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In Focus

Treating the Pain of Renal Colic

Roberts, James R. MD

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    Learning Objectives: After reading this article, the physician should be able to:

    1. Discuss the use of various analgesics for the relief of pain in patients with renal colic.
    2. Explain the side effects of various analgesic regimens.
    3. Describe the efficacy of various analgesic regimens.

    Kidney stones are a relatively common condition, well known to emergency physicians and to many unfortunate patients. As many ureterolithic patients will attest, little can match the agony of passing a kidney stone. These patients appear quite ill to everyone, and the excruciating pain is associated with nausea, vomiting, sweating, and eerie pacing that tempt the novice to consider a catastrophic process. Fortunately, the diagnosis is readily made, and the treatment is relatively straightforward.

    One note of caution, however, is that some serious problems — renal infarction, retroperitoneal bleeding, ruptured abdominal aortic aneurysm, and an aortic dissection — can mimic a kidney stone, so let the clinician beware. Aortic catastrophes even can be accompanied by the hematuria that is common but not omnipresent with a kidney stone.

    Intravenous fluids do not hasten the passage of a kidney stone, nor will hydration likely worsen the pain. An abdominal radiograph is a useless endeavor that only wastes time and misleads the clinician; a non-enhanced spiral CT scan quickly settles the issue of the presence or absence of a kidney stone, and can adroitly detect a plethora of other medical problems with similar presentations. I advocate for the almost-universal use of a CT scan to come to a quick clinical conclusion.

    Many clinicians, however, will use their clinical acumen to diagnose a kidney stone in selected patients. Few urologists have such bravado. If the patient is 34 and presents with a chief complaint of “I am passing another stone,” and the history and physical are otherwise consistent, some will eschew routine CT scanning, at least in the ED. This approach has support in the literature and in clinical practice. I prefer to call the question, get the answer, and proceed with aggressive therapy while being off to see another patient. The CT finds and measures the stone, and can assess the degree of hydronephrosis, thereby defining many prognostic parameters.

    This month's column has a relatively narrow focus, and concentrates on interventions that relieve the pain of renal colic. Once the prescient and sagacious clinician has nailed down the diagnosis, providing analgesia is about all the emergency physician can offer. Certainly we should offer the most reasonable, aggressive, and logical approach. A kidney stone is no time to save money by being parsimonious with morphine, Dilaudid, or ketorolac.

    Efficacy of Ketorolac versus Meperidine in the ED Treatment of Acute Renal Colic, Larkin G, et al, Am J Emerg Med 1999;17:6

    The authors of this article compared the NSAID ketorolac (Toradol) with meperidine (Demerol) for treating acute renal colic in the ED. The downsides of narcotics are likely overemphasized by the authors, but untoward effects may include sedation, nausea, respiratory depression, hypotension, and the possibility of tolerance and theoretically addiction. None of these should, however, be an issue with the proper use of judicious narcotic analgesia in the ED. In my opinion, such unwarranted and somewhat misdirected cautions have taught the neophyte to believe that narcotics are somehow problematic for short-term relief of pain in the ED. I, on the other hand, consider narcotics the Holy Grail of analgesics, and am flummoxed by such concerns.

    In some instances, nonsteroidal anti-inflammatory drugs (NSAIDs) are a possible alternative to narcotics. They work by inhibiting prostaglandins, with the resultant relaxation of ureteral spasm and decrease of renal capsular distension and associated pain. The authors state that previous studies have demonstrated that ketorolac was equal or superior to meperidine for treating postoperative surgical and dental pain. This pronouncement was usually confirmed by manufacturer-sponsored studies, comparing the NSAID to piddling doses of narcotics. The authors claim that this is the first prospective trial comparing ketorolac with narcotics for treating renal colic pain. Prior studies comparing this NSAID with narcotics for this condition have been small, and have not used adequate doses of narcotics, calling into question the validity of the conclusions.

    In this study, a kidney stone was confirmed by an IVP, and patients were randomly assigned to receive 60 mg of IM ketorolac or 100 mg to 150 mg of meperidine IM (based on the patient's weight). Physicians were blinded to the study medication. The authors assessed the degree of pain relief, the need for rescue medication, and the time to discharge from the ED. Pain was measured on a standard 10 cm visual analogue scale. If no relief was obtained after 20 minutes, rescue analgesia was offered to the patient, with the choice of medication being left to the attending physician.

    A total of 70 patients were included in the trial. Patients were similar at baseline for a variety of parameters. At 40 minutes, patients treated with ketorolac reported more pain relief than those treated with meperidine, and they demonstrated a significantly greater improvement on the pain scale. The use of rescue medication was similar in both groups, with about a third requiring additional therapy. A similar number of patients in both groups were discharged (about 75%), with a slightly earlier time of discharge in the NSAID group. The authors conclude that 60 mg of IM ketorolac is well tolerated, and was at least as efficacious as 100 mg to 150 mg of meperidine in relieving acute renal colic.

    The first therapeutic goal in treating a kidney stone is to provide adequate analgesia. This requires the titration of intravenous medications with requisite alacrity, and the emergency physician should be the best doctor in the hospital for this task. This is no time for pills or piddling doses of morphine/hydromorphone. The judicious use of parenteral narcotics is standard, and the correct dose is always the same: enough to do the job without overshooting. Combining the antiprostaglandin effects of IV ketorolac with a narcotic is a common regimen. Nausea and vomiting are common companions of renal colic, but usually when the pain subsides, so do the GI effects. Antiemetics are, however, occasionally useful. Adding 20–30 mg metoclopramine (Reglan) to an IV saline infusion quells nausea and vomiting while minimizing extrapyramidal side effects (akathisia).

    The authors state that their study confirms previous investigations supporting the use of NSAIDs for pain, especially for renal colic. They postulate that the prostaglandin inhibition, a mechanism that opiates do not provide, may be helpful for specific relief of a stone in the ureter. One limitation of the study is that the drugs were administered by the IM route, a less than ideal intervention. The reason for this is unknown.

    Comment: This study is relatively straightforward, but it's problematic in a few areas. The drugs were given IM rather than IV for unspecified reasons. Patients with renal colic should receive IV medication without question. The dose of ketorolac was a rather high 60 mg by current standards, and although the dose of meperidine was reasonable, the limitations of meperidine are well known. Most EDs have moved away from using meperidine for any pain control because of its short duration of action, side effect profile, and high abuse potential. The literature also suggests that smaller doses of ketorolac are quite effective. The standard dose now is 15 mg to 30 mg IV. The major disadvantage of an NSAID is that it can cause decreased renal blood flow, not a problem in most patients, but an issue in those with underlying renal insufficiency. The GI effects of prolonged NSAID use are well known. Only one dose of either medication was given. Ketorolac is only used every six hours while narcotics can be titrated every five to 15 minutes.

    The Cochrane Library's evidence-based database reviewed the use of NSAIDs versus opiates for acute renal colic by examining randomized controlled trials, regardless of dose or route of administration. The database identified 20 trials from nine countries that included 1613 patients. (Br Med J 2004;328[7453]:1401.) Most of the trials compared ketorolac with meperidine, and the benefit and possible superiority of ketorolac to this narcotic was supported. The conclusion of the Cochrane analysis was that both NSAIDs and opioids can provide effective relief for acute renal colic, but opiates may be associated with a higher incidence of adverse effects, particularly vomiting. Meperidine is well known to cause vomiting, so I am not sure that's a fair comparison. More importantly, the analysis extracts data from some poorly designed studies, most of which lacked scientific rigor.

    It is my analysis and clinical experience that both NSAIDs and opiates are generally effective for the relief of acute pain. I have always been an advocate for the use of narcotics for all painful conditions, and frequently pontificate that “real pain requires real medicine.” Indomethacin by rectal suppository was a common trick that we used for renal colic when I was an intern, and it seemed to help, but it was only anecdotal evidence. I prefer morphine or hydromorphone (Dilaudid) for pain control in most circumstances. I could not find a randomized double-blind, placebo-controlled trial comparing IV ketorolac with IV morphine/Dilaudid.

    One problem with NSAIDs is that they are not ideal drugs to continue in the outpatient setting. I can't see sending anyone home with a kidney stone still in his ureter with just a prescription for oral ketorolac or any NSAID in lieu of an oral narcotic. I am surprised that no one has studied my routine regimen, a combination of ketorolac and morphine. This would take advantage of the pain control of narcotics and the antiprostaglandin effect of ketorolac, and it seems to be the best of both worlds. My initial unstudied approach to patients with acute renal colic is 10 mg of IV morphine and 15 mg of IV ketorolac.

    My personal experience is that this is a good combination, but it doesn't work on everyone. I don't repeat the ketorolac, but I frequently repeat the morphine. Although 10 mg of IV morphine seems high to some, it's only a very modest dose. Interestingly, 2 mg of Dilaudid equals about 16–18 mg of morphine, and no one quibbles about this standard Dilaudid dose. Those who may be sent home with the expectation that the stone will pass can be given baseline around-the-clock oral NSAIDs (like 600 mg ibuprofen every six hours), with supplemental oxycodone or hydrocodone as needed.

    Nausea is omnipresent with renal colic. While narcotics themselves can cause nausea, and parenteral ketorolac does not, the nausea and vomiting usually abate when the pain is controlled. Adding an antiemetic with a narcotic is a common intervention by the residents, but I personally don't use it routinely. Nurses often ask if I want to give Reglan, and my answer is usually, “Let's wait and see.”

    I would not argue that ketorolac, the only NSAID currently available for IV injection, has some efficacy in treating renal colic. It also has been said to have a similar benefit for patients with acute biliary colic. Tweaking the NSAID approach with an IV narcotic seems to be the ideal approach, and that's the next study I would like to see, and not with 50 mg of meperidine as the narcotic (see the next paper). As with any process, the individual variation in presentation and patient profile will cause any regimen to work well or poorly, and one needs to be flexible and willing to adjust and modify any initial approach that doesn't seem to work.

    Finally, a number of other pharmacologic interventions for renal colic have been suggested, but I could find none that had specific relevance to emergency medicine. Intranasal desmopressin has been suggested. (BJU Int 2001;87:332.) The antispasmodic/antimuscurinic atropine-like agent, hyoscine, may be useful, but it's not commonly prescribed. (J Urol 2005;174:572.) A number of alternative agents for managing lower ureteral stones, with the aim of facilitating stone passage, has been suggested. The use of nifedipine or tamsulosin seems to increase stone expulsion rate and reduce the need for analgesic therapy. (J Urol 2004;172:568.) Apparently the alpha-blocking characteristics of these agents may be beneficial. I don't know of any emergency medicine literature advocating the ED use of these agents, and the jury is still out. There also is some evidence that the addition of the steroid deflazacort might help increase the stone expulsion rate.

    Emergency physician can't cure much, but they certainly can cure pain in the vast majority of circumstances. Nothing challenges the analgesic armamentarium of the clinician more than renal colic. By the time most physicians finish their residency, they have deeply ingrained approaches to pain relief, and are certain that their regimen is safe and effective. Most become highly reticent to listen to alternative interventions, and have packed on more than a few pounds from the pizza offered by the hovering drug rep. I believe that I am quite generous in doling out narcotics to patients in pain, and even don't mind getting fooled for a hefty dose of morphine in the drug seeker.

    In fact, I am quite amazed by the nefarious, nay ingenious, ways that highly accomplished drug addicts can weasel narcotics out of even the most seasoned clinician. You can spot some of them as soon as they enter the ED carrying their CT scan, with a chief complaint of “my doctor is out of town,” but that's all part of emergency medicine. That being said, it's time to concentrate on real pain relief in the ED. Emergency physicians become highly skilled in many areas, but they should be the bona fide experts and the most vocal patient advocates in the hospital on the judicious use of narcotic analgesics for rapid relief of short-term acute pain.

    Regardless of the regimen you choose, you should institute it rapidly, evaluate it frequently, use enough, and not be hesitant to change course, drug, or dosage as the clinical scenario unfolds. Patients have a wide tolerance to pain, but clinicians have a narrow tolerance for altering an intervention that has become a stalwart in their daily practice. These two conditions clash when it comes to renal colic. Whether you choose your favorite narcotic, NSAID, or a combination of the two, you should be ready to go with the flow and quickly suppress the moans and groans emanating from the unfortunate soul passing a kidney stone.

    Make sure your diagnosis is correct and proceed with all due haste with aggressive pain management that works. Use all medications intravenously, and reassess the results on a frequent basis. If the patient has not obtained analgesia from an injection within 10 to 15 minutes, it's simply not going to be any better half an hour later — add some more. Because patients with kidney stones are generally young and otherwise healthy, the 2 mg morphine bolus would not be an ideal initial approach. Leave that to the internist or the pediatrician, and step up to the plate with emergency medicine doses of pain medications, while paying requisite attention to the side effects and other important details.

    Once the pain is initially controlled in the ED, it's time to decide whether the patient can go home or needs to be admitted to the hospital. I have no hard and fast rules about this, and I believe one cannot be dogmatic. A common-sense approach would be to consider the availability of follow-up, the social and psychological support of the patient outside the hospital, the size of the stone, and previous history. Infection coexisting with a stone or a single kidney are usually candidates for admission. If the patient has a 2 mm stone, it's likely to pass, often in the ED. If it's 8 to 10 mm, it's likely to stay there until somebody breaks it up or takes it out. If the patient is vomiting, he can't hold down oral narcotics and can't stay well hydrated. Some patients want to try outpatient therapy; others won't even consider it. I always tell the patient that he gets no points for suffering, and I have no way of predicting the future. I am quite generous with admission, but I don't consider it a personal failure if the discharged patient comes back two hours later having failed outpatient attempts.

    Oral oxycodone (Percocet), hydrocodone (Vicodin), or hydromorphone (Dilaudid) are all reasonable choices. Oral meperidine is probably is a dinosaur, and sustained-release products, such as MS Contin, OxyContin, and fentanyl patches, are probably too fancy for the first go-round. In the hospital, patient-controlled analgesia (PCA pump) is a nifty way to control pain. You can start this in the ED if you're set up to do so.

    Comparison of Intravenous Ketorolac, Meperidine, or Both (Balanced Analgesia) for Renal Colic, Cordell WH, et al, Ann Emerg Med, 1996;28(2):151

    This is a small, randomized, double-blind study on the use of ketorolac, meperidine, or both for treating renal colic. It is one of the few studies where narcotics and NSAIDs are viewed as a combination intervention. It was sponsored by the manufacturer of Toradol. Patients were given one of three treatments: 50 mg IV meperidine, 60 mg IV ketorolac, or a combination of both when they had moderate to severe pain and documented renal colic. Within 30 minutes, three-quarters of the patients given the ketorolac or the combination drugs reported at least a 50 percent reduction in pain (not overly impressive to say the least). Only 23 percent of those treated with this small dose of meperidine alone reported similar results. More than half of the patients initially treated with the combination regimen required additional meperidine for pain control. The use of the ketorolac-very modest meperidine combination appeared to be superior to either drug given alone.

    Comment: This is another example of a small study that uses inadequate doses of a minor analgesic to treat renal colic. The poor initial pain response in most patients demonstrates the lack of aggressive therapy that I want when I get my kidney stone. The literature certainly lacks scientific rigor, and all of these studies leave much to be desired. It's interesting that the rescue drug in all studies is a narcotic, not the NSAID. Although I would not eschew NSAIDs as part of my combination regimen, I still prefer emergency medicine-sized doses of narcotics for severe pain of any source. Adding ketorolac for the patient with biliary colic or renal colic is not problematic for me; it seems physiologic and scientific, but I generally don't use NSAIDs alone for significant pain.

    Caveats for Relieving Pain in Patients with Renal Colic

    • ▪ Give all medications by the IV route.
    • ▪ The judicious use of parenteral narcotics is standard, and side effects and the potential for addiction with ED use are miniscule.
    • ▪ Titrate the dose and frequently assess for effect.
    • ▪ IV fluids do not increase the intensity of renal colic.
    • ▪ NSAIDs have a role in renal colic because of their antiprostaglandin mechanism and the inherent analgesia of the medications.
    • ▪ The combination of NSAIDs and narcotics is an acceptable initial regimen.
    • ▪ Rescue medications should be narcotics.
    • ▪ The nausea and vomiting of renal colic is usually quelled by the relief of pain, but antiemetics may be required.
    • ▪ Alpha blockers may hasten the passage of distal ureteral stones in the outpatient.

    Antispasmodics are of no proven value, and are not usually used.

    © 2006 Lippincott Williams & Wilkins, Inc.