Explain why sodium bicarbonate IV is used in cases of cardiac arrest or circulatory shock?

Answer:
First of all, the pacemaker of the heart is the SA (sinoatrial), not the AV (atrioventricular). Secondly, sodium bicarbonate has nothing to do with the conduction or depolarization of either the SA or AV node, unless we're talking about sodium levels so high or so low that they cause conduction abnormalities.To answer your question, there are two main reasons.One: when a person is coding, or in shock, you always want to push fluids, to help increase blood pressure. You want to use a physiologic solution, so you don't use water, you use something that is the same pH and the same osmolarity. So why not just use a 0.9% sodium chloride solution? That brings us to:Two: when a person is not getting enough blood to their tissues, as is the case in a code, they cannot make energy via aerobic respiration. Instead, they switch to a more inefficient process that is anaerobic, and has lactic acid as an end product. Bicarbonate is a great buffer, and is used to help decrease the acidity in the blood that builds up when a person is coding.

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It stimulates the pumping action of the heart - starting with the 'pacemaker' of the heart - the AV node, in other words.

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