*Cardiac Arrest Flashcards
Define cardiac arrest.
Sudden cardiac arrest is a sudden state of circulatory failure due to a loss of cardiac systolic function.
What are the 4 specific cardiac rhythm disturbances that can cause cardiac arrest?
- Ventricular fibrillation,
- Pulseless ventricular tachycardia (VT) - e.g. TDP
- Pulseless electrical activity (PEA)
- Asystole.
What are the reversible causes of cardiac arrest?
4Hs = hypoxia, hypothermia, hypovolaemia, hyperkalaemia(hypokalaemia, hypoglycaemia, hypocalcaemia/acidaemia)
4Ts = tension pneumothorax, tamponade, thrombosis(ACS/VTE), toxins
What is shown here?
*Torsades de pointes = a sub-group of polymorphic VT in patients with an underlying prolonged QT interval, sometimes related to hypomagnesaemia.
What are the two most common shockable rhythms?
- Pulseless VT
- VF
What is the survival rate for out of hospital cardiac arrest?
VF = <20%
cardiac arrest = <10%
In hospital this is 36% and 11% resepctively. This is 30 day survival rates.
What are the risk factors for cardiac arrest?
- coronary artery disease (CAD)
- left ventricular dysfunction
- hypertrophic cardiomyopathy (HCM)
- arrhythmogenic right ventricular dysplasia (ARVD)
- long QT syndrome (LQTS)
- medications that prolong the QT interval or cause electrolyte disturbances - quinidine, procainamide, sotalol, amiodarone, disopyramide, dofetilide, phenothiazines, and TCAs
- acute medical or surgical emergency
- illicit substances e.g. opioids
weak:
- Brugada syndrome
- valvular heart disease
- smoking
- history of eating disorders
What are the most common causes of cardiac arrest?
Ischaemic heart disease (62%)
Cardiomyopathy/dysrhythmias (9%)
Other cardiovascular disease (12%)
VF and VT may also be caused by:
- R-on-T phenomenon
- prolonged QT interval secondary to medicines
- electrolyte abnormalities
- familial syndromes of conduction abnormality
- drug intoxication (e.g. cocaine)
- cardiomyopathies
What are the most common causes of PEA?
- MI
- hypovolaemia
- hypoxia
- PE
What are the clinical signs of cardiac arrest?
Do ABCDE assessment
- Unresponsive
- No normal breathing
- No signs of circulation
Assessment before or after successful resuscitation:
- Symptoms
- PMH
- FH
What investigations should be done during/after cardiac arrest?
- During - continuous cardiac monitoring
- FBC - look for haemorrhage
- Serum electrolytes - look for abnormality
- ABG - acid-base status
- Cardiac biomarkers - troponins
- Echo - assess contractility, volume status, tamponade, LV function.
Other:
- ECG - prolonged QT interval, ST-segment or T-wave changes (indicating ischaemia), conduction abnormalities, V hypertrophy, cardiomyopathy, ARVD.
- coronary angiography +/- PCI
- CXR - pneumothorax, pulmonary oedema, endotracheal tube placement.
- toxicology screen - VT drugs
- Cardiac MRI - assess for ARVD/cardiomyopathies.
What approaches are used by bystanders for cardiac arrest?
BLS - DRS ABC
- 30 chest compressions 2 rescue breaths at 100/min with depth 5-6cm
- Dial 999 and ask someone to get an AED
NB:
- timely chest compressions are required
- mouth to mouth improves survival -
- rhythms may change from VF/VT to PEA/asystole
What protocol is used for cardiac arrest in hospital?
- Recognise and call 2222
- Start CPR and continue until defibrillator is retrieved
Shockable rhythms:
- Give 1 shock ASAP - remove oxygen to prevent fire during defibrillation. NB: Witnessed monitored cardiac arrest due to VF/pVT: 3 stacked shocks
- Each shock followed by 5 cycles (=2mins) of chest compressions
- Airway adjuncts inserted ASAP (tracheal tube or SGA) with 100% oxygen - NB: CPR given at 10/min without pausing CPR (unless leakage occurs with SGA → 30:2)
- Vasopressor: Give adrenaline after 3rd shock then repeat every 3-5mins
- Antiarrhythmic: Give amiodarone 300mg IV/IO after 3rd shock then again 150mg after the 5th shock
- Then restart algorithm at adrenaline again if rhythm still shockable
Non-shockable rhythms:
- Vasopressor: Give adrenaline 1mg IV/IO ASAP then every 3-5mins
- Airway adjuncts for oxygen delivery
- Chest compressions 2 mins/5cycles
Describe post resuscitation care in cardiac arrest.
- Monioring - ECG
- Organ support
- Correct electrolytes and acidosis
- Transfer to ICU
- Anoxic brain injury is a frequent complication - keep patient warm to reduce this
When should you terminate resuscitation?
Ethically challenging - no single factor determines this but rather clinical judgement and respect for human dignity.
In prehospital setting, resuscitation may be terminated if:
- The patient had no return of spontaneous circulation (ROSC) before transport
- No shock was administered
- Emergency medical services did not witness the arrest.
- Delayed initiation of CPR in unwitnessed arrest
- Unsuccessful after 20min of ACLS
- Conditions of pt compromise safety of care providers
- Pt has “do not resuscitate” order
How common is cardiac arrest in terms of hospital admissions?
1.6 per 1000
What are the most common presenting rhythms in cardiac arrest?
Shockable (pulseless VT/VF) - 16.9%
Non-shockable (PEA/asystole) - 72.3%
What are 3 signs of hyperkalaemia on this ECG?
- flattened or absent P waves
- tall (tented) T waves
- widened QRS
- VT
What are the ECG changes in different electrolyte disturbances?
hypocalcaemia - QT prolongation
hypercalacemia - ST shortening
hypokalaemia - long QU interval, prominent U
hyperkalaemia - peaked T waves
hypomagnasaemia - tall T, depressed ST segment
hypermagnasaemia - prolonged PR, widened QRS
