**8. Results**

### **8.1 In-hospital cardiac arrest**

Patients who have IHCA are usually witnessed and have high likelihood of a good outcome with CCPR. A considerable proportion of these patients are candidates for ECPR. However, of all patients who had an in-hospital cardiac arrest (IHCA), only less than 1% were treated with ECPR in the United States [61]. With widespread availability and increasing familiarity of physician with ECMO, ECPR is gradually increasing in the past 20 years in a hospital setting. Encouraging results of ECPR for IHCA lead to renewed interest in research in this field with the development of automated CPR tools, percutaneous cannula, and localization of vessels under ultrasound guidance. Even with this limited research, there have been promising results of ECPR on patients who had IHCA with survival rates between 17 and 28% [31, 32]. These survival rates have led to great optimism in ECPR as a treatment for CA. Chen et al. conducted a 3-year prospective observational study using ECLS. The inclusion criteria were patients aged 18–75 years old who had an IHCA of cardiac origin having CPR >10 min compared to patients with CCPR. The prognostic factors in both groups *Overview of Venoarterial Extracorporeal Membrane Oxygenation (VA-ECMO) Support… DOI: http://dx.doi.org/10.5772/intechopen.105838*

were balanced by propensity score resulting in a comparable cohort, 113 with CCPR, and 59 in the ECPR group. Patients with ECPR had superior 1-year survival and survival to discharge rate, which was also the primary endpoint [62]. Shin et al. from Korea conducted a single-center, retrospective observational study from January 2003 to June 2009. A total of 406 patients had IHCA, broken down into a population getting CCPR (n = 321) vs. ECPR (n = 85). Propensity matching was used to balance the groups, and discharge with minimal neurologic impairment was used as the primary endpoint. ECPR group was superior in the primary endpoint. In addition, survival rates at 6-month survival were statistically significant in ECPR group [63].

#### **8.2 Out-of-hospital cardiac arrest**

Encouraging results with IABP in patients with coronary artery disease, cardiogenic shock, and postcardiotomy shock led to use of IABP for resuscitation of patients with CA. However, subsequent studies performed to review the results of IABP in patients with CA failed to show any survival benefit [64]. In a study by Iqbal et al. comparing the effects of IABP in patients with CA (55 patients with IABP vs. 174 without IABP), authors found no difference in favorable functional status at discharge (49.1% in IAPB group vs. 57.1% in without IABP group) and mortality rate at one year (45.5% in IABP group vs. 35.5% in without IABP group) [65]. In a randomized clinical trial by Firduas et al. including 60 patients with CA due to acute coronary syndrome patients (ACS) (30 patients received IABP after CA vs. 30 patients without IABP), there was no difference between the groups in terms of hospital mortality, hospital stay, cell death marker, or improvement in lactate clearance [66].

#### **8.3 Comparison between in-hospital and out-of-hospital cardiac arrest**

The length of CA, which is more relevant than the site of CA, is an important variable for the disparity in outcomes. IHCA patients are more likely to witnessed with a shorter time to initiate BLS and ACLS and a shorter period until the initiation of ECMO, as well as that their comorbidities are known to the treating physician, implying a bias in the choice to implant an ECMO. The key element in determining the success of ECPR in a patient with CA is the amount of time elapsed between the occurrence of the CA and initiation of ECMO. In most cases, IHCA would have a shorter time in achieving the ECMO flow as the tools and equipment are more readily available than OHCA. Still, survival to discharge in patients managed with ECPR for OHCA was reported to be significantly higher compared to patients managed with CCPR (56.9% vs. 43.1%, respectively; OR: 1.16, 95% CI: 1.11–1.21, p < 0.001) [67, 68]. The CHEER trial (mechanical CPR, Hypothermia, ECMO, and Early Reperfusion), a single center, prospective, observational study done in The Alfred Hospital Australia, included 24 patients with IHCA and OHCA who were eventually put on ECMO. ROSC was seen in all the patients, and more than half could be taken off ECMO, eventually making the survival rate above fifty percent. Neurological recovery was seen in over half of the patients who were discharged from the hospital in similar numbers [54]. Another retrospective review from Canada by Sun et al. in patients who received ECMO for cardiac arrest (8 IHCA, 1 OHCA) or cardiogenic shock (13 patients) from April 2009 to July 2015 at Vancouver General Hospital in Canada reported that ECMO was successfully weaned off in 18 patients and 16 could be discharged. Fifteen patients had satisfactory neurological outcomes [69]. Aforesaid studies demonstrate that in appropriately selected patients, ECPR provides survival benefits and more

positive neurological outcomes. In a meta-analysis including 2260 patients from six studies comparing ECPR or CCPR in patients with CA since 2000, Wang et al. reviewed the survival rates and neurological outcomes at discharge and at 3–6 months as well as 1 year after CA. The survival rate to discharge (RR 2.37, 95% CI 1.63–3.45, P < 0.001) and good long-term neurological outcome (RR 2.79, 95% CI 1.96–3.97, P < 0.001) were significantly better in ECPR group. In subgroup analysis, survival to discharge was significantly better with ECPR over CCPR in OHCA patients (RR 2.69, 95% CI 1.48–4.91, P = 0.001), while no significant difference was found in IHCA patients (RR 1.84, 95% CI 0.91–3.73, P = 0.09). The patient's survival rate to discharge was 25.5% in patients who received ECPR, and 19.4% of them had good long-term neurological outcomes [70]. Authors concluded that with the availability of facilities using ECPR for IHCA, more patients would survive and have an active life with little neurological deficiency.
