Picture this: you're in the ED with a 10-year-old girl who's been in cardiac arrest and undergoing CPR for 20 minutes. She hasn't responded. Do you call time of death or keep going?
You couldn't look to the literature for guidance in the past because there wasn't much in the way of evidence about the appropriate duration of CPR. But a consensus based primarily on expert opinion and review had arisen over the years that continued CPR is likely futile after about 20 minutes with no response. Patients were likely to sustain serious, permanent brain damage with devastating neurological consequences, the conventional wisdom went, if they survived after extended CPR.
Two major retrospective review studies in the past two years, however, have turned that conventional wisdom on its head.
The most recent study, which appeared in Circulation in January, analyzed hospital records of 3,419 children in the United States and Canada from 2000 through 2009, prospectively collected from the American Heart Association's Get with the Guidelines-Resuscitation (GWTG-R) registry. (Circulation 2013;127:442.) Just more than 40 percent of the children underwent CPR for 15 minutes or less, 30 percent had CPR for 16-35 minutes, and 29 percent had “prolonged CPR,” defined as resuscitation performed for more than 35 minutes.
A total of 16.6 percent of the prolonged-CPR patients survived to hospital discharge. That's substantially lower than those who had CPR for less than 15 minutes (44% of those children survived to discharge), but it's also nearly 17 kids out of every 100 who lived, who almost certainly would have died had CPR been stopped at 15 or 20 minutes. The additional survivors did not appear to pay the steep neurologic price that might have been expected: 67 percent of kids who survived after undergoing CPR for 15 minutes or less had good neurologic outcomes compared with 57 percent of those who survived after prolonged CPR.
“This doesn't establish an ideal duration for CPR, but it at least says that if you think you have a reversible cause, then it's reasonable to continue CPR and setting an arbitrary limit doesn't make sense,” said Maj. Renee Matos, MD, MPH, the lead author on the study and an investigator at San Antonio Military Medical Center.
The pediatric study's findings were similar to results in an adult population analyzed by Zachary Goldberger, MD, a cardiologist at the University of Washington, and colleagues. Their study, published in Lancet last September, also used GWTG-R data to collect information on 64,339 patients who went into cardiac arrest at 435 hospitals in the United States from 2000 to 2008. (Lancet 2012;380:1473.) They divided the hospitals into quartiles based on median CPR duration in patients who ultimately died. They were then able to identify which hospitals systematically practiced longer efforts before pronouncing a patient dead. (Arrests and CPR that took place in the ED were excluded.)
“We found that patients at hospitals where longer attempts occurred on average had higher survival rates when compared with patients at hospitals where attempts were shorter. These findings were most pronounced in patients with PEA/asystole,” said Dr. Goldberger. Patients at the prolonged-CPR hospitals were 12 percent more likely, in fact, to survive to discharge than those at the shorter-CPR hospitals. “When to stop CPR is one of the most challenging decisions to make at the bedside, and these results suggest that a short amount of more time — possibly even 10 more minutes — may impact survival.”
That said, Dr. Goldberger cautioned against over-enthusiastic interpretation of the data from his and Dr. Matos' studies. “We aren't suggesting that every patient in cardiac arrest needs an extensive resuscitation,” he said. “Bedside decision-making remains the gold standard in terms of duration of resuscitation. However, these observational studies are the first step in challenging the ‘shorter is better’ wisdom, and suggesting that we need to ask ourselves, ‘Is this a patient that may benefit from a longer effort?’”
Dr. Goldberger emphasized that these studies were not designed to determine how long is long enough or how short is short enough. “At present, we have illustrated that once the decision to start cardiac resuscitation has been made, there may be an association between longer attempts and higher rates of survival,” he said.
It's also important to note some limitations to the studies. The findings, based on data from GWTG hospitals, may not apply consistently to non-GWTG hospitals, where the quality of CPR performed may not be comparable. The data also only involve in-hospital CPR, and do not apply to CPR performed by emergency medical personnel in an ambulance or by an on-scene bystander.
Some subgroups of patients who did particularly well — or particularly poorly — may provide guidance for in-the-moment decision-making about whether a particular patient would be a good candidate for prolonged CPR. “We found that surgical cardiac kids can withstand much longer durations of CPR and still have good outcomes,” Dr. Matos said. “We hypothesize that this may be because the etiology of their arrest is different. The most common cause of pediatric cardiac arrest is respiratory in origin, so they stop breathing for a period of time before their heart stops. The period of hypoxia that happens before the arrest begins could mean that there are more organ systems involved. But cardiac patients usually arrest just because of a heart issue, and the oxygen supply to their body was fine right up until the heart stopped functioning.”