An Intravenous Ketamine Test as a Predictive Response Tool in Opioid-Exposed Patients with Persistent Pain
Pain Management Division, Department of Anesthesiology & Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA.Journal of pain and symptom management (Impact Factor: 2.8). 10/2008; 37(4):698-708. DOI: 10.1016/j.jpainsymman.2008.03.018
Chronic pain patients who are treated with opioid therapy represent a significant challenge to medical professionals. When pain recurs in the face of a previously effective opioid regimen, treatment options include dose escalation, opioid rotation, drug holidays, and the addition of adjuvants. Some experts advocate the use of N-methyl-D-aspartate receptor (NMDA-R) antagonists to combat tolerance. Recently, the use of an intravenous (i.v.) ketamine infusion to predict the response to a dextromethorphan (DX) treatment trial has been described. In this study, 56 opioid-exposed patients with recurrent pain were treated with a low-dose (0.1mg/kg) i.v. ketamine test followed by a DX treatment course. Using previously designated cutoff values for a positive response to ketamine (67% or more pain relief) and DX (50% or more pain relief), the sensitivity, specificity, positive predictive value, and negative predictive value for an i.v. ketamine infusion to predict subsequent response to DX treatment were 72%, 68%, 52%, and 85%, respectively. The observed agreement between analgesic responses was 78%, indicating a highly significant correlation (r=0.54, P=0.0001). Subgroup classification revealed no significant differences in the response to either ketamine or DX treatment based on pain classification (i.e., nociceptive, neuropathic, or mixed) or placebo response. In contrast, a weaker correlation between ketamine and DX response was found in subjects requiring high-dose rather than low-dose opioid therapy. A significant correlation also was noted between the development of side effects for the two NMDA-R antagonists. Based on these results, we conclude that an i.v. ketamine test may be a valuable tool in predicting subsequent response to DX treatment in opioid-exposed patients. with persistent pain.
- [Show abstract] [Hide abstract]
ABSTRACT: Since the first description in the early 1990s, the scope of intravenous infusions tests has expanded to encompass multiple drug classes and indications. Purported advantages of these tests include elucidating mechanisms of pain, providing temporary relief of symptoms, and usefulness as prognostic tools in guiding drug therapy. In an attempt to discern the value of these tests, the authors conducted a systematic review to explore the rationale and evidence behind the following intravenous infusion tests: lidocaine, ketamine, opioid, and phentolamine. The studies evaluating all intravenous infusion tests were characterized by lack of standardization, wide variations in outcome measures, and methodological flaws. The strongest evidence found was for the intravenous lidocaine test, with the phentolamine test characterized by the least convincing data. Whereas intravenous opioid infusions are the most conceptually appealing test, their greatest utility may be in predicting poor responders to sustained-release formulations.Anesthesiology 09/2009; 111(2):416-31. DOI:10.1097/ALN.0b013e3181ac1c47 · 5.88 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The use of opioids for the treatment of chronic pain has increased dramatically over the past decade. Whether these drugs provide considerable benefits in terms of pain reduction and improved function to balance the risks associated with their use, however, is unclear. Of particular importance to clinicians treating chronic musculoskeletal pain is opioid-induced hyperalgesia, the activation of pronociceptive pathways by exogenous opioids that results in central sensitization to pain. This phenomenon results in an increase in pain sensitivity and can potentially exacerbate pre-existing pain. Opioids also have powerful positive effects on the reward and reinforcing circuits of the brain that might lead to continued drug use, even if there is no abuse or misuse. The societal risk of increased opioid prescription is associated with increased nonmedical use, serious adverse events and death. Patients with chronic musculoskeletal pain should avoid the long-term use of opioids unless the benefits are determined to outweigh risks, in which case, the use of chronic opioids should be regularly re-evaluated.Nature Reviews Rheumatology 04/2010; 6(4):191-7. DOI:10.1038/nrrheum.2010.24 · 9.85 Impact Factor
- European Journal of Anaesthesiology 01/2011; 28:139. DOI:10.1097/00003643-201106001-00443 · 2.94 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.