Treating the Intense Pain of Renal Colic
Treating the Intense Pain of Renal Colic
Patients with renal colic commonly present to the emergency department, and urolithiasis-associated pain is among the most agonizing visceral pain syndromes. Rapid and effective analgesia is a priority in renal colic, and intravenous nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids are standard treatments. Using indomethacin in suppository form, Cordell and colleagues conducted the first emergency department study of NSAIDs for renal colic, and Safdar and colleagues demonstrated that combination therapy with intravenous opioids and NSAIDs was superior to the use of either agent alone. Among the opioids, morphine, hydromorphone, and fentanyl are most commonly used; among the NSAIDs, intravenous ketorolac is a mainstay. Recently, injectable ibuprofen has been approved for the treatment of pain and fever; however, its use in renal colic is uncommon.
Both opioids and NSAIDs have well-recognized adverse effects. Opioids commonly cause nausea, vomiting, and sedation and, less commonly, hypotension and respiratory depression. NSAIDs are associated with gastrointestinal bleeding and acute renal failure, but both adverse effects are rare after single doses. Intravenous forms of acetaminophen have been available in Europe for several years and are frequently used to treat postoperative pain. Given the relative safety of acetaminophen, particularly in single doses, it would seem an attractive analgesic for the treatment of renal colic if proof of efficacy could be demonstrated in this clinically challenging model of extreme visceral pain.
Bektas F, Eken C, Karadenız O, Goksu E, Cubuk M, Cete Y
Ann Emerg Med. 2009;54:568-574
In a recently published article in Annals of Emergency Medicine, Firat Bektas and colleagues from Akdeniz University, in Antalya, Turkey, conducted a randomized placebo-controlled trial comparing single doses of morphine (0.1 mg/kg), acetaminophen (1 g), and placebo (normal saline) for the treatment of acute renal colic. Both analgesics were administered intravenously. Changes in pain intensity between baseline and 30 minutes after treatment were compared, and subjects requiring additional pain relief received fentanyl for rescue analgesia.
Among 146 subjects completing the study, the mean reduction in visual analogue pain intensity scores at 30 minutes was 43 mm for acetaminophen, 40 mm for morphine, and 27 mm for placebo. As expected, both acetaminophen and morphine provided statistically superior pain relief when compared with placebo; however, no difference was found between acetaminophen and morphine. No serious adverse effects were observed among study subjects; but those receiving morphine reported at least 1 adverse effect more frequently than those receiving acetaminophen or placebo (33% vs 24% vs 16%).
Although the use of placebo controls in such a severe model of visceral pain raises obvious ethical issues, this is an otherwise rather well-conducted trial. One consequence of the decision to incorporate a placebo arm is that the investigators could only study the first 30 minutes of treatment before providing rescue analgesics -- in this case, fentanyl. It is possible that the study findings might differ if a longer period of assessment had been used; however, the investigators argue (and most emergency physicians would agree) that the first 30 minutes of emergency department care are critical in terms of patient pain experience. Additionally, although this is a relatively large single-center study, its sample size does not allow us to determine that intravenous morphine and acetaminophen have equivalent analgesic efficacy, only that they are comparable and both superior to placebo. Indeed, the incidence of adverse effects, decreases in pain intensity at 15 and 30 minutes, as well as the need for rescue analgesics all favored acetaminophen.
This is the first reported clinical trial of intravenous acetaminophen either in renal colic or in the ED. In the near future, intravenous acetaminophen is likely to become available for use in the United States, and additional studies are warranted to confirm its efficacy in renal colic as well as to determine whether its rapidity of onset exceeds that of our analgesic alternatives. Finally, it is likely that combination therapy, including intravenous opioids plus either nonsteroidals or acetaminophen, represent the optimal approach to renal colic. Future studies should incorporate this multimodal approach.
Abstract
Introduction
Patients with renal colic commonly present to the emergency department, and urolithiasis-associated pain is among the most agonizing visceral pain syndromes. Rapid and effective analgesia is a priority in renal colic, and intravenous nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids are standard treatments. Using indomethacin in suppository form, Cordell and colleagues conducted the first emergency department study of NSAIDs for renal colic, and Safdar and colleagues demonstrated that combination therapy with intravenous opioids and NSAIDs was superior to the use of either agent alone. Among the opioids, morphine, hydromorphone, and fentanyl are most commonly used; among the NSAIDs, intravenous ketorolac is a mainstay. Recently, injectable ibuprofen has been approved for the treatment of pain and fever; however, its use in renal colic is uncommon.
Both opioids and NSAIDs have well-recognized adverse effects. Opioids commonly cause nausea, vomiting, and sedation and, less commonly, hypotension and respiratory depression. NSAIDs are associated with gastrointestinal bleeding and acute renal failure, but both adverse effects are rare after single doses. Intravenous forms of acetaminophen have been available in Europe for several years and are frequently used to treat postoperative pain. Given the relative safety of acetaminophen, particularly in single doses, it would seem an attractive analgesic for the treatment of renal colic if proof of efficacy could be demonstrated in this clinically challenging model of extreme visceral pain.
Intravenous Paracetamol or Morphine for the Treatment of Renal Colic: A Randomized, Placebo-Controlled Trial
Bektas F, Eken C, Karadenız O, Goksu E, Cubuk M, Cete Y
Ann Emerg Med. 2009;54:568-574
Summary
In a recently published article in Annals of Emergency Medicine, Firat Bektas and colleagues from Akdeniz University, in Antalya, Turkey, conducted a randomized placebo-controlled trial comparing single doses of morphine (0.1 mg/kg), acetaminophen (1 g), and placebo (normal saline) for the treatment of acute renal colic. Both analgesics were administered intravenously. Changes in pain intensity between baseline and 30 minutes after treatment were compared, and subjects requiring additional pain relief received fentanyl for rescue analgesia.
Among 146 subjects completing the study, the mean reduction in visual analogue pain intensity scores at 30 minutes was 43 mm for acetaminophen, 40 mm for morphine, and 27 mm for placebo. As expected, both acetaminophen and morphine provided statistically superior pain relief when compared with placebo; however, no difference was found between acetaminophen and morphine. No serious adverse effects were observed among study subjects; but those receiving morphine reported at least 1 adverse effect more frequently than those receiving acetaminophen or placebo (33% vs 24% vs 16%).
Viewpoint
Although the use of placebo controls in such a severe model of visceral pain raises obvious ethical issues, this is an otherwise rather well-conducted trial. One consequence of the decision to incorporate a placebo arm is that the investigators could only study the first 30 minutes of treatment before providing rescue analgesics -- in this case, fentanyl. It is possible that the study findings might differ if a longer period of assessment had been used; however, the investigators argue (and most emergency physicians would agree) that the first 30 minutes of emergency department care are critical in terms of patient pain experience. Additionally, although this is a relatively large single-center study, its sample size does not allow us to determine that intravenous morphine and acetaminophen have equivalent analgesic efficacy, only that they are comparable and both superior to placebo. Indeed, the incidence of adverse effects, decreases in pain intensity at 15 and 30 minutes, as well as the need for rescue analgesics all favored acetaminophen.
This is the first reported clinical trial of intravenous acetaminophen either in renal colic or in the ED. In the near future, intravenous acetaminophen is likely to become available for use in the United States, and additional studies are warranted to confirm its efficacy in renal colic as well as to determine whether its rapidity of onset exceeds that of our analgesic alternatives. Finally, it is likely that combination therapy, including intravenous opioids plus either nonsteroidals or acetaminophen, represent the optimal approach to renal colic. Future studies should incorporate this multimodal approach.
Abstract
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