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Interact CardioVasc Thorac Surg 2009;9:269-273. doi:10.1510/icvts.2008.194860 © 2009 European Association of Cardio-Thoracic Surgery
Efficacy of emergent percutaneous cardiopulmonary support in cardiac or respiratory failure: fight or flight?
a Department of Thoracic and Cardiovascular Surgery, Hanyang University Guri Hospital, College of Medicine, University of Hanyang, Guri, Gyeonggi-do, Korea Received 19 September 2008; received in revised form 21 April 2009; accepted 22 April 2009
*Corresponding author. Tel.: +82-2-3410-3480; fax: +82-2-3410-0089.
We retrospectively evaluated early outcome and conducted this study to determine the predictive factors for percutaneous cardiopulmonary support (PCPS) weaning and hospital discharge. From January 2004 to December 2006, 92 patients diagnosed as cardiac or respiratory failure underwent PCPS using the Capiox emergent bypass system (Terumo, Tokyo, Japan). The mean±S.D. age was 56±18 (range, 14–85) years and 59 (64%) were male. The mean duration of PCPS was 90.9±126.0 h and that of cardiopulmonary resuscitation (CPR) was 51.1±27.8 min. The rate of weaning was 59/92 (64%) and the rate of survival to discharge was 39/92 (42%). The results indicated that the etiologic disease (myocarditis) and the cause of PCPS (cardiopulmonary arrest) are significantly correlated with weaning, whereas cardiopulmonary arrest and a shorter CPR duration (<60 min) are considerably correlated with survival. On the contrary, elderly patients (>75 years) have similar rates of weaning and survival compared with younger patients. PCPS provides an acceptable survival rate and outcome in patients with cardiac or respiratory failure. Prompt application and selection of patients with a specific disease (myocarditis) provides good results. It is also effective in elderly patients, providing hospital survival similar to that for younger patients.
Key Words: Extracorporeal membrane oxygenation; Percutaneous cardiopulmonary support; Cardiopulmonary arrest
Extracorporeal membrane oxygenation (ECMO) may be used in patients with respiratory or circulatory failure who are unresponsive to conventional therapy [1, 2]. Especially, since the advantages of peripherally applied cardiopulmonary bypass for the resuscitation of cardiogenic shock patients were first demonstrated [3, 4], this skill has made consistent progress, with the introduction of miniaturized pumps and circuit biocompatibility. Therefore, the indications for percutaneous cardiopulmonary support (PCPS) have expanded to include medically emergent cases. Since a multi-institutional study performed by Hill and colleagues in 1992 [5], several reports on emergent PCPS use have been published with relatively good results. Nevertheless, indications for the use of PCPS have yet to be established. We retrospectively evaluated early outcome of patients and conducted this study to determine the predictive factors for PCPS weaning and survival.
Between 2004 and 2006, 92 patients underwent PCPS with the Capiox emergent bypass system (EBS; Terumo Inc, Tokyo, Japan). The hospital records and PCPS records were retrospectively reviewed. This study received Institutional Review Board approval and informed consent was waived due to the life-threatening emergencies. Patients were selected by the resuscitating physician or surgeon for emergent PCPS owing to cardiac arrest and intractable cardiogenic shock with imminent cardiac arrest or respiratory failure. In cases of postcardiotomy cardiogenic shock, all patients who could not be weaned from cardiopulmonary bypass were placed on PCPS in the operating room or the intensive care unit (ICU). PCPS was contraindicated in patients with previous irreversible brain damage or severe comorbid disease such as the terminal stage of malignancy or cerebral hemorrhage. However, we do not consider cardiopulmonary resuscitation (CPR) time and advanced age alone as contraindications. The PCPS system at our institution is comprised of a centrifugal pump, polypropylene hollow fiber membrane oxygenator, and a heparin-coated circuit (Capiox EBS circuit; Terumo Inc, Tokyo, Japan). The most important benefit of this system is its autopriming, which requires <5 min to prime the circuit before use [6] and does not require specially trained personnel. Cannulation was achieved percutaneously in the femoral artery and vein using the Seldinger technique. The methods and materials of cannulation, PCPS management, and patient care were mentioned in our previous article [7]. In 24 patients, distal femoral arterial perfusion was performed using a central line catheter (Arrow International, Reading, PA) to prevent ischemia of the distal lower leg. In 31 patients, an intra-aortic balloon pump (IABP) was applied simultaneously during PCPS. Once the cannulation was established, the PCPS system could be worked to stabilize the patient; then CPR was discontinued if done. If possible, we tried to maintain the hematocrit above 35%, the platelet count above 100,000/µl, and the activated clotting time (ACT) at 150–200 s to minimize complications of bleeding and thromboembolic complications. Generally, no attempt was made at weaning patients off PCPS until 12–24 h of support was done. When an attempt was made at weaning, transesophageal echocardiography was used to monitor heart function. During weaning, flows were gradually reduced to 1 l/min/m2. Inotropic agents were used to facilitate weaning in all patients. Patients who maintained adequate ventricular function with a cardiac index of at least 2 l/min/m2 were decannulated. After weaning the patients from the PCPS, we surgically removed cannulae and repaired the cannulation sites to prevent ischemic limb complications. Data were analyzed with SPSS 12.0 (SPSS Inc, Chicago, IL, USA). Categorical variables were evaluated with 2 or Fisher exact tests. Continuous variables were compared by unpaired Student's t-test, with P<0.05 considered significant. Predictors for weaning or survival to discharge were analyzed with respect to sex, age, body surface area, diagnosis, diabetes, hypertension, IABP use, the cause of PCPS support (cardiopulmonary arrest), duration of CPR before PCPS, duration of PCPS, and incidence of interventions during PCPS. Univariate logistic regression analysis of these variables was performed. For variables with a P<0.3, multivariate logistic regression analysis was performed, with P<0.05 considered significant. Survival was calculated with the Kaplan–Meier method. All surviving patients were followed-up after hospital discharge in our outpatient department or by telephone to assess their clinical status (New York Heart Association; NYHA class) on the latest follow-up (from July 2007 to May 2008).
The mean±S.D. age was 56±18 (range, 14–85) years and 59 (64%) were male. Patient characteristics and underlying diseases for PCPS are summarized in Table 1.
The mean duration of PCPS was 90.9±126.0 h and the mean CPR duration before initiation of PCPS was 51.1±27.8 min. Fifty-two patients were performed with PCPS due to cardiopulmonary arrest, among whom PCPS were performed in eight patients in respiratory failure. Forty patients needed PCPS due to cardiogenic shock. Interventions on PCPS such as percutaneous coronary intervention (PCI), coronary artery bypass, and other surgical procedures were performed in 14 patients. System exchange was required during diminished oxygenator function, severe hemolysis, thrombus formation within the circuit, or massive serum leakage. System exchange was needed in 27 patients (29%), of whom the mean frequency of system exchange was 1.7 times (range, 1–6) per patient and the mean interval of system exchange was 77.9±36.1 h (range, 18–145). The rate of weaning was 59/92 (64%) and the rate of survival to discharge was 39/92 (42%). Complications related to PCPS occurred in 13 patients (14%; Table 2). Cerebral infarction occurred only in one patient. Three patients had lower extremity ischemia. In the 33 patients who could not be weaned from PCPS, cause of death was multi-organ failure in 30 and bleeding in 3 (pulmonary, surgical site, airway bleeding in each of one).
3.1. Predictors determining PCPS weaning or survival to discharge Univariate analysis was performed with respect to the above-mentioned variables. The patients diagnosed as myocarditis were more likely to wean from PCPS compared with patients diagnosed with other disease [9/9 (100%) vs. 50/83 (60%), P<0.05]. On the contrary, the patients who underwent PCPS caused by cardiopulmonary arrest were less likely to wean and survive to discharge compared to the patients who underwent PCPS caused by cardiogenic shock or respiratory failure (26% vs. 10%, 38% vs. 20%, P<0.05). The rate of weaning and survival at different CPR durations are shown in Table 3. Survivors were likely to have a much shorter CPR duration, which was not statistically significant (40.1±18.9 min in survivors vs. 56.2± 30.0 min in non-survivors, P=0.06). The survival rate was higher for CPR lasting <60 min than for CPR lasting >60 min (P<0.05). Therefore, we could conclude that CPR <60 min followed by PCPS rescue could predict a survival rate of 40% and a successful weaning rate of 58%. The shorter the duration of CPR done, the better the survival.
On the contrary, old age was not associated with weaning from PCPS or survival to discharge (P=0.43) (Table 4). In detail, the age group was divided into two groups (age >75 years, age <75 years). In the group of age >75 years, weaning from PCPS was achieved in seven patients (8%) (P=0.42). Three patients in the group of age >75 years (3%), were discharged from the hospital (P=0.14). Whether patients were >75 years or not was not associated with weaning or survival to discharge. Multivariate logistic regression analysis was performed using these variables, but no variable was statistically significant.
After a follow-up period of up to three years, 27 patients (3 deaths after discharge and 9 follow-up losses) were re-assessed (mean follow-up, 1.8 years). Fig. 1 shows the Kaplan–Meier curve of survival. The 3-year mortality was 63%. On the latest follow-up (from July 2007 to May 2008), the 27 surviving patients reported cardiac symptoms of NYHA class I (19 patients) and II (7 patients). Eleven of the 27 patients needed re-admission. Table 5 shows the cause of re-admission.
ECMO is essential technology for CPR in patients with refractory cardiac or respiratory failure, and recently PCPS is widely used because of its portability, rapid priming, and ease of handling. In our hospital, before the introduction of the EBS, implementation of emergent PCPS using conventional cardiopulmonary bypass required 30 min. Many patients did not survive before introduction of the EBS due to the long duration of CPR. Since the use of EBS, ICU nurses, residents, and fellows can easily operate the EBS after a brief training, irrespective of perfusionists. Aggressively we do not consider CPR time and advanced age alone as contraindications. The methods for PCPS are now well established, and several reports showed 20–60% of survival rates [8–10]. In our study, a considerably high percentage of patients were resuscitated by PCPS and survived to discharge: weaning from PCPS was achieved in 59 patients (64%) and survival to discharge in 39 patients (42%). Our survival rate is comparable with that of other study groups [11]. Although these methods for PCPS are now well established, the indications of PCPS have not been clearly determined. Especially, the use of PCPS for old-aged patients is still controversial. Some reports indicated that old age (>75 years) is considered a contraindication for PCPS [12]. In this study, age is not associated with weaning from PCPS or survival to discharge. Furthermore, in the group of age >75 years, we could not find statistical significance. PCPS with EBS is as effective in saving the lives of elderly patients as for younger patients. In our study, the CPR duration in survivors was 40.1± 18.9 min, which was shorter than that of non-survivors (56.2±30.0 min, P=0.06). However, a significant difference could not be found between weaned and non-weaned patients (P=0.21). Additionally, the survival rate was acceptable in patients receiving CPR <60 min (40%, P=0.04). We conclude that PCPS can extend the CPR time to 60 min with an acceptable survival rate, which is a great benefit of applying ECMO in CPR. Also, we did not need to mention that the patients who underwent PCPS caused by cardiopulmonary arrest were less likely to wean and survive to discharge compared to the patients who underwent PCPS caused by cardiogenic shock or respiratory failure. Interestingly, the patients diagnosed as myocarditis were more likely to wean from PCPS compared with patients diagnosed with other disease. Among them, three patients did not survive to discharge. We can expect that rapid application of PCPS helps the patients with myocarditis to resuscitate. During PCPS, 31 patients were supported with an IABP in addition to PCPS. IABP can generate pulsatile flow, increase coronary blood flow, and might decrease left ventricular afterload [13, 14]. Consequently we think that IABP might facilitate weaning from PCPS. However, we could not find any association between IABP use and PCPS weaning or survival. In this study, the most common complications related to PCPS were bleeding events. That was clearly due to our use of anticoagulation therapy during ECMO support. We tried to maintain the ACT level to about 150–200 s. However, in patients with bleeding complications, we adjust the ACT level to about 150 s. The follow-up period was short, but demonstrated that once successfully discharged from the hospital, patients had an acceptable survival with NYHA class I–II heart failure and relatively low rate of re-admission. These results justify the use of PCPS because about 40% of patients survived up to three years after the PCPS. This study has also several limitations: this study is not a randomized controlled study. Only a few variables can be identified with significant associations to weaning or survival because the case number is not large. Another limitation is that we only used one PCPS system. We cannot suggest the superiority of EBS compared with other PCPS systems. In conclusion, autopriming pre-assembled PCPS systems provides an acceptable survival rate and outcome in patients with cardiac or respiratory failure. Prompt application and selection of patients with a specific disease (myocarditis) provides good results. It is also effective in elderly patients, providing hospital survival similar to that for younger patients. Therefore, complicated patients who currently might not be considered for PCPS could benefit from PCPS in the future.
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Abstract
1. Introduction