Early and Intermediate Results of Rescue Extracorporeal Membrane Oxygenation in Adult Cardiogenic Shock

Early and Intermediate Results of Rescue Extracorporeal Membrane Oxygenation in Adult Cardiogenic Shock Jiangang Wang, MD, Jie Han, MD, Yixin Jia, MD, Wen Zeng, MD, Jiahai Shi, MD, Xiaotong Hou, MD, and Xu Meng, MD Department of Cardiac Surgery, Beijing Anzhen Hospital, Capital Medical University, Beijing, Peoples Republic of China Background. We retrospectively evaluated the early and intermediate results of use of temporary extracorporeal membrane oxygenation (ECMO) support and examined its effect on quality of life (QOL). Methods. Over four years 62 of 12,644 patients (0.49%) undergoing cardiac surgery (valve procedures, n 39; coronary artery bypass grafting, n 13; coronary artery bypass grafting plus valve procedures, n 4; heart transplantation, n 4; and total aortic arch replacement, n 2) required temporary postoperative ECMO support. During a follow-up study (mean 2.3 1.5 years, 100% complete), 32 were still alive and answered the Short- Form 36 Health Survey QOL questionnaire. Results. The mean duration of ECMO support was 61 37 hours. Forty patients (64.5%) were successfully weaned from ECMO. Thirty-four patients (54.8%) were discharged from the hospital after 44.3 17.6 days. The in-hospital mortality rate was 45.2% and the main cause of death was multiple organ failure. A risk factor for in-hospital death was a peak lactate level greater than 12 mol/l before ECMO initiation. There were few significant differences in the mean QOL scores between the ECMO survivors and other patients who had undergone cardiac surgery without ECMO support; only the measures of vitality and mental health were significantly lower in the ECMO survivors (p < 0.05). Both the ECMO survivors and the patients who did not receive ECMO support had significantly lower QOL scores (except for vitality and mental health) than the general Chinese population (p < 0.05). Conclusions. Extracorporeal membrane oxygenation is an acceptable technique for the treatment of postoperative cardiogenic shock in adults, although early intervention and reduced complications could improve results. However, the use of ECMO has little influence on QOL. (Ann Thorac Surg 2009;88:1897 904) 2009 by The Society of Thoracic Surgeons Extracorporeal membrane oxygenation (ECMO) is an established treatment option for adult patients with refractory cardiogenic shock and provides prolonged but temporary cardiac and respiratory support [1, 2]. Approximately 1% of patients who undergo routine cardiac surgical procedures experience refractory cardiac and (or) pulmonary dysfunction that requires prolonged postoperative circulatory support [3 5]. In this small group of patients ECMO may provide hemodynamic support that allows the patients to recover from reversible myocardial injury. Recently, health care providers and consumers have begun to recognize that morbidity and mortality data alone are incomplete measures of surgical outcomes. Improvements in the patient s emotional state, ability to perform social roles, general satisfaction, and ability to return to work and live independently are equally important [6 8]. With advances in technology (including the development of ECMO), morbidity and mortality rates after cardiac surgery have significantly improved Accepted for publication Aug 6, 2009. Address correspondence to Dr Meng, Department of Cardiac Surgery, Beijing Anzhen Hospital, Capital Medical University, Chaoyang District, Beijing, 100029, People s Republic of China; e-mail: mxu@263.net. and it is now assumed that most patients will be able to live independently three months after surgery [9]. However, the impact of ECMO treatment on a patient s quality of life (QOL) is still unclear; we must examine whether, three months after surgery, patients are able to perform their daily physical and social activities and live independently as well as patients who did not receive ECMO treatment. The use of implantable ventricular-assist devices in patients with nonrecoverable cardiogenic shock may reduce mortality rates, lessen the complications of prolonged ECMO, and allow for a later heart transplant. Ventricularassist devices, however, are experience; most Chinese patients could not afford to use them and we therefore have little experience with them. There are two main goals of this study: (1) to retrospectively review the early and midterm outcomes of cardiac surgery patients and to determine predictors of survival, and (2) to evaluate the impact of early and intermediate use of rescue ECMO on QOL. Material and Methods Between January 2004 and May 2008, 62 of 12,644 adult patients (0.49%) with refractory cardiogenic shock were 2009 by The Society of Thoracic Surgeons 0003-4975/09/$36.00 Published by Elsevier Inc doi:10.1016/j.athoracsur.2009.08.009

1898 WANG ET AL Ann Thorac Surg RESULTS OF ECMO IN ADULT CARDIOGENIC SHOCK 2009;88:1897 904 placed on venoarterial ECMO using heparin-coated circuits (Medtronic, Minneapolis, MN). The indications for ECMO included the following: left atrial pressure that increased by more than 15 mm Hg; central venous pressure of more than 12 mm Hg; a decrease in the cardiac index to less than 2 L/min 1 m 2 ; urine output of less than 1 ml/min 1 kg 1 ; mixed venous saturation of less than 60%; and mean systolic arterial pressure less than 60 mm Hg despite adequate filling volumes; use of multiple inotropic agents (dopamine-dobutamine: 10 to 15 g kg 1 min 1 or adrenaline: 0.1 to 0.5 g kg 1 min 1 ); and an intraaortic balloon pump (IABP). According to the above indications cardiac surgeons determined to initiate ECMO. The following cardiac surgical procedures were performed: valve procedures, n 39; coronary artery bypass grafting (CABG), n 13; CABG plus valve procedures, n 4; heart transplantation, n 4; and total aortic arch replacement, n 2. Each patient gave their informed consent; the study was conducted in accordance with recommendations of the Declaration of Helsinki and was approved by the ethics committees of both the hospital and the CDA. ECMO Circuit The ECMO system (catalog no. CB1Q91R6; Medtronic Inc, Anaheim, CA) consisted of a centrifugal pump and a hollow fiber microporous membrane oxygenator with an integrated heat exchanger. The entire ECMO circuit had a heparin-bound Carmeda-bioactive surface (Medtronic). The ECMO circuit was primed with normal saline containing heparin at a concentration of 2 U/mL. An additional 5,000 U of heparin were injected intravenously during cannulation. The femoral route for ECMO support was preferred over the open sternotomy route; the presence of an open sternotomy wound increased the risk of bleeding and infection, and made nursing care more difficult. Ventricular venting was not used. In addition, two patients required cannulation (cannula 26F) of the left atrium to allow for obtain better heart drainage. Management Strategy The ECMO blood flow was calculated to supply at least adequate total systemic circulatory support (2.2 L/ minute) and to achieve a mixed venous oxygen saturation (Svo 2 ) of 70%; oxygen flow (Fio 2 ) was titrated to maintain a postoxygenator partial oxygen pressure of 300 mm Hg or more. Inotropic agents were minimized to allow for optimal myocardial recovery while still maintaining left ventricular ejection. The temperature of the oxygenator that was connected to the water bath was maintained at 37 2 C with a heat exchanger. After 24 hours of ECMO support, a heparin infusion was begun to keep the activated clotting time in the range of 160 to 180 seconds, depending on clinical judgment of the patient s risk of bleeding. A packed red blood cell transfusion was used to correct dilution anemia that occurred after the patient was connected to the ECMO. The hematocrit was maintained at 30% to 35%. Although a lower hematocrit reduced blood oxygen-carrying capacity, a higher hematocrit increased the risk of clot formation in the ECMO. Platelets were transfused when the patients platelet count was less than 50 10 3 /mm 3, unless a bleeding complication was present. Infusions of midazolam and fentanyl were routinely used to sedate patients. The ventilators were most commonly set for a tidal volume of 8 ml/kg, 8 breaths per minute, a positive end expiratory pressure of 10 cm H 2 O, a maximum ventilation pressure of 25 cm H 2 O, and a Fio 2 of 0.4. To prevent pulmonary failure, the respirator set- Table 1. Preoperative Patient Characteristics Variable Total Valve CABG Valve CABG HTX Others Number 62 39 13 4 4 2 Age, years 51 15 48 16 61 14 63 8 50 6 50 2 Gender, M/F, n 32/30 15/24 8/5 4/0 4/0 1/1 BSA, m 2 1.66 0.19 1.60 1.74 1.92 0.10 1.84.02 1.7 0.06 1.53 0.04 NYHA III IV 36 25 5 2 4 0 Atrial fibrillation 24 22 0 0 2 0 Previous cardiac operation 4 4 0 0 0 0 LVEDD, mm 52 13 49 12 56 12 59 18 75 6 48 5 LVEF 0.50 0.16 0.53 0.16 0.42 0.19 0.44 0.14 0.33 0.10 61 1 Inotrope scores a 67 40 72 45 69 38 60 32 50 36 89 53 IABP scores b 3.2 0.7 4.2 0.5 3.5 0.8 2.1 0.9 1.5 0.8 5.0 0.0 a Inotrope score: dosages of dopamine dobutamine (in g kg 1 min 1 ) [dosages of epinephrine norepinephrine isoproterenol (in g kg 1 min 1 )] 100 dosages of milrinone (in g kg 1 min 1 ) 15. Inotrope score here quantified the inotropes being infused when the extracorporeal membrane oxygenation was applied. b IABP score: I(adrenaline dose 0.5 g kg 1 min 1 ) 2 I(urine output 100 ml) I(mixed venous saturation 60%) (left atrial pressure 15 mm Hg), where I(X) denotes the indicator function, being equal to 1 if X holds and 0 otherwise. BSA body surface area; CABG coronary artery bypass grafting; HTX heart transplantation; IABP intraaortic balloon pump; LVEDD left ventricular end-diastolic dimension; LVEF left ventricular ejection fraction; NYHA New York Heart Association functional class.

Ann Thorac Surg WANG ET AL 2009;88:1897 904 RESULTS OF ECMO IN ADULT CARDIOGENIC SHOCK 1899 Table 2. Extracorporeal Membrane Oxygenation (ECMO) Results Variable Total Valve CABG Valve CABG HTX Others Number 62 39 13 4 4 2 Duration of ECMO (hours) 61 37 60 32 62 37 118 24 70 58 12 6 Successful weaning 40 (65%) 25 (64%) 7 (54%) 4 (100%) 4 (100%) 0 (0%) Mechanical Ventilation (hours) 81 86 63 32 170 181 166 37 28 16 14 13 ICU stay (days) 5.2 3.8 4.5 2.6 8.6 6.2 9.5 3.5 4.0 2.8 1.0 0.1 In-hospital mortality 28 (45%) 19 (49%) 6 (46%) 1 (25%) 0 (0%) 2 (100%) Discharged from hospital 34 (55%) 20 (51%) 7 (54%) 3 (75%) 4 (100%) 0 (0%) CABG coronary artery bypass grafting; HTX heart transplantation; ICU intensive care unit. tings were kept at parameters that are known to avoid additional lung injury. The criteria for ECMO weaning included a Svo 2 that was greater than or equal to 70%, stable hemodynamics, the absence of tamponade (determined by an echocardiogram), the absence of left heart distention, and a left ventricular ejection fraction of 0.40 or more. During weaning the ECMO blood flow was slowed to 0.5 L/minute and vital signs were observed. If the hemodynamics remained stable, the ECMO was removed using intravenous anesthesia at the patient s bedside, and the patients vessels were primarily repaired. As the patient was weaned from ECMO, inotropic agent infusions and ventilator settings were increased as necessary. All of the surviving patients (100%) were contacted every six months after they were discharged; the patients were either seen in the hospital s outpatient department or were contacted by telephone. Each patient s clinical status, exercise capacity, and quality of life were assessed. Quality of Life Assessment Although numerous methods exist for evaluating QOL, the validated Short Form 36 (SF-36) questionnaire, is comprehensive concise, can be completed in 10 to 15 minutes, and can be administered in person, by phone, or by mail, even in elderly patients [7 10]. The SF-36 questionnaire that was used is written in Chinese and consists of 36 items that are grouped into eight domains [11 13]. (1) Physical functioning (10 items) measures an individual s limitations in lifting, bending, kneeling, or walking moderate distances. (2) Role-physical (4 items) measures an individual s ability to perform normal activities for his or her age and social status (ie, job and community activities). (3) Bodily pain (2 items) measures the intensity, frequency, and duration of bodily pain and limitations in normal activities due to pain. (4) General health (6 items) measures perceived overall health, including past and present health. (5) Vitality (4 items) measures feelings of energy, fatigue, and tiredness. (6) Social functioning (2 items) measures an individual s ability to develop and maintain mature social relationships. (7) Role-emotional (3 items) measures personal feeling of job performance at work or in other activities. (8) Mental health (5 items) measures the emotional, cognitive, and intellectual status of the patient. All of the SF-36 domains are scaled from 0 to 100 points, and higher scores indicate a better QOL. Table 3. Postoperative Complication Variable Total Valve CABG Valve CABG HTX Others Number 62 39 13 4 4 2 Rethoracotomy 10 (16%) 7 (18%) 1 (8%) 1 (25%) 1 (25%) 0 (0%) RBC transfusion 19.8 1.8 18.6 9.2 26.4 8.3 22.5 9.2 13 1.0 21 1.0 Renal failure 23 (37%) 18 (46%) 3 (23%) 1 (25%) 1 (25%) 0 (0%) Infection 19 (31%) 13 (33%) 4 (31%) 1 (25%) 1 (25%) 0 (0%) Ischemia of the lower limbs 5 (8%) 3 (8%) 1 (8%) 1 (25%) 0 (0%) 0 (0%) Neurologic complication 8 (13%) 3 (8%) 3 (23%) 2 (50%) 0 (0%) 0 (0%) Leg amputation 1 (2%) 0 (0%) 1 (8%) 0 (0%) 0 (0%) 0 (0%) Change of oxygenator 11 (18%) 8 (21%) 1 (8%) 2 (50%) 0 (0%) 0 (0%) CABG coronary artery bypass grafting; HTX heart transplantation; RBC red blood cell.

1900 WANG ET AL Ann Thorac Surg RESULTS OF ECMO IN ADULT CARDIOGENIC SHOCK 2009;88:1897 904 Table 4. Postoperative Peak Lactate Levels Before ECMO Initiation and ECMO Implantation Timing in Surviving and Nonsurvivors Variable Total Died on ECMO Weaned, but Died Weaned and Survived p Value Number 62 22 6 34 Lactate levels (mmol/l) 13.2 5.0 17.1 3.9 14.7 4.9 10.4 4.0 0.001 a Implantation timing (hours) 5.6 6.2 8.9 2.6 3.7 3.1 2.6 1.5 0.025 b a Lactate levels is different between die-on-ecmo and wean-and-survive groups (p 0.001). ECMO and wean-and-survive groups (p 0.025). ECMO extracorporeal membrane oxygenation. b Implantation timing is different between die-on- Statistical Analysis Continuous data were expressed as the mean standard deviation and compared using either the Student t test or one-way analysis of variance (ANOVA). Categoric variables were expressed as percentages and were evaluated with the 2 or Fisher exact tests. Logistic regression analysis was used to determine the predictors of survival. Long-term survival was calculated according to the Kaplan-Meier method. A one-way ANOVA was used to compare the scores on each of the eight domains of the SF-36 questionnaire; comparisons were made both between the two groups of the study population as well as with the age and sex-matched general Chinese population [12]. Statistical significance was established at a p value less than 0.05. Data were analyzed using SPSS 12.0 statistical software (SPSS Inc, Chicago, IL). Results ECMO Outcomes Table 1 shows the demographic characteristics and pre- ECMO risk profiles of the 62 patients. The patients were divided into subgroups according to their indications for cardiac surgery. The ECMO support system was used in the operating room for 36 (58%) patients and in the intensive care unit for 26 (42%) patients. The ECMO implantation was successful in all cases. Table 2 shows the outcomes of ECMO support for the different groups. The mean duration of ECMO support was 61 37 hours; mean ECMO blood flow was 2.53 0.84 L/minute; 40 patients (64.5%) were successfully weaned from ECMO. However, it was impossible to successfully wean 22 patients (35.5%) from ECMO support; when the support was withdrawn, these patients died. Of the 40 patients who were weaned from ECMO, 34 (85%) were subsequently discharged from the hospital after a mean of 44.3 17.6 days. The overall 30-day hospital mortality rate was 45.2% (28 patients). An additional 6 patients could not be discharged from the hospital because of complications from multiorgan failure and they subsequently died. The main cause of mortality in patients who were successfully weaned from ECMO was sepsis with consecutive multiorgan failure. These complications occurred more frequently in older patients and those with comorbidities. The main cause of death for patients who could not be weaned from ECMO was persistent heart failure without any improvement in cardiac function (11 of 22 patients). Additional causes of mortality included sepsis with consecutive multiorgan failure (7 patients), cerebral infarction and bleeding (2 patients), and disseminated intravascular coagulation (2 patients). There was no statistically significant difference between the groups in the duration of ECMO support, ability to wean from ECMO, or ventilation time. An intraaortic balloon pump was used in a total of 19 patients (31%), including 30% of the patients who were weaned from ECMO and 32% of the patients who could not be weaned. Limb ischemia was observed in 5 patients in on whom direct peripheral cannulation had been performed. If the average blood pressure of the dorsal pedal artery was less than 40 mm Hg, the distal limb perfusion was optimized with a 7-mm central venous catheter in the common femoral artery. Systemic infection (defined by a positive blood culture) was 31% (19 of 62). A Gram-positive coccus grew in the blood culture of 13 patients, and a Gram-negative bacillus grew in the culture of another 6 patients. Antibiotics were used according to the corresponding susceptibility test. Eight patients (13%) had neurologic complications caused by cerebral stroke (n 6) or hemorrhage (n 2). During the ECMO period, urine outputs were maintained at more Table 5. Baseline Characteristics of ECMO Survivors and the Survivors Without ECMO Variable ECMO Survivors (n 62) Survivors Without ECMO (n 85) p Value Age, years 51 15 58 12 0.125 Gender, M/F, n 32/30 44/41 NS NYHA III IV 1.66 0.19 1.93 1.64 0.454 LVEF 0.50 0.16 0.53 0.12 0.273 Operative procedures Valve 39 45 0.246 CABG 13 20 0.843 Valve CABG 4 10 0.400 HTX 4 6 NS Others 2 4 NS CABG coronary artery bypass grafting; ECMO extracorporeal membrane oxygenation; HTX heart transplantation; LVEF left ventricular ejection fraction; NYHA New York Heart Association functional class.

Ann Thorac Surg WANG ET AL 2009;88:1897 904 RESULTS OF ECMO IN ADULT CARDIOGENIC SHOCK 1901 lactate levels that were greater than or equal to 12 mmol/l before ECMO support independently predicted increased mortality (p 0.05). Follow-Up All of the discharged patients were reassessed up to four years later (mean 2.3 1.5 years), and 32 patients were alive. Two patients who had taken an oral anticoagulant medication after a mechanical valve replacement experienced a cerebral hemorrhage and died from encephalorrhagia. The total four-year mortality rate was 48% (30 of 62); Figure 1 shows the Kaplan-Meier curve of survival. The 32 surviving patients reported cardiac symptoms that correspond to the New York Heart Association class I (13 patients), class II (15 patients), or class III (4 patients). The latest result of echocardiograms showed that he left ventricular ejection fraction was 0.39 to 0.68 (0.56 0.11). Fig 1. Kaplan-Meier survival curve of all patients with extracorporeal membrane oxygenation and the number of patients at risk. than 1 ml/kg hour 1. Renal failure was the most common complication and occurred in 23 patients (37%). All of the patients with renal failure required continuous venovenous hemofiltration. Ten patients (16%) had to be returned to the operating room for a rethoracotomy to correct either bleeding or tamponade. No wounds were packed open and closed later. Table 3 lists the complications resulting from ECMO support. The mean number of transfused red blood cell units for all of the patients was 19.8 1.8 units. There were no significant differences between the groups in the incidence of sepsis, neurologic complications, blood transfusions, rethoracotomy, or renal failure. In this study the time period from when the patients had the indications for ECMO to the ECMO cannulation means the implantation timing. Table 4 shows the differences in implantation timing among the patients who died, who were weaned from ECMO and died, and who were weaned from ECMO and survived. Implantation timing was significantly longer in patients who die-on- ECMO than in those who were weaned and survived (p 0.025). Patients who were weaned from ECMO and discharged from the hospital had lower initial serum lactate levels, while patients who failed to be weaned from ECMO had consistently increased serum lactate levels. Patients with septic shock and end-stage multiorgan failure late in the postoperative period frequently had treatment-resistant lactate acidosis. Table 4 shows peak lactate levels of patients who died during postoperative care. The peak lactate levels of nonsurviving patients were significantly higher than those of the survivors (p 0.05). A logistic regression analysis revealed that peak Quality of Life Follow-up included the assessment of perceived QOL through the SF-36, which has an established validity and reliability. Patients were contacted by mail with a cover letter, the SF-36 questionnaires, and an addressed and stamped return envelope. A total of 32 patients (94% of survivors) satisfactorily completed the SF-36 questionnaire by themselves. The mean scores obtained from the three study groups were compared with those of patients who underwent cardiac surgery without ECMO support and with the scores of members of the general Chinese population who were matched for age and sex. The survivors who did not receive ECMO support were Fig 2. Scores obtained in the eight domains of the Medical Outcomes Study Short-Form 36 Health Survey questionnaire in patients without extracorporeal membrane oxygenation (ECMO) support and in ECMO survivors compared with the general Chinese population matched for age and sex. (PF physical functioning; RP role-physical; BP bodily pain; GH general health; VT vitality; SF social functioning; RE role-emotional; MH mental health.)

1902 WANG ET AL Ann Thorac Surg RESULTS OF ECMO IN ADULT CARDIOGENIC SHOCK 2009;88:1897 904 chosen randomly from a database of adult cardiac surgery patients during the study time period. As shown in Table 5, there was no significant difference in the baseline characteristics between the ECMO survivors and the survivors who did not receive ECMO. Perceived QOL scores are presented in Figure 2. The mean QOL scores on each of the SF-36 scales were satisfactory and comparable among the three groups. The mean QOL scores after cardiac surgery were similar for the ECMO survivors and the patients who did not receive ECMO support, except that the vitality (VT) and mental health (MH) scores were significantly lower among the ECMO survivors (p 0.05). However, there was no statistically significant difference between the VT and MH scores of patients without ECMO support and the general Chinese population. Both the ECMO survivors and the patients without ECMO support have significantly lower mean QOL scores than the general Chinese population (p 0.05) (with the exception of VT and MH scores); role physical (RP) and role emotional (RE) scores are especially different. Comment Extracorporeal membrane oxygenation provides temporary support to patients who have severe cardiac failure after cardiopulmonary bypass and who have not responded to inotropes and intraaortic balloon pumps. The growing number of patients referred for ECMO treatment has focused attention on the outcomes of the procedure in this subset of patients. However, a rigorous analysis of an institution s results should focus not only on whether ECMO procedures have an acceptable rate of hospital mortality, but also on whether there are improvements in survival and QOL after ECMO support. Recent studies have found that the use of ECMO is associated with in-hospital survival rates that range from 20% to 50% and with mortality rates that range from 50% to 70% [14, 15]. In this study the in-hospital mortality rate was 45.2%, and the 3-year mortality was 48%. Our survival rate is better than those of other study populations [4, 15 17]. In our institution, ECMO therapy is considered to be a valuable option for the treatment of myocardial infarction and low output syndrome during cardiac procedures in the operating room. We suggest that patients with severe left ventricular dysfunction and myocardial infarction might benefit more if they receive ECMO support during surgery or very early in the postoperative time period. The early use of circulatory support might avoid the myocardial damage that can be caused by inotropic medication or hypoxia and therefore offer a treatment option that allows for recovery from the myocardial injury over a prolonged period of time. While there is no consensus in the literature on proper ECMO implantation timing, our study found that the time before implantation was significantly longer for patients who died while on ECMO support than for patients who were weaned and survived (p 0.025). Therefore mortality rates could be decreased with the earlier use of ECMO. Higher lactate levels reveal severe tissue hypoxia and acidosis. The earlier use of ECMO could improve tissue perfusion and inhibit the progression of multiorgan failure. In our study the peak lactate levels of nonsurviving patients were significantly higher than the peak levels of surviving patients. A peak lactate level of 12 mmol/l or more before ECMO was an independent predictor of increased mortality. These findings also suggested that the early use of ECMO could lead to better results. In our study, of interest is the use of IABP was not a predictor for better survival. However, in other studies [16, 18] the concomitant use of IABP was recommended for all patients on ECMO support based on the hypothesis of additional pulsatile flow, reduction of afterload, and better coronary flow. In these other studies, however, coronary artery disease was the main etiologic factor while valve disease was more common (43 of 62 or 69%) in our study group; coronary artery disease may benefit more from IABP. These findings suggest that the best treatment of adult postcardiotomy cardiogenic shock may be different in cases of valve disease and coronary artery disease. Although bleeding was the most frequent complication among the patients in our study, it was well controlled by exact surgical hemostasis. In addition, while platelet inhibitors were not used before surgery for the patients with valve disease, some patients still had to undergo reoperation during postoperative care. If a patient had no risk of bleeding, a heparin infusion was used to maintain a satisfactory activated clotting time. Insufficient anticoagulation can lead to disastrous results like limb or cerebral embolism during ECMO. Renal failure and the need for hemofiltration was the most common complication in our study population. A decreased renal reserve capacity and intolerance of hypoxia and hypoperfusion may be the main reasons for the high incidence of renal failure in rheumatic valve patients. In the surviving patients in this study renal function recovered as cardiac function improved and no survivor examined during the follow-up period needed long-term dialysis. Infection was another common complication which produced mediators of inflammation that led to multiorgan failure and ultimately death. Most researchers agree that morbidity and mortality rates are often inadequate measures of outcomes [19]. Health-related QOL is a multidimensional concept based on the patient s perception of his or her health and integrates physical functioning with psychologic status and social dimensions. Standardized questionnaires, especially those completed by patients themselves, are a practical, efficacious, and inexpensive method of collecting data. Health status is increasingly used to evaluate clinical strategies and because improvement in QOL is considered to be one of the principal goals of cardiac surgery, methods of QOL assessment are increasingly adopted in the clinical research in this field [20 22]. Patients deciding among treatment options may value information about the changes in QOL that they can expect after cardiac surgery. The use of QOL measures in clinical practice ensures that treatment is focused on the patient

Ann Thorac Surg WANG ET AL 2009;88:1897 904 RESULTS OF ECMO IN ADULT CARDIOGENIC SHOCK 1903 rather than simply on the disease. The QOL instruments help to integrate the patient s view into clinical practice and into the evaluation of new therapeutic strategies. Extracorporeal membrane oxygenation for example, involves more severe surgical stress and a higher risk of postoperative complications than other procedures; all of these factors may hinder improvement in QOL. In this study, the mean QOL scores after cardiac surgery were similar in the ECMO survivors and the patients without ECMO support; the primary difference was that the VT and MH scores (as well as in the global physical and mental scores) were significantly lower in the ECMO survivors. These findings suggest that ECMO survivors still had poor cardiac function that affected their vitality and that must be improved. Moreover, during ECMO support the stress caused by a prolonged intensive care unit stay and related complications like renal failure and infection negatively affected patients mental health. There were no statistically significant differences in the VT and MH scores of patients who did not receive ECMO support and those of the general Chinese population; this suggests that cardiac surgery contributed to overall physical and mental health. Nevertheless, we also found that, except for the VT and MH scores, the mean scores of both ECMO survivors and the patients without ECMO support were significantly lower than the scores of the general Chinese population; this was especially true for the RP and RE scales. These findings suggest that psychologic assistance is necessary for patients who have undergone cardiac surgery in China and may improve QOL. In conclusion, this study suggested that the early use of ECMO support and a reduction in complications could improve results. Although the follow-up period was short, it demonstrated that after patients were successfully discharged from the hospital they had an acceptable midterm survival rate, cardiac symptoms that are classified as class I and II by the New York Heart Association, and a low rate of hospital readmission. However, ECMO survivors also had lower physical and mental health. These trends and their effects on long-term clinical outcomes must be explored further. This study has several limitations. First, a baseline measure of QOL should be considered in risk adjustment when commenting or comparing QOL among three groups. Because this was a retrospective study, we could not get a baseline QOL score. In the future, studies should consider capturing a baseline QOL measurement before a patient s operation; this measurement could then be compared with follow-up measurements and used for risk adjustment. Second, upper body oxygen levels may play a large role in QOL; patients brains may be perfused at length with hypoxic blood that moves through the heart and enters the arch without mixing with the highly oxygenated blood coming from the groin. Many researchers believe that cardiopulmonary support with femoral cannulation leads to poorly perfused blood in the upper body. More research is needed to determine whether upper body oxygen levels influence QOL scores. References 1. Hill JD, O Brien TG, Murray JJ, et al. Prolonged extracorporal oxygenation of acute posttraumatic respiratory failure (shock-lung syndrome). N Engl J Med 1972;286:629 34. 2. Bartlett RH, Roloff DW, Custer JR, Younger JG, Hirschl RB. Extracorporeal life support: the University of Michigan experience. JAMA 2000;283:904 8. 3. Thiagarajan RR, Bratton SL. Extracorporeal membrane oxygenation for cardiac arrest: when to use it, and what are the outcomes? Crit Care Med 2006;34:1285 6. 4. Smedira NG, Moazami N, Golding CM, et al. Clinical experience with 202 adults receiving extracorporeal membrane oxygenation for cardiac failure: survival at five years. J Thorac Cardiovasc Surg 2001;122:92 102. 5. Golding LAR. Postcardiotomy mechanical support. Semin Thorac Cardiovasc Surg 1991;3:29 32. 6. Latal B, Helfricht S, Fischer JE, Bauersfeld U, Landolt MA. Psychological adjustment and quality of life in children and adolescents following open-heart surgery for congenital heart disease: a systematic review. BMC Pediatr 2009;9:6. 7. Lundberg C, Albåge A, Carnlöf C, Kennebäck G. Long-term health-related quality of life after maze surgery for atrial fibrillation. Ann Thorac Surg 2008;86:1878 82. 8. Vicchio M, Della Corte A, De Santo LS, et al. Tissue versus mechanical prostheses: quality of life in octogenarians. Ann Thorac Surg 2008;85:1290 5. 9. Goldsmith IR, Lip GY, Patel RL. A prospective study of changes in the quality of life of patients following mitral valve repair and replacement. Eur J Cardiothorac Surg 2001;20:949 55. 10. Jenkinson C, Layte R, Wright L, et al. The UK SF-36: an analysis and interpretation manual. University of Oxford, 1996. 11. Li L, Wang H, Shen Y. Development and psychometric tests of a Chinese version of the SF-36 Health Survey Scales. Chin J Prev Med 2002;36:2109 13. 12. Ware JE Jr, Sherbourne CD. The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care 1992;30:473 83. 13. Liu C, Li N, Ren H, et al. Feasibility of using Short Form 36 in Chinese population. J WCUMS (Journal of the West Chinese University of Medical Science) 2001;32:39 42. 14. Thiagarajan RR, Brogan TV, Scheurer MA, Laussen PC, Rycus PT, Bratton SL. Extracorporeal membrane oxygenation to support cardiopulmonary resuscitation in adults. Ann Thorac Surg 2009;87:778 85. 15. Doll N, Kiaii B, Borger M, et al. Five-year results of 219 consecutive patients treated with extracorporeal membrane oxygenation for refractory postoperative cardiogenic shock. Ann Thorac Surg 2004;77:151 7. 16. Bakhtiary F, Keller H, Dogan S, et al. Venoarterial extracorporeal membrane oxygenation for treatment of cardiogenic shock: clinical experiences in 45 adult patients. J Thorac Cardiovasc Surg 2008;135:382 8. 17. Ko WJ, Lin CY, Chen RJ, Wang SS, Lin FY, Chen YS. Extracorporeal membrane oxygenation support for adult postcardiotomy cardiogenic shock. Ann Thorac Surg 2002;73:538 45. 18. Doll N, Fabricius A, Borger MA, et al. Temporary extracorporeal membrane oxygenation in patients with refractory postoperative cardiogenic shock a single center experience. J Card Surg 2003;18:512 8. 19. Wood-Dauphinee S. Quality of life assessment: recent trends in surgery. Can J Surg 1996;39:368 72. 20. Koch CG, Khandwala F, Blackstone EH. Health-related quality of life after cardiac surgery. Semin Cardiothorac Vasc Anesth 2008;12:203 17. 21. Koch CG, Li L, Shishehbor M, et al. Socioeconomic status and comorbidity as predictors of preoperative quality of life in cardiac surgery. J Thorac Cardiovasc Surg 2008;136:665 72, 672.e1. 22. Navia D, Vrancic M, Vaccarino G, et al. Total arterial off-pump coronary revascularization using bilateral internal thoracic arteries in triple-vessel disease: surgical technique and clinical outcomes. Ann Thorac Surg 2008;86:524 30.