Titrating Medications

 

We've already discussed some of the math that is used to calculate dosage when titrating - usually mg/min or mg/kg/min.  This page is a brief introduction to the process of titrating medication.  As an introduction, the information on this page is intended to describe some of the basic concepts used during  titration. It is not any where near complete enough to serve as the basis to safely be able to titrate medications. It is only intended to help the new nurse or nurse interested in Critical Care identify some of the important aspects of the process that one needs to learn to be able to safely titrate medications.

Introduction

A good place to begin, is to identify the some of the characteristics of the process we use whenever we give a patient a medication. We should know the purpose of the medication, safe dosage,  route and have some understanding of how it works. With respect to the patient, we should know why they are getting the medication and after giving the medication, there should be an assessment of its effectiveness and that no untoward effects have occurred.

How about a mundane example?  Our patient is complaining of a headache & their orders include Tylenol 650mg P.O. Q4H-Q6H PRN. We know Tylenol is an analgesic and antipyretic, that its usual dose is 325-650mg Q4H with a maximum of 4g/day and its usual route is oral. Its mechanism of action for analgesia is unknown, but thought to be related to inhibition of prostaglandin synthesis within the CNS. We know the patient is getting the medication because they are having pain. We give them the Tylenol tablets & a half hour later check with them to see if their pain is relieved. We would also be looking for any reaction to the medication. A single dose of Tylenol is usually pretty benign, but reactions of rash and urticaria are known to occur.

When we titrate, many of these same characteristics are present but with some very notable differences. First, the medications are never benign. Most have significant, dramatic and immediate effects, often on more than one body system. Often the effects on different body systems will vary with dose.  The point is we have to know a whole lot more about these drugs, their dosage, and how they work than we do with Tylenol.

A second difference related to the significant & immediate effect of these drugs: with Tylenol we checked back in a half hour; with the drugs we titrate, we are assessing all body systems on an ongoing basis, particularly when initiating the medication. Also, a dose of Tylenol is generally benign. Not so with these drugs where even a "safe" dose has the potential to introduce a fatal response and dosage errors can quickly produce catastrophic results.

A third difference is how we handle the patient's response to the medication. With Tylenol, if their headache isn't improved, we can see about giving an extra tablet or perhaps an NSAID in addition to it. When titrating, we are responsible for ongoing adjustment of the dose of the medication to maintain the state of a particular body system and at the same time make sure we have not introduced a deleterious state in other body systems.

A fourth difference is related to drug interaction. It is not uncommon with a critical patient to have to juggle multiple medications that may have overlapping effects or even opposing effects on a particular body system. Remember most of these drugs affect more than one system, so adjusting one medication's dose (who's main purpose is X) may affect another medication's dose (who's main purpose is Y). 

The idea I'm trying to emphasize is that while the process of titration incorporates many of the same characteristics of the process we use when we administer any medication, what we need to know, be aware of, do and are responsible for when titrating is much more extensive.  One might say it takes your nursing process skills and knowledge of medication to a "critical level" J.

Titration Example - getting ready

This example uses one of the "less complicated" medications we titrate. Please be aware that the values used in this example are not absolute - depending on the patients status, the circumstances, the physician, and the policies of the facility there may well be other values for dosage and limits.

Nitroglycerine is often used following an AMI to reduce chest pain. The pain is reduced R/T to decreased coronary oxygen demand. Three mechanisms contribute to this: decreased preload (the heart pumps less hard - Starling's Law),  dilatation of coronary collateral blood vessels (increased blood flow to heart muscle) and reduced afterload (less work for the heart) that occurs because peripheral blood vessels are also dilated. Our "reason" for giving the medication is to decrease chest pain but common collateral effects include increased cardiac perfusion and reduced systemic blood pressure.

Our order reads:  NTG IV start at 10ug/min, titrate for chest pain, maximum 80ug/min, keep SBP > 90. Titration orders should always include the purpose of titrating & maximum dose.  A starting dose should be specified, but may not - often, physicians expect you to know minimum therapeutic doses.  Since a therapeutic dose can vary because of a number of factors, if there is any question about it, get an order.  Also, be aware that some facilities have protocols that define dose ranges & parameters.  Depending on the medication, there will often be additional parameters such as blood pressure, heart rate, respiratory rate or level of consciousness that must be maintained while titrating. Even if these other parameters are not specified, you are still responsible for making sure this patient remains safe!

What else should we be aware of before starting this medication? Co-morbid conditions and any home medications. As an example, HTN & CAD often go hand in hand. Is the patient hypertensive? Do they take medication for it? Did they have today's dose?  This patient was probably in E.R. before coming to the unit. What medication was the patient given there? When and what were the doses? Any or all of these can influence the titration process. And don't forget medication allergies - nitrate allergy?

A key part of titrating any medication is knowing the useful dosage adjustment increments: how much do we increase or decrease the medication by as we attempt to achieve the "ordered state". The "useful increment" may vary depending on the patient's status, co-morbid conditions and other factors. For this example, we are going to use 10ug/min as our "useful increment". This is not to say we would only increase or decrease by this amount!  Keep in mind this is a balancing act.  If the drip is running, say at 40ug/min & the patient is still having pain, we try to increase by 10ug/min.  If this resulted in the patients SBP dropping below 90, we might try backing off by 5ug/min.

Another key aspect of titrating is the frequency that we make dose adjustments. The frequency of upward and downward adjustments is usually not the same. How often we make upward adjustments depends on how quickly the drug acts (its onset) & how long before it peaks.  And the onset of the collateral effects can vary. With NTG, pain relief is usually pretty quick, but the drop in SBP (if one) can be a little slower.  Our downward adjustments are largely related to the drugs half-life & duration. And again, the collateral effects can vary.  NTG acts almost immediately and peaks in 3-5 minutes. It has a short duration, also 3-5 minutes.  These characteristics make it one of the "less complicated" medications. For our example, we'll use 10 minutes as our "increase" interval. When the time comes, we'll be a lot more conservative as we titrate the patient off the medication & use 30-60 minute intervals. Just as with the dose, there is nothing about these intervals "cast in stone".  In the case of severe pain, we can increase our dose more quickly (assuming we are maintaining adequate BP). In the case of significant drop in BP, we can decrease our dose more quickly - but would not stop the drip! Rapid withdrawal of nitrates can induce coronary vasospasm - something this patient can definitely do without.

Titration Tables

When titrating medication there is a frequent need to change dose. Rather than have to calculate the IV rate for a dose at each change, we calculate a range of rate vs. dose compiled into a table. This should be done when a medication is initiated and after a change in the patients weight (if the medication dose relies on weight). The minimum information in our table should be from dose_min- dose_max in the increments we are using to adjust the dose.  In practice, we will most likely calculate the table using using either the monitor system or a computer and the table will have more values than this. Using the math from Example 2 of Mg/Min, we build the following table expressing IV rates in 10ug/min increments for the range we will be titrating (pharmacy has supplied NTG in 50mg/250cc concentration):

 

Titrating the medication

The patient has arrived from ER, is on the monitor, O₂ at 3l per NC & we have baseline VS (110, 20, 174/92). The patient describes their pain as "crushing" and 9/10. We set the monitor to automatically record VS q5m and start our drip at 3cc/hr. Our second set of VS are at baseline & the pain is unchanged, so even though it is only 5 minutes, we increase our drip to 20ug/min.  Generally, we would not increase our drip rate in a period shorter than 5 minutes because it takes 5 minutes for the drug to peak and thus, that long before we know the complete effect of our previous change.  A few minutes pass, the pt. states the pain is less, 5/10. The next set of VS are improved 96, 20, 168/84. Should we wait out our "frequency interval" or increase the rate now?  This patient's pain is still significant & their VS are still elevated, so increasing the drip to 30ug is appropriate.  The patient now reports the pain is better, 2-3/10. Our next set of VS show further improvement, 82, 16, 140/62 & the pt. reports pain as 2/10.  At this point, waiting out the 10 minute interval is appropriate.  At that time, the pt. still reports pain as 2/10 and VS are 78, 16, 132/58. We increase our drip rate to 40ug. After a couple minutes, the pt. reports the pain is "gone". Our next set of VS 74, 16, 130/60.  At the moment, we have achieved our titration goal - the patient is pain free & has adequate BP.

We are not, however, done.  Remember this patient has been under tremendous stress & had intense pain. What are the physiologic responses to this? You can bet this patient's adrenal glands were working overtime - what happens when this "wears off"?  And now that the pain is relieved and the patient is likely to see themselves as being "ok" (or at least "not dying"), we can expect these stressor responses to begin to resolve. We will need to keep a close eye on this patient's BP as its quite possible that as the adrenaline (and friends) metabolizes, we will see further decreases in BP. Perhaps enough that we will need to decrease our NTG drip rate.  There is a secondary mechanism here too. As the patient begins to relax, the amount of work their heart needs to do is decreasing. The decreasing cardiac demand may result in needing less NTG to keep the patient pain free.  Generally, with NTG if we have a pain free patient and a good BP will will leave the drip at the rate that's "working", but if the BP is low, we will probably be able to reduce the drip rate and still maintain a pain free state.

Conclusion

I hope this has given you a "taste" of what titration is about and a better understanding of what is involved in learning this process.  There is a whole lot more to it than I've been able to express in this short essay.  If you've found this of interest, there is a large body of excellent reference material available on this and related topics. 

Critical care nursing can be challenging, interesting and exciting on the one hand and stressful and heartbreaking on the other.  If you're interested in finding out more about Critical Care Nursing, visit the American Association of Critical Care Nurses.

 

 

©1997-2006 Dale Sampson, RN