Materials and Methods: This randomized clinical trial study was performed on 60 candidates for thoracoscopy in Imam Reza hospital (Tabriz-Iran) during 2014-2016. The intervention was started after the random allocation of patients into control and intervention groups each containing 30 people. Before the surgery, patients in the control group received bupivacaine and those in the intervention group received bupivacaine + ketamine through an intrapleural catheter. Then, pain intensity and a need for an opioid after the surgery were measured in two groups based on visual pain criteria. The results of the two groups were compared by paired t test, chi-square test, and Mann-Whitney test using SPSS 23.

Results: Based on the results, the intensity of pain was significantly lower in the intervention group 6 (P = 0.032), 12 (P = 0.049), and 24 (P = 0.048) hours after the surgery compared with the control group, and the amount of the consumed pethidine in both groups showed that the average pethidine consumption in the intervention group was significantly lower compared to the control group in the first (P = 0.009), the second (P = 0.014), the third (P = 0.031), and the fourth (P = 0.02) six hours after the surgery.

Conclusions: In general, intrapleural low-dose ketamine in combination with bupivacaine is effective in post-thoracoscopy pain control.