia is a clinically significant limitation of femoral-artery cannulation. However, use of a distal-limb perfusion technique at the time of cannulation substantially reduces the risk of ischemia.1,2 Buscher and Nair make the essential point that the femoral arterial approach does not guarantee adequate oxygenation of the upper body — most importantly, the brain and heart. This lack of a guarantee should be of considerable concern to clinicians using venoarterial ECMO in patients with hypoxemic respiratory failure. For such patients, we recommend the use of the subclavian or axillary artery approach, with a graft sewn in an end-to-side fashion, when technically feasible. This approach addresses the issue of limb ischemia while also providing adequate upper-body oxygenation.2,3 Alternatively, sufficient oxygen to the upper body may be delivered with the use of a venous reinfusion cannula in the internal jugular vein, in addition to the femoral arterial reinfusion cannula.
We agree with Hutchens and colleagues that the care of patients receiving ECMO requires highly specialized knowledge and a collaborative multispecialty approach; this can only take place in an ICU where such high-level services are available. We are not suggesting that it is mandatory for patients with ARDS to be treated in a medical ICU if such an ICU is not equipped to provide the appropriate level of expertise.
Our model is based on the same principle that governs the assignment of any patient to a specific ICU: the underlying disease process is matched to the expertise of that ICU. In patients receiving ECMO, the ability to do this requires exporting the knowledge and skill of an experienced ECMO team to other ICUs. This is not a trivial undertaking. However, once this expertise is available in multiple ICUs, the shift in emphasis from device management to disease management becomes feasible and potentially advantageous.
We thank Meltzer and Fins for raising issues of considerable importance to the field. Although most relevant in patients who are receiving venoarterial ECMO, these and other ethical questions clearly require careful reflection.
Daniel Brodie, M.D.
Matthew Bacchetta, M.D.
Columbia University College of Physicians and Surgeons, New York, NY
hdb5@columbia.edu Since publication of their article, the authors report no further potential conflict of interest.
3 References1
Foley PJ ,Morris RJ ,Woo EY , et al. Limb ischemia during femoral cannulation for cardiopulmonary support. J Vasc Surg 2010;52:850-853
CrossRef | Web of Science | Medline2
Stulak JM ,Dearani JA ,Burkhart HM ,Barnes RD ,Scott PD ,Schears GJ . ECMO cannulation controversies and complications. Semin Cardiothorac Vasc Anesth 2009;13:176-182
CrossRef | Medline3
Bacchetta M ,Javidfar J ,Sonett J ,Kim H ,Zwischenberger J ,Wang D . Ease of conversion from venovenous extracorporeal membrane oxygenation to cardiopulmonary bypass and venoarterial extracorporeal membrane oxygenation with a bicaval dual lumen catheter. ASAIO J 2011;57:283-285
CrossRef | Web of Science | Medline
