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BACKGROUND Propofol is a commonly used intravenous drug during anesthetic induction because of its rapid onset and short duration. However, the injection pain that patients experience is so severe that they recall the induction of anesthesia as the most painful part of the perioperative period. Therefore, the objective of this study was to determine the effect of heated carrier fluids (40℃) in decreasing propofol injection pain. METHODS A randomized, controlled clinical trial was conducted in 90 patients aged 18 to 65 who were scheduled for either elective or urgent surgery under general anesthesia classified as American Society of Anesthesiologists physical status I or II. Patients were allocated into the following 3 groups: 1) Group W (n = 30) who received 200 ml of heated carrier fluids for 20 minutes prior to propofol injection; 2) Group L (n = 30) who received 200 ml of heated carrier fluids for 20 minutes prior to 0.5 mg/kg 1%lidocaine 1 minute before propofol injection; 3) Group C (control group, n = 30) who received 200 ml of room temperature fluids prior to propofol injection. Pain was evaluated using verbal pain score (VPS). RESULTS Group W and Group L showed significant reduction (P = 0.001) in the incidence and severity of injection pain compared to Group C. VPS scores were significantly lower in Group W and Group L compared to those of Group C. Incidence of propofol injection pain was statistically different between Group W (P = 0.005) and Group L (P = 0.037) compared to Group C, but not statistically different between Group W and Group L (P = 0.432). CONCLUSIONS Both sole injection of heated carrier fluids and the combination of 0.5 mg/kg 1%lidocaine pretreatment effectively reduced propofol injection pain.

Background: This clinical study was designed to evaluate the effect of midazolam as a premedication on the onset of propofol and rocuronium during propofol target-controlled infusion (TCI). Methods: Seventy four patients (ASA class I or II) were randomly allocated to receive either no premedication (control group) or premedication with 0.04 mg/kg intravenous midazolam (midazolam group). Anesthesia was induced and maintained with propofol TCI. Time from propofol injection to loss of consciousness (LOC) and estimated effect concentration at LOC were recorded. After LOC, rocuronium (0.6 mg/kg) was injected. We monitored the degree of neuromuscular blockade by acceleromyography. The following parameters were measured and compared between groups: Time from rocuronium injection to depression of twitch height below 25%, time to maximal depression of twitch height (defined as rocuronium onset time). Results: Systolic blood pressure before induction was lower in midazolam group (125±15 vs 135±20 mmHg), however, there was no difference in blood pressure at LOC between groups (111±16 vs 106±21 mmHg). In midazolam group, time to LOC in propofol TCI was shorter (63±22 vs. 203±118 sec) and estimated effect site concentration of propofol was significantly lower than control group (0.9±0.3 vs. 2.2±0.4 μl/ml). The onset time of rocuronium was not different between groups (120±39 vs. 137±42 sec). Conclusions: Midazolam pretreatment fastens the onset time of propofol and decreases the propofol requirement for LOC. However, it does not influence the onset of rocuronium. (Korean J Anesthesiol 2009;57:434∼7)

Background: The aim of this study is to investigate the characteristics of propofol abuse based on the results of a survey analysis of abusers among non-healthcare professionals in Korea. Methods: Thirty-eight propofol abusers were questioned between October and December 2010, and were enrolled and voluntarily participated in a structured survey consisting of an interview and completing a previously prepared questionnaire. The questionnaire was divided into three distinct parts: part 1 dealt with the history of propofol abuse; part 2 highlighted the problems caused by propofol abuse; and part 3 enquired regarding demographics of abusers. Results: Thirty-one (81.6%) of the 38 interviewees abused propofol for more than one year. During the last 12 months, 34 (89.0%) received propofol at two or three times a week. The minimum and maximum amounts of propofol (median, range) administered each time were 500 (100, 1000) and 2000 (500, 4000) mg, respectively. Stress relief and the maintenance of a sense of well-being were quoted the most important reasons for the first-time administration of propofol and its subsequent abuse, respectively. The majority of abusers (36.0, 97.3%) reported a sense of pleasure or euphoria at the time of their propofol injection. Withdrawal symptoms occurred in five abusers (13.2%). Thirteen (36.1%) reported disruptions in their work life. None of the respondents had previously admitted to and or reported abuse of any other controlled substances. Conclusions: These results provided reference data for the regulation of propofol in Korea as a controlled substance and may also be of interest to international agencies in other countries.

Background: Lidocaine has been used widely to prevent propofol injection pain. Various methods of administration exist, such as lidocaine premixed with propofol or lidocaine pretreatment using a tourniquet, but it is unclear which method of lidocaine administration is more effective for the prevention of injection pain of propofol LCT/MCT. The purpose of this study was to compare pretreatment of lidocaine with a tourniquet and a premixed injection of lidocaine to prevent injection pain of propofol-LCT/MCT. Methods: Patients were randomly allocated into the pretreatment group (n = 117) or the premixed group (n = 117). The pretreatment group was pretreated with 2 ml of lidocaine 2%, held with a tourniquet, before propofol-LCT/MCT injec tion. The premixed group was injected with a premixed solution of propofol-LCT/MCT and 2 ml of lidocaine 2%. To evaluate the incidence and severity of pain, spontaneous verbal expressions of pain, movement of hand, frowning, and moaning were recorded, and the patients were asked to recall their pain with the visual analogue score (VAS) 30 minutes after awakening from anesthesia. Results: Overall, injection pain occurred in 13.7% of the pretreatment group and 15.4% of the premixed group, without any statistical difference (P = 0.71). There was no difference in spontaneous verbal expressions of pain, movement of hand, frowning, and moaning between the two groups. The pain intensity (VAS) also showed no difference between the two groups (P = 0.49). Conclusions: Pretreatment of lidocaine with a tourniquet showed no more benefit to prevent injection pain of propofol LCT/MCT compared to a premixed injection with lidocaine. (Korean J Anesthesiol 2014; 66: 95-98)

Background: Propofol injection pain is an unpleasant experience to patients and its prevalence can be influenced by age and gender. We determined the half maximal effective concentration (EC 50) of remifentanil for preventing the microemulsion propofol injection pain in the male and female adult groups. Methods: After institutional review board approval, a total of 60 patients were assigned into 2 groups depending on their gender: group M (male, 20-65 yr) and group F (female, 20-65 yr). Anesthesia was induced with propofol and remifentanil, by a target-controlled infusion. Target effect-site concentration (Ce) of propofol and remifentanil for the first patient started at 4.0 ug/ml and 4.0 ng/ml. Ce of remifentanil for each subsequent patient was determined by the response of the previous patient by the Dixon's up-and-down method (DUDM) with an interval of 0.2 ng/ml. After equilibration of plasma and effect site remifentanil concentration, propofol was administered, and the pain responses were observed. Results: The remifentanil EC 50 was 3.8 ± 0.2 and 2.7 ± 0.2 ng/ml in groups M and F, respectively, by DUDM. From Probit regression model, the remifentanil EC50 was 3.7 (3.0-4.3) and 2.7 (1.8-2.9) ng/ml in groups M and F, respectively. Conclusions: The remifentanil EC 50 for preventing the moderate to severe injection pain of propofol was higher in males than in females. (Korean J Anesthesiol 2012; 63: 504-509)

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. (Korean J Anesthesiol 2011; 61: 30-34)

Background: Pain upon the injection of propofol is a common adverse effect. This study was conducted to evaluate the analgesic effect of remifentanil and cold propofol during propofol injection for the induction of anesthesia and to determine if a combination of cold propofol and remifentanil produced additional analgesic efficacy. Methods: A total of 160 patients aged 20-65 years old were randomly allocated into one of four groups (n = 40, in each). Control and remifentanil group patients received 2 mg/kg propofol that had been stored at room temperature (20-23 o C), while the cold and combination group received cold (4 o C) propofol. The patients received remifentanil 0.5 μg/kg IV in the remifentanil and combination groups or saline in the control and cold groups. Ninety seconds after administration the patients were administered propofol over a 30 second period. The pain intensity and incidence were then evaluated using a 4-point verbal rating scale. Results: The incidence of pain was significantly reduced in groups that received remifentanil in the cold and combination groups when compared with the control group (27.5%, 30%, and 2.5% vs. 70%, respectively). Moreover, the severity of pain was significantly lower in groups that received remifentanil in the cold and combination groups when compared with the control group. The incidence and severity of pain from the propofol injection in the combination group was significantly lower than that in the remifentanil and cold groups. Conclusions: The combination of cold propofol and pretreatment with remifentanil more effectively reduced the incidence of pain upon the injection of propofol than either treatment alone. (Korean J Anesthesiol 2010; 59: 305-309)

Background Similar to lipid emulsion propofol, microemulsion propofol also causes a high incidence of pain during intravenous injection. Various methods have been used to minimize the incidence and severity of pain on injection of lipid emulsion propofol. In this study, we investigated the effect of a lidocaine mixture on pain induced by microemulsion propofol injection, and sought to determine the optimal dose of lidocaine that could reduce pain on injecting a propofol-lidocaine mixture. Methods One hundred sixty (n = 160) patients of American Society of Anesthesiologists physical status class I or II were randomly allocated to four groups: Group A, control; Group B, 20 mg lidocaine; Group C, 30 mg lidocaine; Group D, 40 mg lidocaine. In each patient, pain on microemulsion propofol solution injection was graded as none, mild, moderate, or severe. Results The incidence of pain in groups A, B, C, and D was 97.5%, 80%, 65%, and 50%, respectively. Increasing the lidocaine dose significantly reduced pain (P < 0.05). One patient in Group D (2.5%) had moderate to severe pain, which was significantly lower than groups B (42.5%) and C (32.5%) (P < 0.05). Conclusions The lidocaine and propofol mixture is effective in alleviating pain associated with microemulsion propofol injection. Within this dose range and in this patients population, increasing lidocaine dosage significantly reduced pain during injection of microemulsion propofol.

Background: Microemulsion propofol produces more frequent and severe pain upon injection than lipid emulsion propofol. This study examined the analgesic effect of lidocaine-premixed microemulsion propofol in patients pretreated with remifentanil. The induction of anesthesia with this combination was compared with microemulsion propofol accompanied with either remifentanil or lidocaine. Methods: One hundred twenty patients aged between 20-65 years old were allocated randomly into one of three groups (n = 40, in each). The patients in the remifentanil group received remifentanil 0.5 μg/kg IV for 30 seconds before a microemulsion propofol injection. The patients in the lidocaine group received propofol 2 mg/kg premixed with 40 mg lidocaine over a 60 second period. The patients in the combination group received both remifentanil and lidocaine. Results: There was a significantly lower incidence of microemulsion propofol injection pain (severity 2 or more) in the combination group (12.5%) than in the remifentanil and lidocaine groups (90% and 65%, respectively, P < 0.05). The incidence of moderate pain disappeared completely in the combination group (0%) compared to that in the remifentanil and lidocaine group (32.5% and 20%, respectively, P < 0.05). Severe pain did not appear in any of the three groups. There were no complications on the injection site in the lidocaine alone and combination groups. Conclusions: The combination of microemulsion propofol premixed with lidocaine after a pretreatment with remifentanil was more effective in reducing the incidence of pain upon the injection of microemulsion propofol than either treatment alone. (Korean J Anesthesiol 2010; 58: 435-439)

Background: Propofol produces anesthesia with rapid recovery but also causes pain on injection. This study was designed to evaluate the effects of two different concentrations of remifentanil for minimizing the pain caused by propofol and to compare the hemodynamic changes during propofol-remifentanil infusion. Methods: In a randomized, double-blind study of 80 patients, we compared the severity of the injection pain of propofol between two groups of patients. The initial effect-site target concentration of remifentanil was set at 4 ng/ml (the R4 group, n = 40) or 8 ng/ml (the R8 group, n = 40). After the effect-site concentration of remifentanil was achieved, the infusion of propofol was started with the concentration of 4 μg/ml. The remifentanil-related complications were evaluated and the severity of the pain caused by propofol was compared by using a four-point scale during the propofol infusion. The heart rate and arterial blood pressure were measured at pre-induction, just before intubation and at 1 minute after intubation. Results: The severity of injection pain of propofol was significantly lower in the R8 group than in the R4. There was no significant difference in the incidence of remifentanil-related complications between the two groups. Compared with the pre-induction values, the heart rate and arterial blood pressure were significantly lower at pre-intubation and at 1 minute after intubation in the R4 and R8 groups. Conclusions: Pretreatment with an effect-site concentration of 8 ng/ml remifentanil may be useful for minimizing the propofol injection pain compared with 4 ng/ml remifentanil. (Korean J Anesthesiol 2009; 57: 155∼60)

The temporomandibular joint can be dislocated during anesthesia as a result of excessive oral opening and direct laryngoscope handling. Occasionally, yawning can be observed during the induction of anesthesia with propofol. The forceful and voluntary yawning after a propofol injection can lead to a dislocation of the temporomandibular joint. We report a case of an anterior dislocation of the temporomandibular joint upon induction with propofol, which caused difficulties in mask ventilation and endotracheal intubation. Although intubation had been carried out successfully in this case, an unanticipated difficult airway can be confronted at anytime. Therefore, anesthesiologists should be aware of the management of a difficult airway and practice various methods according to a difficult airway algorithm.

Background : Induction of anesthesia with propofol commonly associated with reduction in systemic arterial pressure, especially in elderly and high risk patients. This reduction is influenced by the dose and rate of propofol injection. The aim of this study was to examine the effect of different injection rate of propofol on vital signs, dose requirement and induction time during induction period. Methods : Unpremedicated one hundred and twenty ASA physical status I and II patients aged 20∼60 years scheduled for elective surgery were randomly allocated into one of four(150, 300, 600, 1200 ml/hr) groups according to speed of injection of propofol during induction period. Loss of verbal contact was taken as the end-point of induction. Vital signs, SpO2, dose requirement of propofol and induction time were checked. Results : As the injection rate of propofol became slower, there were significant reduction in induction dose and increase in induction time(P