Continuous lumbosacral block using a Tuohy needle and catheter technique

Three cases are reported where continuous lumbosacral block was performed using a catheter through an epidural needle technique. Good unilateral lower limb surgical anaesthesia was achieved in all three cases with successful blockade of the lumbar and sacral plexuses. A 17-gauge Tuohy needle was positioned between the transverse processes of L4 and L5 and an epidural catheter inserted into the space between the quadratus lumborum and psoas muscles. Forty to seventy millilitres of local anaesthetic were injected and resulted in good surgical anaesthesia within 12-20 min. Radiographic studies in these patients confirmed placement of the catheter in close proximity to the lumbosacral plexus. Experience in a further 12 cases is also reported. There were no side-effects. The technique is successful and is recommended when unilateral lower limb anaesthetic is required and when spinal and epidural anaesthesia are contraindicated.     

Epidural injection of lidocaine reduces the response to dural puncture accompanying spinal needle insertion when performing combined spinal-epidural anesthesia

During placement of needles for combined spinal-epidural anesthesia (CSEA), patients may experience pain, pressure, paresthesia, or discomfort during skin and deeper injection of local anesthetic, needle impingement on periosteum, dural puncture by the spinal needle, and insertion of the epidural catheter. We investigated the incidence of perception of and spontaneous verbal and motor responses to insertion of a spinal needle through the dura mater and pia mater and the effect of injecting lidocaine into the epidural space through the epidural needle before inserting the spinal needle through the meninges. Forty-three patients presenting for elective cesarean delivery under CSEA were studied. After localization of the epidural space using loss of resistance to air using a 17-gauge Tuohy needle, either 3 mL preservative free normal saline or 3 mL lidocaine 2% plus epinephrine 1:200,000 was injected through the Tuohy needle. "Needle through needle" dural puncture was performed 1 min later using a 27-gauge Whitacre pencil-point needle. At the moment of dural puncture, 2 (9%) parturients given lidocaine and 17 (81%) parturients given saline (P < 0.005) responded to dural puncture by spontaneously moving (33%), spontaneously vocalizing (62%), or, in response to direct questioning, by acknowledging (76%) having perceived sensation during thecal penetration. This study reveals that dural puncture by a Whitacre 27-gauge pencil-point needle inserted through a Tuohy epidural needle sited using loss of resistance to air causes involuntary movement, spontaneous vocalization, or is perceived by the majority of patients presenting for cesarean delivery under CSEA and that lidocaine injected into the epidural space before dural puncture largely eliminates these responses and sensations.     

Comparison of technical and block characteristics of different combined spinal and epidural anesthesia techniques

BACKGROUND AND OBJECTIVES: The combined spinal and epidural (CSE) technique can reduce or eliminate some of the disadvantages of spinal and epidural anesthesia, while still preserving their advantages. CSE anesthesia is now commonly performed with a single-segment needle-through-needle technique; however, this technique involves some controversies about needle handling and the risk of catheter migration. To avoid some of these potential problems, special CSE sets have been produced. In the present study, 2 of these sets were compared with the traditional double-segment technique. METHODS: Ninety patients undergoing orthopedic surgery of the lower extremity were randomly allocated into 3 groups of equal size: Group 1, CSE set with an interlocking device between the spinal and epidural needle; group 2, CSE set with a "backeye" at the epidural needle curve for the passage of the spinal needle; group 3, double-segment technique. All epidural needles were 18-gauge, and spinal needles were 27-gauge with a pencil-point tip. In groups 1 and 2, the puncture was performed at the L3-4 interspace, and in group 3 the epidural catheter was first inserted at the L2-3 interspace followed by spinal puncture one interspace lower. Hyperbaric 0.5% bupivacaine, 2 mL, was used for the spinal block, and 4 mL of 2% lidocaine with epinephrine through the epidural catheter was used as a test dose. The block performance characteristics were recorded, and the level of analgesia was studied in a blinded fashion. Postoperatively, a bolus of epidural morphine 2 to 4 mg was used for the control of postoperative pain. All patients were interviewed on the 1st and the 7th postoperative days. Afterwards, the needles and catheters were examined by microscopy. RESULTS: The frequency of the successful CSE block was higher in groups 3 (100%) and 2 (90%) than in group 1 (63%) (P <.05). The mean duration of successful block performance, as well as the median level of analgesia, were similar in all the groups. One case of epidural catheter migration intrathecally was observed (group 1). Postoperative nausea and vomiting occurred in 23% of patients, and the incidence of postdural puncture headache was 2.2%. The incidence of backache at the puncture site was similar in the groups. Microscopy showed 6 distorted spinal needle tips (all in group 1), but no material damage to the epidural catheters. CONCLUSIONS: The use of the CSE sets does not seem to save time compared with the double-segment technique. Technical problems, unsuccessful CSE block, and damaged spinal needle tip were noted relatively often with the interlocking CSE set. Anesthetic characteristics in the successful blocks were similar with the different techniques.     

A comparison of Espocan and Tuohy needles for the combined spinal-epidural technique for labor analgesia

When using the needle-through-needle combined spinal-epidural (CSE) technique for labor analgesia, failure to obtain cerebrospinal fluid (CSF), paresthesias, and intrathecal or intravascular migration of the catheter are of concern. Epidural needles with spinal needle apertures, such as the back-hole Espocan (ES) needles, are available and may reduce these risks. We describe the efficacy and adverse events associated with a modified epidural needle (ES) versus a conventional Tuohy needle for CSE. One-hundred parturients requesting labor analgesia (CSE) were randomized into 2 groups: 50-ES 18-gauge modified epidural needle with 27-gauge Pencan atraumatic spinal needle, 50-conventional 18-gauge Tuohy needle with 27-gauge Gertie Marx atraumatic spinal needle. Information on intrathecal or intravascular catheter placement, paresthesia on introduction of spinal needle, failure to obtain CSF through the spinal needle after placement of epidural needle, unintentional dural puncture, and epidural catheter function was obtained. No intrathecal catheter placement occurred in either group. Rates of intravascular catheter placement and unintentional dural puncture were similar between the groups. Significant differences were noted regarding spinal needle-induced paresthesia (14% ES versus 42% Tuohy needles, P = 0.009) and failure to obtain CSF on first attempt (8% ES versus 28% Tuohy needles, P < 0.02). Use of ES needles for CSE significantly reduces paresthesia associated with the insertion of the spinal needle and is associated with more frequent successful spinal needle placement on the first attempt. IMPLICATIONS: The use of modified epidural needles with a back hole for combined spinal-epidural technique significantly reduces paresthesia associated with the insertion of the spinal needle and is associated with more frequent successful spinal needle placement on the first attempt.     

Epidural catheter penetration of human dural tissue: in vitro investigation

BACKGROUND: Factors contributing to subarachnoid catheter passage after epidural placement are not well understood. This study explored mechanisms that might explain its occurrence. METHODS: Human cadaveric dura was mounted on a model and pressurized to physiologic levels. In a standardized fashion, a 20-gauge Portex three-port, closed end (nonflexible) tip catheter was passed through an epidural needle mounted on a micromanipulator at a 90 degree angle, attempting to penetrate dura with the catheter. Attempts then followed with a 19-gauge Arrow Flex Tip Plus single-port catheter. Subarachnoid catheter passage was compared in (1) intact dura, (2) clinically occult versus obvious epidural needle punctures, and (3) single 25-gauge Whitacre spinal needle punctures after combined spinal-epidural placement. RESULTS: Neither catheter penetrated intact dura: Portex, 0 of 300 attempts (0.0000; 95% confidence interval [CI]: 0.0000, 0.0158); Arrow, 0 of 300 attempts (0.0000; 95% CI: 0.0000, 0.0158). In clinically occult epidural needle punctures, the 20-gauge Portex catheter penetrated 1 of 3 specimens in 1 of 14 attempts (0.0714; 95% CI: 0.0021, 0.3583). The 19-gauge Arrow did not pass (0 of 15 attempts, 0.0000; 95% CI: 0.0000, 0.2535). In clinically obvious epidural needle punctures, the Portex passed in 6 of 33 attempts (0.1818; 95% CI: 0.0760, 0.3608) and the Arrow passed in 1 of 35 attempts (0.0286; 95% CI: 0.0012, 0.1662). Neither catheter passed through a single 25-gauge spinal needle puncture after an uncomplicated combined spinal-epidural: Portex, 0 of 90 attempts (0.0000; 95% CI: 0.0000, 0.0510); Arrow, 0 of 90 attempts (0.0000; 95% CI: 0.0000, 0.0510). CONCLUSIONS: Catheter passage is unlikely in the presence of intact dura or after an uncomplicated combined spinal-epidural. Unintentional subarachnoid passage suggests dural damage with the epidural needle.     

Sensorimotor anesthesia and hypotension after subarachnoid block: combined spinal-epidural versus single-shot spinal technique

The extent of the intrathecal compartment depends on the balance between cerebrospinal fluid and subatmospheric epidural pressure. Epidural insertion disrupts this relationship, and the full impact of loss-of-resistance on the qualities of subarachnoid block is unknown. In this study we sought to determine if subarachnoid block, induced by combined spinal-epidural (CSE) using loss-of-resistance to air could render higher sensory anesthesia than single-shot spinal (SSS) when an identical mass of intrathecal anesthetic was injected. Sixty patients, scheduled for minor gynecological procedures, were randomly allocated into three groups all receiving 10 mg of 0.5% hyperbaric bupivacaine. In the SSS group, intrathecal administration was through a 27-gauge Whitacre spinal needle inserted at the L3-4 level. For the CSE group, the epidural space was identified with an 18-gauge Tuohy needle using loss-of-resistance to 4 mL of air. After intrathecal administration, a 20-gauge catheter was left in the epidural space. No further drug or saline was administered through the catheter. The procedure was repeated in group CSE ((no-catheter)) except without insertion of a catheter. Sensorimotor anesthesia was assessed at regular 2.5-min intervals until T10 was reached. In all aspects, there was no difference between CSE and CSE ((no-catheter)). Peak sensory level in SSS was lower than CSE and CSE ((no-catheter)) (median T5 [max T3-min T6] versus (T3 [T1-4] and (T3 [T2-5]) (P < 0.01). During the first 10 min postblock, dermatomal thoracic block was the lowest in SSS (P < 0.05). Time for regression of sensory level to T10 was also shortest in SSS. Hypotension, ephedrine use and period of motor recovery were more pronounced in CSE and CSE ((no-catheter)). We conclude that subarachnoid block induced by CSE produces greater sensorimotor anesthesia and prolonged recovery compared with SSS. There is also a more frequent incidence of hypotension and vasoconstrictor use despite using identical doses and baricity of local anesthetic. IMPLICATIONS: This study confirms that induction of subarachnoid block by a combined-spinal epidural technique produces a greater sensorimotor anesthesia and results in prolonged recovery when compared with a single-shot spinal technique. There is a more frequent incidence of hypotension and vasoconstrictor administration despite identical doses of intrathecally administered local anesthetic.     

Combined spinal-epidural anesthesia for cesarean section; needle-through-needle approach

Purpose The Portex “Spinal/Epidural Set” is designed for combined spinal-epidural (CSE) anesthesia by the needle-through-needle approach. We evaluated the technical and clinical usefulness of CSE with this needle set, and also isobaric tetracaine, for cesarean section. Methods Thirty patients for cesarean section were included. In the left decubitus position, a 16-gauge epidural needle was introduced by the loss-of-resistance method into the lumbar intervertebral space. A 26-gauge spinal needle was threaded through the epidural needle into the subarachnoid space. Tetracaine dissolved in saline was injected. A 17-gauge catheter was advanced into the epidural space. The analgesic level was checked by the pin-prick method. Results The insertion in the first attempt was successful in 21 cases (70%) of the patients, and difficulty in insertion was not experienced. Inadvertent dural puncture occurred in one case, but no accidental subarachnoid catheterization was observed. Spinal anesthesia with tetracaine (11.1±0.5 mg) reached the level of Th₆ on average, with a relatively wide range. Five cases (13%) were supplemented by epidural anesthesia. No postspinal headache was noted. Conclusion CSE technique by the needle-through-needle approach is easy to handle, and provides a speedy, reliable, and flexible analgesia as well as postoperative pain relief for patients undergoing cesarean section.     

Epidural Catheter Penetration of Human Dural Tissue: In Vitro Investigation

Background: Factors contributing to subarachnoid catheter passage after epidural placement are not well understood. This study explored mechanisms that might explain its occurrence.

Methods: Human cadaveric dura was mounted on a model and pressurized to physiologic levels. In a standardized fashion, a 20-gauge Portex(R) three-port, closed end (nonflexible) tip catheter was passed through an epidural needle mounted on a micromanipulator at a 90[degrees] angle, attempting to penetrate dura with the catheter. Attempts then followed with a 19-gauge Arrow Flex Tip Plus(R) single-port catheter. Subarachnoid catheter passage was compared in (1) intact dura, (2) clinically occult versus obvious epidural needle punctures, and (3) single 25-gauge Whitacre(R) spinal needle punctures after combined spinal-epidural placement.

Results: Neither catheter penetrated intact dura: Portex, 0 of 300 attempts (0.0000; 95% confidence interval [CI]: 0.0000, 0.0158); Arrow, 0 of 300 attempts (0.0000; 95% CI: 0.0000, 0.0158). In clinically occult epidural needle punctures, the 20-gauge Portex catheter penetrated 1 of 3 specimens in 1 of 14 attempts (0.0714; 95% CI: 0.0021, 0.3583). The 19-gauge Arrow did not pass (0 of 15 attempts, 0.0000; 95% CI: 0.0000, 0.2535). In clinically obvious epidural needle punctures, the Portex passed in 6 of 33 attempts (0.1818; 95% CI: 0.0760, 0.3608) and the Arrow passed in 1 of 35 attempts (0.0286; 95% CI: 0.0012, 0.1662). Neither catheter passed through a single 25-gauge spinal needle puncture after an uncomplicated combined spinal-epidural: Portex, 0 of 90 attempts (0.0000; 95% CI: 0.0000, 0.0510); Arrow, 0 of 90 attempts (0.0000; 95% CI: 0.0000, 0.0510).     

Ultrasound-guided subgluteal sciatic nerve blocks with stimulating catheters in children: a descriptive study

We describe our clinical experience of combining ultrasound guidance and nerve stimulation for the insertion of subgluteal sciatic catheters in children. Ten children scheduled for lower limb surgery with a combined general anesthetic and a subgluteal sciatic catheter placement for both operative anesthesia and postoperative pain relief were studied. Under ultrasonographic guidance the sciatic catheter was placed using an 17-gauge 50-mm Arrow continuous peripheral nerve block needle and a 19-gauge stimulating catheter (Stimucath). The minimal electrical current required for muscle contraction on the stimulating needle and catheter differed widely among patients. Based on the visualization of the spread of local anesthetic during injection through the catheter, a successful prediction for the sciatic block was made in all patients. All catheters were successfully placed and provided excellent postoperative pain relief without complications.     

Comparison of three catheter sets for continuous spinal anesthesia in patients undergoing total hip or knee arthroplasty

BACKGROUND AND OBJECTIVES: Continuous spinal anesthesia (CSA) with microcatheters may be complicated because of technical problems. In elderly patients, some of the problems may be solved by using thicker catheters. A recent invention, involving a catheter-over-needle system, may prevent leakage of cerebrospinal fluid (CSF) and may also improve the prediction of the intrathecal position of the catheter tip. METHODS: This study included 90 patients undergoing primary hip or knee replacement, randomly allocated into 3 groups, with 30 patients in each group: Group EC, a 24-gauge epidural catheter through a 19-gauge Tuohy needle; group MC, a 28-gauge microcatheter through a 22-gauge spinal needle; group SC, a 22-gauge spinal catheter over a 27-gauge spinal needle through an epidurally placed 18-gauge Crawford needle. All subarachnoid catheterizations were performed with the patient in the lateral position and the initial spinal block dose was 2 mL of plain 0.5% bupivacaine. Increments of 0.5 mL were administered when required. The block performance characteristics were recorded, and the level of analgesia was studied in a blinded fashion. Catheter function during the postoperative infusion was assessed. Afterwards the needles and catheters were examined by microscopy. RESULTS: The frequency of the successful catheterization was higher in the EC and MC groups (90% in each) than in the SC group (63%) (P <.05). The mean duration of the successful catheterizations, as well as the median level of analgesia, were similar in the groups. The postoperative infusion had to be stopped in 3, 1, and 1 patients in groups EC, MC, and SC, respectively, because of a technical reason. No neurologic sequelae occurred in this study. Microscopy showed 4 distorted spinal needle tips (2 each with MC and SC) and minor material damage of the SC catheters when bone had been met during block performance. CONCLUSIONS: Placement of the SC catheters was unsuccessful to a high degree, and bone contact produced distortion of the tip of some of these catheters. Otherwise, the quality associated with catheterization time, anesthetic distribution, and catheter function was similar with the 3 catheters.     

硬膜外注气对脊椎-硬膜外联合阻滞时腰穿的影响

目的 探讨硬膜外注气对脊椎-硬膜外联合阻滞时腰穿的影响.方法 拟在脊椎-硬膜外联合阻滞下行剖宫产术的足月单胎妊娠患者210例,ASA分级Ⅰ或Ⅱ级,年龄20～42岁,身高152～170 cm,体重57～82 kg,采用随机数字表法,将患者随机分为3组(n=70):悬滴法组(Ⅰ组)、少量注气组(Ⅱ组)和大量注气组(Ⅲ组).Ⅰ组以悬滴法验证硬膜外腔,Ⅱ组和Ⅲ组以注气试验验证硬膜外腔.Ⅱ组注气量以能感觉到阻力消失为准,Ⅲ组注气量为4 ml.置入腰穿针后见脑脊液回流则为腰穿成功.腰穿失败则改行硬膜外麻醉.记录腰穿成功情况、腰穿失败但硬膜外穿刺成功情况及不良反应发生情况.结果 Ⅰ组、Ⅱ组和Ⅲ组腰穿成功率分别为91%、93%和79%,Ⅰ组和Ⅱ组高于Ⅲ组(P<0.05),Ⅰ组和Ⅱ组间差异无统计学意义(P>0.05).所有腰穿失败患者均取得了双侧躯体节段性痛觉消失的硬膜外麻醉效果;所有腰穿成功患者也均取得了预期的麻醉效果.均未见严重不良反应发生.结论 硬膜外注气与脊椎-硬膜外联合阻滞时腰穿成功有关,大量注气可降低腰穿成功机率.

Abstract：

Objective To investigate the effect of injection of air into the epidural space on the subarachnoid puncture during the combined spinal-epidural anesthesia (CSEA) .Methods Two hundred and ten ASA Ⅰ or Ⅱ parturients who were at full term with a singleton fetus, aged 20-42 yr, weighing 57-82 kg (height 152-170cm) , undergoing cesarean section under CSEA, were randomly divided into 3 groups ( n = 70 each) : hanging drop technique group (group Ⅰ ) and injection of small volume of air group (group Ⅱ ) and injection of large volume of air group ( group Ⅲ ) . The epidural space was indentified using hanging drop technique in group Ⅰ and using loss of resistance to air technique in Ⅱ and Ⅲ groups. Injection of air was stopped as soon as the clear loss of resistance identified the epidural space in group Ⅱ , whereas all 4 ml of air was injected in group Ⅲ . After the epidural space was confirmed at L3,4 interspace, a 25-gauge spinal needle protruding 14 mm beyond the 18-gauge epidural needle was introduced through the epidural needle. Subarachnoid placement was confirmed by backflow of cerebrospinal fluid (CSF) . If no backflow of CSF was observed, the spinal needle was withdrawn and an epidural catheter was inserted through the epidural needle to perform epidural anesthesia. Successful subarachnoid puncture, failures to observe backflow of CSF and adverse reactions were recorded. Results The three groups were comparable with respect to age, height, body weight and gestation weeks. The success rate of subarachnoid puncture was 91% ,93% and 79% in Ⅰ ,Ⅱ and Ⅲ groups respectively, and it was significantly higher in Ⅰ and Ⅱ groups than in group Ⅲ ( P < 0.05) . There was no significant difference in the success rate of subarachnoid puncture between Ⅰand Ⅱ groups ( P > 0.05) . Bilateral segmental analgesia presented in all cases who received only epidural anesthesia after no backflow of CSF was observed, and the expected analgesia also presented in all cases in whom back flow of CSF was observed. No adverse reactions occurred. Conclusion Injection of air into the epidural space is related to the success of subarachnoid puncture during CSEA and injection of a large volume of air lowers the success rate.     

Prospective experience with a 20-gauge Tuohy needle for lumbar epidural steroid injections: Is confirmation with fluoroscopy necessary?

BACKGROUND AND OBJECTIVES: Small (20-gauge) Tuohy needles have been introduced for epidural steroid injection to optimize patient comfort and decrease the risk of spinal headache. These needles may be less reliable for indentification of the epidural space than standard 17- or 18-gauge needles because of their small size. We prospectively examined the success rate of lumbar epidural steroid placement with loss-of-resistance (LOR) technique compared with fluoroscopy confirmation. METHODS: One hundred patients without history of lumbar spine surgery were enrolled. A 20-gauge Tuohy needle was placed into the epidural space using LOR to saline. Confidence in epidural placement was recorded (Yes/No). Radiologic contrast was then injected and a fluoroscopic epidurogram interpreted by a blinded radiologist for correct placement, (Yes/No) separate from the clinical process. RESULTS: Reliability of LOR was less than our "gold standard" of fluoroscopy (P <.004). Sensitivity of LOR was 99% and specificity was 27%. Positive and negative predictive values were 92% and 75%. Increased patient age (>70 years) and male sex were associated with poor reliability of LOR (P <.05). CONCLUSIONS: In contrast to the reported 99% success rates for epidural placement of standard 17- or 18-gauge Tuohy needles, we observed a success rate of 92%. Small-gauge Tuohy needles are technically more difficult to use than larger needles and may require confirmation with fluoroscopy for correct epidural placement, especially in elderly male patients.     

An evaluation of a combined spinal/epidural needle set utilising a 26-gauge, pencil point spinal needle for Caesarean section

We have conducted a prospective study into the ease of use and incidence of postdural puncture headache with the 'Portex' combined spinal/epidural set. The pack contains a 16-gauge Tuohy needle of standard 8 cm shaft length with a matching 26-gauge pencil point spinal needle. The study included 150 consecutive combined spinal/epidural anaesthetics for lower segment Caesarean section. Eighty-eight percent of the cases fulfilled the criteria as technically perfect, i.e. cerebrospinal fluid obtained at the first attempt after identifying the epidural space. There were two cases of significant postdural puncture headache requiring blood patch due to puncture by the 26-gauge spinal needle giving an incidence of 1.3%. This compares favourably with previously reported rates in obstetric patients.     

The epidural structure changes during deep breathing

PURPOSE: Previous experience has suggested that the insertion of an epidural catheter becomes easier when the patient takes a deep breath. The purpose of this study is to investigate the effects of respiration on the epidural space. METHODS: We examined the epidural space using a flexible epiduroscope in 20 patients undergoing thoracic epidural anesthesia. A 17-gauge Tuohy needle was inserted using the paramedian technique and the loss-of-resistance method with 5 ml air. The epiduroscope was introduced into the epidural space via the Tuohy needle. Each patient was requested to take a deep breath when the epiduroscope was positioned at the needle tip and at approximately 10 cm cephalad from the needle tip within the epidural space. The changes in the epidural structure during deep breathing at each site were then measured. RESULTS: In 80% of the patients, fatty tissue occupied the needle tip. Through the patients' maximal inspiration, the fatty tissue moved and a visible cavity expanded at the needle tip. Cross section area of the visible cavity at the needle tip was greater at the maximal inspiratory level than at the resting expiratory level: 12.1 +/- 6.7% vs 2.8 +/- 2.1% (mean +/- SD, P < 0.0001). In all patients, the visible cavity within the epidural space, which had already been expanded by injected air, became more expanded after maximal inspiration. Cross section area of the visible cavity at the 10 cm cephalad position was greater at the maximal inspiratory level than at the resting expiratory level: 20.6 +/- 10.0% vs 7.0 +/- 5.3% (P < 0.0001). CONCLUSION: Epiduroscopy showed that deep breathing expanded the potential cavity of the epidural space. We suggest that the changes in the epidural structure during deep breathing may assist in the insertion of an epidural catheter.     

Inadvertent intrathecal injection of labetalol in a patient undergoing post-partum tubal ligation

After receiving a continuous spinal anesthetic for labor following an inadvertent dural puncture with a 17-gauge epidural needle, a morbidly obese parturient underwent post-partum tubal ligation 12 h after vaginal delivery. The patient received a total of 2 mL of 0.75% hyperbaric bupivacaine for the surgery. In response to moderate hypertension the patient received intravenous labetalol hydrochloride 20 mg. She subsequently was inadvertently administered approximately 15 mg of labetalol through the spinal catheter. The spinal catheter was removed immediately after the procedure. She suffered no apparent adverse neurologic effects.     

Epidural infusion pressure in degenerative spinal disease before and after epidural steroid therapy.

The analgesic mechanism of epidural steroids in reducing pain associated with degenerative spinal disease (DSD) is poorly understood. We report increased inline epidural infusion pressure in patients with DSD and assess whether this phenomenon is affected by administration of an epidural steroid injection. We collected data during epidural placement for routine surgery or epidural steroid therapy. Using a 17-gauge Tuohy needle, with patients in the right lateral decubitus position, loss of resistance to 2 mL of saline identified the epidural space. Two minutes later the needle was attached to saline-filled tubing connected to a pressure transducer (Baxter PX 260 pressure monitoring kit with Truwave TM disposable pressure transducer). In the first part of the study, 4 successive boluses of 3 mL of local anesthetic were administered at a rate of 6 mL/min to 15 patients (age 47 +/- 6 yrs) with radicular back pain and magnetic resonance imaging (MRI) or computed tomography (CT) evidence of DSD, and to 8 control patients with no history of back pain (age 44 +/- 5 yr) while inline epidural infusion pressure was measured. In the second part of the study 44 patients with low back pain and MRI or CT evidence of DSD presenting to the pain clinic were infused with 8 mL of 0.125% bupivacaine and 40 mg of methylprednisolone (20 mg/mL) at a rate of 6 mL/min while inline epidural infusion pressure was measure and recorded. This was repeated 3 wk later. Initially, DSD patients had significantly increased infusion pressures over normals, which most likely reflects outflow resistance or obstruction. A significant decrease in inline epidural infusion pressure was observed after epidural steroid treatment. This change in pressure may indicate efficacy from epidural steroid injection. IMPLICATIONS: During injection into the epidural space we observed increased resistance in patients with degenerative spinal disease. This resistance was significantly less when measured 3 wk after an epidural steroid injection. This change in pressure may indicate efficacy from epidural steroid injection.     

Spinal epidural anaesthesia

We present our experience with a new combined spinal epidural system through which regional anaesthesia was performed in 30 male patients undergoing suprapubic prostatectomy. The technique consists of two needles, a 17 G Tuohy needle with a hole in its distal curve (back eye) and a 29 G spinal needle which is passed through the back eye before being introduced into the subarachnoid space. We found the back eye combined spinal-epidural system effective and simple to use. The Tuohy needle with its back eye did not impede insertion of the epidural catheter and was a suitable introducer for the thin 29 G spinal needle.     

Threshold current for an insulated epidural needle in pediatric patients

We designed this study to determine the threshold current for nerve stimulation of an insulated needle in the epidural space. The intended dermatome was identified using the bony landmarks of the spine. An 18-gauge insulated Tuohy needle was inserted perpendicularly to the skin and advanced until "loss of resistance" was felt. A nerve stimulator was then connected to the insulated needle. Twenty patients were studied using an insulated Tuohy needle and one patient was studied using a noninsulated Tuohy needle. Muscle twitch was elicited with a current of 11.1 +/- 3.1 mA (mean +/- sd) in all patients in which an insulated needle was used. Muscle twitches were within 2 myotomes of the intended level (based on bony landmarks). Muscle twitch was not elicited with a noninsulated needle. After catheter threading, positive stimulation tests were elicited via epidural catheters in all patients (4.9 +/- 2.3 mA). Postoperative radiograph confirmed all catheter placements within 2 myotomes of the muscle twitches. Electrical stimulation may be a useful adjuvant tool to loss of resistance for confirming proper thoracic epidural needle placement. The threshold current criteria for an insulated needle (6-17 mA) would be higher than the original Tsui test criteria described for an epidural catheter (1-10 mA) in the epidural space.     

Postspinal headache in young and elderly patients

In two randomised, double-blind studies of elderly patients with a mean age of 68.9 (range 21-88) years and young patients, mean age 29.4 (range 20-40) years, the effect of needle size on the incidence of postspinal headache was compared. The two needle groups, 20- and 25-gauge, were comparable in both studies with regard to number, sex, age and type of surgery. The incidence of postspinal headache in young patients was 27.6% when a 20-gauge needle was used and 12.6% with a 25-gauge needle. There was no significant difference in either the incidence of headache in the elderly patients (10.8% and 7.8%, respectively) or between the sexes. It is concluded that it does not matter if a 20- or a 25-gauge needle is used for spinal analgesia in elderly patients with regard to postspinal headache, but if spinal analgesia is indicated in young patients a fine needle is preferred.     

Single-shot spinal anaesthesia, combined spinal-epidural and epidural volume extension for elective caesarean section: a randomized comparison

BackgroundSingle-shot spinal and combined spinal-epidural block, with or without epidural volume extension, can be used for caesarean section. There is no trial comparing their block characteristics and adverse effects under identical conditions.Methods60 ASA I or II parturients with gestational age 37 weeks or more, scheduled for elective caesarean section under regional anaesthesia, were included in the trial. Women were randomized to three groups: group SSS: single-shot spinal; group CSE: combined spinal-epidural; group EVE: epidural volume extension of a combined spinal-epidural. Intrathecal injection was identical in the three groups (0.5% hyperbaric bupivacaine 9 mg with fentanyl 10 μg) and was injected via a 25-gauge pencil-point spinal needle, either as a single-shot spinal or through the spinal needle of the needle-through-needle CSE set. In group EVE, 5 mL of normal saline was injected through the epidural catheter. All blocks were performed with the women sitting. Haemodynamic parameters and block characteristics were assessed.ResultsThe onset of maximum sensory and motor block was significantly faster in the SSS group than in the other two. Extent and duration of sensory and motor block and the incidence of adverse effects were similar in the three groups (P > 0.05).ConclusionsIntrathecal block is similar in extent and duration whether given as a single-shot spinal or a combined spinal-epidural with or without epidural volume extension when performed for elective caesarean section using hyperbaric bupivacaine in the sitting position.