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.     

Decrease in the incidence of post-dural puncture headache: maintaining CSF volume

The incidence of epidural needle-induced post-dural puncture headache (PDPH) in parturients following dural puncture with a large bore (18-gauge) needle has been reported to range 76-85%. We describe seven cases in which the performance of epidural anesthesia in parturients was complicated by an unintentional dural puncture with an 18-gauge epidural needle. In all seven cases, the unintentional dural puncture was followed by (i) injection of the CSF in the glass syringe back into the subarachnoid space through the epidural needle, (ii) insertion of a epidural catheter into the subarachnoid space (now referred to as an intrathecal catheter), (iii) injection of a small amount of preservative free saline (3-5 ml) into the subarachnoid space through the intrathecal catheter, (iv) administration of bolus and then continuous intrathecal labor analgesia through the intrathecal catheter and then (v) leaving the intrathecal catheter in-situ for a total of 12-20 h. PDPH occurred in only one of these cases (14%).     

Complications with 25-gauge and 27-gauge Whitacre needles during combined spinal-epidural analgesia in labor

Needle size and shape may influence the incidence of paresthesias, post-dural puncture headache and other complications during combined spinal-epidural (CSE) procedures. We have noted a relatively high incidence of transient paresthesias during placement of the spinal needle during CSE for labor analgesia. The purpose of this study was to compare the occurrence of paresthesia and post-dural puncture headache in parturients who received CSE analgesia with either a 25-gauge or 27-gauge Whitacre needle. In a prospective observational study, data were gathered from 478 consecutive women receiving labor analgesia. Incidence, duration, and character of any paresthesias upon spinal needle placement and the incidence and treatment of headache were recorded. The incidence of paresthesia with the two needles was similar (16% with 25-gauge vs 15.4% with 27 gauge) but the incidence of post-dural puncture headache was higher with the 25-gauge needle (4% vs 0.7% with 27 gauge, P < 0.05). Our data suggest that with Whitacre needles, 27-gauge might be preferable to 25-gauge needles to reduce the rate of post-dural puncture headache in parturients but that they do not alter the incidence of transient paresthesias.     

A sheared off and sequestered epidural catheter: a case report

This is a report of a retained epidural catheter segment after placement of 20-G polyethylene catheter (Hakko Medical) through 17-G Tuohy needle and 25-G spinal needle (Top Company) for a patient receiving combined spinal-epidural anesthesia. Retained catheter fragment (approximately 10.6 cm) was removed easily with small incision under local anesthesia. Electron microscopic findings of the catheter showed that the catheter might have been traumatized by the Tuohy needle through which the catheter was placed or by the spinal needle for intrathecal anesthesia, resulting in having been sheared off.     

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.     

201 combined spinal-epidurals for anaesthesia using a separate needle technique

BACKGROUND AND OBJECTIVE: Combined spinal-epidural (CSE) anaesthesia may be performed using separate needles or by passing the spinal needle through an epidural needle. The latter technique requires that subarachnoid block is performed before the epidural catheter is placed. This paper examines a series of 201 consecutive CSEs performed with a novel separate needle technique, designed to avoid potential and actual problems associated with the CSE technique. METHODS: The CSE technique involved placement of the spinal needle in the subarachnoid space, followed by replacement of the spinal needle stylet. The epidural catheter was then positioned separately before returning to the spinal needle and injecting the subarachnoid drug. RESULTS: The technique had a high technical success rate. Both needles were successfully placed in 200 (99.5%) cases. Spinal anaesthesia was successful in all cases. The epidural catheter was used in 179 cases and failure of the epidural occurred in 2 (1.1%) cases. Paraesthesia, inability to advance the epidural catheter or blood in the epidural catheter occurred in 31 (15.4%) and necessitated immediate replacement of the epidural catheter in 14 (7%) cases. Postoperatively, typical post-dural puncture headache was reported by one patient (0.5%) and mild backache by four (2%). There were no neurological complications. CONCLUSIONS: This method of CSE anaesthesia can be associated with high success and low complication rates.     

The techniques to identify the epidural space do not influence the success rate in combined spinal-epidural anesthesia: a comparison between loss-of-resistance and hanging-drop]

The hanging-drop (HD) technique has been attributed to a negative epidural pressure induced by making a tent of the dura by the Tuohy needle. We, therefore, hypothesized that the HD technique would result in more successful intrathecal placement of the spinal needle in combined spinal-epidural anesthesia (CSEA) compared with the loss-of-resistance (LR). Seventy patients received CSEA using the needle-through-needle method with a spinal needle extending 9 mm beyond the Tuohy needle. Success rate in obtaining cerebrospinal fluid (CSF) at the first attempt was considerably low; 60% in HD and 57% in LR, which was not significantly different. Failure to obtain CSF after 3 attempts was not significantly different between the two techniques; 26% and 31% in HD and LR, respectively. In conclusion, there was no advantage of the HD technique for obtaining CSF in CESA compared with the LR. It seems that spinal needle length beyond the Tuohy needle should be more than 9 mm.     

Eine atraumatische Kanüle für die kontinuierliche Peridural- und Plexusanästhesie

The needle type introduced by Edward Tuohy for continuous spinal anaesthesia in 1944 is still used as the standard instrument for epidural anaesthesia up to the present day. Puncture of the dura and severance of the epidural catheter are the typical, though rare, complications of this procedure, giving rise to most of the actions brought for damage suffered during obstetic anaesthesia. The cerebral spinal fluid loss caused by thick needles can have serious consequences, including subdural and intracranial haematoma, cranial nerve pareses, labyrinthine hearing impairments and pneumocephalus. Special Sprotte needle for catheter introduction. In spinal anaesthesia and lumbar puncture the Sprotte needle has proven a very suitable instrument for prevent the CSF loss syndrome and, to a large degree, post-spinal headaches. To adapt the atraumatic properties of this needle point for epidural anaesthesia, the needle has been equipped with a plastic ramp to direct catheter insertion, and the opening geometry has been slightly modified for epidural application (see Fig.?1). The lateral catheter channel projects into the base of the needle point, which is thus shortened, and the edges of the needle opening are rounded so that the catheters cannot be severed. This needle bears the type designated ?Special Sprotte needle“ (EP no. 271715, USP no. 4842585). Needle diameter and application fields. The 1.1-mm (19.5?G) needle with 23-G catheter was introduced for epidural anaesthesia and continuous plexus anaesthesia at the Würzburg University Hospital and has proven itself in routine clinical practice. A 20-G version is being tested with a 25-G catheter for continuous spinal anaesthesia at several centers in USA, because finer spinal catheters are not permitted there by the FDA. For continuous spinal anaesthesia this needle has been available without the modified opening geometry since 1989 in sizes 22 G and 24 G and is wide by used in Europe. CSE technique with special and standard Sprotte needles. Spinal analgesia or anaesthesia (combined spinal-epidural anaesthesia) can be performed with the special needle and 123-mm-long 27 G or 29 G standard Sprotte needles before placement of the peridural catheter.     

Dural tissue trauma and cerebrospinal fluid leak after epidural needle puncture: effect of needle design, angle, and bevel orientation

BACKGROUND: The effects of epidural needle design, angle, and bevel orientation on cerebrospinal fluid leak after puncture have not been reported. The impact of these factors on leak rate was examined using a dural sac model. Dural trauma was examined using scanning electron microscopy. METHODS: Human cadaveric dura, mounted on a cylindrical model, was punctured with epidural needles using a micromanipulator. Tissue was punctured at 15 cm H2O (left lateral decubitus) system pressure, and leak was measured at 25 cm H2O (semisitting) pressure. Leak rates and trauma were compared for the following: (1) six different epidural needles at 90 degrees, bevel parallel to the dural long axis; (2) 18-gauge Tuohy and 18-gauge Special Sprotte epidural needles, 30 degrees versus 90 degrees; (3) 18-gauge Tuohy, bevel perpendicular versus parallel to the dural long axis. RESULTS: With the 90 degrees puncture, bevel parallel, the greatest leak occurred with a 17-gauge Hustead (516 +/- 319 ml/15 min), and the smallest leak occurred with a 20-gauge Tuohy (100 +/- 112 ml/15 min; P = 0.0018). A 20-gauge Tuohy puncture led to statistically significant reductions in leak (P value range, 0.0001-0.0024) compared with all needles except the Special Sprotte. With the 30 degrees versus 90 degrees angle, 30 degrees punctures with an 18-gauge Tuohy produced nonstatistically significant leak reductions compared with the 18-gauge Tuohy at 90 degrees. The puncture angle made no difference for the Special Sprotte. Nonsignificant reductions were found for the Special Sprotte compared with the Tuohy. With the 18-gauge Tuohy bevel orientation, perpendicular orientation produced nonstatistically significant reductions in leak compared with parallel orientation. CONCLUSIONS: Cerebrospinal fluid leak after puncture was influenced most by epidural needle gauge. Leak rate was significantly less for the 20-gauge Tuohy needle.     

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.     

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.     

Dural Tissue Trauma and Cerebrospinal Fluid Leak after Epidural Needle Puncture: Effect of Needle Design, Angle, and Bevel Orientation

Background: The effects of epidural needle design, angle, and bevel orientation on cerebrospinal fluid leak after puncture have not been reported. The impact of these factors on leak rate was examined using a dural sac model. Dural trauma was examined using scanning electron microscopy.

Methods: Human cadaveric dura, mounted on a cylindrical model, was punctured with epidural needles using a micromanipulator. Tissue was punctured at 15 cm H2O (left lateral decubitus) system pressure, and leak was measured at 25 cm H2O (semisitting) pressure. Leak rates and trauma were compared for the following: (1) six different epidural needles at 90[degrees], bevel parallel to the dural long axis; (2) 18-gauge Tuohy and 18-gauge Special Sprotte(R) epidural needles, 30[degrees]versus 90[degrees]; (3) 18-gauge Tuohy, bevel perpendicular versus parallel to the dural long axis.

Results: With the 90[degrees] puncture, bevel parallel, the greatest leak occurred with a 17-gauge Hustead (516 +/- 319 ml/15 min), and the smallest leak occurred with a 20-gauge Tuohy (100 +/- 112 ml/15 min; P = 0.0018). A 20-gauge Tuohy puncture led to statistically significant reductions in leak (P value range, 0.0001-0.0024) compared with all needles except the Special Sprotte(R). With the 30[degrees]versus 90[degrees] angle, 30[degrees] punctures with an 18-gauge Tuohy produced nonstatistically significant leak reductions compared with the 18-gauge Tuohy at 90[degrees]. The puncture angle made no difference for the Special Sprotte(R). Nonsignificant reductions were found for the Special Sprotte(R) compared with the Tuohy. With the 18-gauge Tuohy bevel orientation, perpendicular orientation produced nonstatistically significant reductions in leak compared with parallel orientation.     

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.     

The median effective dose of intrathecal hyperbaric bupivacaine is larger in the single-shot spinal as compared with the combined spinal-epidural technique

The combined spinal-epidural technique (CSE) has been associated with prolonged motor recovery and more frequent arterial hypotension as compared with a single-shot spinal (SSS) technique. We determined the median effective dose (MED) of intrathecal hyperbaric bupivacaine for CSE and SSS by using the up-down sequential allocation technique. Sixty male patients were randomly allocated to receive intrathecal administration through an SSS or CSE technique. Needle insertion occurred at the L3-4 interspace in all patients. In SSS, 9.5 mg of hyperbaric bupivacaine was administered through a 27-gauge Whitacre spinal needle. In CSE, a 17-gauge Tuohy needle with 4 mL of air was used to locate the epidural space, through which a 27-gauge Whitacre spinal needle was introduced and 7.0 mg of hyperbaric bupivacaine was administered. The dosing adjustment was 0.5 mg. A "successful" outcome was arbitrarily defined as sensory anesthesia at or above the T6 dermatome lasting for 60 min. A "success" resulted in a 0.5-mg decrement, whereas a "failure" resulted in a 0.5-mg increment in the next patient. There were 13 successes in both groups. The MED of bupivacaine was 9.18 mg (95% confidence interval, 8.89-9.47 mg) for CSE as compared with 11.37 mg (95% confidence interval, 10.88-11.86 mg) for SSS (P < 0.001). CSE required 19.3% (95% confidence interval, 14.9%-23.6%) less local anesthetic to achieve the defined clinical target. We found significant discrepancies in the MED of hyperbaric bupivacaine between the two techniques. Under similar clinical conditions, a 20% decrement in the dose of bupivacaine may be warranted whenever CSE is intended in place of SSS.     

Evaluation of a lockable combined spinal-epidural device for use with needle-through-needle technique

BACKGROUND: Recently, a new combined spinal-epidural (CSE) device has been introduced which allows the spinal needle to be extended a maximum of 15 mm beyond the Tuohy needle and locked onto the epidural needle after dural puncture. The aim of this study was to compare this lockable CSE device with the conventional CSE device, which allows the spinal needle to be extended 9 mm beyond the Tuohy needle, and to measure the length of the protrusion of the spinal needle beyond the Tuohy needle (top-to-top distance: TTD). METHODS: We studied sixty patients scheduled to undergo elective gynecological surgery and cesarean section. Patients were divided into three groups: patients in Group I (n = 20) using the conventional CSE device in gynecological surgery; patients in Group II (n = 20) using the lockable CSE device in gynecological surgery; and patients in Group III (n = 20) using the lockable CSE device in cesarean section. RESULTS: The success rate of spinal anesthesia with needle-through-needle technique was higher with the lockable CSE device (100%) than with the conventional CSE device (75%). The TTD was 7.9 +/- 1.8 (SD) cm in non-pregnant group (Group II) and 8.7 +/- 1.5 cm in pregnant group (Group III). This difference was not statistically significant. In the lockable CSE device groups (Group II and III), 10 patients (25%) had a TTD of 10 mm or more. CONCLUSIONS: The lockable CSE device improves the success rate of spinal anesthesia in needle-through-needle CSE anesthesia.     

A comparison of the 24-gauge Sprotte and Gertie Marx spinal needles for combined spinal-epidural analgesia during labor

BACKGROUND: Prior experience with the combined spinal-epidural technique (CSE) for labor analgesia demonstrated a high (up to 14%) failure rate because of failure to obtain cerebrospinal fluid (CSF) or lack of response to appropriate doses of intrathecal sufentanil. The current study was designed to test whether a longer needle with a shorter side port (Gertie Marx needle; 127 mm long) would eliminate failures to obtain CSF compared with the needle we had used previously (Sprotte needle; 120 mm long). METHODS: Seventy-three parturients were randomly assigned to have a CSE performed with one of these two needles. After identifying the epidural space with an 18-gauge Touhy needle at the L2-L3 or L3-L4 interspace, the spinal needle was introduced through the Touhy needle until penetration of the dura was felt or until the needle was maximally inserted. If no CSF was obtained, the alternate needle was tried. After obtaining CSF, 10 microg sufentanil diluted in 1.8 ml saline was injected. Verbal pain scores (0-10) were obtained every 5 min for 30 min. RESULTS: Failure to obtain CSF occurred six times in the Sprotte group compared with none in the Gertie Marx group (P < 0.05). In all six failures in the Sprotte group, the Gertie Marx needle subsequently proved successful in obtaining CSF. There were no differences in pain scores between the groups. CONCLUSIONS: The extra length of the 127-mm Gertie Marx needle resulted in a higher success rate for obtaining CSF when used in the CSE technique. Side port design was not a factor influencing success in this clinical setting.     

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.     

A comparison of epidural and cerebrospinal fluid glucose in parturients at term: an observational study

BackgroundDetecting inadvertent dural puncture during labour epidural insertion can be difficult when using a loss of resistance to saline technique. Testing fluid for glucose that leaks from a Tuohy needle may confirm the presence of cerebrospinal fluid and infer inadvertent dural puncture. This study compared the glucose content of intrathecal fluid obtained during spinal anaesthesia for elective caesarean delivery with that of fluid from a Tuohy needle or epidural catheter when establishing epidural analgesia for labour.MethodsWomen aged ?18 years undergoing elective caesarean delivery and labouring parturients who requested epidural analgesia were recruited prospectively in a tertiary referral centre over a three-month period. Fluid was collected into a sterile container either during spinal anaesthesia or from a labour epidural needle. Glucose content was evaluated using a bedside blood glucometer and laboratory colorimetric analyzer.ResultsOf the 118 women approached, 115 participated. All 40 women having spinal anaesthesia and 2/75 (2.7%) women having epidural analgesia, in whom inadvertent dural puncture was subsequently confirmed, had fluid samples testing positive for glucose. Median [range] laboratory glucose readings were 2.9 [1.3–5.1] mmol/L for cerebrospinal fluid and <0.3 mmol/L in fluid that leaked from a Tuohy needle (P = 0.0001).ConclusionWhen using a loss of resistance to saline technique for epidural catheter placement, bedside glucometer testing of fluid leaking from the epidural needle may be of value in the early detection of inadvertent dural puncture.     

A Comparison of the 24-Gauge Sprotte® and Gertie Marx® Spinal Needles for Combined Spinal-Epidural Analgesia during Labor

Background: Prior experience with the combined spinal-epidural technique (CSE) for labor analgesia demonstrated a high (up to 14%) failure rate because of failure to obtain cerebrospinal fluid (CSF) or lack of response to appropriate doses of intrathecal sufentanil. The current study was designed to test whether a longer needle with a shorter side port (Gertie Marx(R) needle; 127 mm long) would eliminate failures to obtain CSF compared with the needle we had used previously (Sprotte(R) needle; 120 mm long).

Methods: Seventy-three parturients were randomly assigned to have a CSE performed with one of these two needles. After identifying the epidural space with an 18-gauge Touhy needle at the L2-L3 or L3-L4 interspace, the spinal needle was introduced through the Touhy needle until penetration of the dura was felt or until the needle was maximally inserted. If no CSF was obtained, the alternate needle was tried. After obtaining CSF, 10 [mu]g sufentanil diluted in 1.8 ml saline was injected. Verbal pain scores (0-10) were obtained every 5 min for 30 min.

Results: Failure to obtain CSF occurred six times in the Sprotte group compared with none in the Gertie Marx group (P < 0.05). In all six failures in the Sprotte group, the Gertie Marx needle subsequently proved successful in obtaining CSF. There were no differences in pain scores between the groups.     

Can continuous low current electrical stimulation distinguish insulated needle position in the epidural and intrathecal spaces in pediatric patients?

BACKGROUND: Muscle twitches elicited with electrical stimulation (6-17 mA) during epidural insertion indicate correct epidural needle placement while muscle twitches at a lower current (<1 mA) may indicate intrathecal needle placement. This study examined whether applying continuous electrical stimulation at 6 mA could indicate needle entry into the epidural space without inadvertently penetrating the intrathecal space. METHODS: After institutional review board (IRB) approval, 10 pediatric patients scheduled for lumbar puncture were studied. Following sedation with propofol, an insulated 24-gauge Pajunck unipolar needle was inserted through an 18-gauge introducer needle placed at the L4-5 interspace. The needle was first connected to a nerve stimulator (6 mA) and advanced. At the first sign of muscle twitching, needle advancement was stopped and the threshold current for motor activity was determined. The current was then turned off, the stylet was removed and the needle checked for cerebrospinal fluid (CSF). If CSF was not present, the needle was advanced into the intrathecal space (as confirmed by the presence of CSF). Ten pediatric patients (ASA II or III) aged 7.8 +/- 4.3 years (2.8-16.0 years) were studied. RESULTS: All patients had two distinguishable threshold currents as the needle advanced. The mean threshold current to elicit muscle twitch in the presumed epidural space was 3.84 +/- 0.99 mA. CSF was not present in any of the patients at this location. The mean threshold current in the intrathecal space was 0.77 +/- 0.32 mA. The average estimated distance from the first threshold location to the intrathecal space was 3 mm. All muscle twitches were at the L3-5 myotomes. Nine muscle twitches were unilateral and one was bilateral. CONCLUSIONS: Monitoring with an insulated needle with electrical stimulation at 6 mA may prevent unintentional placement of epidural needles into the intrathecal space.