Spinal anesthesia

Spinal anesthesia Monica M. Mordecai and Sorin J. Brull

Purpose of review The aim of this article is to review current practice of spinal anesthesia regarding technique and medication use; review recent applications of spinal anesthesia to subspecialty care in outpatient, cardiac, and obstetrical anesthesia; and update risk assessment associated with spinal anesthesia. Recent findings Epidural volume extension enhances the spread of local anesthetics using a combined spinal-epidural technique. Chloroprocaine has become the agent of choice at some institutions. The growth in both the number and complexity of ambulatory surgery procedures has redefined the role of spinal anesthesia for outpatients. The 27-gauge Whitacre spinal needle is associated with a lower incidence of post-dural puncture headaches. Retrospective reviews can predict the incidence of rare complications such as neurologic injury and cardiac arrest. Summary Innovations in technology, equipment, and needle design improved safety and decreased complication rates from spinal anesthesia. The increased popularity of ambulatory surgical procedures has resulted in more frequent use of spinal anesthesia. Intrathecal narcotic analgesia is used increasingly in fast-tracking cardiac surgical protocols. Modern anesthetic and analgesic techniques include resurgence of older agents (2-chloroprocaine) as well as new agents (levobupivacaine and ropivacaine) that are used in conjunction with adjuvant intrathecal medications (opioids, vasopressors, and a-2 adrenergic agonists). Surgical thromboprophylaxis and the increased use of anticoagulants in patients with cardiovascular disease have challenged anesthesiologists to update clinical guidelines to minimize the risk of hemorrhagic complications such as epidural hematoma. The risk/benefit ratio of spinal anesthesia should be individualized. The continued popularity of spinal anesthesia is due to the safety, effectiveness and efficiency of this technique. Keywords bupivacaine, cardiac arrest, 2-chloroprocaine, combined spinal-epidural anesthesia, lidocaine, post-dural puncture headache, ropivacaine, spinal anesthesia, transient neurologic symptoms Curr Opin Anaesthesiol 18:527–533. ß 2005 Lippincott Williams & Wilkins. Department of Anesthesiology, Mayo Clinic, Jacksonville, Florida, USA Correspondence to Monica M. Mordecai, MD, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA Tel: +1 904 296 5288; fax: +1 904 296 3877; e-mail: [email protected] Current Opinion in Anaesthesiology 2005, 18:527–533

Abbreviations CABG CSE PDPH TNS

coronary artery bypass grafting combined spinal-epidural post-dural puncture headache transient neurologic symptoms

ß 2005 Lippincott Williams & Wilkins 0952-7907

Introduction Spinal anesthesia remains a fundamental part of the modern practice of anesthesia because of its proven success, predictability, increased patient satisfaction, and low complication rate. Advancements in technology in terms of spinal needle diameter and tip designs have been responsible for a reduction in complications such as post-dural puncture headaches (PDPHs). New imaging modalities are available to assist with difficult spinal placement. Subspecialty practices such as cardiac anesthesia have incorporated regional techniques into the practice to adapt to changing trends of fast-tracking cardiac patients for early tracheal extubation. A number of ambulatory surgical procedures are well suited for spinal anesthesia. The combined spinal-epidural (CSE) technique has been incorporated into the practice of obstetrical anesthesia, both for labor analgesia and surgical cesarean section. Local anesthetic agents, doses and agent baricity are selected based on specific surgical procedures. Guidelines for patients taking anticoagulant or antifibrinolytic medications are reviewed. The practice of spinal anesthesia continues to adapt in response to new equipment, techniques, local anesthetics and adjuvants, and clinical indications.

Anatomy and identification of the lumbar interspace Classic teaching of induction of spinal anesthesia begins with the use of anatomical landmarks for the placement of lumbar spinal needles. At the bedside, the lumbar interspinal space is identified by palpation using an imaginary line connecting both iliac crests to indicate the fourth and fifth lumbar interspace. Identification with this technique is prone to error when compared with plain radiographic films [1]. Jung and colleagues [2] proposed using the 10th rib line as a new, more reliable and reproducible landmark of the lumbar vertebral level during spinal block. Using radiographs to place radiopaque markers, the 10th rib line was used to identify the L2 spinous process or interspinous space for placement of the spinal anesthetic and to safeguard against placing the 527

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spinal needle at a dangerously cephalad level, thus injuring the spinal cord [2]. Ultrasound also has been used to identify the lumbar interspace. The L3–4 interspace was identified by the performing anesthesiologist using ultrasound in 17 patients, and was confirmed by a magnetic resonance imaging scan. Of these 17 patients, 13 had correct identification of the lumbar interspace, with a calculated success rate of 76.4% [3]. This rate of correct identification of the appropriate target lumbar interspace is greater than that using palpation of the iliac crest as an identification technique. Real-time ultrasound also has been used to aid visualization of the epidural structures and guide needle manipulation in patients receiving a CSE technique in pregnant patients scheduled for cesarean section. Compared with conventional CSE anesthesia, followed by an offline scan technique, the real-time ultrasound group had a reduction in the number of attempts at puncture, a reduction in the number of interspaces that were attempted for puncture, and a reduction in the number of spinal needle manipulations [4]. Fluoroscopic imaging has been used successfully in the operating room to guide the placement of a technically difficult spinal anesthetic in a morbidly obese patient. Fluoroscopic needle guidance provides visual confirmation to direct accurate needle placement in patients without palpable bony landmarks. The routine use of fluoroscopy for spinal needle guidance, however, would be time consuming and may expose the anesthesiologist and patient to unnecessary radiation [5]. An attempt to develop a difficulty score for spinal anesthesia concluded that spinal bony landmarks and radiological characteristics of the lumbar vertebrae are independent predictors of difficulty during spinal anesthesia placement. Accurate preoperative prediction of difficulty could help reduce the incidence of multiple attempts and possibly complications. Characteristics noted on physical examination included subjective assessment of bony landmarks, ability to palpate spinous processes, scoliosis, and kyphosis. Radiographic findings of lumbar vertebrae osteophytes, ligament calcification, or narrow intervertebral spaces were also associated with difficult block placement [6]. While the use of imaging techniques such as bedside ultrasound, offline ultrasound, real-time ultrasound, and fluoroscopy may not be necessary in the routine placement of a spinal anesthetic, these techniques may have a beneficial role in anticipated difficult block placement.

Techniques and clinical settings The introduction of newer techniques such as the CSE anesthetic has widened the clinical application of regional anesthesia.

Combined spinal-epidural anesthesia

Factors that affect intrathecal spread of a local anesthetic are the dose of the administered drug, the site of injection, baricity of the agent, position of the patient, and the age of the patient. The introduction of air, saline, or local anesthetic into the epidural space also enhances the spread of spinal anesthesia. The CSE technique requires identification of the epidural space. Common practice uses either an air or saline filled syringe for the loss of resistance technique. A study of 60 patients divided into three groups compared sensorimotor anesthesia after CSE with catheter placement, CSE technique without catheter placement, and a single-shot spinal technique. In the CSE groups, the epidural space was identified by loss of resistance to 4 ml of air that was injected into the epidural space. No other epidural medications were administered. The subarachnoid block induced by the CSE technique produced greater spread of sensorimotor anesthesia and prolonged recovery than single-shot spinal anesthesia, despite identical doses of intrathecal local anesthetic [7]. The introduction of fluid or air into the epidural space disrupts the pressure relationship between the epidural space and the subarachnoid space resulting in greater spread of the local anesthetic. This change is reflected in the enhancement of extent and duration of a local anesthetic block. Data also suggest that spinal anesthesia as part of a CSE technique may lead to more frequent clinically relevant hypotension than spinal anesthesia alone. A retrospective review [8] compared the incidence of relevant hypotension between CSE anesthesia and spinal anesthesia in a large number of patients. The authors found that there was a higher incidence of hypotension and need for vasoconstrictor use in patients receiving CSE anesthesia [8]. Using epidural saline injection to enhance an intrathecal block placed by a CSE technique is known as epidural volume extension. In a prospective, randomized, doubleblind study of elective cesarean delivery, CSE anesthesia with epidural volume extension resulted in faster motor recovery than after a spinal anesthetic. Patients in the spinal group were administered 9 mg of hyperbaric bupivacaine with 10 mg of fentanyl. The CSE technique was performed with a loss of resistance technique with minimal air and the slow injection of 5 mg of hyperbaric bupivacaine and 10 mg of fentanyl. An epidural catheter was placed, and the patient turned supine for 5 min. The epidural space was injected with 6 ml of 0.9% saline over 30 s. The study found that CSE with epidural volume extension provided adequate anesthesia for elective cesarean delivery while using only 55% of the bupivacaine dose, thus allowing more rapid motor recovery of the lower limbs [9].

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Spinal anesthesia for ambulatory surgery

A number of outpatient surgical procedures are ideal for spinal and regional anesthesia including knee arthroscopy, cystoscopy, laparoscopy and inguinal hernia repair. The growth in both the number and complexity of ambulatory surgical procedures has contributed to the increased use of spinal anesthesia in this setting. The advantages of spinal anesthesia include rapid onset and good operative conditions, early fulfillment of discharge criteria, and fast recovery with minimal side effects. Local anesthetics most commonly studied for outpatient surgery include procaine, lidocaine, and bupivacaine. Concerns with the use of spinal anesthesia in the outpatient setting include possible delay in motor recovery, risk of PDPH, inability to micturate, and the association of lidocaine with the development of transient neurologic symptoms (TNSs). The ideal local anesthetic agent would have rapid onset, predictable fast recovery, and early fulfillment of discharge criteria with minimal side effects. In limited studies, spinal anesthesia was shown to provide equal recovery times with less frequent side effects than general anesthesia [10].

response during cardiac surgery. A double-blind, randomized, controlled trial [13] of 38 patients examined the effects of 37.5 mg bupivacaine given intrathecally before the administration of general anesthesia. Variables studied included atrial receptor desensitization and downregulation, levels of circulating catecholamines, and hemodynamic variables. High spinal anesthesia for cardiac surgery, when combined with general anesthesia, has been shown to have less b-receptor dysfunction and a lower stress response during CABG [13]. The risk of epidural hematoma in patients undergoing cardiac surgery is unknown. The current guidelines from the American Society of Regional Anesthesia and Pain Medicine state that there are insufficient data and experience to determine if the risk of epidural hematoma is increased when combining neuraxial techniques with the full anticoagulation of cardiac surgery. Recommendations include postoperative monitoring of neurologic function and a selection of neuraxial medications that minimize postoperative sensory and motor block to facilitate the detection of new or progressive neurodeficits [14].

Cardiac anesthesia

The role of regional anesthesia in cardiac surgery has increased with the use of fast-tracking cardiac cases and in the management of off-pump cardiac surgery. The use of cardiopulmonary bypass requiring systemic anticoagulation with heparinization initially discouraged the use of regional anesthesia due to the fear of epidural hematoma formation. Numerous fast-track protocols incorporate some type of regional anesthesia including spinal, epidural, and peripheral techniques. Thoracic epidural anesthesia has been associated with the most cardiac benefits by improving myocardial oxygen balance. Intrathecal narcotics have been shown to shorten the duration of mechanical ventilation and tracheal intubation by improving analgesia in fast-track cardiac surgery [11]. In fact, perioperative central neuraxial blockade may actually improve outcome after coronary artery bypass grafting (CABG). A meta-analysis of controlled trials in patients undergoing CABG who were randomized to general anesthesia versus general anesthesia plus thoracic epidural anesthesia versus general anesthesia plus intrathecal analgesia, found no differences in morbidity or mortality in the three groups. There were, however, benefits in patients receiving central neuraxial analgesia, such as faster time until tracheal extubation, decreased pulmonary complications and cardiac dysrhythmias, and reduced pain scores [12]. Cardiac surgery and cardiopulmonary bypass are associated with a significant stress response and release of endogenous catecholamines, which can remain elevated in the postoperative period. High-dose intrathecal bupivacaine has been used in an attempt to blunt the stress

Anticoagulation Neuraxial blockade in the presence of anticoagulants, antifibrinolytics, and antiplatelet medications requires careful timing of the block placement due to the risk of bleeding and hematoma formation. The common use of anticoagulants for the prevention of thromboembolic complications related to surgery has complicated the practice of regional anesthesia. As newer medications are incorporated into the treatment of patients with cardiovascular disease, there is the need to continue to review the safety of spinal anesthesia blockade. The American Society of Regional Anesthesia and Pain Medicine published the results of the Second Consensus Conference on Neuraxial Anesthesia and Anticoagulation in May 2003, defining the risks of neuraxial blockade in anticoagulated patients [15]. The consensus statement includes guidelines for regional anesthesia in patients receiving thrombolytic therapy, unfractionated heparin, low molecular weight heparin, oral anticoagulants, antiplatelet medication, herbal therapy, and direct thrombin inhibitors. European societies have developed similar guidelines. The Dutch Institute for Healthcare developed practice guidelines for neuraxial blockade and anticoagulation published last year [16]. The guidelines state, ’In patients with a clinically acquired tendency toward increased bleeding, the management is highly dependent on the cause of the bleeding tendency. If the patient uses acetylsalicylic acid or clopidogrel, the medication must be withdrawn at least 10 days before neuraxial blockade is started. Therapy with glycoprotein-IIb/IIIa-receptor

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antagonists is an absolute contraindication for neuraxial blockade. In patients who are using coumarin derivatives, neuraxis blockade results in an increased risk of neuraxial hematoma. The coumarin derivatives should then be withdrawn and replaced by a different form of anticoagulation.’ All of the practice guidelines and consensus statements are careful to point out that the statements are based on collective experiences and that decisions for spinal anesthesia should be made on an individual basis. Despite adhering to the guidelines in the perioperative management of clopidogrel intake and perioperative low molecular weight heparin, epidural hematoma has been reported after uncomplicated spinal anesthesia [17].

Local anesthetic agents and adjuvant therapy The modification of the ester procaine to 2-chloroprocaine provided a local anesthetic with the characteristics of rapid onset, lower toxicity, and faster recovery. Initially formulated with the antioxidant sodium metabisulfite, the local anesthetic was associated with lower extremity paralysis and sacral nerve dysfunction. Concerns over the potential neurotoxicity contributed to the change from sodium metabisulfite to the preservative ethylenediaminetetraacetic acid (EDTA); but the local anesthetic was associated with severe lumbar muscle spasms and back pain. Although it has been reformulated as preservative and antioxidant free, 2-chloroprocaine has not regained significant clinical use in anesthetic practice until recently. The return of 2-chloroprocaine?

Current literature has demonstrated the reliability and safety of the preservative-free 2-chloroprocaine. Some studies compared 2-chloroprocaine to procaine for spinal anesthesia in outpatient surgery. At the doses tested, intrathecal 2-chloroprocaine was deemed to be a better choice than procaine for short outpatient procedures because it provided good surgical anesthesia with rapid attainment of institutional discharge criteria [18]. When compared with small-dose bupivacaine in a small number of volunteers, spinal 2-chloroprocaine had significantly faster resolution of block and return to ambulation, while providing adequate duration and density of block for ambulatory surgical procedures [19]. A retrospective review of 122 patients who received 2chloroprocaine at one institution during a 10-month period found 2-chloroprocaine to be a safe and effective alternative to lidocaine and procaine for ambulatory surgical procedures. There were no cases of TNS or neurotoxicity, probably because of the limited number of participants in these studies. The authors concluded

that 2-chloroprocaine is a safe, reliable, and effective agent that is currently the short-acting local anesthetic of choice in their clinical practice [20].

Intrathecal narcotics

The addition of a narcotic to a local anesthetic in the intrathecal space has a synergistic anesthetic effect and prolongs the duration of analgesia. The addition of fentanyl has been shown to improve the quality of analgesia, prolong the duration of anesthesia, and reduce postoperative analgesic use in the postoperative period [21]. Narcotics are also used in combination with local anesthetics to decrease the dose of a local anesthetic and gain faster recovery from motor blockade. In ambulatory surgery, short-acting narcotics such as sufentanil and fentanyl have been added to spinal anesthesia to decrease the local anesthetic doses used for the procedure. In 49 patients randomized to receive 50 mg intrathecal lidocaine versus 15 mg intrathecal lidocaine with 10 mg sufentanil, the addition of sufentanil to lidocaine resulted in shorter time to ambulation for outpatient surgery. The dose of lidocaine was decreased by 70% with the addition of the narcotic, while still providing excellent operative anesthesia [22]. In addition to shorter recovery periods, lowering the dose of local anesthetics in combination with a narcotic has also been shown to reduce the incidence of hypotension associated with spinal anesthesia. A reduced dose of bupivacaine plus sufentanil in patients with hip fractures provided reliable anesthesia with fewer events of hypotension and little need for vasopressor support [23].

Patient positioning and spinal anesthetic spread The position of the patient during block placement and the baricity of the local anesthetic can affect the spread of an intrathecal block performed for elective cesarean section. In a comparison of 150 patients receiving hyperbaric, isobaric, or hypobaric solutions of 10 mg of intrathecal bupivacaine administered to patients in a sitting position versus a right lateral decubitus position, baricity had no effect on the spread of local anesthetic. Hypobaric bupivacaine produced statistically significantly higher levels of anesthesia than the hyperbaric solution, though the maximal spread only differed by one dermatome. Motor block was reduced with increasing baricity only in the lateral position patients. Baricity also appears to be related to the frequency of hypotension and vasopressor use. Not unexpectedly, hypotension occurred most frequently in the patients who received hypobaric bupivacaine in the sitting position [24].

Complications and treatment Modifications in equipment used for spinal anesthesia (spinal needles) and local anesthetic agents (preservative

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and antioxidant free chloroprocaine) have reduced, but not eliminated, complications. Post-dural puncture headache

The development of fine-gauge diameter spinal needles and modified needle tip designs has reduced the frequency of PDPH. The frequency decreases with decreasing spinal needle diameter and is estimated to be 40% with a 22 gauge needle; 25% with a 25 gauge needle; 2–12% with a 26 gauge Quincke needle (BD Medical Systems, Inc, Franklin Lakes, New Jersey, USA) and less than 2% with a 29 gauge needle [25]. In a meta-analysis of obstetric patients, the incidence of PDPH in a small gauge, pencil-point spinal needle (27 gauge Whitacre; BD Medical Systems, Inc) was calculated to be 1.7% [25]. Needle tip design also can lead to a reduction in the incidence of PDPH. Comparison of the 25G Quincke spinal needle with the 25G Whitacre spinal needle in obstetrical patients suggested the use of 25G Whitacre for elective and emergency cesarean section to reduce the frequency of PDPH without increasing failure rate [26]. In a multicenter study [27] of 700 patients comparing the performance conditions and side effects of the newly designed Ballpen (Rusch France, Betschdorf, France) pencil-like tip spinal needle with the Sprotte (B. Braun Medical, Inc, Bethlehem, Pennsylvania, USA) needle, there was no difference in technical variables or outcome. In a prospective, randomized study [28], 676 patients were given a spinal anesthetic for outpatient surgical procedures with either a 27 gauge Quincke or a 27 gauge Whitacre spinal needle. The incidence of PDPH in the Quincke group was 2.7% versus 0.37% with the Whitacre group, thus recommending the routine use of the 27 gauge Whitacre spinal needle. Prolonged duration of a PDPH warrants further evaluation due to the potential for more serious neurologic injury after even uneventful spinal anesthesia. Prolonged headache after spinal anesthesia can be associated with meningitis, intracranial hemorrhage, or subdural hematoma [29–31].

underestimated due to underreporting. During the survey period, approximately 1 260 000 spinal anesthetics, 450 000 epidural anesthetics, and 200 000 epidural anesthetics for labor analgesia were administered. Complications in all three groups included epidural hematoma (33 cases), cauda equina syndrome (32 cases), meningitis (29 cases), epidural abscess (13 cases), and miscellaneous (20 cases). Permanent neurologic injury was reported in 85 patients. The incidence of complications was 1:20 000– 30 000. Complications were more frequent after epidural than after spinal anesthesia. Of the 33 cases of epidural hematoma, only seven occurred after a spinal anesthetic. The calculated incidence of epidural hematoma was 1:180 000, or slightly higher than previous reports [32]. It is important to emphasize that predisposing factors such as spinal stenosis, preexisting coagulopathy, or the use of surgical thromboprophylaxis are associated with an increased risk of neurologic complications.

Transient neurologic symptoms TNSs are described as a syndrome of pain in the lower extremities after administration of an uncomplicated spinal anesthetic. The symptoms usually appear within a few (up to 24) hours after full recovery from spinal anesthesia, and are self-limiting, usually with resolution by the second to fifth postoperative day. The pain is located in the gluteal area with radiation to both lower extremities. The cause is unclear, and no abnormalities are detected on neurologic examination, magnetic resonance imaging, or electropathological testing. Early ambulation time has not been shown to increase the incidence of TNS [33]. A systematic review of randomized, controlled trials comparing lidocaine with other local anesthetics to predict the frequency of TNS and neurologic complications after spinal anesthesia confirmed that lidocaine was associated with TNS more frequently than other local anesthetics (bupivacaine, prilocaine, procaine, mepivacaine). The frequency of TNS was approximately one in seven patients who received spinal anesthesia with lidocaine [34]. Cardiac arrest

Neurologic complications

Though rare, neurologic complications can be severely debilitating in previously healthy individuals. Estimating the risk of infrequent complications requires data from multiple sources including surveys, large multicenter trials, administrative files, statistical modeling, and case reports. Neurologic dysfunction after spinal anesthesia can result from direct injury to the spinal cord, nerves or nerve roots, infection, neurotoxicity, or from hemorrhagic complications. One of the largest comprehensive, retrospective reviews performed in Sweden reviewed severe neurologic complications after central neuraxial blockade over a 10-year period [32]. The authors postulated that the incidence of severe complications may be

A retrospective review [35] evaluated the frequency of cardiac arrest, preexisting medical conditions, and periarrest events during neuraxial anesthesia between 1983 and 2002. During this 20-year period, there were 26 cardiac arrests during neuraxial blockade with an overall frequency of 1.8:10 000 patients. Patients receiving spinal anesthesia experienced more frequent cardiac arrests than patients receiving epidural anesthesia. In approximately half of the patients, the anesthetic directly contributed to cardiac arrest. The other arrests were associated with a specific surgical event such as cementation of prostheses, bone reaming, and other surgical manipulation. Patient survival from cardiac arrest during neuraxial blockade was better than the survival rate of

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patients suffering cardiac arrest during general anesthesia [35].

2 Jung CW, Bahk JH, Lee JH, Lim YJ. The tenth rib line as a new landmark of the  lumbar vertebral level during spinal block. Anaesthesia 2004; 59:359–363. Palpation of the tenth rib line as the site at which spinal anesthesia is performed may safeguard against introducing the spinal needle at a dangerously cephalad level.

Voluntary surveys from 1992 to 2002 by the Japanese Society of Anesthesiologists analyzed the incidence of cardiac arrest and mortality with spinal anesthesia. In the 409 338 patients receiving spinal anesthesia, the incidence of cardiac arrest and mortality due to all etiologies was 1.69 and 0.76, respectively. Inadvertent high spinal anesthesia was the leading cause of cardiac arrest in patients receiving spinal anesthesia [36].

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Use of vasopressors

Cardiac instability and hypotension associated with spinal anesthesia administration are usually managed with intravenous fluids and vasopressor administration. Hypotension in the obstetrical patient must be treated aggressively as maternal hypotension is associated with fetal acidosis. The most common vasopressor currently used is intravenous ephedrine. A randomized trial of intravenous infusion of ephedrine or mephentermine for the management of hypotension during spinal anesthesia for cesarean delivery concluded that mephentermine could be used as safely and effectively as ephedrine [37]. Prophylactic phenylephrine infusion decreased the incidence, frequency, and magnitude of hypotension with equivalent neonatal outcome when compared with a control group receiving intravenous bolus phenylephrine [38]. The combination of ephedrine and phenylephrine given as an intravenous bolus was not found to be superior to ephedrine alone in preventing or treating hypotension [39]. The choice of vasopressor given to maintain maternal systolic arterial pressure may affect the rostral spread of spinal anesthesia during cesarean delivery. When compared with ephedrine, intravenous phenylephrine decreased the rostral spread of spinal anesthesia by two dermatomal levels [40].

Conclusion Spinal anesthesia remains an integral part of the practice of anesthesia, and its use continues to expand. Innovations in technology, equipment, monitoring capabilities and needle design improved safety, and new techniques such as CSE allow improved surgical conditions and patient outcome. Although complications remain very rare, maintenance of a high index of suspicion in patients at risk for neurologic complications and cardiac arrest will ensure the continued use of this safe, effective and efficient technique.

References and recommended reading Papers of particular interest, published within the annual period of review, have been highlighted as:  of special interest  of outstanding interest 1

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Watson MJ, Evans S, Thorp JM. Could ultrasonography be used by an anesthetist to identify a specified lumbar interspace before spinal anesthesia? Br J Anaesth 2003; 90:509–511.

4 Grau T, Leipold RW, Fatehi S, et al. Real time ultrasonic observation of  combined spinal-epidural anesthesia. Eur J Anaesthesiol 2004; 21:25–31. The use of real-time ultrasonic scanning facilitates accurate performance of combined spinal-epidural anesthesia. 5

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Goy RW, Sia AT. Sensorimotor anesthesia and hypotension after subarachnoid block: combined spinal-epidural versus single-shot spinal technique. Anesth Analg 2004; 98:491–496. The subarachnoid block induced by combined spinal-epidural in the lumbar region produces a greater extent of sensorimotor anesthesia than that produced by the single-shot spinal technique. The difference may be explained by disruption of the equilibrium that exists between the cerebrospinal fluid and the subatmospheric epidural pressures produced by the injection of 4 ml of air as part of the lossof-resistance technique.

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Lew E, Yeo SW, Thomas E. Combined spinal-epidural anesthesia using epidural volume extension leads to faster motor recovery after elective cesarean delivery: a prospective, randomized, double-blind study. Anesth Analg 2004; 98:810–814. A volume of 6 ml of normal saline injected epidurally enhanced the intrathecal block induced by a combined spinal-epidural technique and resulted in faster motor recovery than with a spinal anesthetic.

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10 Korhonen AM, Valanne JV, Jokela RM, et al. A comparison of selective spinal  anesthesia with hyperbaric bupivacaine and general anesthesia with desflurane for outpatient knee arthroscopy. Anesth Analg 2004; 99:1668–1673. A selective spinal anesthetic for outpatients undergoing knee arthroscopy provided equal recovery times with less frequent side effects (pain, nausea, and vomiting) than a general anesthetic with desflurane. 11 Cheng DC. Regional anesthesia and ultra-fast-track cardiac anesthesia. Can J Anaesth 2005; 52:12–17. 12 Liu SS, Block BM, Wu CL. Effects of perioperative central neuraxial analgesia  on outcome after CABG surgery: a meta-analysis. Anesthesiology 2004; 101:153–161. In this meta-analysis, there were no differences in the rates of mortality or myocardial infarction after coronary artery bypass grafting with central neuraxial analgesia, but there were significant benefits in terms of faster times to tracheal extubation, decreased pulmonary complications and cardiac dysrhythmias, and reduced pain scores. 13 Lee TW, Grocott HP, Schwinn D, Jacobsohn E. Winnipeg High-Spinal Anesthesia Group. High spinal anesthesia for cardiac surgery: effects on beta-adrenergic receptor function, stress response, and hemodynamics. Anesthesiology 2003; 98:499–510. 14 Horlocker TT, Wedel DJ, Benzon H, et al. Regional anesthesia in the anti coagulated patient: defining the risks. Reg Anesth Pain Med 2004; 29:1–12. This is an excellent review of the risks of regional anesthesia in the anticoagulated patient with practical recommendations based on a Consensus Conference. 15 Horlocker TT, Wedel DJ, Benzon H, et al. Regional anesthesia in the anticoagulated patient: defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation). Reg Anesth Pain Med 2003; 28:172–197. 16 De Lange JJ, Van Kleef JW, Van Everdingen JJ. The practice guideline  ’neuraxis blockade and anticoagulation’ [in Dutch]. Ned Tijdschr Geneeskd 2004; 148:1528–1531. The Dutch Institute for Healthcare developed guidelines for the performance of neuraxial blockade in combination with anticoagulant therapy. 17 Litz RJ, Gottschlich B, Stehr SN. Spinal epidural hematoma after spinal  anesthesia in a patient treated with clopidogrel and enoxaparin. Anesthesiology 2004; 101:1467–1470. This interesting case report emphasizes the additive effect of anticoagulants with different mechanisms of action. 18 Gonter AF, Kopacz DJ. Spinal 2-chloroprocaine: a comparison with procaine  in volunteers. Anesth Analg 2005; 100:573–579. Intrathecal 2-chloroprocaine was found to provide equally efficacious anesthesia as procaine, but with more rapid fulfillment of discharge criteria in volunteers.

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30 Tran T, Culley DJ, Crosby G. Hemorrhagic stroke after spinal anesthesia and minor surgery. J Clin Anesth 2004; 16:293–295.

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31 Acharya R. Chronic subdural haematoma complicating spinal anesthesia. Neurol Sci 2005; 25:348–350.

21 Techanivate A, Urusopone P, Kiatgungwanglia P, Kosawiboonpol R. Intrathecal fentanyl in spinal anesthesia for appendectomy. J Med Assoc Thai 2004; 87:525–530. 22 Waxler B, Mondragon SA, Patel SN, Nedumogottil K. Intrathecal lidocaine and  sufentanil shorten postoperative recovery after outpatient rectal surgery. Can J Anaesth 2004; 51:680–684. The addition of sufentanil reduced the lidocaine requirement by 70%, while providing excellent operative anesthesia and shorter time to ambulation. 23 Olofsson C, Nygards EB, Bjersten AB, Hessling A. Low-dose bupivacaine with sufentanil prevents hypotension after spinal anesthesia for hip repair in elderly patients. Acta Anaesthesiol Scand 2004; 48:1341. 24 Hallworth SP, Fernando R, Columb MO, Stocks GM. The effect of posture  and baricity on the spread of intrathecal bupivacaine for elective cesarean delivery. Anesth Analg 2005; 100:1159–1165. This double-blind, prospective study documented a greater extent of sensory denervation and incidence of hypotension with hypobaric solutions than with equivalent hyperbaric bupivacaine solutions. 25 Turnbull DK, Shepherd DB. Post-dural puncture headache: pathogenesis, prevention and treatment. Br J Anaesth 2003; 91:718–729. 26 Bano F, Haider S, Aftab S, Sultan ST. Comparison of 25-gauge. Quincke and  Whitacre needles for postdural puncture headache in obstetric patients. J Coll Physicians Surg Pak 2004; 14:647–650. This single-blinded, interventional experimental study of 100 women undergoing caesarean section found that the use of 25-gauge Whitacre needles reduced the frequency of post dural puncture headaches compared with 25-gauge Quincke needles. 27 Standl T, Stanek A, Burmeister MA, et al. Spinal anesthesia performance conditions and side effects are comparable between the newly designed Ballpen and the Sprotte needle: results of a prospective comparative randomized multicenter study. Anesth Analg 2004; 98:512–517.

32 Moen V, Dahlgren N, Irestedt L. Severe neurological complications after  central neuraxial blockades in Sweden 1990–1999. Anesthesiology 2004; 101:950–959. This is an excellent review of neurological complications in almost two million neuraxial anesthetics in a 10-year period in Sweden. 33 Silvanto M, Tarkkila P, Ma¨kela¨ M-L, Rosenberg PH. The influence of ambulation time on the incidence of transient neurologic symptoms after lidocaine spinal anesthesia. Anesth Analg 2004; 98:642–646. 34 Zaric D, Christiansen C, Pace NL, Punjasawadwong Y. Transient neurologic  symptoms after spinal anesthesia with lidocaine versus other local anesthetics: a systematic review of randomized, controlled trials. Anesth Analg 2005; 100:1811–1816. Computerized database search of the relative risk for developing transient neurologic symptoms after lidocaine spinal anesthesia found the incidence to be 4.35 times higher than after the use of other local anesthetics, but that all symptoms resolved spontaneously. 35 Kopp SL, Horlocker TT, Warner ME, et al. Cardiac arrest during neuraxial  anesthesia: frequency and predisposing factors associated with survival. Anesth Analg 2005; 100:855–865. This was a retrospective, 20-year study of the frequency of cardiac arrest during neuraxial anesthesia found better survival than in patients undergoing general anesthesia. 36 Irita K, Kawashima Y, Morita K, et al. Critical incidents during regional anesthesia in Japanese Society of Anesthesiologists-certified training hospitals: an analysis of responses to the annual survey conducted between 1999 and 2002 by the Japanese Society of Anesthesiologists [in Japanese]. Masui 2005; 54:440–449. 37 Kansal A, Mohta M, Sethi AK, et al. Randomised trial of intravenous infusion of ephedrine or mephentermine for management of hypotension during spinal anesthesia for caesarean section. Anaesthesia 2005; 60:28–34. 38 Ngan Kee WD, Khaw KS, Ng FF, Lee BB. Prophylactic phenylephrine infusion for preventing hypotension during spinal anesthesia for cesarean delivery. Anesth Analg 2004; 98:815–821.

28 Santanen U, Rautoma P, Luurila H, et al. Comparison of 27-gauge (0.41-mm)  Whitacre and Quincke spinal needles with respect to post-dural puncture headache and non-dural puncture headache. Acta Anaesthesiol Scand 2004; 48:474–479. The incidence of post-dural puncture headache was significantly lower with a 27-gauge Whitacre spinal needle than with a 27-gauge Quincke needle.

39 Loughrey JP, Yao N, Datta S, et al. Hemodynamic effects of spinal anesthesia  and simultaneous intravenous bolus of combined phenylephrine and ephedrine versus ephedrine for cesarean delivery. Int J Obstet Anesth 2005; 14:43–47. The combination of intravenous bolus doses of ephedrine and phenylephrine was equally effective in preventing or treating hypotension as ephedrine alone.

29 Yildirim GB, Colakoglu S, Atakan TY, Buyukkirli H. Intracranial subdural hematoma after spinal anesthesia. Int J Obstet Anesth 2005; 14:159– 162.

40 Cooper DW, Jeyaraj L, Hynd R, et al. Evidence that intravenous vasopressors can affect rostral spread of spinal anesthesia in pregnancy. Anesthesiology 2004; 101:28–33.