CALCIUM Chloride

 

1) Therapeutic drug action & mechanism(pharmacology)

•     Calcium chloride acts as a source of Ca2+ ions

•     Calcium plays an important part in the functional integrity of the nervous & muscular systems

•     Calcium influences inotropic state of heart [via its availability in sarcoplasm reticulum]

•     Calcium is also necessary for normal electrical conduction & rhythm of the heart

•     Inotrope if hypocalcaemic

•     Vasopressor if normocalcaemic

 

2) Indications

•     In cardiac resuscitation, particularly after open heart surgery, is used when adrenaline has failed to improve cardiac contractility

•     Antagonist to magnesium toxicity

•     Antagonist to potassium toxicity

•     Hypocalcaemic tetany

•     Hypocalcaemia (from CPB, albumin, citrate)

•     Hypotension eg 2° protamine

•     Myocardial depression eg 2° residual cardioplegia, hyperkalaemia, or hypocalcaemia

•     Calcium channel blocker overdose

 

3) Effects on organs—side effects

•     Too fast an infusion may be associated with coronary artery spasm, arrhythmias

 

4) Toxic effects/ precautions with administration

•     Must be administered IV[slowly] or intracardiac [within ventricle]

•     May be associated with exacerbating reperfusion injury: avoid  given immediately subsequent to removal of X-clamp: hypocalcaemia during CPB may reduce unnecessary ATP breakdown & myocardial oxygen consumption [role of low calcium cardioplegia]

•     Calcium should be administered when CPB is about to be terminated thereby increasing contractility & BP

 

5) Contraindications

•     Ventricular fibrillation

•     Hypercalcaemia

•     Digitalis toxicity

 

7) Loading dose, maintenance dose, frequency & method of administration

•     Ampoule: Calcium chloride 10% in 10 mls = CaCl2 [100mg/ml] =

      Calcium [27.2 mg/ml] = Ca2+ 6.8 mmol [10ml]

•     Ampoule: Calcium gluconate 10% in 10 ml = 2.25 mmol Ca2+

 

•     Normal total Ca2+ :2.25-2.65 mmol/l

•     Of this: 40% is bound to albumin, 10% ion bound, 50% ionised

•     Therefore Hypoalbuminaemia: total calcium low, ionised normal

•     Alkalosis: total Ca2+ normal with increased protein binding & ionised Ca2+ low

•     2—10 mg/kg IV bolus effect lasts 10 - 20 minutes

 

[ionised Ca2+]

Hypercalcaemia

Hypocalcaemia

ECG

 

Refractory VF

Impaired cardiac contractility

clinical signs

Muscle irritability/weakness

Muscle cramps/ spasms

Neuromuscular irritability

tetany