(OBJECTIVES)
To study the effects of the stellate ganglion block (SGB) on respiratory function, and in particular to elucidate the mechanism of the decrease in tidal volume after SGB observed in our previous study, we measured the CO₂ response curve with FIO₂ higher than 60%.
(MATERIALS AND METHODS)
CO₂ response curves and respiratory function parameters including tidal volume, minute volume, Spo₂, ETCO₂, and respiratory rate were assessed using a bedside respiratory monitor (Capnomac UltimaTM, DATEX) before and after SGB in 21 adults without respiratory disease (SGB group). The same parameters were measured before and after SGB with 6ml of saline in 7 healthy volunteers (control group).
(RESULTS)
Before and after SGB, tidal volume showed a positive correlation with ETCO₂. The slope of the regression line between ETCO₂ and tidal volume decreased after SGB. Saline injection in volunteers did not result in any particular changes in CO₂ ventilatory response.
(CONCLUSION)
SGB may blunt the ventilatory response to CO₂, which is a possible explanation for the observed decrease in tidal volume associated with this treatment.

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The purpose of this study was to determine whether injection speed affects the spread of isobaric spinal anesthesia. Spinal anesthesia was performed on 50 patients for minor lower limb surgery using isobaric solution of 3ml of 0.5% tetracaine. Subarachnoid space was confirmed with a 25-gauge Quincke needle at the L2-3 interspace with each patient in the lateral position and the injection speed was 0.4 (G I), 0.2 (G II), 0.1 (G III), 0.05 (G IV), and 0.017ml/s (G V). We measured the level of analgesia by pinprick and the time to complete motor block of both legs after intrathecal injection.
No significant difference was found in the highest level of analgesia and the time to complete motor block after intrathecal injection between the five groups. There was no difference between the five groups in the level of analgesia at each measured time point. We conclude that injection speed has no effect on the level of isobaric spinal anesthesia.

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Fractional excretion of, β₂-microglobulin (FE-BMG) and serum C-reactive protein (CRP) were measured in 18 patients undergoing elective thoracotomy to assess the correlation between β₂-microglobulin production and acute phase reaction. FE-BMG was markedly higher 2 hours after the operation, and had decreased significantly the next morning, whereas serum CRP levels were markedly higher the next morning than 2 hours after the operation. The time course of changes in FE-BMG differed from the course of changes in serum CRP levels in the early phase after thoracotomy, indicating that the increase in FEBMG is unrelated to acute phase reaction.

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Closed circuit anesthesia with sevoflurane and oxygen using an intra-circuit vaporizer was performed in 10 patients for a duration of 6 hours. Excessive anesthetic gases from the anesthesia gas monitor were led to an expiratory breathing tube. An anesthesia gas monitor was connected with a breathing tube to avoid the entrance of room air into the breathing tube. Anesthesia was induced by intravenous administration of thiopental and endotracheal intubation was performed with vecuronium. After denitrogenation with 100% oxygen, the sevoflurane vaporizer was set at 0.5%. Inspired sevoflurane concentration reached 2% at 14±3min. The dial setting of the vaporizer was phased to decrease to 0.1% and inspired sevoflurane concentration was kept at about 2%. SpO₂ was never lower than 97% during this study. The concentration of compound A in the closed circuit was 0 ppm at the beginning of inhalation anesthesia and 24.9±4.1 ppm at 1 hour. No large change in compound A concentration was noted. The total concentration of inspired sevoflurane and oxygen decreased from 94±0% at the beginning of inhalation anesthesia to 87±4% at 1 hour after inhalation, and no large change in concentration was noted during the course of anesthesia.
The above findings suggest that the reduction of the total concentration of sevoflurane and oxygen depend on the entry of dissolved nitrogen in blood, fat and tissue into the breathing circuit. The breathing circuit contained 47mmHg vapor (6%) and 7% nitrogen. As FIO₂ 0.3 is needed at least in clinical anesthesia, the concentration of anesthetic agent will be 60% at maximum. Clinically, 1.3 MAC is required to maintain sevoflurane anesthesia, so at least 43% anesthetic agent in 1 MAC is necessary in closed circuit anesthesia.

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Position changes of the internal jugular vein and the common carotid artery due to inflation of a laryngeal mask cuff were observed by ultrasonography. Introduction of air into the cuff caused lateral displacement of the common carotid artery, deformation of the internal jugular venous wall and disturbed blood flow in the internal jugular vein. However, no pressure change was detected in the internal jugular vein measured on the cranial side of the cuff. Our findings show that a laryngeal mask causes little vascular congestion in the cranium, but because of vascular displacement and deformation and disturbed blood flow, care should be taken so as not to puncture the common carotid artery when jugular venous puncture is attempted.

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Thoracoscopic sympathectomy (TSS) was conducted in seven patients with sympatheti-cally maintained pain. Indications for surgery were postherpetic neuralgia (PHN) in three patients, reflex sympathetic dystrophy (RSD) in two, and possible RDS in two.
Two patients had an excellent and three had a persistently favorable long-term response. While the remaining two patients had an immediate good response, pain relief was only for a short time.Patients with persistent long-term pain responded poorly.
Although TSS has to be done under endotracheal general anesthesia, it appears to be a more reliable therapy than the traditional sympathetic blockade.
Conclusion: Thoracoscopic sympathectomy is an effective, minimally invasive therapy for sympathetically maintained pain such as reflex sympathetic dystrophy and post-herpetic neuralgia. This technique should be regarded as a possibly better alternative to sympa-tholytic blockade.

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The influence on respiratory frequency of pentazocine was determined in 4 patients under general anesthesia. Pentazocine was infused for 3 minutes at a dose of 1mg/kg. Respiratory frequency was recorded every 30 seconds. The mean minimum respiratory frequency was 10/min approximately 10 minutes after infusion. The semiparametric model of pharmacokinetic-pharmacodynamic analysis was applied. The elimination rate constant (k_e0) of the effect site was 0.016/min, significantly smaller than the plasma elimination rate constant (k_el, 0.43/min) of pentazocine. This study shows that the respiratory depression of infused pentazocine can be evaluated by a measure of respiratory frequency.

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A new technique, lung volume reduction surgery, has been designed to reduce total lung volume and improve chest wall and diaphragmatic mechanics for ventilation in patients with severe emphysema. We experienced three cases of anesthetic management for bilateral volume reduction surgery for the first time in Japan. Anesthesia was maintained using isoflurane in 100% oxygen and thoracic epidural bupivacaine. A double lumen tube was used to facilitate lung isolation and mechanical-controlled hypoventilation was used during the operation to prevent barotrauma. Hypercapnia was noticed in all three cases during the surgical procedure. All patients were extubated at the end of surgery under deep anesthesia. Perioperative anesthetic management for patients with emphysema requires (1) controlled hypoventilation with permissive hypercapnia to avoid barotrauma and air leakage, (2) early extubation at the end of surgery, (3) pain management by thoracic epidural local anesthetic administration and (4) chest physical therapy in the ICU after the surgery.

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