Time effectiveness of NaHCo3 in TCA od?

[NecosMom]

Ok, for all you ems junkies out there I have a question that my medical control doc has put to me to investigate.......I am trying to find out how long it takes bicarb to reverse the widened QRS on ekgs for TCA overdose pts. Been searching the web lie an idiot & can tfind a dang thing. Anyone out there know how long it taked for bicarb to start reversing wide QRSs in TCA OD?????? HELP!!!

[hypocaffeinemia, BSN, RN]

For starters, the physiology behind the wide QRS is that the TCA blocks the fast Na conduction channel in cardiac tissue, which slows depolarization.

According to emedicine, NaHCO3 increases protein binding and by alkalizing the blood to pH 7.45-7.55 it helps to remove TCA from the sodium channels (as well as increasing Na levels).

Here's an article on it: http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1483312&blobtype=pdf

As for how long, NaHCO3 starts to work as soon as you push it and frequent (q5-15min) ABGs are needed to evaluate as you titrate to get the pH up to ~7.5ish.

[ERNurse752, RN]

In my experience, you can watch it work while you're pushing it. But you might have to give repeat pushes, then a drip.

We closely monitor serum potassium since giving bicarb will cause it to drop. We add K to the bicarb drip routinely, and give K riders as needed.

[Noryn]

That is a pretty vague question and scenario. Kind of like saying how long will it take bicarb to correct acidosis--It depends on how progressive the symptoms are. For instance if you have a ph of 7.3, that will be easier and faster to correct than one of 6.8. So it would depend on the pt's ph and degree of conduction delay.

The concept you are talking about is systemic alkalinization. But once you get the ph close to 7.45-7.5 the symptoms should begin to resolve.