Sudden cardiac arrest gives rise to haemodynamic collapse, and in most cases—results in patient death. Those who are already in, or are quickly transferred to a hospital equipped with sophisticated devices, machines, and highly trained professionals, are treated using every conceivable means possible, and thus have a chance of returning to their daily routine without any neurological consequences. On the other end of the spectrum, however, there is the patient who drops dead without any witnesses in which case, mortality is 100%.
The most frequent scenario though, is the case that falls between these two extremes, in which some sort of cardiac resuscitation can be performed, either in an outpatient space or within the inpatient arena.
Most of the data we have concerns outpatients; there are 30-year-old studies from New York describing those who had suffered, and subsequently survived, cardiac arrest for a period of 1 year (Lombardi et al, 1994; Westfal et al, 1996). The studies documented a mortality rate of 90% in one year with 5% of the survivors experiencing significant neurologic sequelae. Unfortunately, over the past three decades, these statistics have not changed much.
Many patients often arrest in the public arena, in places such as supermarkets, restaurants or similar venues. Initiation of cardiopulmonary resuscitation (CPR) is tested against the inexorable passing of time and a bystander's training experience. We also know that the chances of surviving decreases by approximately 10% per minute if no resuscitative efforts are performed. Or, if after 10 minutes, there are no resuscitation efforts, mortality tends to be certain.
When cardiac arrest occurs in the hospital, if the patient is not on telemetry, it means that he or she has to be found and then CPR can be initiated. The outcome in this circumstance is roughly 85% mortality (Bloom et al, 2007). The inpatient population ‘should theoretically have’ the best chance of survival given the availability of personnel and equipment, as well as early initiation of CPR and advanced cardiovascular life support (ACLS).
All the data over the past 40 years indicate that rates for survival success to discharge hover around 10% (Rea et al, 2003a). Higher rates have been cited but include only first admissions, and not those that have multiple admissions after the initial incident.
Certainly, performing cardiac resuscitation to the best of our abilities is what we are trained to do. On a daily basis, such efforts are undertaken and the patients do get transferred to hospitals or emergency rooms while undergoing these emergency measures. However, it is important we are aware of statistical results (Rea et al, 2003b).
While CPR standards seem to change yearly, and the drugs used are also ever-changing, the reality is that over the course of decades, cardiac arrest results seemingly remain constant. Now, we do possess more technology to support post-cardiac arrest victims; however, this often equates to weeks or months of acute suffering—prolonging the agony.
Those who go into cardiac arrest endure a physiologic strike with severe implications, especially from a neurologic point of view; this can thereby render patients into high-level resource consumers. The healthcare industry currently spends $200 billion every year on the last 6 months of care prior to a patient's demise. This figure takes into account hospital expenses, nursing homes, and acute rehab units. Not to mention, this does not factor in the rate of readmission as many of these patients pass away essentially in silence, undocumented by the actual hospital database.
Unfortunately, the negatives in terms of resuscitation efforts performed every day are not well-known. The misconception is that such efforts are much more effective than what the numbers reveal, thus generating false survival expectations. In many ways, we have a culture of silence as we hold back necessary information from patients and families. We do not discriminate when it comes to CPR; everybody receives it and everybody is on the same protocol, regardless of the situation.
But what about those situations in which resuscitation is futile—where such efforts would not be advised, e.g. terminal patients with diffusely metastatic cancer? In some states in the US, such as Florida, paramedics have been able to declare such a patient dead at the scene without any resuscitative efforts attempted.
It is crucial to understand the survival statistics. There are various categories which have an impact on how we understand the numbers. Inpatients, outpatients, witnessed, unwitnessed cardiac arrests, time until CPR is initiated—all of these factors bear upon the reported efficacy and outcome. Yet, the numbers largely remain consistent, even when extended to other countries (Kitamura et al, 2012).
For example, a decade-old Japanese report on a half a million patients shows that neurologic survival was less than 5%, with ventricular fibrillation patients faring a little bit better. The Cardiac Arrest Registry to Enhance Survival (CARES) medical registry of 70 000 patients had survival in the 5.7% to 8.3% range (Chan et al, 2014). Statistics from Canada of 30 000 patients showed a survival range from 8% to 12%; and in 7000 Australian patients, the results are similar (Smith et al, 2015).
Regional differences do seem to exist, but the numbers are still poor. Remember also, the survivals are measured only to first discharge, thereby excluding what happens in the subsequent year (Wong et al, 2014). In Seattle WA, ventricular fibrillation patients, commonly from a myocardial infarction, had the best prognosis and, in other cities, cardiac arrest stemming from non-cardiac causes had an initial resuscitation rate of 40%, but only 11% to discharge.
Time to CPR and ACLS has been cited. In the Seattle Experience, the response time for basic life support increased from 4 to 5 minutes between 1977 and 2001, and the ALS response from 8 to 9 minutes. In the same cities, bystander CPR improved statistics a bit. Further elaboration on the Seattle study shows that trained personnel bystander CPR plus defibrillation doubled the percentages of survival.
In Sweden, early CPR between 1990 and 2010 in 15 000 patients also showed some improvement from 4% to 10%. Even with chest compression-only CPR, the results are similar faring in the 10% to 14% range. So far, paramedic mechanical CPR devices have shown no improvement over standard methods. Timing to defibrillation, whether it is 30, 60 or 180 seconds after the initiation of CPR, did not have any effect either on discharge survival. Even the use of automated external defibrillators has not made a significant difference, nor has pre-hospital ACLS implementation.
Chances in older patients, especially those aged 80 years and above, are about half that of the rest of the population. As expected, chronic conditions, including heart disease, hypertension and diabetes make matters worse.
What all of these statistics show is that improvement in sudden cardiac arrest patients—in whatever segment of the population, and especially in those with higher risk factors—is very low, with the numbers somewhere in the 10% range or perhaps, at the very highest, 15% (Smith et al, 2015).