Eliana Marisa Ganem

Neurotoxicity of subarachnoid hyperbaric bupivacaine in dogs

Background and Objectives. The study investigated possible neurotoxic effects of increasing concentrations and doses of bupivacaine administered into the subarachnoid space in dogs. Methods. Fifty animals were allocated to five experimental groups: G1, control; G2, 5 mg 0.5 bupivacaine in 10% glucose solution; G3, 10 mg of 1% bupivacaine in 10% glucose solution; G4, 20 mg 2% bupivacaine in 10% glucose solution, and G5, 20 mg 2% bupivacaine in water. After 72 hours of observation, the animals were killed and the spinal cords removed for histologic examination by light microscopy. Results. None of the animals showed any neurologic clinical disturbance following recovery from spinal anesthesia. One case of necrosis of nerve tissue was observed in G3 and four in G4. Conclusions. Increasing concentrations and doses of hyperbaric bupivacaine solutions increased the incidence of nerve tissue damage, which did not occur with hypobaric solutions. These results should contribute to the further understanding of neurologic complications following spinal anesthesia when large doses of local anesthetics in hyperbaric solutions are used.Background and Objectives The study investigated possible neurotoxic effects of increasing concentrations and doses of bupivacaine administered into the subarachnoid space in dogs. Methods Fifty animals were allocated to five experimental groups: G1, control; G2, 5 mg 0.5 bupivacaine in 10% glucose solution; G3, 10 mg of 1% bupivacaine in 10% glucose solution; G4, 20 mg 2% bupivacaine in 10% glucose solution, and G5, 20 mg 2% bupivacaine in water. After 72 hours of observation, the animals were killed and the spinal cords removed for histologic examination by light microscopy. Results None of the animals showed any neurologic clinical disturbance following recovery from spinal anesthesia. One case of necrosis of nerve tissue was observed in G3 and four in G4. Conclusions Increasing concentrations and doses of hyperbaric bupivacaine solutions increased the incidence of nerve tissue damage, which did not occur with hypobaric solutions. These results should contribute to the further understanding of neurologic complications following spinal anesthesia when large doses of local anesthetics in hyperbaric solutions are used.

Effects on mother and fetus of epidural and combined spinal-epidural techniques for labor analgesia

OBJECTIVE Epidural (EA) and combined spinal-epidural (CSE) techniques have both been utilized for labor analgesia. This study compared the effects on the mother and newborn of these techniques in labor analgesia and anesthesia. METHODS Forty pregnant women received epidural analgesia with 15 mL of 0.125% ropivacaine (EA group) and 5 microg of sufentanil plus 2.5mg bupivacaine in the subarachnoid space (CSE group). Pain intensity, sensory blockade level, latency time, motor block intensity, labor analgesia duration, epidural analgesia duration, maternal hypotension, and pruritus were evaluated. The newborns were evaluated by Apgar and the neurological and adaptive capacity score (NACS) developed by Amiel-Tison. RESULTS There were no significant statistical differences between groups for pain scores, latency time, sensory blockade level, and Apgar score. Motor block, labor analgesia duration, and epidural analgesia duration were greater in the CSE group, whose seven mothers had mild pruritus. The NACS were greater in the EA group after half, two, and 24 hours. Ninety five percent of EA group newborns and 60% of CSE group newborns were found to be neurologically healthy at the 24 hour examination. CONCLUSION EA and CSE analgesia relieved maternal pain during obstetric analgesia, but CSE mothers had pruritus and a longer labor. Newborns of mothers who received epidural analgesia showed the best NACS.

The Anatomy of the Thoracic Spinal Canal Investigated with Magnetic Resonance Imaging

BACKGROUND: We investigated, with magnetic resonance imaging, the distance of the dura mater to the spinal cord in patients without spinal or medullar disease at the 2nd, 5th, and 10th thoracic segments. METHODS: Fifty patients in the supine position underwent magnetic resonance imaging. Medial sagittal slices of the 2nd, 5th, and 10th thoracic segments were measured for the relative distances using the 1.5-T superconducting system (Gyroscan Intera, Philips Medical Systems, Best, the Netherlands). In 10 patients, the angles relative to the tangent at the insertion point on the skin were measured. RESULTS: The posterior dural-spinal cord distance is significantly greater at the midthoracic region (5th thoracic = 5.8 ± 0.8 mm) than at the upper (2nd thoracic = 3.9 ± 0.8 mm) and lower thoracic levels (10th thoracic = 4.1 ± 1.0 mm) (P < 0.015). There were no differences between interspaces T2 and T10. There was no correlation between age and the measured distance between the dura mater and the spinal cord. The entry angle of the needle at T2 was 9.0° ± 2.5°; at T5, 45.0° ± 7.4°; and at T10, 9.5° ± 4.2°. CONCLUSIONS: This study demonstrated that there is greater depth of the posterior subarachnoid space at the T2, T5, and T10 levels. The greater distance was found at T5.

Preoperative warming combined with intraoperative skin-surface warming does not avoid hypothermia caused by spinal anesthesia in patients with midazolam premedication

CONTEXT AND OBJECTIVE Inadvertent perioperative hypothermia is common during spinal anesthesia and after midazolam administration. The aim of this study was to evaluate the effects of intraoperative skin-surface warming with and without 45 minutes of preoperative warming in preventing intraoperative and postoperative hypothermia caused by spinal anesthesia in patients with midazolam premedication. DESIGN AND SETTING Prospective and randomized study at Hospital das Clínicas, Universidade Estadual Paulista, Botucatu. METHODS Thirty patients presenting American Society of Anesthesiologists (ASA) physical status I and II who were scheduled for elective lower abdominal surgery were utilized. The patients received midazolam premedication (7.5 mg by intramuscular injection) and standard spinal anesthesia. Ten patients (Gcontrol) received preoperative and intraoperative passive thermal insulation. Ten patients (Gpre+intra) underwent preoperative and intraoperative active warming. Ten patients (Gintra) were only warmed intraoperatively. RESULTS After 45 min of preoperative warming, the patients in Gpre+intra had significantly higher core temperatures than did the patients in the unwarmed groups (Gcontrol and Gintra) before the anesthesia (p < 0.05) but not at the beginning of surgery (p > 0.05). The patients who were warmed intraoperatively had significantly higher core temperatures than did the patients in Gcontrol at the end of surgery (p < 0.05). All the patients were hypothermic at admission to the recovery room (T CORE < 36 degrees C). CONCLUSIONS Forty-five minutes of preoperative warming combined with intraoperative skin-surface warming does not avoid but minimizes hypothermia caused by spinal anesthesia in patients with midazolam premedication.

Influence of S(+)-ketamine analgesia in renal intraoperative ischemia: histological study in rats

PURPOSE To study in rats the effect of S(+) ketamine on the renal histology after intraoperative hemorrhage. METHODS Twenty male Wistar rats, anesthetized with sodium pentobarbital, were randomly divided in 2 groups: G1 - control (n=l0) and G2 - S(+)-ketamine (n=10), both submitted to arterial hemorrhage of 30% of volemia in 3 moments (10% each 10 min) 60 min after anesthesia. G2 received S(+)-ketamine, 15 mg. kg-1, i.m., 5 min after anesthesia and 55 min before the 1st hemorrhage moment (Ml). Medium arterial pressure (MAP), rectal temperature (T) and heart rate were monitored. The animals were sacrificed in M4, 30 min after the 3rd hemorrhage moment (M3) and the kidneys and blood collected from hemorrhage were utilized for histological study and hematocrit (Ht) determination. RESULTS There were significant reduction of MAP, T, and Ht. The histological study verified G1 = G2 for tubular dilation, congestion, and necrosis. The total score addition were significantly different and G2 > G 1. CONCLUSION Hemorrhage and hypotension determined changes in kidney histology. The rise in catecholamine blood concentration probably was the cause of S(+)-ketamine-induced higher score of histological changes.

The Incidence of Paresthesia and Neurologic Complications after Lower Spinal Thoracic Puncture with Cut Needle Compared to Pencil Point Needle. Study in 300 Patients

Background: Anesthesiologists are reluctant to considerer higher levels for spinal anesthesia largely due to direct threats to spinal cord. Paresthesias are relatively common during spinal needle insertion; however, the clinical significance of the paresthesia is unknown. The main objective of this prospective study was to evaluate the incidence of paresthesia and neurologic complications after lower thoracic spinal anesthesia with a cut needle compared to a pencil point needle. Methods: Low thoracic spinal puncture (T10-T11) was performed in 300 patients in elective surgery using different techniques in this single-blind prospective trial. Patients randomized to 2 groups: group 1, subarachnoid puncture using a cut needle without introducer and group 2, subarachnoid puncture using a pencil point needle with introducer. In both groups patients were in the lateral or sitting position. Results: Paresthesias occurred in 20/300 (6.6%) of patients. Seven patients experienced a paresthesia with cut needle compared with 13 patients with pencil point, without statistical difference. All paresthesias were transient. No neurologic complications were observed in all patients during this study. Conclusions: Our data suggest that all transient paresthesia are transitory. Lower thoracic puncture is safe. Traumatic injury to the spinal cord is a rare cause of neurologic deficits in the thoracic puncture.

The effects of intrathecal administration of betamethasone over the dogs' spinal cord and meninges

PURPOSE To determinate the potential clinical and histological changes due the injection of betamethasone, when administered into the canine intrathecal space. METHODS Twenty one animals were included in a random and blind manner in the study. After general anesthesia, intrathecal puncture was performed and 1 ml of the random solution was injected. The G1 dogs received 0.9% saline solution, the G2 dogs received 1.75 mg betamethasone and the G3 dogs received 3.5 mg of betamethasone. The animals were clinically evaluated for 21 days and then sacrificed. The lumbar and sacral portions of the spinal cord were removed for light microscopy histological analyses. RESULTS No clinical changes were observed in any of the animals included in this study. No histological changes were observed in G1 animals. Inflammatory infiltration was observed in two dogs, one in G2, another in G3. Hemorrhage and necrosis were also seen in the G2 dog which inflammatory infiltration was detected. In other two dogs, one from G2 and another from G3, there was discreet fibrosis and thickness of the arachnoid layer which was focal in one and diffuse in the other. CONCLUSION Intrathecal administration of betamethasone caused histological changes in the spinal cord and meninges in some of the dogs involved in this study.

Anestesia na Pré-Eclâmpsia

BACKGROUND AND OBJECTIVES Although affecting a small obstetric population, pre-eclampsia is responsible for considerable maternal morbidity and mortality. Therefore, the adequate anesthetic control of this group is yet a challenge for anesthesiologists. This paper aimed at presenting pathophysiology, pharmacological treatment and anesthetic options to normal or surgical delivery in pre-eclampsia patients. CONTENTS Classification and terminology of pregnancy-induced arterial hypertension, its pathophysiology, changes in different systems and organs, general principles for patients control and anesthetic options for normal or surgical delivery are described. CONCLUSIONS The anesthesiologists knowledge of the pathophysiology, treatment options, and pharmacological characteristics of drugs used to control arterial hypertension and prevent seizures, as well as their interactions with anesthetic drugs and techniques, may decrease perioperative complications and maternal and fetal mortality.

Retrospective analysis of risk factors and predictors of intraoperative complications in neuraxial blocks at Faculdade de Medicina de Botucatu-UNESP.

BACKGROUND AND OBJECTIVES Cardiovascular changes associated with neuraxial blocks are a cause of concern due to their frequency and because some of them can be considered physiological effects triggered by the sympathetic nervous system blockade. The objective of this study was to evaluate intraoperative cardiovascular complications and predictive factors associated with neuraxial blocks in patients ≥ 18 years of age undergoing non-obstetric procedures over an 18-year period in a tertiary university hospital--HCFMB-UNESP. METHODS A retrospective analysis of the following complications was undertaken: hypertension, hypotension, sinus bradycardia, and sinus tachycardia. These complications were correlated with anesthetic technique, physical status (ASA), age, gender, and preoperative co-morbidities. The Tukey test for comparisons among proportions and logistic regression was used for statistical analysis. RESULTS 32,554 patients underwent neuraxial blocks. Intraoperative complications mentioned included hypotension (n=4,109), sinus bradycardia (n=1,107), sinus tachycardia (n=601), and hypertension (n=466). Hypotension was seen more often in patients undergoing continuous subarachnoid anesthesia (29.4%, OR=2.39), ≥ 61 years of age, and female (OR=1.27). CONCLUSIONS Intraoperative hypotension and bradycardia were the complications observed more often. Hypotension was related to anesthetic technique (CSA), increased age, and female. Tachycardia and hypertension may not have been directly related to neuraxial blocks.

Comparative Study between Combined Sciatic-Femoral Nerve Block, via a Single Skin Injection, and Spinal Block Anesthesia for Unilateral Surgery of the Lower Limb

BACKGROUND AND OBJECTIVES Unilateral spinal anesthesia has advantages when used in outpatient basis. The objective of the present study was to compare unilateral spinal anesthesia with combined sciatic-femoral nerve block in unilateral orthopedic surgeries in outpatients. METHODS Sixty patients were randomly divided into two groups of 30 patients to receive 6 mg of hyperbaric or hypobaric bupivacaine (RQ group) in left lateral decubitus, or 800 mg of 1.6% lidocaine with epinephrine on sciatic and femoral nerves (CFI group) in dorsal decubitus. A 150-mm needle connected to a neurostimulator, inserted in the middle point between both classical approaches, was used for the nerve block, with the injection of 15 mL on the femoral nerve and 35 mL on the sciatic nerve. The time for the blockades and their duration were evaluated. After twenty minutes, patients were evaluated regarding the sensorial and motor blockades. RESULTS Time for performance of spinal anesthesia was substantially lower than for combined sciatic-femoral nerve block. Unilateral blockade was achieved in 90% of the patients in the RQ group, and 100% in the CFI group. Bradycardia or hypotension was not observed. CONCLUSIONS This study concluded that combined sciatic-femoral nerve block is technically easy to perform and it can be an alternative for unilateral blockade of the lower limbs. Unilateral spinal anesthesia with low doses of bupivacaine resulted in shorter time to perform it, lower number of attempts, and earlier recovery than combined sciatic-femoral nerve block, but with the same efficacy.