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Letters to the Editor |
Department of Radiology, Duke University Medical Center, Box 3808, Erwin Road, Durham, NC 27710 e-mail: mryan98454@yahoo.com
Editor:
By reading the current literature, including the abstracts from the 87th Scientific Assembly and Annual Meeting of the Radiological Society of North America, one would be led to assume that uterine artery embolization (UAE) for the treatment of symptomatic fibroid disease is, by necessity, a painful procedure (1). Such a perception has dissuaded some vascular and interventional radiologists from offering this service to their patients and has been used by some gynecologists to undermine the technique.
We would like to describe a simplified protocol for pain control that we have been using for approximately 12 months. We are clearly seeing different levels of pain than those we saw before we switched to this protocol. With our protocol, the average pain is now described as mild cramping, with many patients describing no pain at all.
We start the patient-controlled analgesia (PCA) pump prior to the procedure, while the patient is in the preparation area. We use fentanyl citrate at a concentration of 50 µg/mL. It is administered as a continuous infusion during the procedure at a rate of 0.3 µg/kg/hr on the basis of actual total body weight (TBW).
We use adjusted body weight (ABW) for calculating the dose for morbidly obese patients, calculated as follows: (0.4 [TBW - IBW] + IBW), where IBW is ideal body weight (in kilograms), calculated as 2.3(inches < 60) + 45.5. We also increase the dose of continuous infusion by 20% if the patient has opioid tolerance, alcohol abuse, active substance abuse, or habitual benzodiazepine use.
During the procedure, an additional bolus of 30–60 µg of fentanyl citrate is available every 6 minutes as required, which is either self-administered or administered by the vascular-interventional radiology nurse.
After the procedure, the continuously infused hourly dose is decreased by 40%. Additional self-administered boluses of 30–60 µg, again with a lock-out period of 6 minutes, remain available to the patient during the 23-hour observation period. We do not impose a 4-hour dose limit. We also prescribe 400 mg of ibuprofen four times a day administered orally for 5 days and 12.5–25.0 mg of intravenous promethazine hydrochloride every 4 hours, as necessary.
The morning after the procedure, we convert to oral analgesia at a dose that reflects the PCA use. For patients with higher PCA use, we prescribe controlled release of 20 mg of oxycodone hydrochloride (Oxycontin; Perdue Pharma, Stanford, Conn) every 12 hours for 3 days, with 10 mg every 12 hours for 3 days given to patients with lower PCA use. Five to 15 milligrams of oxycodone is provided every 4–6 hours for any breakthrough pain. We prophylactically prescribe 200 mg of colace twice a day for 5 days to avoid constipation.
Otherwise, our embolization technique differs little from that reported in the literature. Therefore, we attribute our successful management of pain predominantly to our pain-control protocol. We use unilateral arterial access and bilateral selective catheterization of the uterine arteries and perform embolization to an end point of nonfilling of the arterial branches to the fibroids not to uterine artery stasis. We do not administer an intraarterial vasodilator or lidocaine. We use 500–700-µm of trisacryl gelatin particles (Microsphere Embospheres; Biosphere Medical, Rockland, Mass). During hospitalization, all of our patients are cared for solely by the vascular-interventional service.
In the literature, there have been descriptions of somewhat more complex pain-control protocols, with varied success reported by using a combination of several medications administered by means of intramuscular injection, intravenous injection, and oral routes. Such approaches to pain control can be labor intensive for the nursing staff and prone to the occurrence of breakthrough pain if the timing of dose is not carefully adhered to (2–4). Many patients still experience several hours of discomfort following embolization, because the effectiveness of the protocol may lag behind the pain curve.
We believe that our simplified protocol has markedly improved pain control in our patients and has enhanced our ability to provide the patients with a minimally invasive therapy. We believe that the key components of our protocol that differ from other protocols are (a) starting the PCA pump before commencing the procedure and (b) administering a continuous infusion of analgesics during and after the procedure. The protocol requires little monitoring and is non–labor intensive.
As long as the perception exists that pain is inevitable after UAE, it is unlikely to attain its place at the forefront of treatment of symptomatic fibroid disease.
REFERENCES
Department of Radiology, Georgetown University School of Medicine , 3800 Reservoir Road NW, GC201, Washington, DC 20007-2197 e-mail: spiesj@gunet.georgetown.edu
I am pleased to have the opportunity to comment on the letter by Dr Ryan and colleagues regarding their innovations in pain management after UAE for leiomyomata. As the authors have noted, usually there are several hours of moderate to intense pain after the procedure, with cramping pain recurring for several days after the procedure (1–5). Findings from prior research have indicated that the severity of pain after UAE is not predictable on the basis of baseline factors, nor does it predict outcome (6). While still awaiting definitive study, pain after UAE is likely due to a combination of leiomyoma ischemia and, perhaps more important, transient ischemia of the normal myometrium. Pain control after embolization is one of the key clinical-care problems interventionalists must face, and the protocol proposed by the authors is a welcome addition to our armamentarium.
What is new and interesting in their approach is the use of a continuous intravenous infusion of a narcotic supplemented by additional doses that are available on demand by the patient. While continuous dosing is commonly used for epidural analgesia, to my knowledge, it has not been previously proposed for intravenous use in this setting. The authors determine the continuous dosing with a formula that is based on TBW, with an adjustment for morbidly obese patients. The dosing regimen is begun before the procedure and continues after treatment, with a 40% reduction after the procedure.
The authors do not explain how their dosing regimen was developed. It is heavily weighted toward a high-demand dose, which raises the question of the effectiveness of the continuous dose. For example, by using the formula described for a 70-kg woman, the continuous dosing would be 21 µg/hr of fentanyl citrate during the procedure and 12.6 µg/hr after the procedure, when most patients have noted the greatest degree of pain. This dose seems low, given that the intermittent-demand dose allowed after the procedure is 30–60 µg every 6 minutes. Even at the 30-µg rate, a patient might self-administer 300 µg each hour, which would overwhelm the small continuous infusion. In our institution, the standard dose range recommended for patients taking fentanyl citrate with intravenous dose pumps is 5–20 µg every 8 minutes. It would be interesting to know how the protocol was derived and to have the authors comment on the relative contributions of the continuous and intermittent doses.
The authors also base postdischarge medication protocols on the amount of medication needed during the in-hospital postprocedure period. This is also an interesting approach and is worthy of additional study. Does the amount of pain experienced in the immediate postprocedure interval correlate with the amount of pain in the first week after discharge?
Many of us have empirically adjusted recommendations of medications and doses for patients on the basis of our perception of the postprocedure course and particularly on the amount of pain still experienced at the time of discharge. The authors have used controlled-release oxycodone hydrochloride. This would likely give a "continuous" dose (similar to the continuous dose of PCAs) over a 12-hour period, with supplemental oxycodone as needed. We have used one or two tablets oxycodone hydrochloride (5 mg)-acetaminophen (325 mg) combination (Percocet; Endo Pharmaceuticals, Chadds Ford, Pa) every 3–4 hours as needed, with a backup prescription for 2 mg of hydromorphone (Dilaudid; Knoll Laboratories, Mount Olive, NJ) every 3–4 hours. Our concern with continuous or slow-release medications is that many patients have pain that is easily controlled by the ibuprofen; therefore, they might receive medication that is not needed. Thus, we have not taken this path.
There is one alternative explanation for the authors’ experience with better pain control after UAE. Many practitioners have noted that patients experience less pain with trisacryl gelatin particles. While this experience is anecdotal, it may reflect the less-extensive uterine artery occlusion that occurs with the use of trisacryl gelatin particles. The recommended endpoint of embolization with trisacryl gelatin particles is occlusion of only the fibroid-feeding branches, with sluggish forward flow in the main uterine arteries (7). The typical endpoint that has been used with polyvinyl alcohol particles has been stasis or near stasis of flow in the uterine arteries (1,4,5). Although speculative, this difference may be as much a factor in better pain control as are improved pain-management protocols. We have initiated a randomized study to compare the periprocedural pain associated with the use of trisacryl gelatin particles versus polyvinyl alcohol particles to determine if the difference that many of us have suspected is real.
The authors also provide an opportunity to discuss an important ancillary issue. As interventionalists begin to care for these patients, they need to be aware of some of the problems that may be associated with prescribing narcotics. While we have had remarkably few problems, a few patients (or perhaps their friends, family members, or acquaintances) have attempted to obtain duplicate prescriptions from different pharmacies, and we have had at least one patient forge a prescription for narcotics. Most narcotics, but particularly oxycodone hydrochloride-acetaminophen combination and hydromorphone, have considerable street value. Pharmacists have recommended to us that all prescriptions be handwritten in the same handwriting, and that quantities be written in longhand. It is more difficult to alter a number written in longhand. I typically use blue ink, which is more difficult to photocopy than black ink.
In many states, triplicate forms are necessary for narcotics prescriptions. In those states that do not require triplicates, interventionalists who will be regularly prescribing narcotics should obtain prescription pads imprinted with their names, office numbers, and pager numbers to facilitate easy communication with the pharmacist. These pads should be carefully controlled to prevent theft. Another concern with any regular prescription of oral narcotics for outpatient use is the possibility that a patient may become dependent on the medications. For this reason, we have tried to provide enough medication for only 5–7 days; if additional medications are needed, we evaluate the patient at an office visit and provide additional prescriptions as necessary. For difficult cases or in cases in which the patient has a prior problem with drug dependency, we often consult the pain management service in our hospital for assistance.
I applaud the authors’ innovation in trying to improve the patient experience associated with UAE. They have given us much food for thought and new insights into pain management. Each inteventionalist who is practicing in this area should take note and use this opportunity to review their own protocol with their pain management consultants. It is our responsibility (not that of the patient’s gynecologist or primary care physician) to care for these patients, and pain relief is a central part of that care.
REFERENCES
We thank Dr Spies for his generous and insightful comments regarding our pain protocol following UAE. Indeed, the issues he raises are issues that we ourselves have considered many times. We are delighted to have the opportunity to briefly address some of the issues raised by Dr Spies.
This specific UAE regimen is based on modification of the PCA weight-referenced dosing we use at our institution for postoperative pain control. The modifications evolved after some early experimentation with the original protocol.
The protocol, for good reason, is heavily weighted toward the bolus dose, as mentioned by Dr Spies. Fentanyl citrate is rapidly distributed during initial intravenous therapy, and steady-state blood levels become established quickly (1). The higher-dose continuous infusion supplements the use of PCA by the radiology nurse during the procedure and also the patient’s use of the button after the procedure. An increase in the continuous infusion would be counterproductive because the patient becomes more sedated, and when this occurs, patients remain asleep for longer periods and do not push the button again for PCA until they awaken with pain. Thus, cycles of pain and excessive pain at night can occur. Without continuous infusion, a larger bolus dose of PCA would be required to provide the necessary pain control, with a resultant greater risk of side effects (2). Our goal is to keep the number of PCA bolus doses below three doses per hour.
We perform the conversion to oral therapy not on the basis of immediate postprocedural pain but on the 12-hour parenteral opioid requirement immediately prior to conversion to oral therapy. We do not yet have definitive evidence that there is a correlation, though we currently have a prospective study underway that will focus on this among other things. Anecdotally it appears to work.
We do not have concerns that we are overtreating pain during the hospital stay or after discharge. UAE has the potential to produce substantial acute pain that will rapidly resolve in 3–5 days. We practice and strongly recommend tapering of the long-acting opioid doses to account for the decreasing pain. Tapering also minimizes excessive prescription of opioids and limits the number of tablets that are left over and available for diversion or misuse. Ethically, we should never allow concerns about possible abuse inhibit the proper use of opioids to treat patients experiencing substantial pain. The practical advice given by Dr Spies regarding safety measures for narcotic prescribers is timely. We certainly agree with his approach.
We also agree with Dr Spies that some of the effect we are seeing may indeed be partially related to the use of trisacryl gelatin particles and embolization to a "different endpoint." However, there is still considerable clinical evidence that UAE is potentially very painful whether performed with trisacryl gelatin particles or polyvinyl alcohol particles.
If, as we predict, interventional radiology continues to become more like the clinical specialties, with all of the in-hospital and follow-up management performed by interventional radiologists, we will need to fully reacquaint ourselves with pain control. We believe that a simple, safe, and effective pain-control protocol should be in every interventional radiologist’s armamentarium. Failure to care for patients adequately may have the potential to become our "Achilles heel." This needs to be avoided, as not everyone in the medical profession is as interested in seeing a bright future for interventional radiology as those who practice it.
REFERENCES
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