incompatible iv medication

nurseprnRN, BSN, RN · Aug 10, 2011

"i reread this.... you don't want any chance..:) a y-site is not a way to deal with incompatible meds. if you only have one line, check your p & p for how to deal with it. the precipitate may never dissolve if the patient has an mi or stroke because of it....."

no, no, no. if you do believe this is possible, i regret that you are not alone, but now you can help others avoid this common error. once again, i implore anyone who believes that this (or a dvt or a bit of air in iv tubing, for that matter) would cause a stroke or mi to follow along with me as we trace the blood circulation pathways. this is why you took anatomy.

peripheral veins-> vena cava -> right atrium -> right ventricle -> pulmonary artery -> pulmonary capillary bed ->[color=pink] lungs -> pulmonary veins -> left atrium -> left ventricle -> aorta -> systemic arteries

now, just how does a floating object (crystal, clot, air bubble) go from the veins to the arteries? does it say, "beam me up, scottie," and bypass nature's natural strainer, the pulmonary capillary bed, and then have a clear shot at coronary arteries or cerebral flow? no, it does not. this is, in fact, one reason we have a pulmonary capillary bed-- we are always shooting little venous clots from minor trauma or whatever, and this is where they go to get caught and dissolve harmlessly. big clots, or big air bubbles, different story. but small ones, happens all the time.

exception, rare: an intracardiac defect in the atrial or ventricular septum could offer a direct pathway between the right and left circulations. however, since the blood pressure in the left side is much higher than in the right (think: 120/80 vs 20/10), one would see what's called a left-to-right shunt, when the blood passes from the area of higher pressure to the area of lower pressure, so even then, it would be very unlikely. right-sided pressure would have to exceed left-sided pressure to make an oject travel from the right side to the left side. this is, however, the commonest cause of strokes in otherwise healthy young people. tedy bruschi, the heart and soul of the new england patriots line and a helluva nice man, did exactly this, probably as a result of a valsalva in the bottom of the pile. valsalva increses venous pressure, popped something thru a previously unsuspected and hemodynamically insignificant asd. clot went to his head, and he suffered a (fortunately very small) cva. he had his atrial septal defect patched in the cath lab and was back at work before the end of the season.

further pearl: although this explains why you needn't worry about small floaties in the normal venous system, you must worry about every little opportunity for the tiniest bubble or clot in someone with a cardiac defect with a right-to-left shunt, like tetralogy of fallot, single ventricle, really big asd/vsd with elevated right pressures (pulmonary hypertension), hypoplastic l heart with palliative r-to-l opening, etc. they are at risk for mi, cva, or other arterial embolic event; this is a common cause of morbidity/mortality in this population.

wooh, BSN, RN · Aug 11, 2011

Great explanation GrnTea. One of those things I already know, but now I really understand. :)

MunoRN, RN · Aug 11, 2011

I agree that the myth that everything you put in a vein goes straight to your brain is prevalent, although that's not necessarily a bad thing. It was once common knowledge that right to left shunts were relatively rare, although that's changing. PFO's, which exist in 25-30% of the population are diagnosed by the presence of right to left shunting during an echo bubble study. A valsalva maneuver is often used to induce this right to left shunting by manipulating the right and left pressure differences, so you could maybe assume that right to left shunting PFO's don't occur at a rate of 25-30% "at rest". Except, there are studies of TEE bubble studies only (where a valsalva is typically not used) that still show a right to left shunt in as much as 25% of the population. So with a 25% prevalence of a right to left shunt at rest in the population it's not necessarily a bad idea to assume every patient has one.

MunoRN, RN · Aug 11, 2011

thanks guys! unfortunately I have seen incompatible meds hung together a couple times, meds that could cause precipitation when combined. Incident reports were done both times, and the patients were ok luckily. I was just curious what happens to the precipitation, just curious if it did dissolve eventually (I know worse can happen). One of the times the med was hung via Y-site and a pharmacist told me b/c the two meds were not in contact for very long this may have not given the medication enough time to form precipitate. Thanks for ur time!

As a general rule, don't infuse precipitates, but to answer your question, yes they can dissolve and some dissolve very quickly and without much chance of adverse effects to the drug or to the patient. IV diazepam is well known for forming a sediment when combined with IVF, which isn't due to a incompatibility like many precipitates, but is due to it's poor solubility in fluids, which is why it is stored in a mixture of mainly propylene glycol. It takes about 10ml of NS to dissolve 1mg of diazepam, so at concentrations less that that you'll get a precipitate. I'm not advocating that anyone do this, but that are studies that show a precipitated solution of diazepam is safe to infuse because it takes a relatively small amount of plasma to re-dissolve the diazepam.

MomRN0913 · Aug 12, 2011

"i reread this.... you don't want any chance..:) a y-site is not a way to deal with incompatible meds. if you only have one line, check your p & p for how to deal with it. the precipitate may never dissolve if the patient has an mi or stroke because of it....."
no, no, no. if you do believe this is possible, i regret that you are not alone, but now you can help others avoid this common error. once again, i implore anyone who believes that this (or a dvt or a bit of air in iv tubing, for that matter) would cause a stroke or mi to follow along with me as we trace the blood circulation pathways. this is why you took anatomy.

peripheral veins-> vena cava -> right atrium -> right ventricle -> pulmonary artery -> pulmonary capillary bed ->[color=pink] lungs -> pulmonary veins -> left atrium -> left ventricle -> aorta -> systemic arteries

now, just how does a floating object (crystal, clot, air bubble) go from the veins to the arteries? does it say, "beam me up, scottie," and bypass nature's natural strainer, the pulmonary capillary bed, and then have a clear shot at coronary arteries or cerebral flow? no, it does not. this is, in fact, one reason we have a pulmonary capillary bed-- we are always shooting little venous clots from minor trauma or whatever, and this is where they go to get caught and dissolve harmlessly. big clots, or big air bubbles, different story. but small ones, happens all the time.

exception, rare: an intracardiac defect in the atrial or ventricular septum could offer a direct pathway between the right and left circulations. however, since the blood pressure in the left side is much higher than in the right (think: 120/80 vs 20/10), one would see what's called a left-to-right shunt, when the blood passes from the area of higher pressure to the area of lower pressure, so even then, it would be very unlikely. right-sided pressure would have to exceed left-sided pressure to make an oject travel from the right side to the left side. this is, however, the commonest cause of strokes in otherwise healthy young people. tedy bruschi, the heart and soul of the new england patriots line and a helluva nice man, did exactly this, probably as a result of a valsalva in the bottom of the pile. valsalva increses venous pressure, popped something thru a previously unsuspected and hemodynamically insignificant asd. clot went to his head, and he suffered a (fortunately very small) cva. he had his atrial septal defect patched in the cath lab and was back at work before the end of the season.

further pearl: although this explains why you needn't worry about small floaties in the normal venous system, you must worry about every little opportunity for the tiniest bubble or clot in someone with a cardiac defect with a right-to-left shunt, like tetralogy of fallot, single ventricle, really big asd/vsd with elevated right pressures (pulmonary hypertension), hypoplastic l heart with palliative r-to-l opening, etc. they are at risk for mi, cva, or other arterial embolic event; this is a common cause of morbidity/mortality in this population.

off subject.... my very close friend has a 6 year old daughter with hlhs. all 3 surgeries done. doing great. actually she is at chop tomorrow doing some testing for research. do they eventually end up on anticoagulant therapy for this risk?

by the way, that was super impressive.

nurseprnRN, BSN, RN · Aug 12, 2011

"pfo's, which exist in 25-30% of the population are diagnosed by the presence of right to left shunting during an echo bubble study. a valsalva maneuver is often used to induce this right to left shunting by manipulating the right and left pressure differences, so you could maybe assume that right to left shunting pfo's don't occur at a rate of 25-30% "at rest". except, there are studies of tee bubble studies only (where a valsalva is typically not used) that still show a right to left shunt in as much as 25% of the population. so with a 25% prevalence of a right to left shunt at rest in the population it's not necessarily a bad idea to assume every patient has one."

true that. however, the volume of bubbles injected for this test is small, is done once, and is done with the cooperation of the patient by having him/her perform a valsalva or cough. unless all your patients go around valsalva-ing all the time, it is vanishingly unlikely that they will have something bad happen to them under the conditions we've been discussing. if not, then we would all see a lot more strokes in young people (like our tedy).

let's all hear it for the pulmonary capillary bed, your friend!