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.

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.

The Effects of Lidocaine and Clonidine Premedication on Cardiovascular Response during Induction of Anesthesia with Ketamine / 대한마취과학회지

Ketamine may increase blood pressure and heart rate and should be avoided in hypertensive patients. However, in hypovolemic and asthmatic patients, ketamine is used as an induction agent because of its cardiovascular stimulating effect and bronchodilating effect. This study aims to assess the effects of clonidine and lidocaine on the cardiovascular response of intravenous ketamine administration during induction of anesthesia. sixty patients were divided into 3 groups as followed: group I: control ( received no lidocaine or no clonidine) group II: received lidocaine (1.5 mg/kg IV) 3 minutes before intubation group IIl: received clonidine (0.3 mg PO) 90 minutes before induction of anesthesia The changes of blood pressure, heart rate and rate pressure product following intubation were measured at different time interval (before induction,before intubation just after intubation, postintubation 1, 3, 5, 10 min) and compared with the value of control (2 hours before induction of anesthesia). The results are as follows 1) Group I and Group II: The systolic and diastolic blood pressure increased significantly compared to the control value from preinduction to 5 minutes after intubation(p<0.05). It recovered to the control value in 10 minutes, but heart rate and rate-pressure product increased significantly for 10 minutes after intubation(p<0.05) 2) Group III: The systolic and diastolic blood pressure, heart rate and rate-pressure product of preinduction and preintubation values decreased significantly compared to control values but 1 minute after intubation,all values increased significantly(p<0.05). The systolic and diastolic blood pressure and rate-pressure product values recovered to control value in 3 minutes after intubation and heart rate recovered in 5 minutes. Comparing group III with group I and II, it showed significant changes(p<0.05). From the above results, it can be concluded that clonidine inhibits cardiovascular stimulating response by ketamine during induction of anesthesia. the above results, it can be concluded that clonidine inhibits cardiovascular stimulating response by ketamine during induction of anesthesia.