Minimum Effective Anesthetic Concentration of Hyperbaric Tetracaine 10 mg for Spinal Anesthesia / 대한마취과학회지

BACKGROUND: Minimum effective anesthetic concentration (MEAC) of local anesthetics for spinal anesthesia, defined as the concentration at which a spinal anesthetic agent produces surgical anesthesia within 20 minutes of administration in 50% of patients. This concept is similar to the concept of minimum alveolar concentration (MAC) for inhalation anesthetic. Furthermore, as MEAC may vary with the administered dose, it will be determined using 10 mg of hyperbaric tetracaine. METHODS: 10 mg hyperbaric tetracaine containing dextrose 10 % was administered intrathecally to 12 patients (ASA I-II, age 20~40 yr), who were undergoing lower limb or urological procedures within 90 minutes, at concentrations ranging from 0.07~0.1%. The choice of tetracaine concentration was determined by Dixon's up-and-down method. Complete anesthesia was defined as: (1) pinprick anesthesia at or higher than T10 and (2) complete leg paralysis; all occurring in both lower extremities within 20 min. General anesthesia was initiated if spinal anesthesia was incomplete. RESULTS: MEAC of 10 mg hyperbaric tetracaine was 0.083 %. Mean anesthetic duration was 75.2 minutes (range: 40~100 min). The maximum sensory block level ranged from T3~T8. CONCLUSION: The aim of this study was to establish new concept of minimum effective anesthetic concentration of hyperbaric tetracaine for spinal anesthesia. We recognized that spinal anesthesia can be accomplished with very dilute solution. As fixed dose, no correlation was found between concentration of the spinal tetracaine solution with the highest sensory level, anesthetic duration and the degree of mean arterial pressure decreased.

Minimum Effective Anesthetic Concentration of Hyperbaric Tetracaine 10 mg for Spinal Anesthesia / 대한마취과학회지

BACKGROUND: Minimum effective anesthetic concentration (MEAC) of local anesthetics for spinal anesthesia, defined as the concentration at which a spinal anesthetic agent produces surgical anesthesia within 20 minutes of administration in 50% of patients. This concept is similar to the concept of minimum alveolar concentration (MAC) for inhalation anesthetic. Furthermore, as MEAC may vary with the administered dose, it will be determined using 10 mg of hyperbaric tetracaine. METHODS: 10 mg hyperbaric tetracaine containing dextrose 10 % was administered intrathecally to 12 patients (ASA I-II, age 20~40 yr), who were undergoing lower limb or urological procedures within 90 minutes, at concentrations ranging from 0.07~0.1%. The choice of tetracaine concentration was determined by Dixon's up-and-down method. Complete anesthesia was defined as: (1) pinprick anesthesia at or higher than T10 and (2) complete leg paralysis; all occurring in both lower extremities within 20 min. General anesthesia was initiated if spinal anesthesia was incomplete. RESULTS: MEAC of 10 mg hyperbaric tetracaine was 0.083 %. Mean anesthetic duration was 75.2 minutes (range: 40~100 min). The maximum sensory block level ranged from T3~T8. CONCLUSION: The aim of this study was to establish new concept of minimum effective anesthetic concentration of hyperbaric tetracaine for spinal anesthesia. We recognized that spinal anesthesia can be accomplished with very dilute solution. As fixed dose, no correlation was found between concentration of the spinal tetracaine solution with the highest sensory level, anesthetic duration and the degree of mean arterial pressure decreased.

Intravenous Nitroglycerin Administration for Manual Removal of Retained Placenta: A Case Report / 대한마취과학회지

Retained placenta around which the uterus firmly contracted occurs in about 1% of all vaginal deliveries and may require uterine muscle relaxation to facilitate manual extraction. It is associated with profuse hemorrhage and life threatening shock. Therefore anesthesiologist may face the difficulty to provide analgesia and rapid uterine relaxation. A 32-yr-old multigravida was transferred to the emergency room in hypovolemic shock state at 1 hour after vaginal delivery. Ketamine 30 mg, fentanyl 50 mcg were given intravenously for analgesia and sedation. Oxygen 6 L/min was supplied via face mask. With ongoing fluid resuscitation, nitroglycerin 500 mcg was injected as an intravenous bolus. Within 80 seconds, the uterus relaxed enough to extract the retained placenta. The recovery of uterine muscle tone occurred approximately 1 minute after manual removal with administration of intravenous methylergonovine. In summary, the use of intravenous nitroglycerin may be a useful and safe alternative to general anesthesia in cases of manual removal of retained placenta.

The Effects of Tracheal Intubation with McCoy or Macintosh Laryngoscope on Blood Pressure, Heart Rate / 대한마취과학회지

BACKGROUND: The aim of this study was to compare the cardiovascular changes followed by laryngoscopy with the McCoy laryngoscope blade with those followed by laryngoscopy with the Macintosh laryngoscope blade. METHODS: Forty eight patients were randomly divided into two groups. Following induction with fentanyl 2 mcg/kg and thiopental 5 mg/kg, and muscle relaxation with vecuronium 0.1 mg/kg, the vocal cords were visualized with either the McCoy or the Macintosh laryngoscope blade, then tracheal intubation was performed. Heart rate and arterial blood pressure were measured just before and after laryngoscopy, and 1, 3 and 5 min later. RESULTS: There was a significant increase in both heart rate and arterial blood pressure after tracheal intubation using the Macintosh laryngoscope. Also, use of the McCoy blade resulted in a significant increase in both heart rate and arterial blood pressure. CONCLUSIONS: There was no significant difference on arterial pressure and heart rate to laryngoscopy and tracheal intubation with either the McCoy blade or the Macintosh.