Publication/Presentation Date

7-25-2014

Abstract

Abstract

This study sought to analyze and better understand the different etiologies of in-hospital cardiac arrest (IHCA), to determine the short and long term outcomes for these patients, to review and look for trends within the “code blue” data, and to identify patients who may benefit from an advanced and aggressive cardiopulmonary support system like extracorporeal membrane oxygenation (ECMO) during the cardiopulmonary resuscitation (CPR) process. A retrospective study of 182 patient charts and resuscitation records from the years 2011-2012 was completed with patients ranging in age from 24-70 years with a median age of 58. The most significant results found were an IHCA 30 day survival rate/survival rate to discharge of 28% and that at least 44 patients may have benefitted from ECMO-CPR. Though this study includes only a very small sample size and two years of data, it is significant because it highlights places where implicating a new resuscitation process for select IHCA patients could directly save lives. It warrants further research into implementing ECMO-CPR within the Lehigh Valley Health Network and continued analysis of the current data on “code blues” and CPR protocol.

Introduction

In-hospital cardiac arrest (IHCA) is a relatively uncommon event but is very resource intensive and associated with a poor outcome including a low rate of survival. Cardiac arrest in the hospital setting can be the result of a variety of etiologies. The progression of cardiopulmonary resuscitation (CPR) for these arrests can vary greatly between patients. Many factors including initial cardiac rhythm, duration of CPR, quality of CPR, and cause of the arrest account for these differences and the end prognosis for the patient.1 Even when given optimal care, survival rates for IHCA are still with the majority of patients are unable to regain proper and lasting circulation to discharge.

Analyzing in-hospital cardiac arrest data allows the Lehigh Valley Health Network to review their cardiopulmonary resuscitation protocols and pinpoint trends and differences within the data. This information can highlight areas of possible improvement in patient outcomes and care.

As technology continues to advance, more options are slowly becoming available to improve prognoses of IHCA patients. Extracorporeal membrane oxygenation (ECMO) is a highly aggressive and advanced cardiopulmonary support system that can benefit select patients who cannot be successfully resuscitated through traditional cardiopulmonary resuscitation. Essentially, veno-arterial ECMO works similarly to the cardiopulmonary bypass machines utilized during open heart surgeries. The blood is drained from the patient and oxygenated outside of the body before it is returned to circulation. This temporarily allows for adequate bodily perfusion in patients whose hearts will not pump properly. Because ECMO is an expensive and only temporary solution for patients in refractory cardiac arrest, selection is restricted to those who have ‘reversible’ causes of cardiac arrest. ECMO offers valuable time for the pathologies behind the cardiac arrest to be evaluated and treated.2 Studies have shown that ECMO is most effective for these patients as well as patients whose arrests were witnessed and had immediate CPR intervention, which is why it is more of an option for IHCA versus out-of hospital cardiac arrests.1,3 One study found the rate of survival of ECMO-CPR for IHCA patients was 42% and out of hospital cardiac arrest only 15%.1 Patient gender, age, and body weight have not been found to be statistically significant factors in survival rates of ECMO-CPR.3

Introducing ECMO-CPR for select IHCA patients in the Lehigh Valley Health Network is a realistic way to produce positive outcomes for patients who would otherwise face grave prognoses and better the overall survival statistics for IHCA in the network.

Methodology

This was a retrospective study involving the 182 patients in 2011 and 2012 between the ages of 18 and 70 within the Lehigh Valley Health Network for which a “code blue” was called for a cardiac arrest.

Data was examined for each patient from their medical charts, electronic medical records, and resuscitation records that are filled out for each “code blue” incidence. The overall exclusion criteria were an age 70 years or an existing do not resuscitate (DNR) before the code took place. A database was made using Microsoft Access to compile and condense relevant information for each included patient. This information included demographics, medical history, date of the cardiac arrest, cause of the cardiac arrest, initial cardiac rhythm, location within the hospital, reason the code was terminated, if there was a return of circulation (>20minutes), if multiple cardiac arrests were experienced in the day, if the patient became DNR after coding, and if the patient survived to 30 days and 1 year following the arrest with or without good neurological condition. Some gender differences in IHCA within the hospital were explored, with statistics being analyzed using a Fischer’s Exact Test. All included patients were used for each analysis, except for analysis of initial cardiac rhythms where nine patients had to be excluded because of unrecorded or unknown initial rhythms.

When identifying patients who may have benefitted from ECMO, additional exclusion criteria used were: previous severe neurological damage, intracranial hemorrhage, cardiac arrest of traumatic origin, uncontrolled bleeding, terminal malignancy, irreversible organ failure (like hepatic failure), original unwitnessed out of hospital cardiac arrest, severe COPD, and severe PVD.2 Criteria for cardiopulmonary resuscitation with ECMO is relatively selective because ECMO-CPR is by nature much more involved, invasive, and expensive than traditional CPR. Patients recognized for possible ECMO benefit were then sorted by the etiology of their cardiac arrest.

Results

The results in Table 1 (see Appendix A) show that of the 182 patients suffering IHCA in 2011-2012 within the outlined age range, only 51 (28%) survived at least 30 days following their arrest despite 106 (58%) gaining some kind of return of circulation (ROC) greater than 20 minutes. 24 patients who had ROC became DNR following their first code and subsequently passed away soon after, while 35 patients who had ROC had repeat codes with only 2 surviving. The average age of all survivors to 30 days was 53 years with a range of 24-70 years, and the average duration of CPR for survivors was 15.5 minutes with a standard deviation of about 14.5 minutes and a range of

About 59% of all of the IHCA patients were male and the remaining 41% female. Surprisingly, there was a difference in survival seen between male and female patients with rates of 23% and 35% respectively (Table 1). Rates of the initial cardiac rhythms at arrest between males and females were also found to be different but not significantly so (Figure 2). Survival rates varied for each initial rhythm with ventricular fibrillation or ventricular tachycardia arrests having a survival rate of almost 50%, statistically significantly (p values

After reviewing comorbid conditions and causes of cardiac arrest, 44(about 34%) of the 131 patients who did not survive with traditional CPR were found to have likely benefitted from ECMO-CPR (Table 3). A variety of causes of cardiac arrest are represented within this population (Figure 3), the most common being acute coronary syndrome, pulmonary embolism, cardiomyopathy, and sepsis.

Conclusion

The results show a few noteworthy trends within the IHCA data for 2011-2012 including gender differences in survival, survival rates in patients who code multiple times, and patients who may have benefitted from ECMO-CPR and the causes of their arrests.

The differences in survival rates between the genders in the two years have a few possible explanations. First, the small sample size and limited age range examined could have skewed the data. Secondly, there was a significantly smaller ratio of percentage of males versus females that went into ventricular fibrillation or ventricular tachycardia arrests than previous studies have found. This study found only 24% of male and 22% of female in-hospital cardiac arrests had an initial ventricular tachycardia/ventricular fibrillation rhythm, while other studies have found men to have a statistically significant larger percentage of arrests originating in this type of rhythm.4 Since an initial rhythm of ventricular fibrillation or tachycardia is well documented to have the highest rate of survival, this helps to explain the difference in survival found between the genders. This study confirmed the greater survival rate for this rhythm, with 55% of men and 43% of women surviving 30 days post arrest.

From looking at the results of this study, patients who suffered repeat cardiac arrests within the same day appear to have very grave prognoses. Less than 6% of these patients survive 30 days, excluding the additional 24 patients that were DNR after their first arrest and subsequently coded. Further studies incorporating additionally years of data and data from additional hospital systems would be able to confirm if this is a consistent trend.

Of the 131 patients that did not survive to 30 days post their IHCA, 44 would have been included as good candidates for ECMO-CPR per criteria listed above. Survival rates to discharge for patients undergoing ECMO-CPR for IHCA vary between studies but are most often found to be around 30-42%.1,2 Conservatively this indicates that about 13-18 patients could have been saved in 2011-2012 and increased the overall IHCA survival rate for the two years from 28% to 35-39%. This shows that introducing ECMO-CPR for select IHCA patients in the Lehigh Valley Health Network is a realistic way to produce positive outcomes for patients who would otherwise face grave prognoses and better the overall survival statistics for IHCA in the network.

The study has quite a few limitations. It cannot be broadly applied due to the small sample size of only 182 total patients with only 2 years of IHCA data, limited age range of patients reviewed, and because only statistics from a single hospital system were examined. However, the findings outlined above suggest that further research of IHCA patients within the Lehigh Valley Health Network and into adopting ECMO-CPR protocols is at least warranted.

Appendix A

Comments

Mentor: James Wu

Department(s)

Department of Surgery, Department of Surgery Faculty, Research Scholars, Research Scholars - Posters, USF-LVHN SELECT Program, USF-LVHN SELECT Program Students

Document Type

Poster

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