Advanced Life Support Algorithm: Learning Outcomes
Advanced Life Support Algorithm: Learning Outcomes
Advanced Life Support Algorithm: Learning Outcomes
Algorithm
6
interventions, they are of secondary importance to high-
Learning outcomes quality, uninterrupted chest compressions and early
defibrillation.
To understand:
쑺 The function of the advanced life support
(ALS) algorithm Shockable rhythms (VF/VT)
쑺 The importance of minimally interrupted The first monitored rhythm is VF/VT in approximately 25%
high quality chest compressions of cardiac arrests, both in- or out-of-hospital. VF/VT will
also occur at some stage during resuscitation in about
쑺 The treatment of shockable and non- 25% of cardiac arrests with an initial documented rhythm
shockable rhythms of asystole or PEA.
쑺 When and how to give drugs during
cardiac arrest Treatment of shockable rhythms (VF/VT)
쑺 The potentially reversible causes of
cardiac arrest 1. Confirm cardiac arrest - check for signs of life or if
trained to do so, breathing and pulse simultaneously.
Unresponsive?
Not breathing or
only occasional gasps
Call
resuscitation team
CPR 30:2
Attach defibrillator / monitor
Minimise interruptions
Assess
rhythm
Shockable Non-Shockable
(VF / Pulseless VT) (PEA / Asystole)
Return of
1 Shock spontaneous
circulation
Figure 6.2 Continuing chest compressions during even if the defibrillation attempt is successful in restoring a
charging with a manual defibrillator perfusing rhythm, it is very rare for a pulse to be palpable
immediately after defibrillation and the delay in trying to
If organised electrical activity compatible with a palpate a pulse will further compromise the myocardium if
cardiac output is seen during a rhythm check, seek a perfusing rhythm has not been restored. If a perfusing
evidence of ROSC: rhythm has been restored, giving chest compressions
does not increase the chance of VF recurring. In the
• Check a central pulse and end-tidal (ETCO2) trace if presence of post-shock asystole chest compressions may
available usefully induce VF.
Subsequent doses of adrenaline are given after alternate A precordial thump should be undertaken immediately
2-minute loops of CPR (which equates to every 3 - 5 min) after confirmation of cardiac arrest and only by healthcare
for as long as cardiac arrest persists. If VF/VT persists, or professionals trained in the technique. Using the ulnar
recurs, a further dose of 150 mg amiodarone may be edge of a tightly clenched fist, deliver a sharp impact to
given. Lidocaine, 1 mg kg-1, may be used as an alternative the lower half of the sternum from a height of about 20 cm,
if amiodarone is not available, but do not give lidocaine if then retract the fist immediately to create an impulse-like
amiodarone has been given already. stimulus. There are very rare reports of a precordial thump
converting a perfusing to a non-perfusing rhythm.
When the rhythm is checked 2 min after giving a shock, if
a non-shockable rhythm is present and the rhythm is
organised (complexes appear regular or narrow), try to
Witnessed, monitored VF/VT in the cardiac
palpate a central pulse and look for other evidence of catheter laboratory or after cardiac surgery
ROSC (e.g. sudden increase in ETCO2 or evidence of If a patient has a witnessed and monitored cardiac arrest
cardiac output on any invasive monitoring equipment). in the catheter laboratory or early after cardiac surgery:
Rhythm checks must be brief, and pulse checks
undertaken only if an organised rhythm is observed. If an
• Confirm cardiac arrest and shout for help.
organised rhythm is seen during a 2-minute period of CPR,
do not interrupt chest compressions to palpate a pulse
• If the initial rhythm is VF/VT, give up to three quick
unless the patient shows signs of life suggesting ROSC. If
successive (stacked) shocks. Start chest
there is any doubt about the presence of a pulse in the
compressions immediately after the third shock and
presence of an organised rhythm, resume CPR. If the
continue CPR for 2 min. With respect to the ALS
patient has ROSC, begin post-resuscitation care. If the
algorithm, these three quick, successive shocks are
patient’s rhythm changes to asystole or PEA, see non-
regarded as the first shock.
shockable rhythms below.
It is important in shock-refractory VF/VT to check the This three-shock strategy may also be considered for an
position and contact of the defibrillation pads. The initial, witnessed VF/VT cardiac arrest if the patient is
duration of any individual resuscitation attempt is a matter already connected to a manual defibrillator - these
of clinical judgement, and should take into account the circumstances are rare. There are no data supporting a
perceived prospect of a successful outcome. If it was three-shock strategy in any of these circumstances, but it
considered appropriate to start resuscitation, it is usually is unlikely that chest compressions will improve the
considered worthwhile continuing as long as the patient already very high chance of ROSC when defibrillation
remains in identifiable VF/VT. occurs early in the electrical phase, immediately after
onset of VF.
If there is doubt about whether the rhythm is asystole or
very fine VF, do not attempt defibrillation; instead, continue Non-shockable rhythms (PEA and
chest compressions and ventilation. Very fine VF that is
difficult to distinguish from asystole is unlikely to be
asystole)
shocked successfully into a perfusing rhythm. Continuing Pulseless electrical activity (PEA) is defined as organised
good-quality CPR may improve the amplitude and cardiac electrical activity in the absence of any palpable
frequency of the VF and improve the chance of pulses. These patients often have some mechanical
subsequent successful defibrillation to a perfusing rhythm. myocardial contractions but they are too weak to produce
Delivering repeated shocks in an attempt to defibrillate a detectable pulse or blood pressure. PEA may be caused
what is thought to be very fine VF will increase myocardial by reversible conditions that can be treated (see below).
injury both directly from the electric current and indirectly Survival following cardiac arrest with asystole or PEA is
from the interruptions in coronary blood flow. If the rhythm unlikely unless a reversible cause can be found and
is clearly VF, attempt defibrillation. treated quickly and effectively.
The four Hs
Figure 6.4 Intraosseous device Minimise the risk of hypoxia by ensuring that the patient’s
lungs are ventilated adequately with 100% oxygen. Make
sure there is adequate chest rise and bilateral breath
Reversible causes sounds. Using the techniques described in Chapter 7,
Potential causes or aggravating factors for which specific check carefully that the tracheal tube is not misplaced in a
treatment exists must be considered during any cardiac bronchus or the oesophagus.
arrest. For ease of memory, these are divided into two
groups of four based upon their initial letter - either H or T Pulseless electrical activity caused by hypovolaemia is
(Figure 6.5). More details on many of these conditions are due usually to severe haemorrhage. Evidence of
covered in Chapter 12. haemorrhage may be obvious, e.g. trauma (Chapter 12),
or occult e.g. gastrointestinal bleeding, or rupture of an
• Hypoxia aortic aneurysm. Intravascular volume should be restored
rapidly with fluid and blood, coupled with urgent surgery
• Hypovolaemia to stop the haemorrhage.
The four Ts
A tension pneumothorax may be the primary cause of
PEA and may follow attempts at central venous catheter
insertion. The diagnosis is made clinically. Decompress
rapidly by thoracostomy or needle thoracocentesis and
then insert a chest drain.
Figure 6.6 Use of ultrasound during advanced life
Cardiac tamponade is difficult to diagnose because the support
typical signs of distended neck veins and hypotension
cannot be assessed during cardiac arrest. Cardiac arrest Signs of life
after penetrating chest trauma or after cardiac surgery If signs of life (such as regular respiratory effort,
should raise strong suspicion of tamponade - the need for movement) or readings from patient monitors compatible
needle pericardiocentesis or resuscitative thoracotomy with ROSC (e.g. sudden increase in exhaled carbon
should be considered in this setting (Chapter 12). dioxide or arterial blood pressure waveform) appear
during CPR, stop CPR briefly and check the monitor. If an
In the absence of a specific history of accidental or
organised rhythm is present, check for a pulse. If a pulse
deliberate ingestion, poisoning by therapeutic or toxic
is palpable, continue post-resuscitation care and/or
substances may be difficult to detect but in some cases
treatment of peri-arrest arrhythmias if appropriate. If no
may be revealed later by laboratory investigations
pulse is present, continue CPR. The use of waveform
(Chapter 12). Where available, the appropriate antidotes
capnography may enable ROSC to be detected without
should be used but most often the required treatment is
pausing chest compressions. A significant increase in
supportive. The commonest cause of thromboembolic or
ETCO2 during CPR may be seen when ROSC occurs.
mechanical circulatory obstruction is massive pulmonary
embolism. If pulmonary embolism is thought to be the
cause cardiac arrest consider giving a thrombolytic drug Discontinuing resuscitation and
immediately. Following fibrinolysis during CPR for acute
pulmonary embolism, survival and good neurological
diagnosing death
outcome have been reported in cases requiring in excess If attempts at obtaining ROSC are unsuccessful the
of 60 min of CPR. If a fibrinolytic drug is given in these cardiac arrest team leader should discuss stopping CPR
circumstances, consider performing CPR for at least with the resuscitation team. The decision to stop CPR
60 - 90 min before termination of resuscitation attempts. requires clinical judgement and a careful assessment of
the likelihood of achieving ROSC.
Use of ultrasound during advanced life
After stopping CPR, observe the patient for a minimum of
support 5 min before confirming death. The absence of
In skilled hands, ultrasound can be useful for the detection mechanical cardiac function is normally confirmed using a
of potentially reversible causes of cardiac arrest (e.g. combination of the following:
cardiac tamponade, pulmonary embolism, ischaemia
(regional wall motion abnormality), aortic dissection, - absence of a central pulse on palpation;
hypovolaemia, pneumothorax). The integration of
- absence of heart sounds on auscultation.
ultrasound into advanced life support requires
considerable training if interruptions to chest One or more of the following can supplement these criteria:
compressions are to be minimised. A sub-xiphoid probe
position is recommended (Figure 6.6). Placement of the - asystole on a continuous ECG display;
probe just before chest compressions are paused for a
planned rhythm assessment enables a well-trained - absence of pulsatile flow using direct intra-arterial
operator to obtain views within 10 s. The Focused pressure monitoring;
Echocardiography Extended Life Support Course (FEEL-
UK) provides a valuable introduction to echocardiography - absence of contractile activity using
in this setting. echocardiography.
Further reading
Academy of Medical Royal Colleges. A code of practice for the diagnosis
and confirmation of death. 2008. http://www.aomrc.org.uk
Deakin CD, Morrison LJ, Morley PT, et al. 2010 International Consensus on
Cardiopulmonary Resuscitation and Emergency Cardiovascular Care
Science with Treatment Recommendations. Part 8: Advanced Life Support.
Resuscitation 2010;81:e93-e169.
Deakin CD, Nolan JP, Sunde K, Koster RW. European Resuscitation Council
Guidelines for Resuscitation 2010. Section 3. Electrical Therapies:
Automated External Defibrillators, Defibrillation, Cardioversion and Pacing.
Resuscitation 2010;81:1293-1304.
Yeung J, Meeks R, Edelson D, Gao F, Soar J, Perkins GD. The use of CPR
feedback/prompt devices during training and CPR performance: A
systematic review. Resuscitation 2009;80:743-51.