Effect of Different Concentration of Fentanyl on Maintenance, Recovery and Postoperative Pain Relief in Propofol-Fentanyl-N2O Anesthesia / 대한마취과학회지

BACKGROUND: Skin incision has been used as a standard stimulus in most concentration versus response relationship studies for anesthetics. However, skin incision is not the most intense stimulation and inconvenient method during operation. Mean arterial blood pressure, but not heart rate, is convenient and predicts surgical stress as well as propofol blood concentration. We evaluated the effects of different fentanyl concentration on propofol-fentanyl-N20 anesthesia using mean arterial blood pressure as an indicator of surgical stress during operation. METHODS: Eighty ASA I or II patients (age: 20~55 yrs) scheduled for spine fusion were randomly allocated to four groups according to expected fentanyl blood concentration (Group 1, 2, 3, 4: 0, 1.5, 3.0, 4.5 ng/ml respectively, n=20 for each group). Fentanyl was infused according to isoconcentration nomogram, and propofol infusion rate was titrated by changes of mean arterial blood pressure (0~12 mg/kg/hr). Fifteen minutes before expected end of surgery, propofol and fentanyl infusion were discontinued. Thereafter IV-PCA using fentanyl was applied for postoperative pain relief. Average propofol flow rate, recovery of orientation, verbal rating scale were cheked. RESULTS: Group 2, 3, 4 showed decreased average propofol flow rate, delayed recovery and decreased postoperative 24 hr fentanyl requirement for pain relief gradually compared with group 1. Group 4 showed ceiling effect in terms of average propofol flow rate, recovery of orientation and 24 hr fentanyl requirement for postoprerative pain relief compared with group 1~3. CONCLUSIONS: Keep the fentanyl concentration below 3.0~4.5 ng/ml and titrate propofol flow rate was reasonable method for adequate control of drug infusion during a propofol-fentanyl-N20 anesthesia.

An Anesthetic Experience in a Patient with EDTA-induced Pseudothrombocytopenia: A case report / 대한마취과학회지

Pseudothrombocytopenia caused by platelet clumping is an in vitro phenomenon that occurs in ethylene-diamine-tetra-acetic acid (EDTA) anticoagulated blood at room temperature. Pseudothrombocytopenia may lead to erroneous diagnosis, unnecessary and costly additional laboratory examinations, and inappropriate medical or surgical therapy. We experienced 75-year old female pseudothrombocytopenia patient scheduled for orthopedic surgery, who showed abnormal thrombocytopenia (35,000/mm3) in preoperative routine platelet count using EDTA anticoagulant, but showed normal platelet count in sodium citrate anticoagulant.

Anesthesia Induction with Propofol Using a Target Controlled Infusion (TCI) / 대한마취과학회지

BACKGROUND: Target Controlled Infusion (TCI) is designed to achieve a predicted target blood concentration based on population pharmacokinetics and it provides the closest approximation for any individual patients. This study determined which target is appropriate for propofol induction using a TCI in korean adullt patients premedicated with midazolam. METHODS: Sixty six patients (ASA I or II, 18~55 years) premedicated with midazolam were allocated randomly to receive an infusion to achieve and maintain a target blood concentration of 3, 4, 5 and 6 microgram/ml using a TCI. Induction time was measured as the interval from the start of the infusion to loss of verbal contact and induction within 3 min was considered as successful. Calculated concentration, induction dose, context sensitive decrement time, vital signs, pain score and side effects were checked and compared each other during induction period. RESULTS: The success rate when the target was 3 microgram/ml was 25%, 58.8%, 77.8% and 100% when targets were 4 microgram/ml, 5 microgram/ml and 6 microgram/ml respectively. EC50 for induction was 3.87 microgram/ml and EC95 was 5.71 microgram/ml. Calculated concentration, induction dose, context sensitive decrement time in 3, 4, 5 microgram/ml group showed no differences among groups, but 6 microgram/ml group showed statistically significant differences compared with other groups. Vital signs, pain score and side effects showed no differences among groups. CONCLUSIONS: Target concentration of 5~6 microgram/ml would successfully induce anesthesia in the majority of patients premedicated with midazolam without major hemodynamic changes.

Clinical Usefulness of Isoconcentration Nomogram for Continuous Infusion of Fentanyl in Propofol-Fentanyl Total Intravenous Anesthesia (TIVA) / 대한마취과학회지

BACKGROUND: To estimate real time concentration of drugs during TIVA is theoretical, but it is not easy and inefficient. To maintain designed target concentration with continuous infusion using methods that account for the multicompartmental pharmacokinetic profile of fentanyl, isoconcentration nomogram is one of the methods. We evaluated the clinical usefulness of the isoconcentration nomogram using two different expected concentration of fentanyl. METHODS: Thirty ASA class I or II adult patients scheduled for spine fusion were randomly allocated into two groups according to 1.5 or 3 ng/ml of expected fentanyl concentration. Using isoconcentration nomogram, fentanyl concentration was adjusted and the propofol concentration was fixed to 3.5 g/ml according to Prys-Roberts method. Vital signs were titrated using variable flow rate of propofol. Fentanyl and propofol were discontinued 15 min before the end of operation. And, IV-PCA using fentanyl were applicated for postoperative pain control. The dosage of propofol and fentanyl, recovery time of consciousness and orientation were checked. Also, first buttoning time and 24hr fentanyl dosage in IV-PCA were checked. RESULTS: Average flow rate of propofol used were 7.5 1.2 mg/kg/hr in group 1, 5.7 1.1 mg/kg/hr in group 2 which was significantly lower than group 1 (p<0.05). Spontaneous eye opening and recovery of orientation was delayed 1.8 times in group 2. First buttoning time and 24hr fentanyl requirement for postoperative pain control using IV-PCA was delayed by 2 and decreased 60% in group 2, respectively. CONCLUSIONS: Isoconcentration nomogram was useful tool to control the expected concentration of fentanyl during TIVA and postoperative pain control using fentanyl IV-PCA.