Antiarrhythmic and haemodynamic effects of the commonly used intravenous electrolytes.

OBJECTIVE To review the physiology and cardiovascular effects of the commonly used intravenous electrolytes. DATA SOURCES Abstracts, articles and published reviews of studies reported from 1966 to 2000 and identified through a MEDLINE search on cardiac arrhythmias and electrolytes. SUMMARY OF REVIEW While isotonic saline solutions are used to improve the haemodynamic status in critically ill patients who are hypotensive and hypovolaemic, other intravenous solutions including potassium chloride, calcium chloride, magnesium sulphate and sodium or potassium phosphate as well as hypertonic saline and sodium bicabonate have unique and often therapeutically useful haemodynamic and antiarrhythmic effects. Potassium chloride solutions are used to treat hypokalaemia with a maximum speed of correction in an adult of 20 mmol per 30 minutes when an acute myocardial infarct is present. A greater infusion rate may be necessary when ventricular or supraventricular tachyarrhythmias are present although close ECG monitoring will be required. Magnesium sulphate (2-20 mmol) has been used for hypomagnesaemic and normomagnesaemic cardiac arrhythmias (particularly when digoxin induced) and calcium chloride (3.4-6.8 mmol) is used to treat hyperkalaemic and hypermagnesaemic cardiac arrhythmias. Both hypertonic sodium bicarbonate and sodium chloride solutions have antiarrhythmic effects that may be beneficial in conditions that include tricyclic poisoning, hyperkalaemia and bupivicaine toxicity, although sodium bicarbonate is generally used for tricyclic cardiotoxicity. Low cardiac output states and arrhythmias have also been reported in hypophosphataemic patients that are reversed by infusions of potassium or sodium phosphate. CONCLUSIONS Intravenous potassium chloride, calcium chloride, magnesium sulphate, sodium and potassium phosphate, sodium bicarbonate and hypertonic saline can be used effectively to alter the haemodynamic status and manage cardiac arrhythmias. However, their indications are selective and complications may occur, so careful administration and monitoring are required with their use.