Tuesday 8 March 2016

Why we should no longer terminate resuscitations after 20 minutes

Why we should no longer terminate resuscitations after 20 minutes
Dr K K Aggarwal
 
A National Association of EMS Physicians (NAEMSP) position statement in 2000 proposed that “an adequate effort” of CPR was 20 minutes.

The American Heart Association (AHA) 2015 Guidelines discuss the limited data on how long to continue resuscitation, and ultimately choose not to make any recommendation because of such insufficient data.

Although the maximum tolerated duration of CPR may not be known precisely, there are evidence-based guidelines for identifying patients for whom extended resuscitation is futile.

For Basic Life Support (BLS)-only resuscitation, termination of resuscitation is recommended for patients who:
•    Aren’t witnessed to arrest by EMS
•    Never received a rescue shock
•    Never have return of pulses prior to commencing transport

For Advanced Life Support (ALS) resuscitations, termination of resuscitation is recommended for patients who:
•    Aren’t witnessed to arrest by EMS
•    Aren’t witnessed to collapse by bystanders
•    Have no bystander CPR
•    Never receive a rescue shock
•    Never have return of pulses prior to commencing transport

There were no survivors among patients who met all the five criteria.
Patients where the BLS rule was negative (at least one of the three criteria wasn’t met) survived at a rate of 11.9%.
Among patients where the ALS rule was negative (at least one of the five criteria wasn’t met), survival was 7.9%. Therefore, it’s reasonable to continue CPR efforts in patients who don’t meet these rules.

In a series of 1,014 patients in Pittsburgh who had an overall 11% survival to hospital discharge, 90% of the patients with good functional status at hospital discharge had return of pulses within 16 minutes of the paramedics initiating CPR.

A Korean database has shown that EDs that have an institutional policy to continue CPR for only 20 minutes had lower survival (2.1%) than hospitals who continued CPR for 20–30 minutes (5.2%) or > 30 minutes (5.6%).

How can we recognize the 10% of patients where efforts > 20 minutes are worthwhile? In many of these cases, the patient is “coming and going.” For example, a patient has brief responses to rescue shocks, but rapid re-fibrillation, resulting in many brief periods of circulation with lots of brief periods of CPR in between.

When the total number of shocks gets into double digits, that patient is trying hard not to die. Other patients have occasional pulses after vasopressors but then rapidly deteriorate to pulseless electrical activity. These patients have severe cardiogenic shock or other shock that may require mechanical support while the cause is treated.
In both of these situations, there’s some minimal or interrupted spontaneous circulation during the cardiac arrest, potentially prolonging the tolerance to CPR.

Waveform capnography is one tool to recognize the patient with preserved circulation during CPR. Excretion of CO2 requires good blood flow to the lungs and continued metabolism by the patient.

High end-tidal carbon dioxide (EtCO2) (> 20 mmHg) during CPR is a sign of life just like continued electrical activity in the ECG. It is reasonable to continue resuscitative efforts longer in a patient who’s excreting CO2 during CPR. The 2015 AHA Guidelines suggest that failure to achieve EtCO2 >10 mmHg after 20 minutes of CPR may be used to support termination of CPR.

There are at least two other potential destinations for the patient who’s tolerating long CPR: extracorporeal cardiopulmonary life support (ECLS) and emergency angiography with ongoing CPR.

ECLS consists of cannulating large arteries and veins in order to start cardiopulmonary bypass. This procedure requires surgical expertise, perfusionists and an intensive care unit experienced with the care of these patients.

Once ECLS is instituted, a 30–45 minute procedure, the cardiopulmonary bypass machine has completely replaced cardiac activity. The patient can have other procedures to reverse the cause of cardiac arrest: coronary angiography, pulmonary embolectomy or other treatments.
 
Nevertheless, ECLS will only be appropriate for highly selected patients who are both strong (i.e., young) enough to tolerate the procedure and who have potentially reversible causes of cardiac arrest. When ECLS is used, good functional recovery has been reported for patients with total CPR durations of 60–75 minutes or even durations of 80 minutes.

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