New life support quiz

In out of hospital adult cardiac arrest with a shockable rhythm the third shock will be delivered at 4 minutes after CPR has commenced.

Early intubation is most likely harmful as some interruption of CPR is usually required. It is best deferred until the patient fails to respond to initial CPR and defibrillation attempts or demonstrates ROSC. Chest compressions should only be ceased at the time the intubator is about to insert the laryngoscope into the patient’s mouth and intubation should be achieved within 10 seconds. The initial dose of adrenaline is 1mg, repeated every 2 minutes.

The effectiveness of defibrillation in terminating VF decreases by about 15% for each minute of delay.

The estimated circulation time of drugs given in cardiac arrest is about 90 seconds with CPR in progress.

The most appropriate sedation agent for a patient with VF who is still aware during CPR is nothing. Whilst this may seem harsh, the delay to administration of any agent (allowing for circulation time) will decrease the probability of survival too much to justify.

The appropriate rate of chest compressions in BLS in adults is 100-120/min with most people preferring around 120/min.

Precordial thump is only indicated in monitored VF as if applied to pulseless VT it could precipitate VF (although pVT is only 2% of shockable rhythms). It delivers about 10-20J of energy and appears to be more effective in victims of high voltage electrocution, making it useful in mass arrests due to lightning strike.

Effective cardiac compression to maintain coronary perfusion is the most important of the choices given. Oxygenation is important, however coronary perfusion of poorly oxygenated blood is still better than no coronary perfusion of highly oxygenated blood. Ventilation is usually only required to maintain oxygenation, whilst restoration of normal acid base status is probably of no benefit and possibly harmful. Hypothermia may have a role to play following ROSC from ventricular fibrillation, but is never an initial priority.

The actual correct sequence is Danger Response Send for help Compressions Airway Breathing. The ‘S’ was added in 2011 but unfortunately the ‘ABC’ sequence was not changed in the acronym did not change from DRSABC as this was thought to be potentially confusing for people already familiar with the ‘ABC’ sequence.

The effectiveness of a single 200J biphasic defibrillation in an adult with VF when delivered within 30 seconds of VF onset is approximately 95%.

Depth of compression should be 5 – 6cm (>1/3 of the thoracic diameter). Ventilation compression ratio should be 2:30. The compression rate should be 100-120/min.

In adult cardiac arrest due to VF unresponsive to standard BLS/ALS treatment, vector change defibrillation is most likely to be of benefit - although limited. The other treatments are all associated with even worse outcomes than expected.

In shockable rhythms that have failed defibrillation attempts and adrenaline, lignocaine and amiodarone are considered of equal (but low) effectiveness.