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Ann Thorac Surg 2006;81:892-895
© 2006 The Society of Thoracic Surgeons
a Department of Cardiothoracic Surgery, Medical University Vienna, Vienna, Austria
b Department of Vascular Surgery, Medical University Vienna, Vienna, Austria
c Department of Clinical Pharmacology, Medical University Vienna, Vienna, Austria
Accepted for publication September 26, 2005.
* Address correspondence to Dr Zimpfer, Department of Cardiothoracic Surgery, Medical University Vienna, Wahringer Guertel 18-20, A-1090 Vienna, Austria (Email: daniel.zimpfer{at}meduniwien.ac.at).
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Abstract |
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METHODS: From January 1998 through December 2004, 174 adults (mean age, 45 ± 19 years) undergoing either cardiac surgery (n = 54, 31.4%) or lung transplantation (n = 120, 68.6%) were supported with extracorporeal membrane oxygenation. Data were prospectively collected and retrospectively analyzed. Follow-up extended up to 60 months (mean, 30 ± 10 months). Multivariable regression analysis was used to identify predictors of late vascular complications.
RESULTS: Hospital survival was 57.3%. A total of 12 hospital survivors (12.2%) experienced late vascular complications. All late vascular complications were local stenosis at the former arterial cannulation site. Treatment was done by means of femorofemoral crossover bypass (n = 3), iliofemoral bypass (n = 1), thromboendarterectomy (n = 3), and percutaneous transluminal angioplasty (n = 5). We experienced no limb loss during follow-up. Predictors for long-term vascular complications were technical problems during extracorporeal membrane oxygenation explantation (p = 0.002; odds ratio, 23.2) and history of peripheral vascular disease (p = 0.015; odds ratio, 3.1).
CONCLUSIONS: Extracorporal membrane oxygenation support is associated with the development of late vascular complications at the femoral access site. In selected patients alternative cannulation sites should be considered.
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Introduction |
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The long-term outcome of patients surviving ECMO treatment has been described in the past [4, 5]. However, previous studies reporting long-term outcome after ECMO concentrate on reporting survival rates. There are no data on late complications after ECMO implantation.
The purpose of this study was to evaluate whether ECMO support is associated with the development of late vascular complications and to determine risk factors for the development of late vascular complications. We analyzed the results of a standard ECMO circuit used in large numbers at our institution.
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Material and Methods |
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Patients supported with ECMO ranged from 20 to 80 years (mean, 45 ± 19 years), and 56% were men. Patient demographic data are given in Table 1.
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The ECMO circuit consisted of a Medtronic console 450 or 550, a Medtronic Bio-Cal Blood Temperature Control Module (Medtronic, Inc, Minneapolis, MN), and a hollow-fiber membrane oxygenator with an integrated heat exchanger. Heparin-coated Medtronic Bio-Medicus cannulas were used.
In all patients venoarterial ECMO was instituted by means of peripheral cannulation through the groin. The arterial return cannula (15F to 21F) was inserted into the common femoral artery, and the venous drainage cannula (21F to 28F) was inserted into the common femoral vein with placement of the tip just proximal to the right atrium. This was controlled by transesophageal echocardiography. No percutaneous cannulation was performed. A peripheral leg cannula connected to the arterial cannula using a Y adapter was used in all patients. Implantation of ECMO support through the groin is standardized at our department. After preparation of the arterial and venous vessels, cannulation sutures are placed; thereafter, the arterial and venous cannulas are inserted using the Seldinger technique. After installation of the ECMO support and exact placement of the venous cannula controlled by transesophageal echocardiography, the cannulation sutures are tied and the skin is closed. Peripheral perfusion is continuously monitored clinically; in case of suspicion of peripheral malperfusion, ultrasound studies are performed.
Conduct of ECMO was according to institutional standards. Mechanical ventilation was continued throughout the ECMO with biphasic positive airway pressure. Ventilator settings were most commonly set at a tidal volume of 8 to 10 mL · kg–1 · min–1, a positive end-expiratory pressure of 10 cm H2O, and an inspired oxygen fraction of 0.3.
Patients were evaluated daily for hemodynamic and respiratory improvement and the possibility of weaning. While weaning, the activated clotting time was adjusted to 180 seconds. Flow rate was reduced stepwise in steps of 1 L/min under continuous monitoring of hemodynamic and respiratory variables. Ventricular function was assessed using transesophageal echocardiography. Inotropic and vasodilator support was increased on demand. Acceptable central venous pressure (15 mm Hg) and mean arterial pressure (60 mm Hg) and stable left and right ventricular function for a period of 4 to 6 hours with the reduced device flow demonstrated improvement of cardiac function and represented an indication for removal of the device. The explantation of ECMO was completed on the intensive care unit in a standardized bedside fashion. The operative field is reopened. Before removing the arterial and venous cannulas, cannulation sutures are again placed. Thereafter, the cannulas are removed and the cannulation sutures tied. In case of ongoing bleeding, running or interrupted sutures are placed as appropriate. To ensure peripheral perfusion the arterial vessel is palpated distal to the former cannulation site immediately after decannulation. In case of distal malperfusion or pulselessness, reconstructive procedures are performed. Furthermore, evaluation of peripheral perfusion in the intensive care unit is performed clinically.
Technical problems during decannulation were defined as severe bleeding from the arterial cannulation site requiring multiple sutures, the fact that the operating surgeon found the decannulation procedure to be technically challenging, and the need for a Fogarty catheter maneuver.
Follow-Up
Follow-up was performed by means of annual screening of hospital medical records and screening of a nationwide death registry. Furthermore, the patients' general practitioner was contacted on yearly basis. Follow-up was complete at all points of follow-up.
Statistical Analysis
Continuous variables are expressed as mean ± standard deviation, and means were compared by independent sample Student's t test after testing for normality of distribution. Categorical variables are expressed as percentages and were analyzed by the 
2 test or Fisher's exact test as appropriate. Actuarial patient survival as well as freedom of late vascular complications was calculated by Kaplan-Meier analysis. A multivariable regression analysis was used to identify risk factors for late vascular complications. Probability values of less than 0.05 were considered significant in two-sided comparisons. The study was analyzed using SPSS 11.5 (SPSS, Inc, Chicago, IL).
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Results |
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Comment |
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Extracorporeal membrane oxygenation support has developed as a treatment standard in patients with acute cardiac and respiratory failure and as perioperative support in patients undergoing heart and lung transplantation, as well as being a treatment alternative in patients with acute graft rejection after lung transplantation [6–9]. Previous studies report 30-day survival rates ranging from 34% to 38% in patients needing ECMO support [4, 5]. In the present study overall 30-day survival rate is 58%. The higher survival rate in the present study may well be explained by the fact that indication for ECMO implantation was perioperative support for heart and lung transplantation in the majority of patients in the present series. In the group of patients with cardiac failure being the indication for ECMO implantation, 30-day survival rate was 37%, which is well in line with other published series [4, 5]. Our results support previous studies showing excellent long-term survival in patients who are discharged from the hospital after ECMO support [4, 5].
Extracorporeal membrane oxygenation support has been shown to be associated with a certain morbidity including infections, neurologic events, pump thrombus formation, and limb complications. We observed early complication rates comparable to those previously published [4, 5]. Reasons for the rather high rate of morbidity during ECMO support have been discussed in the past. It has to be stressed that ECMO support is associated with an inflammatory response leading to complement as well as neutrophil, platelet, and cytokine activation as a result of ischemia and consecutive reperfusion organ injury [10, 11]. The high rate of early limb complications, thus the fact that we used leg cannulas, might be explained by the fact that patients with ECMO usually need extensive vasopressor support in the early phase of support. In this setting the absence of pulsatile perfusion might be deleterious.
We observed late vascular complications in 12% of patients successfully weaned from ECMO. Of the total of 12 patients with late vascular complications surgical revascularization was performed in 7 patients. Five patients underwent percutaneous transluminal angioplasty. Indication for percutaneous intervention was severe multiple morbidity in all patients with associated high risk when undergoing surgical revascularization. We identified technical problems during decannulation as well as history of peripheral vascular disease as independent predictors for the development of late vascular complications. With regard to technical problems during decannulation as a predictor for late vascular complications, various issues have to be discussed. Decannulation at our institution is usually performed bedside in the intensive care unit. This is done to minimize transportation and associated stress for the critically ill patient. As the further prognosis of patients who are successfully weaned from ECMO is still uncertain, it was our policy not to perform extensive reconstructive procedures immediately after decannulation to keep the intervention as minimal as possible. With regard to history of peripheral vascular disease being a predictor for late vascular complications, it seems plausible that atherosclerotic vessels are especially vulnerable and placement of a cannula might initiate progression of local plaques.
Facing the high rate of immediate as well as late vascular complications in patients with ECMO support through the groin, management strategies have to be discussed. To avoid late vascular complications we changed the explantation procedure. Explantation is carried out in the intensive care unit. We now perform an autologous patch plastic whenever we experience technical problems during decannulation and in those patients in whom we believe that the femoral artery is significantly compromised. In those patients with peripheral arterial vascular disease we perform a local thromboendarterectomy and patch plastic if applicable. Furthermore, alternative cannulation sites such as central cannulation and cannulation through the subclavian artery have to be discussed in selected patients. Central cannulation through a coated vascular prosthesis seems to be a potential alternative, especially in those patients who are undergoing open heart surgery and indication for ECMO implantation is inability to wean from cardiopulmonary bypass. Central cannulation is also an attractive option in patients with atherosclerotic femoral vessels. In addition to the reduction of limb complications, this technique provides antegrade cerebral perfusion. Nevertheless, it has to be kept in mind that central cannulation is also associated with a certain morbidity as the chest has to remain open, which puts the patients at high risk of developing mediastinitis. Furthermore, ongoing bleeding from the sternal edges can be a significant problem. Subclavian artery cannulation combined with venous cannulation through the groin has been shown to reduce the incidence of limb complications [12, 13]. Subclavian artery cannulation carries the benefits of central cannulation while allowing closure of the chest, reducing the risk of mediastinitis and ongoing bleeding. There should be no discussion about the usefulness of peripheral cannulation through the groin in the acute setting. Percutaneous cannulation through the groin is limited by the inability to insert a cannula for distal leg perfusion.
Extracorporeal membrane oxygenation support is associated with the development of late vascular complications. Technical problems during decannulation as well as preexisting peripheral vascular disease are independent predictors for late vascular complications.
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