Introduction The use of opioids has been increasing in operating room and intensive care unit to provide perioperative analgesia as well as stable hemodynamics. However, many authors have suggested that the use of opioids is associated with the expression of acute opioid tolerance (AOT) and opioid-induced hyperalgesia (OIH) in experimental studies and clinical observations in dose and/or time dependent exposure even when used within the clinically accepted doses. Recently, remifentanil has been used for pain management during anesthesia as well as in the intensive care units because of its rapid onset and offset. Objectives Search of the available literature to assess remifentanil AOT and OIH based on available published data. Methods We reviewed articles analyzing remifentanil AOT and OIH, and focused our literature search on evidence based information. Experimental and clinical studies were identified using electronic searches of Medline (PubMed, Ovid, Springer, and Elsevier, ClinicalKey). Results Our results showed that the development of remifentanil AOT and OIH is a clinically significant phenomenon requiring further research. Discussions and Conclusions AOT - defined as an increase in the required opioid dose to maintain adequate analgesia, and OIH - defined as decreased pain threshold, should be suspected with any unexplained pain report unassociated with the disease progression. The clinical significance of these findings was evaluated taking into account multiple methodological issues including the dose and duration of opioids administration, the different infusion mode, the co-administrated anesthetic drug’s effect, method assessing pain sensitivity, and the repetitive and potentially tissue damaging nature of the stimuli used to determine the threshold during opioid infusion. Future studies need to investigate the contribution of remifentanil induced hyperalgesia to chronic pain and the role of pharmacological modulation to reverse this process.

Intraoperative dexmedetomidine may decrease postoperative emergence agitation in elderly patients due to its sedative effect. In this study, we evaluated the effect of adjuvant dexmedetomidine on smooth emergence from anaesthesia after orthopaedic surgery in elderly patients. A total 115 patients (ASA I–II, aged over 65 years) were randomly allocated into four groups. Anaesthesia was maintained with either sevoflurane or total intravenous anaesthesia (TIVA) comprising propofol and remifentanil. Patients were also administered either dexmedetomidine (0.4 μg kg−1 hr−1; SD and TD) intraoperatively or normal saline (SN or TN) as a control. The bispectral index (BIS) score was maintained from 40–60 intraoperatively. All anaesthetics and dexmedetomidine were discontinued at surgical conclusion, and the recovery times (durations to a BIS = 60, 70, and 80; eye opening; and extubation) were measured. The mean arterial pressure, heart rate, Ricker’s agitation-sedation scale (RSAS), visual analogue scale (VAS) for pain, and incidences of emergence agitation and postoperative nausea and vomiting (PONV) were measured in the recovery room. Dexmedetomidine significantly decreased the RSAS score in the SD and TD groups, and a calm state postoperatively occurred more frequently in these groups than in the control groups. The heart rate and incidence of emergence agitation were lower in the dexmedetomidine groups. Recovery time was higher in the SD group than in the SN group, and no significant differences occurred between the TN and TD groups. The VAS score was lower in the SD group than in the SN group, and the PONV did not differ regardless of the use of dexmedetomidine. Dexmedetomidine may be an effective intraoperative adjuvant for a reducing emergence agitation and smooth emergence from anaesthesia after orthopaedic surgery in elderly patients. Current Controlled Trials NCT01851005 .

Although arthroscopic shoulder surgery is less invasive and painful than open shoulder surgery, it can often cause intra-operative hemodynamic instability and severe post-operative pain. This study was conducted to investigate the efficacy of the interscalene brachial plexus block (IBPB) on intra-operative hemodynamic changes and post-operative pain during arthroscopic shoulder surgery. After institutional review board approval, 50 consecutive patients that had undergone arthroscopic shoulder surgery under general anesthesia were randomly assigned to one of two groups to evaluate intra-operative hemodynamic changes and post-operative pain control. Group 1 patients received an IBPB with 10 ml of normal saline guided by a nerve stimulator before induction, and Group 2 patients received 10 ml of 0.5% ropivacaine hydrochloride with the same technique. The heart rate and systolic and diastolic blood pressures were recorded before the incision and 1, 3, 5, 10, and 20 minutes after the incision. Pre-operative and post-operative pain was evaluated with a visual analog scale 1, 3, 6, 12, and 24 hours after surgery. The patients were given tramadol as a rescue medication option. The total volume of tramadol that was injected was also evaluated over the same intervals. Group 2 showed significantly lower systolic and diastolic blood pressures and heart rates intra-operatively compared to Group 1 (P < 0.05). The visual analog scale pain scores, except at 24 hours after surgery, were significantly lower in Group 2 (P < 0.05). The total tramadol consumption significantly reduced in Group 2 (P < 0.05). IBPB effectively controlled the hemodynamic changes that occurred during arthroscopic shoulder surgery as well as post-operative pain.

Nahm FS, et al. Korean J Pain. 2013 Jan;26(1):21-26. https://doi.org/10.3344/kjp.2013.26.1.21

Background: A microemulsion propofol causes a high incidence of pain during intravenous injection. In this study, we investigated the effect of ramosetron on pain induced by microemulsion propofol injection. Methods: After prospective power analysis and institutional review board approval, a total of 200 ASA I and II patients undergoing general anesthesia were divided into 4 groups. They received one of the following intravenously after tourniquet application on the forearm 1 min before induction of anesthesia using microemulsion propofol; normal saline (Group N, n = 50), lidocaine 20 mg (Group L, n = 50), ramosetron 0.3 mg (Group R, n = 50) and lidocaine 20 mg plus ramosetron 0.3 mg (Group LR, n = 50) diluted into a 5 ml solution. The occlusion was released after 30 seconds and microemulsion propofol was injected over 10-15 seconds. The patients were observed and asked immediately if they had pain in the arm, and their responses were assessed. Results: The incidence of pain in groups N, L, R and LR was 96%, 76%, 60% and 38%, respectively (P < 0.008). Two patients in Group LR (4.0%) and nine in Group R (18.0%) had moderate to severe pain, which was significantly lower than pain in Groups N (84.0%), L (40.0%) and R (P < 0.008). Conclusions: Pretreatment with ramosetron 0.3 mg with or without lidocaine 20 mg with a tourniquet on the forearm 30 seconds before the injection of microemulsion propofol is more effective than lidocaine 20 mg or normal saline in preventing pain from a microemulsion propofol injection.

Background: Increase in intracranial pressure (ICP) is one of the physiologic changes during laparoscopic surgery, which is known to be associated with positional changes. Changes of ICP can be measured directly by invasive method, but ultrasonographic measurement of optic nerve sheath diameter (ONSD) is known to be a rapidly applicable technique for evaluating ICP. The aim of this study is to investigate the change of ONSD according to the positional change during laparoscopic surgery. Methods: Female patients scheduled to undergo laparoscopic surgery were enrolled. Fifty-seven patients were assigned according to the position during surgery (Group T: gynecological surgery, Trendelenburg position, n = 27 vs. Group RT: laparoscopic cholecystectomy, Reverse trendelenburg position, n = 30). After induction of anesthesia, ONSD, PaCO2, end-tidal carbon dioxide (ETCO2), and mean arterial pressure (MAP) were measured. Parameters were measured at 6 time points during surgery. Results: There were no significant differences in the demographic data of patients, procedure time, and anesthesia. After pneumoperitoneum and positional change, ONSD, ETCO2, and MAP increased in both groups until 15 min and returned to the baseline. However, no significant differences in changes of ONSD, PaCO2, ETCO2, and MAP were observed between two groups. Conclusions: ONSD during laparoscopic surgery with pneumoperitoneum increased slightly until 15 minutes, but there were no significant differences according to the position. Increases in ICP during laparoscopic surgery with short period of pneumoperitoneum would be small in disregard of position in patients without intracranial pathology.