Intrathecal Injection Of Bupivacaine Research Articles

A case of myoclonus in a cat after intrathecal injection of bupivacaine and morphine.

A case of myoclonus in a cat after intrathecal injection of bupivacaine and morphine.

Epidural and subdural hematoma following spinal anesthesia in infants rat model.

The aim of this study was to assess the epidural and subdural hematoma following spinal anesthesia in infants' rat model. We investigated during 10, 15, and 20 days' rats in group 1: intrathecal injection of bupivacaine 3.75 mg/kg (n = 7); group 2: received 37.5 μl midazolam 0.1% intrathecal with 37.5μl fentanyl 0.005% (no=7); injected into group 3 methylene blue 1 mg/ml (No. 7). Rats were exposed to spinal anesthesia in infancy and rotarod in motor function in adulthood. Histological evaluation and tissue extraction were also performed after the treatment and magnetic resonance imaging (MRI) of the head. MRI of the head of all rat pups that showed similar symptoms were performed. 4 rat pups showed the symptoms of hematoma Group1: small acute subdural hematoma at the left posterior temporal-parietal junction (PTPJ) and group 2 (one: right temporal epidural hematoma, two: Small acute subdural hematoma in the right temporomandibular area, and three: frontal-temporal-parietal-occipital hematoma). the rat pup that had epidural hematoma died 6 hours later. Finally, in the first group, one rat and the second group three rats showed hematoma symptoms. For these three rats, a histopathologic study was performed and indicate the presence of small acute subdural hematoma at the left posterior temporal-parietal junction, right temporal epidural hematoma, and frontal-temporal-parietal-occipital hematoma. In summary, because subdural or epidural hematoma of the skull can have serious consequences, differential diagnosis is very important for pain after spinal anesthesia.

A randomized, double-blinded comparative study of phenylephrine infusion and norepinephrine infusion for the prevention and treatment of spinal anesthesia-induced hypotension in elective and emergency cesarean deliveries

Context and Aims: Among vasopressors used to treat postspinal hypotension (PSH) in cesarean sections (CS), phenylephrine (PE) is the preferred drug at present but reflex bradycardia and thus reduction in cardiac output still pose a concern. Norepinephrine (NE), with its better pharmacological properties, may be a better alternative to overcome this risk. Hence, we did this study intending to compare both the drugs. Materials and Methods: A double-blinded, randomized, controlled trial (RCT) was carried out on 70 patients, 35 in each group-group P (PE) and group N (NE) undergoing CS, to compare and evaluate the efficacy of both drugs for preventing and treating PSH. Patients in Group P and Group N were given intravenous infusion of PE at the rate of 50 μg/min and NE at the rate of 2.5 μg/min, respectively, after the intrathecal injection of bupivacaine. The number of intermittent bolus doses required, heart rate, and mean arterial pressure (MAP) at predefined intervals were noted. Results: The incidence of hypotension calculated from the number of bolus doses required was lower in Group N than in Group P for the initial 15 min (P Conclusion: This study suggests that NE infusion is superior to PE infusion when used in the potency ratio of 20:1, to prevent and treat PSH in CS, with a lesser number of side effects.

Use of infusion paracetamol in the multimodal management of post myomectomy pain: A randomised control study

Objective: The study evaluated the use of infusion paracetamol in the multimodal management of post myomectomy pain and its analgesic sparing effects while comparing the side effect profile.Methods: Sixty-two ASA I and II patients undergoing myomectomy under subarachnoid block were randomized into two groups which were either given infusion Paracetamol (perfalgan, Bristol-Myers Squibb) 100ml and rectal diclofenac (Voltaren, Novartis ), or infusion normal saline 100ml and rectal diclofenac (voltaren, Novartis) after the last skin stitch. Pain was assessed using NRS (Numerical rating scale). Patients were assessed for the presence of motor or sensory complications, rectal bleeding or gastrointestinal discomfort, postoperative nausea and vomiting and sedation. The presence of other side effects was noted. Patients’ satisfaction with pain relief using the 5-point Likert scale was also evaluated.Results: Time to first analgesic request was longer in the paracetamol/diclofenac group compared to the saline/diclofenac group. The time from intrathecal injection of bupivacaine and pethidine to first request for analgesia was 319.12±9.5 minutes in the paracetamol group as against 213.29±9.5 in the saline group. The mean pain scores at 2nd and 5th hour and at the time of first analgesic request were lower in patients in group P compared to the patients in the saline group. (4.83±1.6 vs 5.93±1.4) (P=0.012-test. Total analgesic consumption was more in the saline group.Conclusion: Infusion paracetamol provides additional analgesia in the management of post myomectomy pain.

Comparison of intravenous tramadol and intravenous ketamine for the prevention of post-anaesthetic shivering

Background: Following general anaesthesia, post-operative shivering, apart from its physiological and haemodynamic effects, has been described as even worse than surgical pain. Methods: After ethical committee approval and informed consent, ninety patients were subjected to study. They were randomly divided into three groups. Just after intrathecal bupivacaine injection, all patients received prophylactically intravenous drug as normal saline (Group C, n = 30) or ketamine 0.5 mg/kg (Group K, n = 30) or tramadol 2 mg/kg (Group T, no = 30) for shivering. The incidence and degree of shivering and the effectiveness and side effects of ketamine and tramadol in preventing shivering during the post-operative period were recorded. Results: We compared the efficacy of tramadol and ketamine in the prevention of post-anaesthetic shivering in patients undergoing surgery under GA. The incidence of post-anaesthetic shivering was significantly less with tramadol and ketamine as compared to that of the control group (P 0.05). Patients in the ketamine group had statistically significant sedation at 20 and 30 min compared to the tramadol and control groups (P

Relationship between changes in regional cerebral blood volume and oxygenation and changes in cardiac output and systemic vascular resistance during spinal anesthesia in women undergoing cesarean section

The decrease in maternal regional cerebral blood volume (rCBV) and oxygenation (rCBO) during spinal anesthesia for cesarean section depends on the severity of hypotension. We examined the relationships between changes in the systemic circulatory parameters, cardiac output (CO) and systemic vascular resistance (SVR), and rCBV and rCBO after induction of spinal anesthesia, evaluated by near-infrared spectroscopy (NIRS) and an arterial pressure-based cardiac output monitoring system (APCOs). Seventeen patients undergoing elective cesarean section under spinal anesthesia were monitored every 1min for mean arterial pressure (MAP), heart rate (HR), end-tidal carbon dioxide (EtCO2) and oxygen saturation (SpO2), and at 20s intervals for CO, SVR, concentrations of oxy-hemoglobin (Hb), deoxy-Hb, total-Hb, and tissue oxygenation index (TOI), until 15 min after the intrathecal injection of bupivacaine. We investigated changes in the parameters from baseline and evaluated correlations between the changes in total-Hb and TOI and changes in CO and SVR, respectively, at the same timepoints. Oxy-Hb, total-Hb, TOI, and SVR significantly decreased and HR significantly increased with a decrease in MAP (P < 0.01). Deoxy-Hb, CO, SpO2, and EtCO2 levels did not change from baseline. There were statistically significant, although weak, positive correlations between both total-Hb and TOI with SVR (total-Hb; r = 0.18, P < 0.01, TOI; r = 0.38, P < 0.01). The decreases in both rCBV and rCBO after induction of spinal anesthesia for cesarean section are probably dependent on the decrease in SVR due to spinal anesthesia.

A Comparative Study of Intrathecal Injection of Bupivacaine Alone or with Fentanyl, Clonidine, and Neostigmine in Lower Abdominal Surgeries

Background: Anesthesiologists are responsible for the development of pain services in the current era. Hence ideal adjuvants that can be used with bupivacaine for stable intraoperative conditions and prolonging the postoperative analgesia with fewer side effects are being investigated. Opioids, despite useful as adjuvants, are associated with undesirable side effects. Aim of the work: The study was done to compare analgesic efficacy and hemodynamic of intrathecal injection of bupivacaine alone or with fentanyl, clonidine, and neostigmine in lower abdominal surgeries, over the first 24 postoperative hours, in a randomized, double-blind, and clinical trial. Methods: 100 Patients were randomized into four equal groups, 25 patients in each group; Group B patients received 2.5 ml of 0.5% hyperbaric bupivacaine and 0.5 ml of normal saline. Group BF patients received 2.5 ml of 0.5% hyperbaric bupivacaine with (25 mics) of fentanyl. Group BC patients received 2.5 ml of 0.5% hyperbaric bupivacaine with 0.5 ml (75 mics) of clonidine. Group BN patients received 2.5 ml of 0.5% hyperbaric bupivacaine with 0.1 ml of neostigmine (50 mics) and 0.4 ml of normal saline. Intrathecal anesthesia was done with a recording of parameters intraoperative and the post-operative period. Each patient was assessed for hemodynamic parameters and effective analgesia in operation, and presence of complications (nausea, vomiting, sedation and pruritus) visual analogue pain score (VAS) postoperatively by a blinded investigator in the post-anesthesia care unit (PACU) and at 1, 2, 3, 4, 8 12, 18 and 24 h postoperatively. Results: The postoperative analgesia is more effective with group BC (the gold standard) than group B, group BF, and group BN. As regard complications during the study in all groups, complications as nausea, and vomiting were mainly with group BN; hypotension was primarily in group BC. Conclusion: Bupivacaine clonidine, bupivacaine neostigmine, and bupivacaine fentanyl intrathecal anesthesia produced a longer duration of postoperative analgesia after lower abdominal surgery in patients than bupivacaine alone. Bupivacaine clonidine mixture had the most extended period of analgesia, but with hypotension. So bupivacaine fentanyl mixture with moderate duration of analgesia and minimal side effects is most safe for a patient.

An Up-down Determination of the Required Seated Duration After Intrathecal Injection of Bupivacaine and Fentanyl for the Prevention of Hypotension During Cesarean Delivery

(Can J Anaesth 2017;64:1002–1008) Prolonged seated time following intrathecal injection can prevent hypotension during cesarean delivery by limiting the upward spread of hyperbaric local anesthesia, but the limited studies of this technique have shown conflicting results. This study aimed to determine the median seated time for the prevention of hypotension following intrathecal injection of either 11.25 or 15 mg of hyperbaric bupivacaine with preservative-free morphine and fentanyl. The secondary aim of the study was to measure the rates of supplemental analgesia requirements for patients with who remained seated for an extended duration after spinal anesthesia administration.

An up-down determination of the required seated duration after intrathecal injection of bupivacaine and fentanyl for the prevention of hypotension during Cesarean delivery

A prolonged seated time after intrathecal injection of hyperbaric bupivacaine and morphine is related to the incidence of hypotension during Cesarean delivery, but results in a high incidence of pain during peritoneal closure. We conducted this study to determine the effect of the addition of intrathecal fentanyl on the relationship between seated time and hypotension and intraoperative analgesia requirements. Women undergoing Cesarean delivery were randomized to receive an intrathecal injection of either 11.25 or 15 mg of hyperbaric bupivacaine with morphine 150 µg and fentanyl 15 µg using a combined spinal-epidural technique. The seated duration following intrathecal injection was assigned using up-down methodology. If the preceding patient was hypo- or normotensive, the next patient sat for 15 sec more or less, respectively. A systolic blood pressure < 80% of the preoperative value was defined as hypotension; a standardized anesthetic was administered, and the presence of pain during the procedure was recorded. Isotonic regression of pooled adjacent violators was used to determine the time at which 50% of each group would avoid hypotension (i.e., the median effective seated time). There were 15 patients in each group. The median seated time was 129 sec (95% confidence interval [CI], 116 to 150) for the 11.25-mg group and 459 sec (95% CI, 444 to 471) for the 15-mg group. Only one (3%) of the 30 patients in the study had pain on peritoneal closure, and this was successfully treated with intravenous fentanyl. We have determined the seated time required following intrathecal injection of hyperbaric bupivacaine, morphine, and fentanyl to prevent hypotension in 50% of patients undergoing Cesarean delivery. www.clinicaltrials.gov , NCT01896960. Registered 2 July 2013.

Relationship between regional cerebral blood volume and oxygenation and blood pressure during spinal anesthesia in women undergoing cesarean section.

During spinal anesthesia for cesarean section, cerebral oxygenation decreases may be related to an abrupt drop in cerebral blood flow due to hypotension. We measured the changes in maternal regional cerebral blood volume (rCBV) and oxygenation (rCBO) using near-infrared spectroscopy (NIRS) to evaluate whether a decrease in arterial blood pressure during spinal anesthesia diminishes rCBV and rCBO. Forty patients scheduled for elective cesarean section under spinal anesthesia were monitored for mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), and concentrations of oxy-hemoglobin (Hb), deoxy-Hb, total-Hb, and tissue oxygenation index (TOI), before spinal anesthesia (baseline) and for 20min after intrathecal injection of bupivacaine. We investigated changes in the values from baseline and evaluated whether the maximum changes in total-Hb (Δ-total-Hb) and TOI (Δ-TOI) correlate with changes in MAP at the same time point. The mean oxy-Hb, total-Hb, TOI, and MAP significantly decreased from baseline after intrathecal injection of bupivacaine (P<0.01). There were significant positive correlations between both Δ-total-Hb and Δ-TOI and the decrease in MAP (Δ-total-Hb: r=0.53, P<0.01; Δ-TOI: r=0.59, P<0.01). Maternal rCBV and rCBO decrease significantly during spinal anesthesia for cesarean section. Reductions in rCBV and rCBO may be associated with the severity of hypotension induced by subarachnoid sympathetic block with bupivacaine.

The Effects of Ephedrine and Phenylephrine on Placental Vascular Resistance During Cesarean Section Under Epidual Anesthesia.

The purpose of this article is to study the effect of ephedrine and phenylephrine on placental vascular resistance during cesarean section under epidural anesthesia via Doppler ultrasonography. Sixty female subjects, scheduled for elective cesarean section and had an intrathecal injection of bupivacaine, were randomly divided into two groups to receive phenylephrine (50μg/min) or ephedrine (4mg/min) via titration to maintain systolic blood pressure at baseline. Doppler ultrasonography was used to measure baseline vascular resistance values prior to administration of anesthesia, and resistance index (RI) and systolic peak velocity/diastolic velocity (S/D) values of umbilical artery and uterine artery were measured at each time point within first 20min following intrathecal injection. Blood samples were collected from umbilical artery and umbilical vein during delivery to assess the blood gas values. No significant differences in RI and S/D values of umbilical artery and uterine artery after intrathecal injection were found between two groups. RI and S/D values of uterine artery slightly increased in both groups at each time point after anesthesia, but remained within the normal range. No significant differences were observed in blood gas values and the total amount of vasoconstriction drugs between two groups. In contrast to previous reports that used animal models, our study did not show increased placental vascular resistance in patients following phenylephrine (50μg/min) or ephedrine (4mg/min) infusion, as well as no significant differences in the effect of either of these two. The discrepancy between the results of human and animal studies may be related to species differences and the mechanism of human placental vascular remodeling.

A Case of Chemical Meningitis Induced by Intrathecal Bupivacaine Injection

Background: Iatrogenic meningitis after spinal anesthesia is a rare condition. Most cases of iatrogenic meningitis have a bacterial etiology; however, there are a few reports of chemical meningitis associated with intrathecal administration of bupivacaine. Case Report: A 74-year-old man underwent cystoscopy, with anesthesia by intrathecal bupivacaine hydrochloride injection. Two hours post-procedurally, he complained of a severe headache and his mental status subsequently deteriorated from alertness to confusion. Cerebrospinal fluid examination on the day of admission showed an increase in cell count (841/mm 3 ; polymorphonuclear 78%: mononuclear 10%) and total protein (460 mg/dL). His clinical findings and laboratory abnormalities were consistent with the diagnosis of bupivacaine-induced chemical meningitis, rather than the bacterial meningitis. Conclusion: We report a case of chemical meningitis after spinal anesthesia with bupivacaine. Differential diagnosis should include chemical meningitis in cases of meningitis after spinal anesthesia. J Neurocrit Care 2014;7(2):122-124

A Case of Chemical Meningitis Induced by Intrathecal Bupivacaine Injection

Background: Iatrogenic meningitis after spinal anesthesia is a rare condition. Most cases of iatrogenic meningitis have a bacterial etiology; however, there are a few reports of chemical meningitis associated with intrathecal administration of bupivacaine. Case Report: A 74-year-old man underwent cystoscopy, with anesthesia by intrathecal bupivacaine hydrochloride injection. Two hours post-procedurally, he complained of a severe headache and his mental status subsequently deteriorated from alertness to confusion. Cerebrospinal fluid examination on the day of admission showed an increase in cell count (841/mm3; polymorphonuclear 78%: mononuclear 10%) and total protein (460 mg/dL). His clinical findings and laboratory abnormalities were consistent with the diagnosis of bupivacaine-induced chemical meningitis, rather than the bacterial meningitis. Conclusion: We report a case of chemical meningitis after spinal anesthesia with bupivacaine. Differential diagnosis should include chemical meningitis in cases of meningitis after spinal anesthesia. Key Words: Meningitis; Spinal anesthesia; Bupivacaine

Low-dose intrathecal local anesthetic does not increase the threshold current for the epidural stimulation test: a prospective observational trial of neuraxial analgesia in labouring women

The purpose of this study was to investigate the ability of the electrical epidural stimulation test (EST) to determine the position of the epidural catheter during combined spinal-epidural (CSE) anesthesia for labour analgesia. This was a prospective observational trial of attempted EST during neuraxial analgesia in labouring women. Ten women received a double-segment CSE technique and one woman underwent continuous spinal analgesia following inadvertent dural puncture and deliberate placement of the catheter tip in the intrathecal space. In all CSE cases, the spinal injection was performed below the level of the epidural insertion. The motor threshold current (MTC) was determined by EST through the existing epidural/intrathecal catheter immediately following and at five, ten, and 15 mins after intrathecal injection of bupivacaine 1.75mg and fentanyl 15μg. Changes in the MTC were expressed as a percent change compared with baseline. The MTC required to elicit muscle contractions in women with epidurally placed catheters was unaffected by the intrathecal injection of the analgesic mixture (P=0.731). The MTC increased following an intrathecal injection of the same mixture in a woman who had the catheter placed intrathecally. The intrathecal injection of a low dose of bupivacaine-fentanyl does not affect the MTC if the catheter is placed in the epidural space; however, it does affect the threshold if the catheter is placed intrathecally. We also confirm that the EST can help to determine the position of the epidural catheter prior to injection of the test dose. This trial was registered at ClinicalTrials.gov (NCT00464841).

Comparing the effect of adding dexmedetomidine versus dexamethasone on prolonging the duration of intrathecal bupivacaine in lower abdominal operations

Objective The aim of this study was to evaluate the efficacy of adding dexmedetomidine compared with dexamethasone to bupivacaine to prolong the duration of spinal anesthesia and analgesia in lower abdominal operations. Patients and methods This randomized double-blind study included 60 ASA I or II patients, aged between 25 and 55 years old, scheduled for lower abdominal operations. They were administered 0.5% intrathecal bupivacaine injection and randomly divided into one of three groups: control group (GC), in which patients were administered additional 1 ml of saline; GDX group, in which patients were administered 4 mg dexamethasone; and GDM group, in which patients were administered 10 μg dexmedetomidine. The patients were monitored for heart rate, mean arterial pressure, oxygen saturation, onset and duration of sensory and motor block, intraoperative and postoperative sedation and pain, and adverse events. Results Compared with GC, GDM had significantly faster onset of sensory block (P = 0.006), longer duration of sensory block (P Conclusion Intrathecal dexmedetomidine and dexamethasone are safe and effective adjuncts to intrathecal bupivacaine anesthesia in lower abdominal surgery. Dexmedetomidine showed to provide more rapid onset and longer duration of sensory block, longer duration of motor block, and longer postoperative analgesia.

Extracts from rabbit skin inflamed by the vaccinia virus attenuate bupivacaine-induced spinal neurotoxicity in pregnant rats.

Extracts from rabbit skin inflamed by the vaccinia virus can relieve pain and promote repair of nerve injury. The present study intraperitoneally injected extracts from rabbit skin inflamed by the vaccinia virus for 3 and 4 days prior to and following intrathecal injection of bupivacaine into pregnant rats. The pain threshold test after bupivacaine injection showed that the maximum possible effect of tail-flick latency peaked 1 day after intrathecal injection of bupivacaine in the extract-pretreatment group, and gradually decreased, while the maximum possible effect in the bupivacaine group continued to increase after intrathecal injection of bupivacaine. Histological observation showed that after 4 days of intrathecal injection of bupivacaine, the number of shrunken, vacuolated, apoptotic and caspase-9-positive cells in the dorsal root ganglion in the extract-pretreatment group was significantly reduced compared with the bupivacaine group. These findings indicate that extracts from rabbit skin inflamed by the vaccinia virus can attenuate neurotoxicity induced by intrathecal injection of bupivacaine in pregnant rats, possibly by inhibiting caspase-9 protein expression and suppressing nerve cell apoptosis.

Upper and lower extremity regional haemoglobin oxygen saturation in spinal anaesthesia

Differential distribution of blood flow to blocked or unblocked areas in regional anesthesia may occur due to the differential vasodilatation following sympathetic efferent nerve blockade. Laser doppler flowmetry and thermography [1, 2] have been used to detect this, successfully predicting the effects of regional anaesthesia, though they are not always available in the operating theatre. Well maintained blood pressure during spinal anaesthesia may, secondary to vasoconstriction in the unblocked area, compensate for the vasodilatation of spinal anaesthesia. Vasodilatation effects measured simultaneously in blocked and unblocked areas have not been reported. Near-infrared spectroscopy (NIRS) gives real-time regional haemoglobin oxygen saturation (rSO2) [3, 4]. In this pilot study, we measured rSO2 simultaneously, above and below the spinal anaesthetic levels during block onset. After approval of the institutional human investigation committee (no. 200808010R), and with informed consent, 20 consecutive patients (29–79 years) without a history of neurological or vascular disorder, having lower extremity operations under spinal anaesthesia were recruited to the study. NIRS (INVOS Cerebral Oximeter Model 5100B; Somanetics, Troy, MI, USA) with two adhesive patches was used to monitor rSO2. One patch was applied over the biceps brachii muscle, (the body part above the anaesthetic level), and the other patch was applied over the medial side of the gastrocnemius muscle of the non-surgical leg, (the body part below the anaesthetic level). In both extremities, rSO2 was monitored continuously and recorded every minute from before intrathecal bupivacaine injection until 15 min after injection. Isobaric bupivacaine 0.5% 12–15 mg was injected intrathecally and the level of anaesthesia was examined 10 min later by loss of cold sensation to alcohol swab by an anaesthetist not involved in the study. Statistical analysis used Sigmastat v.3 by spss. Data are mean (SD). Analysis used two-way ANOVA and a p value < 0.05 was considered significant. Multiple comparisons were used to differentiate between groups. Anaesthesia between T6-T11 was achieved and blood pressure was maintained within 15% of baseline. Baseline arm and calf rSO2 were 70.8 (12.8) and 65.1 (10.4) %, respectively. As shown in Fig. 5, rSO2 in the calf increased soon after induction of spinal anesthesia (p < 0.001). rSO2 in the arm did not decrease significantly. There was a statistically significant interaction between time and site (p = 0.016). Changes in regional haemoglobin oxygen saturation (rSO2) at upper and lower extremities as measured by near-infrared spectroscopy in spinal anesthesia. Data are mean (SE). Our results showed a divergence of rSO2 between unblocked and blocked body parts with the onset of spinal anaesthesia. The slight decrease of rSO2 in the upper limb may indicate mild vasoconstriction with onset of spinal anesthesia. NIRS may serve as a potential monitor for the onset of neuroaxial blockade predicting the success of the block. It may be potentially useful in patients with hearing or speech difficulties. The rSO2 detects haemoglobin oxygen saturation at a depth of 30 and 40 mm in tissue rather than skin oxygen saturation which has been found to be unreliable for detecting sympathetic block [5]. There are limitations to this work, firstly lower extremity rSO2 increased by < 5% in four out of 20 patients although spinal anaesthesia was adequate. Secondly, the lower extremity increase in rSO2 indicated onset of spinal anesthesia but not adequacy of surgical anesthesia. We suggest that detection of rSO2 over non-anaesthetised and anaesthetised body parts could be an alternative monitor for onset of neuroaxial blockade.

Combined spinal–epidural analgesia for labor pain: best timing of epidural infusion following spinal dose

The combined spinal-epidural analgesia (CSEA) technique for labor pain has attained wide spread popularity in obstetric anesthesia. The onset of analgesia is rapid and reliable, and maternal satisfaction is very high. However, the best timing of an epidural infusion following the spinal dose and its effect on the total local anesthetics consumption has not been well determined. A total of 144 consenting healthy nulliparous parturients whose labor was induced and who labored under regional analgesia were enrolled in this study. Following induction of the CSEA with intrathecal injection of bupivacaine, 2.5 mg and fentanyl, 25 microg, the patients were randomized into one of four groups to receive a subsequent continuous epidural infusion [E (3), E (30), E (60) and E (90)], depending on the timing of the initiation of epidural infusion of 0.1% ropivacaine, 0.0002% fentanyl and 1:500,000 epinephrine at the rate of 10 ml/h. In study Groups E (3), E (30), E (60) and E (90), epidural infusion was initiated 3, 30, 60 and 90 min, respectively following spinal induction dose. Patients requesting additional labor analgesia were given an epidural bolus (8 ml) of ropivacaine, 0.2%. The number of parturients requesting additional boluses of ropivacaine and the total dose of ropivacaine required for labor analgesia were registered. The numbers of patients who required additional boluses of ropivacaine in Group E (3) and Group E (30) were significantly less than those in Group E (60) and Group E (90). The total dose of ropivacaine required for labor pain in Group E (3) and Group E (30) was insignificantly smaller than the total dose required in Group E (60) and Group E (90). Our results suggest that the best timing of epidural infusion following spinal dose was within 30 min of spinal induction dose.

Intrathecal bupivacaine protects against extension of lesions in an acute photochemical spinal cord injury model.

The photochemical spinal-cord injury model reproduces extensive secondary lesions that occur after spinal injury. We have evaluated in 27 rats the functional, electrophysiological and anatomical consequences of a photochemical spinal-cord lesion induced before or after intrathecal injection of bupivacaine. After randomization, nine rats received 20 micro L of intrathecal bupivacaine 0.5% 15 min before a photochemical spinal-cord lesion (Group I) and eight rats received 20 micro L intrathecal bupivacaine 15 min after such a lesion (Group II). Ten rats received 20 micro L of saline 15 min before the photochemical injury (control group). Paraplegia was tested on days one, three, five, seven, nine, 12, 15 and 18 using an evaluation of hindlimb movements and an inclined plane stability test. Sensory block was evaluated by the animal's response when each hindlimb was brought into contact with a hot plate. Sympathetic injury was evaluated in terms of bladder voiding dysfunction. On day 18, residual somatosensory evoked potentials (SEP) were measured and the area of the intact spinal cord was determined using a digitalized system. Early paraplegia recovery was found in the two bupivacaine groups (P < 0.05). On day 12, motor recovery was complete in both bupivacaine groups whereas recovery was not complete on day 18 in the control group. Compared to the control group, inclined plane stability recovered earlier in Groups I and II, from day three to day 15. Sensory and sympathetic block scores were not different in the three groups. Nevertheless, SEP latencies were longer and amplitudes were lower in control group rats compared with the two bupivacaine groups on day 18. The intact spinal-cord cross-sectional area around the lesion was not different in the three groups. Twenty microlitres of intrathecal bupivacaine before or after acute photochemical spinal injury improves hindlimb motor recovery and SEP parameters in rats.