Where can I find this paper?

http://www.ncbi.nlm.nih.gov/pubmed/23339874

What is this paper about (what is the research question)?

Does a longer duration of CPR in paediatric cardiac arrest have prognostic bearing on the likelihood of a positive ultimate outcome (i.e. survival to discharge with intact neurological function)?

Summary of the Paper

Design: analysis of data from prospective multicentre registry (cohort study)

Objective: to use the GWTG-R data to evaluate the relationship between CPR duration and intact survival to hospital discharge after paediatric in-hospital cardiac arrest according to illness category

Primary Outcome: survival to hospital discharge. Secondary outcomes included survival with favourable neurological outcome.

Population: patients <18 years of age suffering pulseless cardiac arrest in-hospital at one of 28 US and Canadian institutions between 1st Jan 2000 and 31st Dec 2009.

• Inclusion: At least one minute chest compressions provided
• Exclusion: Events beginning outside hospital or in NNU, delivery room or nursery, illness categories newborn, obstetric or other illness

Results: 3419 paediatric in-hospital cardiac arrests fulfilled the criteria.

Median (IQR) CPR duration was 10 minutes (4-25) for survivors and 25 minutes (12-45) for non-survivors. Survival to discharge was 27.9%; 19.0% of all cardiac arrest patients had a favourable outcome, representing 68.2% of the survivors of the initial insult.

Survival rate and favourable neurological outcome fell linearly in the first 15 minutes; neurological outcome decreased by 1.2% for each additional minute of chest compressions.

Authors’ Conclusions:

CPR duration was inversely associated with survival
to hospital discharge and neurological outcome, even after
adjustment for confounding factors. Surgical cardiac patients had
improved outcomes compared with patients in all other illness
categories. Importantly, this study suggests that a proportion of
children who would presumably die without CPR survive with a
favorable neurological outcome even after prolonged CPR.

Why was the study necessary?

This article was brought to my attention via twitter with the headline “among survivors favourable neurological outcome occurred in 60% undergoing CPR > 35 minutes”. On checking this was indeed word perfect from the abstract. This took me aback as this was not quite my experience, even with the non-survivor group excluded. A paper definitely worth a closer look then!

The article starts with the pretext of the (relatively) low cardiac arrest rate (0.7-3%) in children admitted to hospital with a note that, although still low, survival rates have improved in the last decade. The authors acknowledge a paediatric mantra that CPR beyond 20 minutes or 2 rounds of adrenaline is generally futile although it is interesting the evidence for this has never been robustly demonstrated. A large prospective cohort study then seems a very reasonable undertaking. The American Heart Associations “Get with the Guidelines-Resucitation” [AHA GWTG-R ]initiative providing a national registry for the relationship between in-hospital CPR duration and intact survival to be explored.

On the study design

The AHA-GWTG-R is a prospective registry with data from 328 US and Canadian hospitals between 2000 and 2009. In order to categorise patients pre arrest the following categories were used with those with DNAR orders excluded:

• Medical Illness (non-cardiovascular)
• Medical Illness (cardiovascular)
• Surgical Illness (non-cardiovascular)
• Surgical Illness (cardiovascular)
• Trauma

Patients must have had > 1min of CPR provided and it is worth noting that as well as inpatients those in outpatient clinics were included. Those in whom the event started out of the hospital were excluded. Anyone receiving >180 mins of CPR were defined as having 180mins maximum. The primary outcome measure was survival to hospital discharge and secondary measures included return of spontaneous circulation > 20 mins, 24 hour survival and discharge with favourable neurological outcome – this was defined as a Paediatric Cerebral Performance Category of 1, 2 or 3 on discharge. The PCPC is shown in table one.

The authors are open about the fact that as a multi-centre study classifications between hospitals may differ. They are even frank enough to state that as the users of the AHA-GWTG-R pay a fee to do so they may be more interested in outcomes that other hospitals (the AHA-GWTG-R is used by 10% of hospitals).

It could be argued that included ED patients with in hospital arrests are very different from patients who arrest on the wards but the differences between these two groups were not broken down. This would have been very useful information for the emergency care community.

What were the results and what does this mean?

The data collected included 5922 which were all accounted for in an Utstien diagram (figure 1).

Key demographic details in the study were that the mean age was 4.9+/- 6 years, 8% of events were not witnessed but nearly all (90.5%) were monitored. The majority of patients were General Medical (43.2%). The median CPR duration was 10 minutes for survivors and 25 minutes for non-survivors. Survival to discharge was 27.9%, but only 19.0% of all cardiac arrest patients had a favourable outcome as per the PCPC. Both survival rate and favourable neurological outcome fell linearly in the first 15 minutes, with neurological outcome decreasing by 1.2% for each additional minute of chest compressions. However although only 19% had a favourable neurological outcome this represented 68.2% of the survivors of the initial insult.

The headline figure of 60.1% comes from the 95 out of 158 survivors who received CPR for 35 minutes and had a favourable outcome. Surgical cardiac patients had the highest adjusted probability of neurological outcome with medical, general surgical and general medical similar to the whole cohort. Traumatic arrest has the poorest outcome of 4.3%

The study confirms that generally the outcome after arrest is poor however it demonstrated there is variation in the outcome dependant on the type of patient. Interestingly there was an indication that continuing CPR for more than 20 minutes may be justified given the proportion of those who survived with a positive neurological outcome, using the PCPC classification system. It is important to note that overall surviving numbers were low and there was not a priori attempt to predict in which patient group prolonged CPR may be beneficial. 

The biggest challenge with this study is the use of the PCPC and the classification of 3 as a favourable outcome. Classification 3 is a moderate disability but is quite different from 4 (severe; dependant on others for daily support). The distinction is not always clear cut and an excess of grade 3 due to the strict classification may bias the results especially as this was done on discharge when a more favourable grade may be applied.

Finally although the break down into 0-15, 15-35 and >35 seems reasonable there were patients receiving up to and above of 180 minutes of resuscitation. It would be useful to distinguish resuscitation rates into standard, prolonged, very prolonged and unique for the purposes of evaluation as the patient groups, and potentially teams working on them are likely to be very different.

What can we take from this paper into clinical practice?

This study is the largest of its kind and is an extremely useful platform on which to base further research. It will be important the neurological outcome is clearly defined and followed up for a reasonable period of time. The distinction between medical groups needs to be taken into account and for the emergency care community it is validation of the extremely poor survival and outcome of traumatic cardiac arrest. Until further work is performed it will be difficult to extend the ’20 minute rule’ but it is vital this work is performed. To be working in an area as ethically challenging as resuscitation needs a clear evidence base and work both in and out of hospital.

More questions to ask

•  Do rates differ between ward patients and those suffering cardiorespiratory arrest within the Emergency Department?
• How would results change if we defined “favourable neurological outcome” more clearly?

Follow us on twitter: @PEMLit