Pain, sedation and reaction time during long-term treatment of cancer patients with oral and epidural opioids

Abstract

Continuous reaction times (CRTs) and subjective assessment of pain intensity (PVAS) and sedation (SVAS) were compared in 14 cancer patients during chronic oral opioid therapy (daily doses of morphine: 130-400 mg) and subsequent stable epidural opioid therapy (daily doses of morphine: 32-240 mg). CRTs were also measured in 20 healthy controls. CRT results were summarized using 10%, 50% and 90% percentiles. On the basis of these values a 'variation index' was calculated (90-10%): 50%, describing the spread of the reaction time values. No statistically significant differences were found in PVAS, SVAS and CRT before and after initiation of epidural opioid administration. Calculation of confidence limits of median differences showed absolutely no tendency towards differences in CRT between the treatments. Only 4 patients experienced both increased pain relief and less sedation on epidural opioids. Comparing CRT percentiles of the cancer patients with the controls, differences were found between the control group and the oral opioid group, the latter being statistically significantly slower in the 90% percentiles (P = 0.018) and variation indexes (P = 0.018). In conclusion, no differences were found between CRT values and VAS scores in cancer patients treated with chronic oral opioids versus epidural opioids. Therefore at this dose level of chronic opioid treatment, the advantage of epidural administration seems questionable.