Advanced Life Support Medications: Adrenaline, Amiodarone, Atropine, Bicarbonate, Lidocaine, Magnesium, Calcium

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Adrenaline Advanced Life Support Medications

The vasoconstrictor adrenaline is known to enhance both myocardial and cerebral perfusion, although there is no evidence that it increases the survival to hospital discharge in cardiac arrest. It has a very short half-life and so repeated intravenous (IV) doses (1mg for adults) are given every 3–5min during CPR. In children, the corresponding IV/intraosseous (IO) dose is 10mcg/kg. Adrenaline should be given as soon as circulatory access is obtained in non-shockable rhythms and after the third shock (once chest compressions have been resumed) in shockable rhythms. Adrenaline may be contraindicated in arrests secondary to solvents, cocaine or other sympathomimetic drugs.

Amiodarone Advanced Life Support Medications

Amiodarone is given for refractory VF/pulseless VT after the third shock (once compressions have been resumed). It stabilises cell membranes and thus increases the duration of the action potential and refractory period in both atrial and ventricular myocardial cells. As an antiarrhythmic agent, it prolongs the Q–T interval and slows conduction through both the atrioventricular (AV) node and any accessory pathways. Amiodarone has less negative inotropic effects and fewer proarrhythmic actions than most similar drugs. An initial IV bolus of 300mg should be given in adults; the equivalent IV/IO dose for children is 5mg/kg. A further dose of 150mg may be given for persistent or recurrent VF/VT, followed by an infusion of 900mg over 24h.

Atropine Advanced Life Support Medications

Atropine is no longer recommended in cardiac arrest. Pulseless patients with extreme bradycardia or isolated P waves may benefit from pacing.

Bicarbonate Advanced Life Support Medications

Bicarbonate therapy is contraindicated in early resuscitation. Acidosis develops but aids oxyhaemoglobin dissociation; temporary buffering of pH is achieved by hyperventilation. Sodium bicarbonate is reserved for cardiac arrests that are associated with the following:

1 Hyperkalaemia

2 Poisoning with tricyclic antidepressants.

The initial dose is 50–100mmol (or 1–2mmol/kg). Prolonged arrest (i.e. over 20–25min) causes profound intracellular acidosis and so may also be treated with alkalising agents, especially in children.

Lidocaine Advanced Life Support Medications

Lidocaine reduces ventricular automaticity and ectopic activity and increases the threshold for the development of VF. However, it also causes an in -crease in:

• the energy required for defibrillation

• the incidence of post-shock asystole.

In addition, it is a negative inotrope. For these reasons, it is not routinely used for refractory VF/VT unless amiodarone is unavailable. The initial IV/IO dose for both adults and children is 1.0–1.5mg/kg to a maximum total dose of 3mg/kg in the first hour. Lidocaine and amiodarone should not be used together.

Magnesium Advanced Life Support Medications

Magnesium is an important intracellular cation and co-factor. It should be given for refractory VT that could be associated with low serum magnesium levels, e.g. in a patient known to be taking potassium-losing diuretics. Similar indications include arrests after episodes of torsade de pointes or in patients with digoxin toxicity. The usual dose of magnesium sulphate is 8mmol (2g or 4mL of a 50% solution). For children, the dose is 25–50mg/kg by IV infusion over several minutes. These doses may be repeated after 10–15min.

Calcium Advanced Life Support Medications

Calcium influx occurs at the time of cell death and thus it is illogical to give calcium to patients in cardiac arrest. Exceptions occur during resuscitation from PEA or asystole when there is thought to be one of the following conditions:

1 Hyperkalaemia

2 Hypocalcaemia

3 Poisoning with calcium antagonists

4 Overdosage with magnesium (e.g. during treatment of eclampsia).

The initial IV dose in these situations is 10mL of 10% calcium chloride (6.8mmol calcium ions), repeated as necessary. For children the dose of 10% calcium chloride solution is 0.2mL/kg. Calcium may form a precipitate if given in the same IV line as bicarbonate and is dangerous in the digitalised patient. Calcium channel blocking drugs have not fulfilled their early promise and do not improve outcome after cardiac arrest.

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