Ultrasound-guided Pulsed Radiofrequency Lesioning of the Ulnar Nerve in a Patient with Cubital Tunnel Syndrome: A case report / 대한통증학회지

Ulnar nerve compression in the cubital tunnel is a common entrapment syndrome of the upper limb. Pulsed radiofrequency lesioning (PRFL) has been reported as a treatment method for relieving neuropathic pain. Since the placement of the electrode in close proximity to a targeted nerve is very important for the success of PRFL, ultrasound seems to be well suited for this technique. A 36-year-old woman presented with complaints of numbness and pain on the medial aspect of the elbow and the pain radiated down to the 4th and 5th fingers for 10 years after she suffered an elbow contusion, we then scheduled this woman for the ultrasound guided PRFL of the ulanr nerve. The initial ultrasound examination demonstrated a swollen nerve, loss of the fascicular pattern and an increased cross sectional area of the ulnar nerve. After confirmation of the most swollen site of the nerve via ultrasound, two sessions of PRFL were performed. The postprocedural 10 cm visual analog scale score decreased from 8 to 1 after the two sessions of PRFL.

Nonlinear Mixed Effect Modeling of Population Pharmacokinetics and Pharmacodynamics of Etomidate / 대한마취과학회지

BACKGROUND: Etomidate is used as a fast-acting hypnotic with few cardiovascular effects to induce anesthesia in patients with a poor cardiovascular reserve. The bispectral index (BIS) has been suggested to be a measure of the depth of anesthesia and correlates well with the level of consciousness. This study examined the population pharmacokinetics and pharmacodynamics of etomidate using nonlinear mixed effect (NONMEM) modeling and sigmoid Emax modeling. METHODS: Eighteen middle aged adults, with ASA physical status I or II, who were scheduled for elective surgery, were included. 0.2% etomidate was administerd at 150 ml/h until the patients lost consciousness. The patient recovered spontaneously until they regained consciousness, as determined by a verbal response. The BIS was determined and arterial blood samples were collected. The plasma concentrations were measured with high performance liquid chromatograhy (HPLC). NONMEM was used for population pharmacokinetic and sigmoid Emax model for pharmacodynamic analysis. RESULTS: The induction dose for the loss of eyelid reflexes was 0.38 mg/kg. The induction time from drug infusion to the loss of eyelash reflexes was approximately 3.5 minutes. This study took approximately 8.5 minutes from the start of drug infusion to the recovery of consciousness. The pharmacokinetic parameters were t(1/2alpha) = 1.1 min, t(1/2beta) = 1.9 min, t(1/2gamma) = 106.5 min, k(21) = 0.36 L/min, k(31) = 0.009 L/min, V(1) = 6.43 L, V(area) = 426 L, C(l) = 2.77 L/min. The pharmacodynamics were keo = 0.40 L/min, CE(50) = 1.0 microgram/mL, E(0) = 94, E(max) = 94 and gamma = 1.2. The performance error for the etomidate concentration was 0.14+/-0.99 (typical prediction) and -0.03+/-0.40 (individual prediction) and -0.09+/-1.00 and -0.001+/-0.13 for the BIS score. CONCLUSIONS: When compared with other previously published data, our pharmacokinetic parameters demonstrated a shorter half lives, a larger volume of distribution, and an increased clearance with significant interindividual differences. The pharmacodynamics showed a large interindividual variability. The reason for discrepancy might be the relatively short sampling time. However, further study will be warranted to improve the model performance in the future.

Nonlinear Mixed Effect Modeling of Population Pharmacokinetics and Pharmacodynamics of Etomidate / 대한마취과학회지

BACKGROUND: Etomidate is used as a fast-acting hypnotic with few cardiovascular effects to induce anesthesia in patients with a poor cardiovascular reserve. The bispectral index (BIS) has been suggested to be a measure of the depth of anesthesia and correlates well with the level of consciousness. This study examined the population pharmacokinetics and pharmacodynamics of etomidate using nonlinear mixed effect (NONMEM) modeling and sigmoid Emax modeling. METHODS: Eighteen middle aged adults, with ASA physical status I or II, who were scheduled for elective surgery, were included. 0.2% etomidate was administerd at 150 ml/h until the patients lost consciousness. The patient recovered spontaneously until they regained consciousness, as determined by a verbal response. The BIS was determined and arterial blood samples were collected. The plasma concentrations were measured with high performance liquid chromatograhy (HPLC). NONMEM was used for population pharmacokinetic and sigmoid Emax model for pharmacodynamic analysis. RESULTS: The induction dose for the loss of eyelid reflexes was 0.38 mg/kg. The induction time from drug infusion to the loss of eyelash reflexes was approximately 3.5 minutes. This study took approximately 8.5 minutes from the start of drug infusion to the recovery of consciousness. The pharmacokinetic parameters were t(1/2alpha) = 1.1 min, t(1/2beta) = 1.9 min, t(1/2gamma) = 106.5 min, k(21) = 0.36 L/min, k(31) = 0.009 L/min, V(1) = 6.43 L, V(area) = 426 L, C(l) = 2.77 L/min. The pharmacodynamics were keo = 0.40 L/min, CE(50) = 1.0 microgram/mL, E(0) = 94, E(max) = 94 and gamma = 1.2. The performance error for the etomidate concentration was 0.14+/-0.99 (typical prediction) and -0.03+/-0.40 (individual prediction) and -0.09+/-1.00 and -0.001+/-0.13 for the BIS score. CONCLUSIONS: When compared with other previously published data, our pharmacokinetic parameters demonstrated a shorter half lives, a larger volume of distribution, and an increased clearance with significant interindividual differences. The pharmacodynamics showed a large interindividual variability. The reason for discrepancy might be the relatively short sampling time. However, further study will be warranted to improve the model performance in the future.

The Comparison of Minimum Alveolar Concentration and BIS50 of Inhalation Anesthetics for Evaluation of Anesthetic Potency / 대한마취과학회지

BACKGROUND: The bispectral index (BIS) has been designed to objectively measure the degree of sedation and hypnosis for anesthesia. Although it has been well-known that BIS correlates highly with the concentration of inhalation anesthetics, it is not clear whether analgesic potency expressed as MAC is comparable to hypnotic potency described as BIS50 in inhaled anesthetics. This study was conducted to examine the degree of correspondence by correlating the changes of BIS according to the different MAC of commonly used inhalation anesthetics. METHODS: One hundred ASA class 1 or 2 patients, scheduled for laparoscopic knee surgery were included. Patients were equally divided into 4 groups (n = 25 each) according to the inhalational agent enflurane, isoflurane, desflurane, or sevoflurane. Anesthetic depth for each individual agent was controlled to 2.0, 1.75, 1.5, 1.25, 1.0, 0.75 and 0.5 MAC, respectively. After equilibration for each concentration, BIS values were measured three times at 30 second intervals and an average was obtained. In addition, MAC values for each agent were measured when the bispectral index showed 50. RESULTS: The concentrations of inhaled agents vs. BIS showed high negative correlations (enflurane; -0.91, isoflurane; -0.94, desflurane; -0.84, and sevoflurane; -0.86). BIS50 for each agent was enflurane, 0.93 (1.6 vol%); isoflurane, 0.71 (0.9 vol%); desflurane, 0.95 (5.7 vol%); and sevoflurane, 0.84 MAC (1.7 vol%). Isoflurane-BIS50 showed a significant difference to the others (P<0.05). CONCLUSIONS: We concluded that the MAC of inhalation anesthetics showed poor correlation with BIS, suggesting a difference between the hypnotic and analgesic potency of individual inhaled anesthetic agents.

Atypical Increases of BIS according to Effect Site Concentration of Propofol in Severely Burn Patients Undergoing Early Escharectomy / 대한마취과학회지

BACKGROUND: This bispectral index, which is used for intravenous anesthetics and inhalation anesthesia, is a scale of sedation and hypnotic effect, which is widely used in clinics. Atypical changes in BIS are expected due to increased cardiac output, decreased blood albumin concentrations and renal function in severe burn patients undergoing early escharectomy. The aim of this study was to compare BIS according to effected site concentrations of propofol during anesthetic induction using propofol TCI in severe burn and nonburn patients. METHODS: Forty patients were classified as twenty nonburn elective surgical patients (group 1) and twenty burn patients scheduled for escharectomy (group 2). For induction, a propofol TCI device incorporating a prefilled syringe was adjusted to a target concentration of 6mug/ml in flash mode. The bispectral index was checked before induction and at each effect site concentration of propofol (0.5mug/ml interval) until an effect site concentration of 4.5mug/ml. Other suspected contributory factors such as cardiac index, creatinine clearance and albumin were checked simultaneously. The unpaired t-test and repeated measures ANOVA were performed for the statistical analysis. RESULTS: Below an effect site concentration of propofol of 3mug/ml, no BIS difference was evident between group 1 and group 2. However, at 3.5mug/ml, group 1 was 41.1+/-13.5 and group 2 was 54.7+/-16.6 and at 4mug/ml, group 1 was 40.1+/-2.6 and group 2 was 50.1+/-13.1. Among the suspected contributing factors, cardiac index and albumin showed significant differences between groups 1 and 2 (cardiac index: 3.4+/-0.5 L/min/m2 vs 2.7+/-0.3 L/min/m2, albumin: 4.1+/-0.3 g/dl vs 2.6+/-0.3 g/dl, P<0.05). Creatinine clearance showed no significant difference between the groups. CONCLUSIONS: Severe burn patients who are expecting early escharectomy had higher BIS values than nonburn patients from an effect site concentration of propofol of 3.5mug/ml. This study suggest that cardiac index should be considered as a factor that influences propofol.

A Comparison of the Laryngeal Tube, Laryngeal Mask Airway ClassicTM and Laryngeal Mask Airway ProsealTM during General Anesthesia / 대한마취과학회지

BACKGROUND: The laryngeal tube is a variant of the esophageal obturator airway. We compared laryngeal tube (LT), laryngeal mask airway classicTM (LMA) and laryngeal mask airway ProsealTM (PLMA) as a airway management device during general anesthesia. METHODS: Forty-five fasted healthy adult patients were enrolled in this study into one of three groups in a randomized, single-blinded protocol. Group 1 was to receive LT for airway management, LMA for Group 2, and PLMA for Group 3. General anesthesia was induced identically in three groups with thiopental sodium 5 mg/kg followed rocuronium 0.6 mg/kg. 90 seconds later, LT, LMA or PLMA was placed for airway management. Blood pressure and heart rate were measured immediately pre-induction control value, post-insertion of device 0 min, 1 min, 3 min and 5 min. We also compared times of insertion, the amounts of secretion, blood stain, and postoperative sore throat. RESULTS: There was no significant change of SBP, DBP and HR within three groups. All the groups showed stable hemodynamic results. The success rate on the first attempt was 93.6% (14/15, Group 1), 93.6% (14/15, Group 2) and 86.6% (13/15, Group 3). Minimum cuff volume to prevent gas leakage was 69.9+/-0.5 ml (Group 1), 11.1+/-4.3 ml (Group 2) and 11.9+/-3.2 ml (Group 3). The corresponding cuff pressure was 61.6+/-22.0 cmH2O (Group 1), 4.8+/-0.9 cmH2O (Group 2) and 4.6+/-1.5 cmH2O (Group 3). Moderate, severe sore throat was 20% (3/15, Group 1), 6.6% (1/15, Group 2) and 6.6% (1/15, Group 3). Moderate, profuse secretion was 40% (6/15, Group 1), 20% (3/15, Group 2) and 13.3% (2/15, Group 3). There was a 20% (3/15, Group 1) and 13.3% (2/15, Group 3) blood stain. But there was no blood stain for the Group 2. There was a 20% (3/15) gas leakage in Group 1, so we had to insert gas intermittently, but there were no gastric distension, regurgitation, aspiration, hypoxia, airway obstruction and laryngospasm in all three groups. CONCLUSIONS: All the groups revealed stable hemodynamics, no serious complications such as regurgitation, aspiration, hypoxia and airway obstruction during general anesthesia. But we did not find any evidence that LMA and PLMA have the remarkable advantages than laryngeal tube. So we suggested that laryngeal tube could be an alternative airway management device, even though further study will be needed.

The Experimental Study Using Beagle Dogs for the Clinical Application of Poloxamer-solutol Propofol / 대한마취과학회지

BACKGROUND: To reduce side effects such as hyperlipidemia, pain on injection, and bacterial growth of the present formation of propofol, many attempts to change its formulation have been tried. We have developed a newly formulated poloxamer-solutol propofol, which is includes soy bean oil and egg phosphatide as sufactants. The aim of this study was to evaluate the poloxamer-solutol propofol regarding its pharmacokinetic and pharmacodynamic characteristics and bacterial growth compared to original propofol. METHODS: Thirty Beagle dogs weighing around 10-15 kg were randomly assigned to one of two groups. Group 1 received Diprivan propofol 1% (AstraZeneca Co. UK), Group 2 received poloxamer-solutol formulated propofol by continuous intravenous infusion at 35 mg/kg/h for 3 hours. Three, 6, 9 and 12 hours after the discontinuation of the propofol infusion, venous samples from the anterior tibial vein were analysed for liver and renal function test. Also, blood lipid levels were checked after 3 hours of infusion and blood propofol concentrations were checked every hour during infusion. Eye opening time and orientation time, represented by walking on four legs, were evaluated. Also, broth cultures (100microliter) of four standard preservative efficacy test organisms (Staphylococcus Aureus, Pseudomonas Aeruginosa, Escherichia Coli, Candida Albicans) were added to 9.9 ml of four test formulations at approximately 200 colony forming units/ml. The subjected formulations were; original propofol (AstraZeneca Co, 1% solution, UK), EDTA added propofol (0.0055% EDTA added propofol), Poloxamer-Solutol formulated propofol (poloxamer 188/407 and solutol mixture), and normal saline. The test formulations were incubated at 25degrees C and 32.5degrees C (Tryptic soy agar medium for bacteria and Sabrouraud dextrose agar medium for fungus) and tested for viable counts after 24 and 48 hours. RESULTS: Poloxamer-solutol propofol showed no increase of triglyceride and the propofol concentrations showed no difference between the two groups. Also the original propofol supported the growth of all microorganisms at both temperatures and times. EDTA added propofol inhibited the growth of microorganisms more than the original propofol, but not as much as the poloxamer-solutol formulated propofol. Saline showed a similar pattern as the propofol with added EDTA. CONCLUSIONS: The poloxamer-solutol formulated propofol has advantages by pharmacokinetic-pharmacodynamic studies in terms of the initial TG level during propofol infusion, and shows more bacteriostatic activity against all four microorganisms than the original propofol and the propofol with added EDTA.

Optimal Initial Target Concentration and Minimal Effective Analgesic Concentration for Target Controlled Analgesia Using Fentanyl / 대한마취과학회지

BACKGROUND: The main advantage of drug administration by target-controlled infusion (TCI) is that it allows rapid adjustments of blood concentrations to individual patients requirements. In this study, we tried to confirm the side effects, relation, safety range and minimum effective analgesic concentration (MEAC) of fentanyl at the effect site. METHODS: Sixty ASA physical status 1 or 2 patients (age: 20 - 50 years) undergoing orthopedic surgery with regional anesthesia were randomly allocated to one of three groups according to effect site concentration of fentanyl (1, 1.5, or 2 ng/ml, n = 20 for each group). Total infusion time, total amount of drugs, vital signs, muscular rigidity, respiratory depression, level of consciousness, nausea, vomiting and pruritus was investigated. Meanwhile, we evaluated the MEAC by checking the effect site concentration of fentanyl when the patient complained of pain following propofol-fentanyl-N2O anesthesia using a computer assisted continuous infusion (n = 30). RESULTS: Demographic data and averaging scores of each parameter showed no difference among groups. However, incidences tended to increase above 1.5 ng/ml except with rigidity in the 1.5 ng/ml fentanyl group. The MEAC of fentanyl was checked as 0.61 +/- 0.18 ng/ml. CONCLUSIONS: Estimated MEAC of fentanyl was 0.61 +/- 0.18 ng/ml. There were increased side effects and complaints of patients above 1.5 ng/ml. The optimal initial postoperative target concentration of fentanyl was considered as 1 ng/ml.

Equianalgesic Concentration of Fentanyl Comparable to 67% N2O during Propofol Based General Anesthesia / 대한마취과학회지

BACKGROUND: When using a target controlled infusion (TCI) of propofol, combination with N2O or fentanyl as an analgesic adjuvant is common in clinical practice. In a previous study, a minimal steady state plasma concentration necessary to prevent a response in 50% of the patients following a skin incision (Cp50i) for propofol was reduced from 6ng/ml to 4.5ng/ml with 67% nitrous oxide/oxygen compared to air/oxygen. The goal of this study was to quantify the effect site concentration of fentanyl required to replace 67% N2O at a propofol effect site target concentration of 4.5ng/ml. METHODS: Forty six ASA class I or II adult patients scheduled for lower extremity surgery were randomly allocated to one of three groups according to assigned effect site concentration of fentanyl. Group 1, n = 15; 0.5 ng/ml, Group 2, n = 15; 1.0 ng/ml, Group 3, n = 15; 1.5 ng/ml. Patients received propofol with target concentration 4.5ng/ml and predetermined target concentration of fentanyl in three groups. A laryngeal mask airway was placed after anesthesia induction and all patients were controlled ventilation with 67% air/33% oxygen. The response to the skin incision was observed and the patients categorized as movers or non-movers according to Eger's criteria. Cp50i for fentanyl was evaluated using nonlinear regression analysis. RESULTS: Non-movers to skin incision was 20%, 43.7%, 73.7% in groups 1 3 respectively. Cp50i for fentanyl combined with propofol 4.5ng/ml was 1.08 ng/ml. CONCLUSIONS: We concluded that the MAC for 67% N2O is equivalent to an effect site target fentanyl concentration of 1.08 ng/ml in terms of no movement to skin incision.

Changes of Serum Lipid Concentration during General Anesthesia with Propofol Using Target Controlled Infusion / 대한마취과학회지

BACKGROUND: Propofol is a widely used hypnotic, however hyperlipidemia is one of the disadvantages caused by its formulation. The aim of this study was to investigate the concentration of total cholesterol, high density lipoprotein (HDL-cholesterol) and triglycerides during general anesthesia with propofol using a target controlled infusion. METHODS: With Institutional Review Board approval and informed consent, thirty premedicated (atropine 0.5 mg, I.M) adult patients (ASA class I or II, 18 - 55 yrs) scheduled for elective surgery were studied. A TCI of propofol was started at a target concentration of 6.0ng/ml. After intubation with the aid of vecuronium (0.15 mg/kg), anesthesia was maintained with propofol in combination with 67% N2O and 33% O2. Blood was sampled from the median cubital vein for total cholesterol, HDL- cholesterol, and triglycerides at 0, 1, and 2 hours during anesthesia, the end of surgery, and 24, 48, and 72 hours after anesthesia. RESULTS: At 1 and 2 hours, and the end of surgery, triglyceride concentrations showed a significant increase compared to the control (P < 0.05), however it declined steeply to normal range during the next 24 hours. The total cholesterol and HDL-cholesterol concentrations were within a normal range throughout the study period. There was a correlation between triglyceride concentrations (peak triglyceride concentration-control triglyceride concentration) and amount of infused propofol (Spearman's r = 0.42, P < 0.05). CONCLUSIONS: Because the infusion of propofol during anesthesia results in a significant increase in triglyceride concentrations, we should consider checking the triglyceride concentrations intermittently in critically ill patients who receive propofol. However, propofol may be safe to healthy patient for general anesthesia.

The Changes of Propofol Concentration over Time in a Propofol-Lidocaine or Propofol-Ketamine Mixtures / 대한마취과학회지

BACKGROUND: Pretreatment or addition of lidocaine or ketamine have been reported to reduce pain on injection. However, the stability of propofol following the addition of lidocaine or ketamine is not yet known. Therefore, we checked compatibility and stability of propofol-lidocaine or propofol-ketamine mixtures. METHODS: After mixing 9 ml of 1% propofol and 0, 5, 10, 15, or 20 mg of 2% lidocaine or 10, 20 mg of ketamine, the samples (0.9 ml) were divided into 10 glass vials and stored at room temperature. Macroscopic and microscopic changes, and propofol concentrations were measured at 0, 1/4, 1/2, 1, 2, 3, 4, 5, 6, and 24 hours after mixing. Premedicated 100 ASA classification I or II patients scheduled for elective surgery were randomly allocated into one of three groups(Group 1: propofol only, Group 2: propofol + lidociane 20 mg, Group 3: propofol + ketamine 10 mg). Intensity and frequency of injection pain was checked during induction (150 ml/hr). Intensity of injection pain was evaluated with a pain score (1: no pain, 2: mild, 3: moderate 4: severe). RESULTS: Macroscopic and microscopic changes were only seen in propofol-lidocaine mixtures (more than 15 mg after 1 hour) in a time-dependent manner. In the mixtures with lidocaine 15 or 20 mg, the propofol concentration decreased linearly and significantly compared to the control (time 0) in a time-dependent manner from 1 hour to 24 hours. However, the propofol concentration was not changed in the propofol-ketamine mixtures. The pain score at 20 mg of lidocaine or 10 mg of ketamine were significantly lower than propofol only group and there was no difference in pain score between group 2 and group 3. CONCLUSIONS: Lidocaine (more than 15 mg), but not ketamine, added to 90 mg of propofol reduced the propofol concentration linearly in a time-dependent manner and showed microscopic changes from l hour after mixing. Therefore, this mixture seems to be inappropriate for long-standing storage and thus propofol-ketamine mixtures are more appropriate for this purpose.

The Comparison for the Growth of Microorganisms in Original Propofol, Ethylenediaminetetraacetic Acid (EDTA) Added Propofol, and Poloxamer-Solutol Formulated Propofol / 대한마취과학회지

BACKGROUND: Because there is difficulty in the addition of known preservatives to oil in water emulsion such as propofol, ethylenediaminetetraacetic acid (EDTA) added to this may formulate for the antimicrobial activity; however, this formulation has side effects such as hyperlipidemia and pain on injection. We have developed a newly formulated poloxamer-solutol propofol which is considered to be free from hyperlipidemia. The aim of this study was to evaluate the possibility of bacterial growth in poloxamer-solutol formulated propofol compared to original propofol and EDTA added propofol. METHODS: Broth cultures (100nl) of four standard preservative efficacy test organisms (Staphylococcus Aureus, Pseudomonas Aeruginosa, Escherichia Coli, Candida Albicans) were added to 9.9 ml of four test formulations. Subjected formulations were original propofol (AstraZeneca Co, 1% solution, UK), EDTA added propofol (0.0055% EDTA added propofol), Poloxamer-Solutol formulated propofol (poloxamer 188/407 and solutol mixture), and normal saline at approximately 200 colony forming units/ml. The test formulations were incubated at 25degreesC and 32.5degreesC (Tryptic soy agar medium for bacteria and Sabrouraud dextrose agar medium for fungus) and tested for viable counts after 24 and 48 hours. RESULTS: Original propofol supported the growth of all microorganisms at both temperature and time. EDTA added propofol inhibited the growth of microorganisms more than the original propofol, but not so much as the poloxamer-solutol formulated propofol. Saline showed a similar pattern as EDTA added propofol. CONCLUSIONS: Poloxamer-solutol formulated propofol possesses more bacteriostatic activity against all four microorganisms than the original and EDTA added propofol.

The Effect of Inhaled Desflurane Concentrations on the Bispectral Index / 대한마취과학회지

BACKGROUND: The bispectral index (BIS) has been designed to objectively measure the degree of sedation and hypnosis for several anesthetics. The aim of this study was to evaluate the changes of the BIS during desflurane-N2O-O2 anesthesia. METHODS: With Institutional Review Board approval and informed consent, forty premedicated (atropine 0.5 mg, IM) male and female adult patients (ASA class 1 or 2, 18 55 yrs) scheduled for elective surgery were studied. After intubation with the aid of propofol (2.0 mg/kg) and vecuronium (0.15 mg/kg), anesthesia was maintained with desflurane in combination with 50% N2O and 50% O2. Several transitions between 3.0 and 12.0 vol% were performed. During anesthesia, the BIS was checked at least 30 min after induction to avoid the residual effect of propofol and after 15 min maintenance of a certain inhaled concentration for equilibration. RESULTS: The values of BIS were correlated closely with the desflurane concentrations (r = 0.88). Steep changes in the BIS were shown between 1.5 6.0 vol% and a ceiling effect regarding the BIS over 6.0 vol% was observed. CONCLUSIONS: The BIS is valuable for measuring the degree of sedaton and hypnosis in desflurane anesthesia. Above 6.0 vol%, desflurane showed a ceiling effect regarding the BIS.

The Clinical Experience of Propofol-Alfentanil Anesthesia Using Computer Assisted Continuous Infusion / 대한마취과학회지

The short duration and fast onset of action of alfentanil underpins its suitability for use in anesthetic techniques. In these case studies, we have assessed the efficacy, safety and feasibility of alfentanil as an analgesic adjuvant of propofol based general anesthesia. Propofol was titrated to Keep the bispectral index in the 40 50 range. Alfentanil was infused at the effect site concentration of 80 or 160 ng/ml using a computer assisted continuous infusion. Two patients in this pilot study showed stable hemodynamics, smooth emergence and satisfactory postoperative pain control with additional analgesics in PACU.

Comparison of Poloxamer-407 to Soybean Oil as an Emulsifying Agent for Propofol: Histamine Release and Plasma Lipid Levels / 대한마취과학회지

BACKGROUND: To reduce side effects (hyperlipidemia, pain on injection, etc.) of the present formation of propofol, many attempts to change the emulsifying agent for propofol have been tried. This study was designed to examine the poloxamer-407 as an emulsifying agent for propofol compared to soybean oil regarding histamine release and plasma lipid levels. METHODS: Twelve Beagle dogs weighing 12 - 16 kg were randomly assigned to one of two groups according to the formulation of propofol. Group 1 received Diprivan propofol 1% (AstraZeneca Co. UK), and group 2 received poloxamer-407 formulated propofol by a continuous intravenous infusion at 30 mg/kg/h for 3 hours. Three, 6, 9 and 12 hours after discontinuing the propofol infusion, venous blood samples from the cranial tibial vein were analysed by an ELISA kit for the histamine level. Also, blood lipid levels were checked 3 hours after the infusion and blood propofol concentration were checked every hour during the infusion. RESULTS: Group 2 showed significantly less histamine release than group 1 at 3, 6 and 9 hours after the infusion (P < 0.05). In the plasma lipid study, there was no difference in high-density lipoprotein (HDL) between the two groups, but triglyceride and cholesterol were significantly higher in group 2 (P < 0.05). There was no difference in propofol concentrations between the two groups. CONCLUSIONS: Poloxamer-407 as an emulsifying agent for propofol showed no advantage compared to a present formulation regarding hyperlipidemia, and even decreased the histamine level.

Changes in Bispectral Index during Coinduction with Intravenous Anesthetics Using Synergistic Interaction / 대한마취과학회지

BACKGROUND: Coinduction according to a hypnotic synergistic effect of intravenous anesthetics has an advantage of reducing hemodynamic change, induction dose and side effects of each drug. Meanwhile, the bispectral index has been used to monitor objective measurement of the hypnotic effect of intravenous anesthetics. The aim of this study was to evaluate the changes in the bispectral index during coinduction with two intravenous anesthetics that were known to have synergistic interactions. METHODS: Sixty ASA I or II adult patients undergoing elective surgery were assigned to one of three groups according to induction methods: group 1, thiopental + propofol; group 2, thiopental + midazolam; group 3, midazolam propofol. Anesthesia induction was performed by injecting half of a hypnotic ED50 dose of both drug according to the known time to peak effect. For example, in group 1, propofol was injected first, and then thiopental 1 min. later. The Bispectral index, vital signs, and SpO2 were checked every minute for 5 minutes after injection of a drug. RESULTS: Each group showed the lowest point of the BIS at time to peak effect, but the reduction of the BIS for each group showed no regular pattern between time and amount of degree compared to the lowest BIS of the two drugs when they were used alone. CONCLUSIONS: The BIS has limitations in expressing a synergistic interaction phenomenon when anesthesia induction with two intravenous anesthetics that have a synergistic interaction.

Recognition of Kind and Concentration of a Drug Using an Optical Signal Sensor in a Target Controlled Infusion of Intravenous Anesthetics / 대한마취과학회지

BACKGROUND: An automatic procedure to detect and recognize the specified drugs for a target controlled infusion system based on the absorption ratio of the optical signals (red and infrard light) was proposed. METHODS: A red (660 nm) and infrared (925 nm) light emitting diode (R-IR LED) and photodiode was established at two perforated holes on a 50 ml syringe horizontally and opposite. The syringe was isolated from extra-light sources, such as sun-light or fluorescent light, with a dark sheet. First, the light of the R-IR LED was emitted into free space without insertion of any other syringe. After measuring the intensity of radiation, a 30 ml syringe containing a drug solution was pushed into the 50 ml syringe and again the intensity of light was measured. We measured intensities of light for 1% or 2% propofol and 0.5% thiopental sodium three times and compared it to the measurement of the free space. In order to investigate mechanical error, we measured it again two days later. We calculated errors among each measurement, simple errors and ratios between first and second time measurements and whether the error was within a permissible error range (less than 1%). After all of this, we evaluated the accuracy and clinical usefulness of this new method. RESULTS: Ratio of intensities of transmission of light in each drug solution to free space showed thiopental, 1% propofol and 2% propofol in order. Considering permissible error between the first and second time measurements, this method showed no problem in recognition of kinds and concentrations of drugs. CONCLUSIONS: We supposed that this simple optical method for drug recognition can be applied for target controlled infusion operation instead of the currently available magnetic recognition tag combined to a syringe.

Effects of Flow Rate and Dilution during Anesthesia Induction with Propofol / 대한마취과학회지

BACKGROUND: The Pharmacokinetic parameter and the degree of dilution can have an effect on induction time and vital signs during general anesthesia with propofol. Induction time, induction dose and vital signs according to various flow rates and the degrees of dilution during anesthesia induction with propofol were studied. METHODS: After institutional review board approval, and informed consent, One hundred and eighty ASA I or II adult patients undergoing elective surgery were assigned to one of four groups according to their degree of dilution. One group was undiluted and another 3 groups were diluted with 5% D/W (1:1, 1:2, 1:3). Each group was divided into 3 subgroups according to their flow rates of 25, 50, 100 mg/kg/hr. No premedication was given. With routine monitoring including radial arterial cannulation, propofol was infused using a syringe or infusion pump (Becton Dickinson pump, Franklin Lakes New Jersey, USA) in the previously designed manner. Induction time defined as loss of eyelash reflex, induction dose, and vital signs were checked. RESULTS: The faster the flow rate and the more diluted a drug, the shorter the induction time. The faster the flow rate and the less diluted a drug, the greater the induction dose. The more diluted a drug, the less the decrease in systolic blood pressure. Flow rate has little influenced decreasing systolic blood pressure. CONCLUSIONS: We concluded that it is reasonable to reduce flow rate and dilute propofol when the hemodynamic changes of the patient should be minimal during propofol based sedation/anesthesia.

Evaluation of Marsh's Pharmacokinetic Parameter Set for Target Controlled Infusion of Propofol in Korean / 대한마취과학회지

BACKGROUND: Marsh's pharmacokinetic parameter set is the most widely used parameter for target controlled infusion for propofol. However, Marsh's model was derived from a European population, and it is uncertain whether this model is accurate for Koreans. METHODS: Thirty ASA 1 or 2 adult patients undergoing orthopedic surgery participated in this study. Atropine 0.5 mg was injected for premedication. Anesthesia was induced by a TCI of propofol with a target concentration of 6 microgram/ml and maintained around 3 - 5 microgram/ml according to the bispectral index (35 - 45). In the middle of surgery, target concentrations were increased to 6 microgram/ml and maintained until effect site concentration was the same concentration. Three minutes after equilibration, 3 ml of blood was drawn from the radial artery and contralateral antecubital cephalic vein for measuring blood concentration using HPLC. Target concentrations were gradually decreased at the interval of 1 microgram/ml until the end of surgery and a blood sample was drawn as described in the method. A sample for every 1 microgram/ml was collected in the recovery room. Performance error of the predicted concentration of blood was calculated. RESULTS: The performance error was -12.86 - 16.55% for 1 - 6 microgram/ml of predicted concentration. Measured concentrations were higher than predicted at higher concentrations, but lower at lower concentrations. Measured cardiac output and arteriovenous concentration differences at 1 - 6 microgram/ml showed no difference. CONCLUSIONS: Marsh's pharmacokinetic model was accurate for propofol TCI in Koreans in terms of relatively low performance error (< 20%) in the concentration range of 1 - 6 microgram/ml.

Effect of Fentanyl on the TNF-alpha and IL-1beta Level during Global Ischemia/reperfusion in Rats / 대한마취과학회지

BACKGROUND: To reduce surgical stress, fentanyl is frequently used for neurosurgical procedure where focal and/or global ischemia may occur. However, the effect of fentanyl on the cytokine level during ischemia/reperfusion is still uncertain. The goal of this study was to evaluate the effect of fentanyl infusion on the proinflammatory cytokine, TNF-alpha and IL-1beta, levels during global cerebral ischemia/reperfusion (I/R) in rats using the intracerebral microdialysis technique. METHODS: Forty male S-D rats weighing 280 320 g were randomly assigned to four groups. Group 1: no fentanyl infusion and only I/R, Group 2: 1.5 ng/ml of fentanyl infusion during I/R, Group 3: 3.0 ng/ml of fentanyl infusion during I/R (n = 10 in each group). Rats were anesthetized with a intraperitoneal injection of pentobarbital (50 mg/kg), intubated and ventilated with room air using an animal ventilator. Two femoral arteries and one femoral vein were cannulated with PE-50 tubing for hemorrhagic hypotension, drug infusion and hydration. Both carotid arteries were dissected and a sling was placed for brain ischemia. The head was fixed on a stereotaxic device and a small burrhole was made for probe insertion. A CMA-12 probe was inserted into the left hippocampal CA-1 region according to the guidelines. Artificial CSF was run from the inserted microdialysis probe and infused with or without fentanyl at 3 microliter/min using a microinjection syringe pump during I/R. Ischemia was induced by clamping the carotid arteries while hemorrhagic hypotension for 17 min via the femoral artery and reperfusion were accomplished by the unclamping of the sling and reinfusing the blood via the femoral artery. Nasopharyngeal and rectal temperatures were maintained within the normal range during the whole procedure. After 2 hours of stabilization, the microdialysate was collected every 17 min just before (control) and during I/R and stored at 80oC until analysis using HPLC. RESULTS: During global I/R, TNF-alpha and IL-1 beta significantly increased at reperfusion (R5) compared to the control value (P < 0.05). However, in both cases of fentanyl infusion, TNF-alpha and IL-1 beta did not increase compared to the control value. CONCLUSIONS: Fentanyl inhibited the increase of proinflammatory cytokine TNF-alpha and IL-1 beta levels during global cerebral ischemia/reperfusion in rats.