OBJECTIVES: Renal colic (RC) is a common cause for emergency department visits. This study was conducted to compare the analgesic efficacy of morphine plus ketamine (MK) versus morphine plus placebo (MP) in patients with acute renal colic.
METHOD: Using a single center, double-blind, two-arm, parallel-group, randomized controlled trial, 200 patients were equally and randomly divided to receive 0.1?mg/kg morphine plus normal saline and 0.1?mg/kg morphine plus 0.2?mg/kg ketamine. The severity of renal colic was assessed by VAS at baseline, 20 and 40?min after drug injection. The number of adverse events also was recorded.
RESULTS: Totally, 200 patients completed the study. Mean age of the patients was 35.60?±?8.17?years. The patients were mostly men (68.5%). The severity of pain between the groups was not significantly different at baseline. Both groups showing a significant reduction in VAS scores across the three time points. The main effect comparing the two types of intervention was significant (F?=?12.95, p?=?0.000), suggesting a significant reduction in pain severity of patients in the MK group. The number of patients who suffered from vomiting was significantly higher in MP group than that of MK group (13 and 3, respectively (P?=?0.009)). However, the risk of dizziness in the MK group was >2 times higher than MP group (relative risk: 2.282, 95% CI: 1.030-5.003, P?=?0.039). The number of patients who needed rescue analgesia was significantly lower in the MK group (OR, 0.43 (0.22-0.83)).
CONCLUSION: Adding 0.2?mg/kg ketamine to 0.1?mg/kg morphine can reduce the renal colic pain, nausea and vomiting more than morphine alone; however, it was associated with higher number of patients with dizziness.
This is a nice, simple clinical trial of a very common problem in urology and nephrology.
The authors have looked at a useful combination of adding ketamine to morphine for treating renal colic. The course of the evaluated VAS and other parameters show a better response to the combination. In the discussion, they have also looked at other publications which have used different doses of ketamine. It is clear that there is no general recommendation. Still, their combination appears to be useful and should be further evaluated.
Despite the conclusion of the authors, the partial eta squared of the intervention drug is only 6% with a clinically insignificant 0.48 VAS difference at 40th min. This article shows that in patients already treated with opioids for pain, ketamine is not a valuable addition to routine treatment.
Yes, adding a second agent is likely to cause more adverse effects. No surprise there.