Spinal Anesthesia with Isobaric Tetracaine in Patients with Previous Lumbar Spinal Surgery

PURPOSE: Previous lumbar spinal surgery (PLSS) is not currently considered as a contraindication for regional anesthesia. However, there are still problems that make spinal anesthesia more difficult with a possibility of worsening the patient's back pain. Spinal anesthesia using combined spinal-epidural anesthesia (CSEA) in elderly patients with or without PLSS was investigated and the anesthetic characteristics, success rates, and possible complications were evaluated. MATERIALS AND METHODS: Fifty patients without PLSS (Control group) and 45 patients with PLSS (PLSS group) who were scheduled for total knee arthroplasty were studied prospectively. A CSEA was performed with patients in the left lateral position, and 10 mg of 0.5% isobaric tetracaine was injected through a 27 G spinal needle. An epidural catheter was then inserted for patient controlled analgesia. Successful spinal anesthesia was defined as adequate sensory block level more than T12. The number of skin punctures and the onset time were recorded, and maximal sensory block level (MSBL), time to 2-segment regression, success rate and complications were observed. RESULTS: The success rate of CSEA in Control group and PLSS group was 98.0%, and 93.3%, respectively. The median MSBL in PLSS group was higher than Control group [T4 (T2-L1) vs. T6 (T3-T12)] (p < 0.001). There was a significant difference in the number of patients who required ephedrine for the treatment of hypotension in PLSS group (p = 0.028). CONCLUSION: The success rate of CSEA in patients with PLSS was 93.3%, and patients experienced no significant neurological complications. The MSBL can be higher in PLSS group than Control group.

Comparison of 5% and 10% Glucose for Tetracaine Spinal Anesthesia / 대한마취과학회지

BACKGROUND: One of the most important physical properties affecting the level of analgesia after intrathecal administration of a local anesthetic is baricity. This study was done to compare the distribution of 0.5% tetracaine in 5% glucose solution and in 10% glucose solution. METHODS: Tetracaine 2.6 ml (0.5% with 5% glucose or 10% glucose) added with 0.1% epinephrine 0.2 ml was administered to each of 20 patients. All patients' heights were within 160 170 cm. The cephalad spread of analgesia, the degree of motor block in the legs and hemodynamic values were assessed at 2-min intervals for the first 10 min and then at 5-min intervals until 30 min. RESULTS: In the 5% glucose and 10% glucose solutions, the maximum sensory level was T5.4 and T4.3, the maximum sensory block time was 128.1 min and 118.2 min and the time to complete motor block was 5.4 min and 5.2 min respectively. It was not statistically significant between groups. But T 8.1 (vs T 9.6 in the 5% glucose solution) of initial sensory level measured at 4 min after injection of drug was significantly higher (P < 0.05) in the 10% glucose solution. Maximum hemodynamic changes from the baseline were not different in two groups. CONCLUSIONS: Tetracaine 0.5% with 5% glucose or 10% glucose solutions showed similar distribution in the cerebrospinal fluid.

The Efficacy of Epinephrine Test Doses during Combined Spinal-Epidural Anesthesia in Adult Patients / 대한마취과학회지

BACKGROUND: Combined spinal-epidural anesthesia has been used to reduce the side effect of spinal or epidural anesthesia. The epinephrine test dose to prevent intravascular injection of local anesthetics after subarachnoid block has not been clearly understood. The purpose of present study is to see the efficacy of simulated intravenous test dose during subarachnoid block. METHODS: 20 ASA physical status 1 and 2 patients underwent subarachnoid block with tetracaine 10 mg in hyperbaric solution at the L3-4 interspace and were divided into two groups, Group 1 (n=10) and Group 2 (n=10). 3 ml of Normal saline was injected intravenously to group 1, while 1:200,000 epinephrine 3 ml (15 microgram) was injected intravenously to group 2 at regression of sensory block to T8-10. 1:200,000 epinephrine 3 ml (15 microgram) was given to each volunteer (Group 3, n=10). Heart rate (HR) was measured at 15 seconds intervals for 3 minutes and systolic blood pressure (SBP) was measured at 1 minute intervals for 5 minutes. RESULTS: SBP increased significantly in group 2 and group 3 at 1 minute after epinephrine test dose injection. Maximal HR changes was 39.7 3.7 beat per minute in group 2 and 25.8 5.2 beat per minute in group 3. There was 100% incidence of detection of intravascular injection of 15 microgram epinephrine in both group when HR increase > or = 20 beats per minute is regarded as positive response. CONCLUSIONS: This study demonstrates that the epinephrine test dose is useful method to detect intravascular injection of local anesthetics either in the combined spinal-epidural anesthesia or epidural anesthesia. The heart rate response after injection of epinephrine was greater than the blood pressure response.

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.

Effects of Drug Dose, Volume, and Concentration on the Spinal Anesthesia with Isobaric Tetracaine / 대한마취과학회지

BACKGROUND: The patient's position cannot be changed in the hyperbaric spinal anesthesia until the anesthesia level is fixed because gravity has an effect on the spread of hyperbaric solutions. The isobaric spinal anesthesia has the advantage that the patient's position can be changed soon after drug is injected into the subarachnoid space because gravity has no effect on the spread of isobaric solutions. Most studies of isobaric spinal anesthesia had been made using plain bupivacaine. In this study, effects of drug dose, volume, and concentration on the spinal anesthesia with isobaric tetracaine were investigated. METHODS: Eighty patients were randomly allocated to four groups: 1), group 1 received 1% tetracaine 14mg, 1.4ml (N=20), 2), group 2 received 0.74% tetracaine 14mg, 1.9ml (n=20), 3), group 3 received 0.5% tetracaine 14mg, 2.8ml (n=20), 4), group 4 received 1% tetracaine 19mg, 1.9ml (n=20). Drugs were administered in lateral position at L3~4 level. Neural block was assessed by pinprick. Changes of analgesic level were evaluated with time. RESULTS: Peak analgesic level of group 4 was higher than that of group 2 after 12 minutes and no difference in analgesic level between group 1, 2, and 3 after 18 minutes. Group 4 resulted in longer duration and a higher peak level of sensory block than group 2. CONCLUSIONS: In spinal anesthesia with isobaric tetracaine, the volume is the major factor affecting initial spread of isobaric tetracaine and the dosage was the major factor affecting peak level. High concentration results in longer duration, and higher peak level.

Effects of Epinephrine on the Voltage Dependent Na+, Ca2+ Channels and Cellular Excitability in Dorsal Root Ganglion Neurons, and Its Interaction with Tetracaine / 대한마취과학회지

BACKGROUND: The addition of epinephrine to local anesthetics has been known to prolong the duration of neural blokade and to increase the intensity of analgesia, but underlying mechanisms are unclear. This study was designed to investigate electrophysiologically the analgesic effects of epinephrine and its interaction with tetracaine. METHODS: Whole cell patch clamp recordings were made from acutely dissociated neurons from adult rat dorsal root ganglion (DRG). Using voltage clamp method, we compared the IC50 values of tetracaine for Na+ and Ca2+ channel suppression in the absence and presence of a fixed dose of epinephrine. Action potentials evoked by current pulses were also investigated to evaluate the effect of tetracaine and epinephrine on the excitability of DRG neurons. RESULTS: Clinical doses of epinephrine did not alter the dose-response curves of tetracaine for peak Na+ and Ca2+ channel current, but the amplitude of action potential spikes was reduced and firing rates evoked by sustained current pulse increased. The addition of epinephrine did not affect the changes of action potential parameters caused by tetracaine alone. CONCLUSIONS: The ability of epinephrine to increase the intensity of analgesia induced by tetracaine seems more likely due to an analgesic action at the level of spinal cord rather than a direct analgesic action at a level of primary sensory neurons. Local vasoconstriction and stimulation of descending inhibitory system via alpha-adrenergic pathway may play a role.

Comparison of Sensory and Motor Blockade Effect of Tetracaine and Bupivacaine in Spinal Anesthesia / 대한마취과학회지

BACKGREOUND: Tetracaine has been the most commonly used spinal anesthetic agent. Recently bupivacaine has been found to be a useful agent, and has been reported not to cause neurologic complications as well as being a better quality anesthetic. The purpose of this study was to compare the anesthetic effects of bupivacaine with that of tetracaine. METHODS: Forty patients undergoing lower abdomen and lower limb operation were randomly allocated to two groups. Group I (n=20) received 15mg, 0.5% tetracaine in 10% dextrose, while Group II (n=20) received 15mg, 0.5% bupivacaine in 8% dextrose. After intrathecal injection of the agent at the level of L3-4 intervertebral space, the changes in sensory and motor block, blood pressure and heart rate were measured in two groups. RESULTS: The onset time of sensory block was more rapid in Group I than in Group II. Two segment regression time of sensory block was significantly longer in Group II than in Group I (p<0.05). The time for maximum motor block was shorter in group I than in Group II (p<0.05), but the duration of decreased motor block was significantly longer in Group I. The change of systolic blood pressure in Group II was less than the change in Group I. CONCLUSIONS: Bupivacaine has a longer sensory block duration, a weaker, shorter motor block duration and yields a less change in systolic blood pressure than tetracaine in spinal anesthesia.

Effect of Injection Speed on the Anesthetic Level and Duration of Hypobaric Spinal Anesthesia with 0.1% Tetracaine in Jack-Knife Position at 15o Head-down Tilting / 대한마취과학회지

BACKGROUND: The speed of injection of local anesthetic solutions into the subarachnoid space may influence the spread of these agents in the cerebrospinal fluid by the amount of turbulence generated, especially with large volume. To determine the proper injection speed of anesthetics in hypobaric spinal anesthesia on jack-knife position, the anesthetic level and duration were measured with the fast or slow injection speed. METHODS: Twenty patients for perianal surgery in jack-knife position under hypobaric spinal anesthesia were randomly assigned to one of two groups. Tetracaine (0.1%) in distilled water 5 ml was administered to all the patients. Group I patients received the drug with the speed of injection as 5 ml/20 sec (15 ml/min) and the others (Group II) as 5 ml/4 min (1.25 ml/min). The mean arterial pressures and heart rates at the preanesthetic period, and 5, 10, 15 and 20 min after the end of injection were measured. The anesthetic levels at 5, 10, 15 and 20 min after the injection and anesthesia duration were measured. RESULTS: There was no significant difference in mean arterial pressures, heart rates and anesthetic duration between two groups. The anesthetic level 20 min after the injection was higher in Group I than Group II, and not different at the other time sequences. CONCLUSION: At the injection speed within 1.25-15 ml/min in hypobaric spinal anesthesia on jack-knife position at 15o head-down, we acquired appropriate anesthetic level and duration for perianal surgery without any undesirable effects.