Ann Thorac Surg 2007;83:140-145
© 2007 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Is Extracorporeal Life Support Contraindicated in Elderly Patients?
Shunsuke Saito, MDa,
Takeshi Nakatani, MDb,*,
Junjiro Kobayashi, MDa,
Osamu Tagusari, MDa,
Ko Bando, MDa,
Kazuo Niwaya, MDa,
Hiroyuki Nakajima, MDa,
Shunichi Miyazaki, MDc,
Toshikatsu Yagihara, MDa,
Soichiro Kitamura, MDa
a Department of Cardiovascular Surgery, National Cardiovascular Center, Osaka, Japan
b Department of Organ Transplantation, National Cardiovascular Center, Osaka, Japan
c Department of Cardiology, National Cardiovascular Center, Osaka, Japan
Accepted for publication August 2, 2006.
* Address correspondence to Dr Nakatani, Department of Organ Transplantation, National Cardiovascular Center, 5-7-1 Fujishirodai Suita, Osaka 565-8565, Japan. (Email: tnakatan{at}hsp.ncvc.go.jp).
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Abstract
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BACKGROUND: Extracorporeal life support (ECLS) using percutaneous extracorporeal membrane oxygenation (ECMO) is now considered an important means of resuscitation for patients suffering from refractory cardiogenic shock. The indications for the use of ECLS have yet to be established, however, and its use for elderly patients is still controversial. We retrospectively evaluated the impact of ECLS on the survival of patients with cardiogenic shock to determine the validity of using ECLS in elderly patients (
75 years of age).
METHODS: Between 2000 and 2004, 91 patients were emergently placed on percutaneous ECMO. The patients were divided into two groups by age (group 1, n = 79: less than 75 years; group 2, n = 12: 75 years or older), which were compared for clinical outcome. Logistic regression analysis of the variables was performed to identify predictors of ability to be weaned from ECLS.
RESULTS: Weaning from ECLS was achieved in 50 patients in group 1 (63.3%) and 6 patients in group 2 (50%; p = 0.37). Thirty-five patients in group 1 (44.3%) and 5 patients in group 2 (41.7%) were discharged from the hospital (p = 0.86). Logistic regression analysis revealed that patients with a body surface area of more than 1.50 m2, patients with cardiomyopathy, and patients who underwent interventions under ECMO support were more likely to be successfully supported by ECMO.
CONCLUSIONS: Extracorporeal life support using percutaneous ECMO systems provides excellent cardiac support. It is also effective in resuscitating elderly patients, yielding hospital survival similar to that for younger patients.
The discouraging survival rate after prolonged cardiopulmonary resuscitation with conventional methods such as external compression of the chest has prompted the development of more aggressive methods for saving the lives of patients with refractory cardiogenic shock. Since the advantages of peripherally applied cardiopulmonary bypass for the resuscitation of cardiogenic shock patients were first demonstrated [1–3], this technology has made consistent progress, with the introduction of miniaturized pumps and circuit biocompatibility. Extracorporeal life support (ECLS) using percutaneous extracorporeal membranous oxygenation (ECMO) is now considered one of the important means of resuscitating patients suffering from refractory cardiogenic shock. With developments in ECMO systems and improvement of resuscitation teams, many patients previously considered impossible to resuscitate are now being rescued. Indications for the use of ECLS have yet to be established, however, and the use of ECLS for elderly patients is still controversial. Some previous reports have included age 75 years or older as a contraindication for ECLS [4, 5].
We retrospectively evaluated the impact of ECLS on the survival of elderly patients (75 years of age) with profound cardiogenic shock and examined the validity of using ECLS.
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Patients and Methods
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Between 2000 and 2004, 91 patients were emergently placed on ECLS using percutaneous ECMO at the National Cardiovascular Center (NCVC), Osaka, Japan. The hospital records and ECLS records were retrospectively reviewed. The Ethics Committee of NCVC approved this study, and individual consent was waived because individual patients were not identified in this study.
Patients were selected by the resuscitating physician or surgeon for emergent ECLS owing to cardiac arrest refractory to advanced cardiac life support or for intractable cardiogenic shock with imminent cardiac arrest. In cases of postcardiotomy cardiogenic shock, all patients who could not be weaned from cardiopulmonary bypass in the operating room were placed on ECMO. Extracorporeal life support was contraindicated in patients with previous irreversible brain damage or patients with obvious pupil dilation and no light reflex that did not recover with external cardiac massage. Patients who underwent elective percutaneous ECMO-supported angioplasty or coronary artery bypass grafting were excluded. In cases of cardiomyopathy, patients who did not require right heart support were placed on the left ventricular assist system (LVAS) instead of ECMO if their condition permitted their transfer to the operating room, and these cases were also excluded from this study. The mean age of the patients was 51.5 ± 20.5 years (range, 9 to 88), and 59 (64.8%) were male.
In this series, three different ECMO systems were used based on patient requirements, and are summarized in Table 1. The compact integrated cardiopulmonary bypass unit (CICU; Edwards-DIC, Tokyo, Japan) [6] and Capiox emergent bypass system (Capiox EBS; Terumo, Tokyo, Japan) are designed for rapid induction. Their priming volumes are 280 mL and 480 mL, respectively, and each can be set up in 5 minutes. The CICU circuit is not heparin-coated and does not include a heat exchanger. Maximal flow is about 4 L/min, and it can be used for only about 24 hours. The CICU is the easiest to set up, however, and has been used in our institution by cardiologists when clinical engineers or cardiac surgeons familiar with the set-up and establishment of other units are not readily available. The Capiox EBS circuit is heparin-coated and has a heat exchanger, but can be used for only about 24 to 72 hours. When mechanical support was required for a longer duration of time, these systems were replaced by a NCVC unit consisting of a centrifugal pump (Jostra Rota Flow; Jostra Medizintechnik AG, Hirrlingen, Germany) and a heparin-coated hollow-fiber membrane oxygenator with an integral heat exchanger (MERA Excelung Prime; MERA, Tokyo, Japan). Because the priming volume of the NCVC unit is 550 mL and set-up time is about 20 minutes, it is not suitable to support patients with shock when mechanical support is needed without delay. However, its circuit is heparin-coated and the system includes a heat exchanger, and maximal flow is about 7 L/min. It can be used for about 3 to 7 days.
Cannulation was achieved peripherally by either percutaneous or cut-down placement of cannulas in the femoral artery and vein. In patients with lower extremity ischemia or for whom prolonged perfusion was required, the peripheral femoral artery was also cut down and cannulated.
During ECMO assistance, continuous injection of heparin was used to maintain an activated clotting time of 180 to 220 s.
The 91 patients were divided into two groups by age (group 1, n = 79: less than 75 years; group 2, n = 12: 75 years or more). The groups were compared for indications for the use of ECMO, ECMO management, and clinical outcomes.
To compare outcomes between the two groups, statistical analysis was performed using the unpaired Student’s t test, with p values less than 0.05 considered significant. Predictors for weaning from ECMO or successful bridging to LVAS were analyzed with respect to sex, age, body surface area, diagnosis, incidence of cardiac massage or intra-aortic balloon pump use or incapability of weaning from cardiopulmonary bypass before ECMO, place of ECMO initiation, incidence of interventions during ECMO, and incidence of complications related to ECMO. Univariate logistic regression analysis of these variables was performed. For variables with a p value less than 0.3, multivariate logistic regression analysis was performed, with p value less than 0.05 considered significant.
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Results
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Indications and ECMO Management
Patient background and the reasons for ECLS assistance are summarized in Tables 2 and 3,
respectively. Fifty-one patients needed ECLS for primary cardiac failure. Thirty-three (64.7%) required external cardiac massage before ECLS, and 23 (45.1%) required intra-aortic balloon pump before ECLS. All 18 patients with acute myocardial infarction (AMI) needed external cardiac massage before ECLS, and 6 were complicated with free wall rupture. Ten of 18 patients with AMI underwent interventions such as percutaneous coronary intervention, coronary artery bypass grafting, and release of cardiac tamponade. Thirty-seven patients needed ECLS for postcardiotomy cardiogenic shock. In 30 of them, ECLS was needed because they could not be weaned from cardiopulmonary bypass. Fifteen patients also required intra-aortic balloon pump. The other reasons for ECLS were pulmonary embolism in 2 patients and anaphylactic shock in 1 patient. In group 2, 9 of 12 patients required ECLS for primary cardiogenic shock, and in 7 of these 9, the diagnosis was AMI. In group 1, there was no such tendency, and 14% were AMI patients.
Mean ECMO assist flow was 2.9 ± 0.9 L/min in group 1 and 2.7 ± 0.8 L/min in group 2 (p = 0.62).
The CICU was replaced by a NCVC unit after 24-hour support, and the Capiox EBS by a NCVC unit after 24 to 72 hours of support. For cases in which ECLS was established in the operating room, or when the patient’s condition permitted waiting until the NCVC unit could be set up, the NCVC unit was used from the beginning. System exchange was also required when oxygenator function diminished, severe hemolysis was observed, thrombus formation was observed within the circuit, or massive serum leakage occurred. The mean frequency of system exchange was 0.78 times (range, 0 to 5) per patient in group 1, and 0.67 times (range, 0 to 5) per patient in group 2 (p = 0.77).
Clinical Outcomes
The mean length of ECMO assistance was 103 ± 129 hours (range, 0.5 to 528) in group 1 and 84 ± 100 hours (range, 2 to 360) in group 2 (p = 0.61). Weaning from ECLS or bridging to LVAS was achieved in 50 patients (63.3%) in group 1 and 6 patients (50%) in group 2 (p = 0.37; Table 4). Thirty-five patients in group 1 (44.3%) and 5 patients in group 2 (41.7%) were discharged from the hospital (p = 0.86). The oldest patient who survived to hospital discharge was 84 years of age. Mean duration from weaning from ECLS to hospital discharge was 101 ± 83 days in group 1 and 147 ± 108 days in group 2 (p = 0.38).
Complications related to ECLS occurred in 28 patients (30.8%; Table 5). The frequencies of complications in the two groups were similar. The most frequent complication was bleeding due to anticoagulation therapy, with bleeding events accounting for 78.6% of complications (22 of 28). Arterial thromboembolism occurred in only 1 patient in group 1, who suffered cerebral infarction. Five patients in group 1 had lower extremity ischemia, which was controlled by adding distal perfusion.
In the 34 patients who could not be weaned from ECMO, causes of death were multiple organ failure in 30, septic shock in 3, and airway bleeding in 1.
Predictors of Successful ECMO Support
Predictors of weaning from ECMO or successful bridging to LVAS were analyzed using univariate and multivariate logistic regression analysis. Among the variables used for univariate logistic analysis, the p value was less than 0.3 in males, body surface area greater than 1.50 m2, cardiomyopathy, incapability of weaning from cardiopulmonary bypass, interventions during ECMO, and complications related to ECMO (Table 6). Multivariate logistic regression analysis was performed using these variables, and the p value was less than 0.05 in body surface area greater than 1.50 m2, cardiomyopathy, and interventions during ECMO (Table 7).
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Comment
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Extracorporeal life support is an essential technology for cardiopulmonary resuscitation in patients with refractory cardiogenic shock, and ECMO is widely used for ECLS because of its portability, rapid priming, and ease of handling. In ECLS, percutaneous access through the femoral artery and vein is preferable because these vessels are easily and rapidly approached, with less invasion than that associated with the open-chest approach. These methodologies for ECLS are now well established, and published reports have demonstrated overall survival rates between 20% and 60% [7–12]. In our study, a satisfactorily high percentage of patients were resuscitated by ECLS and survived to hospital discharge: weaning from ECLS was achieved in 56 patients (61.5%) with hospital discharge for 40 patients (44.0%).
In this study, the most frequent complications related to ECLS were bleeding events. That was clearly due to our use of anticoagulation therapy during ECMO support. We used continuous injection of heparin and maintained activated clotting time of 180 to 220 s. Arterial thromboembolism occurred in only 1 patient. Our findings thus differed from those in the studies of Magovern and coworkers [9] and Muehrcke and coworkers [12], in which continuous systemic heparinization was not routinely performed. Intracardiac clot formation and arterial thromboembolism are the most serious complications of ECLS and may potentially limit the use of ECLS. Although it may increase the frequency of bleeding events, we believe that systemic heparinization is essential for ECMO support to avoid thromboembolic events.
Although methodologies of ECLS are now well established, the indications for its use have yet to be clearly determined. Although guidelines have been proposed in previous reports to avoid futile efforts at resuscitation [9–13], the use of ECLS for elderly patients is still controversial. It is apparent that elderly age is an important risk factor for mortality in patients with cardiogenic shock [14], and in some reports being 75 years old or older is considered a contraindication for ECLS [4, 5].
In this study, patients required ECLS for a variety of reasons. In the elderly group, however, the indication for ECLS was primary cardiac failure in 9 of 12 patients, and AMI had been diagnosed in 7 of these 9 patients. The onset of circulatory failure is often acute in AMI patients, with rapid progression. Patients are often already in cardiopulmonary arrest on arrival at the hospital. In such cases, when conventional methods of resuscitation fail, the resuscitating physician or surgeon must decide whether ECLS should be used for the patient, despite insufficient time and information on the patient’s background and risk factors. For elderly patients in particular, decision-making can be very difficult, because it has been believed that the likelihood of survival is quite small for such patients. This study demonstrated that ECLS using percutaneous ECMO is as effective in saving the lives of elderly patients as for younger patients. We used the same ECMO devices for elderly as for younger patients, and there were no differences in ECMO management between the two groups. Weaning from ECLS was achieved at a satisfactorily high rate not only in younger but also in elderly patients, with no difference in survival rate between the two groups.
The only drawback to the use of ECLS in elderly patients is that a long period of recovery is required after resuscitation by ECLS and after weaning from it. In this study, although the difference between groups was not significant because of the relatively small number of patients in group 2, the mean duration from weaning from ECLS to hospital discharge was 46 days longer in group 2 than in group 1. However, this is insufficient reason to avoid resuscitation of elderly patients with refractory cardiogenic shock, given the satisfactory rate of survival of such patients.
In logistic regression analysis, it was again confirmed that age is not a predictor of successful ECMO support. Patients with body surface area more than 1.50 m2 were more likely to be weaned. Patients with a small body size are sometimes associated with malnutrition, which increases the risk of mortality. Another predictor of successful ECMO support was cardiomyopathy. This result is obviously due to the effective use of LVAS. In this study, 12 of 14 patients were bridged to LVAS and 1 was weaned from ECMO. We also found that interventions during ECMO were predictors of successful ECMO support. The ability to correct the underlying pathology seemed to play a role in successful weaning from ECMO. These are the same findings as other authors [2, 3, 10].
In conclusion, we have demonstrated that ECLS using percutaneous ECMO systems provides excellent cardiac support. It is effective in resuscitating elderly patients more than 75 years of age, yielding hospital survival similar to that for younger patients. Although rehabilitation often requires a longer period of time after weaning from ECLS in elderly patients, ECLS resuscitation should be considered even for elderly patients with refractory cardiogenic shock.
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Ann. Thorac. Surg. 2007 83: 145.
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Abstract
Introduction
