Module 8: Assessing and treating tachycardia Flashcards
Tachycardia
HR >100. Very common.
May be physiological –response to fever, exercise, anxiety.
May be an dangerous tachyarrhythmia which predisposes to arrest / deterioration.
The tachycardia algorithm enables the non-specialist ALS provider to treat a patient effectively and safely in an emergency.
The tachycardia algorithm – Step 1.
- ABCDE assessment
- Give oxygen if <94
- IV access
- Monitor ECG, BP, sats, 12-lead ECG
- Correct reversible causes
The tachycardia algorithm – Step 2.
- A–E
- Assess for LIFE THREATENING FEATURES.
1) Shock
2) Syncope
3) Myocardial ischaemia
4) Severe heart failure
These indicate pt is unstable and at risk of deterioration
Step 3. if life-threatening features.
Synchronised DC shock up to 3x
-> Sedation/anaesthesia if conscious
If unsuccessful:
- Amiodarone 300 mg
- Repeat sync DC shock
Step 3. if no life-threatening features and patient stable.
Is QRS narrow <0.12s, or broad >0.12s?
Is patient’s rhythm regular or irregular?
Step 4. Broad QRS, rhythm regular
VT until proven otherwise
- Amiodarone 300 mg IV over 10–60 min
Previous definitive dignosis of SVT with BBB:
- Treat as regular narrow complex tachy
Step 4. Broad QRS, rhythm irregular
Possibilities:
- AF with BBB -> treat as for irregular narrow complex
- Polymorphic VT e.g. Torsades de pointes -> magnesium 2 g over 10 min
Step 4. Narrow QRS, rhythm regular
- Vagal maneuvres
- Adenosine 6 mg IV rapid bolus with continuous ECG monitoring
Step 4. Narrow QRS, rhythm irregular
Probable AF
- Rate control: beta-blocker
- Consider digoxin or amiodarone if evidence of HF
- Anticoagulate if duration >48h
Depending on the clinical status of the patient (i.e. the presence or absence of life-threatening features) and the nature of the arrhythmia, immediate treatments can be categorised under four headings:
- No treatment
- Pharmacological intervention
- Simple clinical intervention (i.e. vagal manoeuvres)
- Electrical (cardioversion for tachyarrhythmia)
-> electrical treatments act faster than most drugs so are the preferred tx for unstable pts
After the successful treatment of an arrhythmia
- Continue monitoring the patient
- Repeat ABCDE
- 12-lead ECG always
- Correct reversible causes
- Seek expert help & advise
Vagal maneuvres
1st line in a regular narrow-complex tachyarrhythmia
- Carotid sinus massage or the Valsalva manoeuvre
(will terminate up to 25%). - Record an ECG during each
If the rhythm is atrial flutter with 2:1 conduction, slowing of the ventricular response will often occur and reveal flutter waves; if so -> seek expert help.
If life-threatening features, can use vagal manoeuvres whilst preparing synchronised cardioversion.
Adenosine
Second line in a regular narrow-complex tachyarrhythmia
Adenosine 6 mg IV as a very rapid bolus
- Large cannula and large (e.g. antecubital) vein
- R/o contraindications e.g. asthma
- Warn pt they will feel unwell and experience chest discomfort for a few seconds
- Continuous ECG
If ventricular rate slows transiently but then speeds up again: look for atrial activity e.g. atrial flutter (or other atrial tachycardia) and treat accordingly.
No response: 12 mg bolus
- No response: 18 mg bolus
- Ensure giving fast enough and into large enough vein
- No response: seek expert help
AF rate control
- Beta-blocker e.g. IV metoprolol
- Diltiazem if beta-blockade contraindicated e.g. asthma
- Digoxin if HF
- Amiodarone can assist with rate control (but mainly rhythm control)
1/2/3 should all be given orally in the first instance (only IV if vomiting, critically sick, etc)
AF rhythm control
If <48h
- Chemical cardioversion
1. Flecainide
2. Amiodarone
- Electrical cardioversion
Cardioversion and anticoagulation in AF
Longer duration AF = greater risk of atrial thrombus
In general:
- AF >48h: do not cardiovert (electrical or chemical) until fully anticoagulated for ≥3 weeks OR TOE ruled out atrial thrombus.
If urgent cardioversion needed: anticoagulate before appropriately, and after orally
What is a “SYNCHRONISED” shocK?
The defibrillator delivers a shock synchronised to coincide with the R wave
An unsynchronised shock could coincide with a T wave and cause ventricular fibrillation (VF).
Energy to convert a broad-complex tachy?
120-150 J
Energy to convert AF?
max defib output
Energy to convert atrial flutter and regular narrow-complex tachys?
70–120 J
Where to apply self-adhesive pads?
For atrial fib & flutter: anteroposterior positions
How to deliver a shock?
- Switch machine to “Pacer”
- Confirm correct energy
- Double-check SYNCHRONISED (dotted mark above each QRS complex)
- No one touching pt + O2 removed
- Press shock button + hold until shock delivered
Pain relief in shocking?
- under GA or conscious sedation
What to do if shock fails?
- Deliver up to THREE shocks of increasing energy.
- Give amiodarone 300mg IV over 10-20 min.
- Attempt further synchronised cardioversion.
Loading dose amiodarone can be followed by an infusion of 900mg over 24h, given into a large vein (preferably via a central venous cannula).
Which drug may be used for the treatment of sinus tachycardia?
None
Sinus tachycardia is not an arrhythmia. It is a common physiological response to stimuli such as exercise or anxiety. Do not attempt to treat sinus tachycardia with cardioversion or anti-arrhythmic drugs as treatment is directed at the underlying cause.
