In Vitro Proton Magnetic Resonance Spectroscopy Detected a Differential Neurochemical Response in Rabbit Brain Administered Thiopental or Ketamine / 대한마취과학회지

BACKGROUND: Cellular target sites and the neurochemical compounds responsible for anesthetic action remain unclear. This study was designed to detect regional changes in neurochemical compounds by NMR spectroscopy of extracted rabbit brain tissue after anesthetizing with thiopental or ketamine. METHODS: Nine healthy white New Zealand rabbits (2.5-3.0 kg) were studied. A marginal ear vein was punctured for continuous intravenous infusion. Controlled breathing was maintained using a Jackson-Ree circuit after intubation during thiopental (n = 3) or ketamine (n = 3) anesthesia. After maintaining anesthesia for 30 minutes, brains were extracted and placed in liquid nitrogen. Rabbits in the control group (n = 3) were sacrificed using KCl and processed in the same manner. Extracted brain tissues were divided into frontal lobe, temporal lobe, occipital lobe, parietal lobe, pons, midbrain, basal ganglia and spinal cord. The 1H-NMR spectra of extracted regional brain tissues were obtained, and neurochemical compounds such as gamma-aminobutyric acid (GABA), N-acetylaspartate (NAA), choline-containing compounds (Cho), and creatine (Cr) were compared with those of normal control tissues. RESULTS: In the thiopental group, the GABA/Cr and NAA/Cr ratios of brain regions were not significantly different from those of the control group. The Cho/Cr ratios of the frontal lobe, parietal lobe, and basal ganglia were significantly higher than those of the control group. In the ketamine group, the GABA/Cr ratio of the midbrain was significantly lower than that of the control group. However, Cho/Cr ratios of the parietal lobe, temporal lobe, and midbrain were significantly higher than those of the control group, though the NAA/Cr ratio was similar to that of the control. CONCLUSIONS: These results suggest that the anesthetic actions of thiopental, such as, its sedative and hypnotic effects are due to increased GABA activity. Inhibition of acetylcholine induced neurotransmission was observed particularly in the frontal lobe, parietal lobe, and basal ganglia in thiopental anesthesia and in the parietal lobe, temporal lobe and midbrain in ketamine anesthesia. Neurotoxicity was not observed for either drug in anesthetized brain tissue.

Proseal Laryngeal Mask Airway for the Resection of a High Grade Upper Tracheal Stenosis: A case report / 대한마취과학회지

Laryngeal mask airways (LMAs) have several advantages compared with conventional endotracheal tube (ETT) in tracheal surgery. LMAs cannot penetrate the airway below the level of the glottis, but enable the access to the larynx and tracheobronchial tree while avoiding airflow impairment, tracheal stimulation, trauma, and the interference of tracheal mucosal blood flow. Moreover, LMAs have lower airway resistance than ETTs. We describe the use of a proseal laryngeal mask airway (PLMA) in patients with high grade upper tracheal stenosis. We suggest that PLMA might have advantages over the classic LMA by preventing aspiration and by allowing the evacuation of air from the stomach in high-grade upper tracheal stenosis.

Core Temperature Changes according to Premedication / 대한마취과학회지

BACKGROUND: It is well known that body core temperature reduces during general anesthesia. Midazolam premedication for relieving anxiety might also reduce body core temperature by inhibiting tonic thermoregulatory vasoconstriction in elderly patients. Therefore, an effort to maintain temperature must be started before anesthesia. This study was designed to evaluate the effect on body core temperature of midazolam, atropine and glycopyrrolate, which are commonly used for premedication. METHODS: Six hundred and eleven patients of ASA physical status 1 or 2, aged 18 to 65, were involved in this study. They were randomly assigned to premedication with: 1) saline control (n = 92); 2) midazolam 0.04 mg/kg (n = 96); 3) midazolam 0.04 mg/kg with glycopyrrolate 0.004 mg/kg (n = 117); 4) midazolam 0.04 mg/kg with atropine 0.01 mg/kg (n = 93); 5) glycopyrrolate 0.004 mg/kg (n = 116); and 6) atropine 0.01 mg/kg (n = 97). All premedication was given intramuscularly about 30 min before operation. Temperatures were measured at the tympanic membrane at the time of premedication and 30 min after premedication. RESULTS: Temperatures increased slightly after injection in the control (0.14 +/- 0.36oC; mean +/- SD) and this increase was less in the midazolam group (0.07 +/- 0.39oC). The changes of temperature in the midazolam with glycopyrrolate (0.16 +/- 0.39oC), midazolam with atropine (0.19 +/- 0.40oC), and in the glycopyrrolate group were no different from that of the control group. However, there was a statistically significant increase in temperature after injection in the atropine group (0.26 +/- 0.42oC) versus the control group. Compared with the midazolam group, a statistically significant increase in temperature was observed in the midazolam with atropine, the glycopyrrolate, and in the atropine group. CONCLUSIONS: From these results, low dose midazolam (0.04 mg/kg), midazolam with glycopyrrolate, and midazolam with atropine for premedication have little affect on temperature. Midazolam with glycopyrrolate premedication is recommended for preserving body core temperature.