Asystole shows no electrical activity in the heart
and eforts may be stopped on scene.
PEA shows electrical activity in the heart, but the patient
has no pulse. Currently, these patients must be transported.
WWW.JEMS.COM AUGUST 2017 | JEMS 53
following ALS. 13 Therefore, the majority of patients transported to a
hospital in the U.K. will be those who persist with pulseless electrical
activity (PEA) on scene. (See Figure 1.)
The Resuscitation Council (U.K.) suggests evidence is less clear
about when to stop a resuscitation where PEA persists. 14 Although
anecdotally senior clinicians do make decisions on whether to continue
to resuscitate PEA, evidence suggests that the rationale for these decisions are many and varied and include internal factors, such as the clinician’s experience, as well as external factors, such as the expectations
of family members and perceived patient characteristics. 15
The European Resuscitation Council’s (ERC) 2015 CPR guidelines suggested that institutional TOR guidelines were needed for
prehospital providers to reduce such variability in decision-making. 16
Our North West Ambulance Service NHS Trust study sought
to determine whether there were characteristics of adult OHCA of
presumed cardiac cause that could predict outcomes, and propose an
out-of-hospital TOR CDR.
We used a retrospective cohort study to review all cases of adult OHCA
of presumed cardiac etiology during a 26-month period. The aim was
to determine characteristics of adult OHCA, which could be used to
develop a CDR for TOR. Two existing TOR guidelines were also
applied to the dataset for comparison.
The study received approval from our institutional research ethics
board, NHS Health Research Authority and University research ethics board. Data for the study were taken from the North West Ambulance Service NHS Trust (the Trust), which covers large urban centers
and remote rural areas, with a population of 7 million people across a
geographical area of approximately 5,400 square miles.
The Trust has a combined technician (BLS) and paramedic (ALS)
staff and has a TOR guideline which allows for termination only if,
following 20 minutes of ALS, the patient is in an asystolic rhythm.
We retrospectively reviewed all adult OHCAs of presumed cardiac
cause that occurred between April 1, 2011, and June 29, 2013, and were
transported to a hospital. These data were collected by trained auditors of the Trust Governance Department from patient report forms
(PRFs) completed by ambulance clinicians following every patient
contact, and hospital records of patient outcomes.
Patients were excluded from the study if:
>> No resuscitation was attempted (e.g., death was diagnosed due to
presence of rigor mortis, decomposition, etc);
>> The patient was under 18 years of age;
>> The arrest wasn’t presumed to have been of cardiac origin (e.g.,
the arrest was due to trauma, drowning or drug overdose);
>> The resuscitation attempt was terminated under current TOR
>> The patient’s outcome was unknown (some hospitals didn’t provide follow-up data).
A total of 4,870 patients met the inclusion criteria for the study. (See
Figure 2, p. 54.) During the study period, 8,316 cardiac arrests were
managed by the Trust. Of these, 173 were under 18 years of age; 808
weren’t presumed to have been of cardiac origin (180 were trauma-re-
lated, 26 were submersions/drownings, 483 respiratory, 104 other and
14 unknown); 1,268 resuscitations were terminated under the existing
Trust policy; 704 were taken to hospitals who didn’t share survival data
and 493 had no data available on survival.
The mean age for the patient group was 71.5 years; 3,033 ( 62.3%)
were male; and the median response interval for the first response
(e.g., public access defibrillator, community first responder, etc.) was
The median response interval from ambulance activation to arriving
on scene was 10. 24 minutes. The median interval on scene was 28.72
minutes and the median transport to hospital interval was 9.05 minutes.
Of 4,870 patients with complete follow-up 4,354 (89.4%) died and
516 ( 10.6%) survived to hospital discharge. In 4,859 cases (99.8%), it
was recorded whether or not the arrest was witnessed; 2,383 of the pat-
ents ( 48.9%) had an arrest witnessed by a bystander and 646 ( 13.3%)
were witnessed by an ambulance clinician. (See Table 1.)
In 100 ( 5.5%) of 1,830 unwitnessed arrests, the patients survived
to discharge. Of the 2,383 witnessed by a bystander, 276 ( 11.6%) sur-
vived. This compares to 140 ( 21.7%) of the 646 patients whose arrest
was witnessed by ambulance clinicians and survived.
The presence of bystander CPR was recorded for 4,836 (99.3%)
Table 1: Characteristics of cardiac arrests
Unwitnessed 1,830 ( 37.7%) 276 ( 11.6%)
witnessed 2,383 ( 48.9%) 276 ( 11.6%)
Clinician witnessed 646 ( 13.3%) 140 ( 21.7%)
Bystander CPR 2,893 ( 59.8%) 335 ( 11.6%)
No Bystander CPR 1,943 ( 40.2%) 180 (09.3%)
Shockable rhythm 1,383 ( 28.4%) 356 ( 25.7%)
rhythm 3,267 (67.1%) 80 (02.4%)
Defibrillated 1,833 ( 37.6%) 399 ( 21.8%)
Not defibrillated 3,035 ( 62.3%) 116 (03.8%)
ROSC 1,778 ( 36.5%) 492 ( 27.7%)
No ROSC 3,093 ( 63.5%) 24 (00.8%)
Figure 1: Termination of resuscitation considerations for asystole vs. pulseless electrical activity