Epidural space and regional anesthesia

Epidural fat provides sufficient cushion for the pulsatile movements of the dural sac, protects nerve structures, facilitates the movement of the dural sac over the periosteum of the spinal column during flexion and extension, and forms a pharmacologic reservoir of lipophilic substances. Root cuffs have a cellular component that affects the passage of substances injected epiduraly or near the intervertebral foramen, depending on the site of injection, preganglionar, postganglionar or ganglionar. We found fat inside root cuffs but not within the dural sac. Fat in this location may have affect kinetics of lipophilic drugs injected near nerve root cuffs. Ultrastructural morphology of the cellular component at preganglionar level may help explain unexpected subdural blockade after injection of local anesthetic via transforaminal route. Other morphological aspects of nerve root cuffs help to understand the function of the blood-nerve barrier.Based in this anatomical knowledge, we can speculate on the possible anesthetic implications of epidural fat in terms of the pharmacokinetics of drugs injected into the epidural space and the tasks of locating the epidural space and inserting an epidural catheter during anesthetic procedures.     

Der Einfluß zentralnervöser Modulation auf die Qualität der Epiduralblockade

Conventional clinical dosages of local anesthetics may not be sufficient to block conduction of all afferent impulses, which is important for an effective epidural sensory blockade. Further depression of the transmission of information can be accomplished by central modulating mechanisms, preventing sensory perception. Since there are interindividual differences in the quality of modulating mechanisms, standardized depression of impulse propagation by the local anesthetic is associated with a wide variation in the total depression of afferent impulses. For that reason, the results of a particular dosage of a local anesthetic will be variable regarding the amount of epidural sensory blockade perceived. A continuous epidural technique using a catheter permits the dosage to be individualized by means of additional injections. Patients with a low pain threshold require a more highly concentrated local anesthetic. The addition of opioids to the local anesthetic will permit the use of lower concentrations of the local anesthetic itself. Optimal use of diagnostic, prognostic, and therapeutic epidural blockades is possible only if the influence of modulating mechanisms is taken into account.     

Lumbar epidurography and epidural analgesia in cancer patients

In an attempt to clarify the correlation between the spread of a local anesthetic and a radiographic contrast medium in the epidural space, a lumbar epidural catheter was inserted in 21 cancer patients. In group I, 10 patients, a single dose of bupivacaine 0.5%, 8 ml, was injected. The epidural block was evaluated by assessing loss of pin-prick sensation. The following day a contrast medium, iohexol 180 mg I/ml, 1.2 ml, was injected and the position of the catheter determined. A second dose of iohexol 180 mg I/ml, 8 ml, was injected and epidurograms were taken. The vertebral spread was measured in cephalad and caudad directions from the catheter tip. Group II, 11 patients, underwent the same procedures as group I with the exception of the volumes injected. On the first day they were given bupivacaine 0.5%, 16 ml, and on the second day iohexol 180 mg I/ml, 1.2 ml by 16 ml. In both groups the position of the patients was supine and the speed of injection standardized. In group I there was no statistically significant correlation between the spread of contrast medium and the extension of the epidural block either in the cephalad or in the caudad direction. In group II there was a statistically significant correlation in both the cephalad and caudad direction. It is concluded that epidurography can provide an estimate of the epidural block, but cannot predict the exact segmental distribution of the block.     

Nurse Practitioner-Administered Chloroprocaine in Children with Postoperative Pain

Background: Pain is a complex physical and emotional experience. Therefore, assessment of acute pain requires self-report when possible, observations of emotional and behavioral responses and changes in vital signs. Peripheral nerve and epidural catheters often provide postoperative analgesia in children. Administration of chloroprocaine (a short acting local anesthetic) via a peripheral nerve or epidural catheter allows for a comparison of pain scores, observations of emotional and behavioral responses and changes in vital signs to determine catheter function. Aims: The aims of this study are to describe the use chloroprocaine injections for testing catheters; patient response; and how changes to pain management are guided by the patient response. Methods: This study describes the use of chloroprocaine injections to manage pain and assess the function of peripheral nerve or epidural catheters in a pediatric population. We examined 128 surgical patients, (0-25 years old), who received chloroprocaine injections for testing peripheral nerve or epidural catheters. Patient outcomes included: blood pressure, respiratory rate, heart rate and pain intensity scores. Results: There were no significant adverse events. The injection guided intervention by determining the function of regional analgesia in the majority (98.5%) of patients. Discussion: Chloroprocaine injections appear to be useful to evaluate functionality of peripheral nerve and epidural catheters after surgery in a pediatric population.     

Chronic cancer pain management with the Du Pen epidural catheter

Chronic epidural administration of narcotics and/or local anesthetics is sometimes required in those few patients where utilization of systemic narcotics and appropriate adjuvant medications is unsuccessful in controlling intractable cancer pain. The Du Pen epidural catheter (Davol, Inc.) a silicone-based tunneled catheter modeled after the Hickman central venous catheter, has provided a safe, reliable means of long-term administration of drugs to the epidural space in over 400 patients to date. A systematic approach to the pharmacology of epidural pain control includes drug choice, bolus dosing versus infusion, volume guidelines, and titration protocols. Utilization of local anesthetics in combination with narcotics allows for enhanced pain relief in those patients refractory to narcotics as is frequently the case with neurogenic involvement. Follow-up care of patients receiving epidural narcotic with or without local anesthetic can be accomplished by a trained home cae team. Successful epidural pain management requires thorough patient and caregiver education, frequent pain assessment, and monitoring of side effects, with close collaboration between patient/family, pharmacist, home care nurse, and physician.     

Ropivacaine (naropin), local anesthetic of choice for epidural blockade]

The purpose of this study, carried out in 132 patients with intense acute radicular pain, was search for an optimal local anesthetic to be used in combination with a steroid for therapeutic epidural blockade. Comparative analysis of analgesia attained by epidural injections of 5 ml 2% lidocaine, 4 ml 0.5% bupivacaine, and 4 ml 1% ropivacaine showed the advantages of the latter drug in stable arrest of radicular pain immediately after injection. The duration of analgesia after blockade was 1.4 +/- 0.5, 3.1 +/- 0.3, and 9.5 +/- 1.2 h, respectively. Use of ropivacaine eliminated the main shortcoming of epidural blockade in the treatment of patients with radicular pain, consisting in temporary pain relapse after discontinuation of the local anesthetic effect before development of antiinflammatory effect of the steroid.     

An anesthetic approach to amputation and pain syndromes

Primary anesthetic intervention is a very effective modality in the prevention of phantom limb pain. The first phase is reduction of the preamputation pain by epidural or intrathecal infusion with local anesthetic and opioid. The catheter can be used for the operative phase, along with an intraneural catheter placement, if necessary. The epidural/intrathecal infusion can continue for 2 to 3 days and eventually be converted to a pharmacologic regimen. This can include opioids for surgical pain, along with a tricyclic antidepressant and an alpha-2 adrenergic agonist. If phantom sensation or phantom limb pain develops, gabapentin (Neurontin) is an effective agent for neuropathic pain. Surgical ablative therapy consists of cordotomy, rhizotomy, dorsal root entry zone lesion, or thalamotomy. Other modalities include dorsal column stimulation to facilitate inhibitory descending pathways. An intrathecal delivery system can be placed to infuse clonidine, local anesthetic, and opioid. For pain management, implantable intrathecal delivery systems may become an important tool for the future management of postamputation pain syndrome.     

腰-硬联合麻醉用于高龄患者的临床经验

目的：总结腰椎-硬膜外（腰-硬）联合麻醉用于高龄（75岁以上）患者的临床经验。方法对重庆市第三人民医院2013年1～11月56例采用腰-硬联合麻醉的高龄患者的临床资料进行回顾性分析,重点收集麻醉起效和维持时间,麻醉中血流动力学变化情况,麻醉中辅助药物使用情况及并发症等资料。结果蛛网膜下腔注药后平均（54±10）s开始出现麻醉平面,平均（5．8±1．2）min后麻醉平面固定,阻滞平面上界胸8～10。与麻醉前基础值比较,麻醉后平均动脉压有所下降,差异有统计学意义（P＜0．05）,但都在正常范围。麻醉中患者生命体征平稳,全部在腰-硬联合麻醉下顺利完成手术。术中有1例患者因平均动脉压（MAP）过低给予麻黄碱纠正;有1例患者MAP升高超过麻醉前基础值30％进行降压处理;另有1例患者出现心率低于55次/分,给予阿托品0．5 mg后纠正,其余患者术中生命体征平稳。麻醉中未观察到明显呼吸抑制,脉搏氧饱和度均维持在96％以上。有9例患者术中经硬膜外导管追加了局部麻醉药物,有21例患者术中给予芬太尼、咪达唑仑或丙泊酚辅助。患者术毕未见恶心、呕吐、头痛等现象,未观察到明确麻醉并发症。结论腰-硬联合麻醉可安全用于高龄患者,其起效迅速,效果完善,麻醉中生命体征稳定,充分的麻醉前准备和完善的麻醉管理措施,有助于保障麻醉的安全性。     

Der postoperative Schmerz

A short survey about the different methods available for producing postoperative analgesia is given, the goal being to make it clear to the clinician that there are quite a number of techniques to be used although the everyday clinical practice often sticks to simple and not too effective methods of pain treatment following surgery. Initially presenting short informations about the neurophysiology of pain and the pathogenesis and causes of postoperative pain two main groups of producing analgesia are then discussed.Thefirst group deals with the systemic use of analgesics be it nonnarcotic analgesic antipyretics or narcotic analgesics (opioids). As for the first subgroup the peripheral action of these drugs (metamizol, acetylsalicylic acid, paracetamol) is brought about by blocking the synthesis of prostaglandins. These substances can only be used for very moderate postoperative pain f.i. following head and neck surgery. The strong acting opioids belong to the second subgroup. Recent informations on receptor sites in the brain and cord and the subgrouping of the receptors throws new light on the understanding of the different effects of these drugs and on the pathomechanisms of agonistic, antagonistic and mixed activities. The clinically used opioids then are mentioned (morphine, fentanyl, methadon, pethidin, piritramide, tilidin, buprenorphin and pentazocine) and dosage, duration of action, antagonisms and untoward side effects are presented. Stress is laid on the recent development of patient-controlled analgesia with all its advantages. Thesecond main group of methods for postoperative analgesia consists of regional anesthesia techniques as there are brachial plexus block, intercostal block and the continuous epidural analgesia using both local anesthetics and spinal opioids. The brachial plexus block in continuous form is absolutely able to prevent pain after operations in the shoulder-arm-region and can be prolonged even for weeks using catheter techniques. The intercostal block on the other hand practically can be performed only as single injection technique being relatively simple however from the technical point of view. The catheter epidural analgesia is the most important method within this group. In comparison to the centrally acting opioids the epidural technique brings some distinct advantages especially in the cardiorespiratory risk case. Choosing between "top up"-technique and continuous infusion of the local anaesthetic depends on the individual circumstances the latter method apparently giving a more steady level of analgesia. The spinal opioid techniques finally gain more and more importance during the last years. They present clear advantages over the local anesthetic methods as there are the long lasting analgesia and the selective blockade of pain not touching motor and sympathetic nerve fibers. A delayed respiratory depression however might be a serious danger showing an incidence of 0,3% in the epidural and some 10% in the subarachnoid route. Aiming to inform the clinician once again about the vast field of possibilities available to make the postoperative course painfree it is hoped that this important task in the postoperative period will be handled with more consequence and effectivity in the future.     

Continuous epidural morphine treatment for intractable pain in terminal cancer patients

In patients with intractable cancer pain who failed to respond to conservative and neurosurgical procedures for pain relief, repeated injections of epidural morphine were found to be beneficial.A small dose of morphine (2–4 mg per injection) relieved pain for 6–24 h. A permanent subcutaneous epidural catheter led to successful ambulatory treatment without complications. The implantation of the epidural catheter is a minor surgical procedure, done under local anesthesia and is considered safe even in terminal cancer patients.     

Effects of predistention with normal saline containing adrenaline on blood-vessel injury during epidural catheter placement

This study investigated the effects of predistention with normal saline containing adrenaline on vascular plexus injury during epidural catheter placement. Three hundred parturients undergoing caesarean sections were randomly divided into three groups. Group I (n = 102) received an epidural injection with 5 ml normal saline; group II (n = 93) received 5 ml normal saline containing adrenaline (5 μg/ml); group III (n = 100) received direct epidural catheter placement. Five women were excluded from the analysis for technical reasons. The incidence of bloody fluid in the epidural needle was significantly lower in groups I and II compared with group III (eight [7.8%] and seven [7.5%] versus 17 [17.0%], respectively). There were no significant differences in the incidence of bloody fluid in the epidural catheter or in the incidence of intravascular epidural catheter placement between the three groups. Predistention with 5 ml normal saline before catheter insertion reduced the incidence of blood-vessel injury during epidural catheter placement, but adrenaline provided no additional protective effects.     

Acute systemic toxicity from bupivacaine during epidural anesthesia in obstetric patients.

Convulsions occurred within 30 seconds after the injection of bupivacaine through the epidural catheter in four obstetric patients in labor, and mild excitation without convulsions occurred in three others. Since the time between injection and the reaction was so short and since the dose was so small, the response probably was due to intravenous injection resulting from lodgement of the catheter in a vein, rather than to absorption from the epidural space itself. It is not generally known that the epidural veins become thin-walled and engorged during labor; thus, inadvertent placement of a cathether in a vein can occur readily. Convulsions, therefore, may follow even injection of a test dose of a drug. Other colleagues have had similar though unreported experiences. Physicians performing epidural blocks should be aware that such an occurrence is possible and that the catheter may be within a vein without blood returning on aspiration.     

Evaluation of Epidurographic Contrast Patterns with Fluoroscopic-Guided Lumbar Interlaminar Ventral Epidural Injection

Background:   Targeted ventral epidural steroid injection with a transforaminal approach has been widely used for the treatment of nerve root inflammation and pain. Lumbar interlaminar approach is also commonly used; however, ventral epidural injection may not be obtained properly. Lumbar interlaminar ventral epidural (LIVE) injection can be achieved as the epidural catheter is placed at the ventrolateral side of the nerve root. The purpose of this study is to evaluate the contrast dispersal pattern with LIVE injection.
Methods:   Forty patients with lower back and L5 radicular pain were studied. LIVE injection was performed with an epidural catheter inserted toward the 9 o'clock position (for the right side) or 3 o'clock position (for the left side) of the pedicle, where the catheter tip was placed at the ventrolateral side of the nerve root. A total of 2 mL of contrast was injected to determine the epidurographic pattern.
Results:   With 1-mL injection, all patients showed excellent filling in the ventral epidural space of L5 nerve root. After a total of 2 mL injection, it showed rostral spread in 26/40 (65%) patients, and caudal spread in 34/40 (85%) patients. None of the patients showed intravascular injection, and no neural complications were reported.
Conclusions:   The data showed excellent spread of contrast into the nerve root and the ventral epidural space in all patients. There were no inadvertent vascular or neural complications. LIVE approach can be an alternative way to achieve targeted ventral epidural injection.     

Mode of delivery following labor epidural analgesia: influence of ropivacaine and bupivacaine.

Epidural analgesia is a popular and effective method for pain relief during labor. Bupivacaine is a commonly used local anesthetic for labor epidural analgesia. Ropivacaine is an amino acid local anesthetic that is structurally related to bupivacaine with a similar potency and duration, but ropivacaine has less cardiac toxicity than bupivacaine and produces less motor blockade. These properties make ropivacaine a desirable local anesthetic agent for obstetrical analgesia. The purpose of the present study was to compare the cesarean section and instrumental delivery rates for patients receiving labor epidural analgesia using bupivacaine and ropivacaine. The medical records of 500 consecutive patients receiving bupivacaine for labor epidural analgesia were reviewed. After a 3-month familiarization period for ropivacaine, the records of 500 consecutive patients receiving ropivacaine for labor epidural analgesia similarly were reviewed. The groups did not differ demographically. The instrumental delivery rate was 14.2% for the bupivacaine group and 9.8% for the ropivacaine group. The cesarean section rate was 14% for the bupivacaine group and 10.2% for the ropivacaine group. At our facility, the use of ropivacaine decreased both cesarean section and instrumental delivery rates when compared with bupivacaine in the population studied.     

Labor analgesia

Regional analgesia has become the most common method of pain relief used during labor in the United States. Epidural and spinal analgesia are two types of regional analgesia. With epidural analgesia, an indwelling catheter is directed into the epidural space, and the patient receives a continuous infusion or multiple injections of local anesthetic. Spinal injections are usually single injections into the intrathecal space. A combination of epidural and spinal analgesia, known as a walking epidural, also is available. This technique combines the rapid pain relief from the spinal regional block with the constant and consistent effects from the epidural block. It allows sufficient motor function for patients to ambulate. Complications with regional analgesia are uncommon, but may include postdural puncture headache. Rare serious complications include neurologic injury, epidural hematoma, or deep epidural infection. Regional analgesia increases the risk of instrument-assisted vaginal delivery, and family physicians should understand the contraindications and risks of complications. Continuous labor support (e.g., doula), systemic opioid analgesia, pudendal blocks, water immersion, sterile water injections into the lumbosacral spine, self-taught hypnosis, and acupuncture are other options for pain management during labor.     

Addition of Local Anesthetic Epidural Infusion Catheter to Intravenous Opioid Analgesia for Postoperative Pain Control in Children Undergoing Video Assisted Thoracoscopic Surgery (VATS)

PurposePostoperative analgesia following minimally invasive video assisted thoracoscopic surgery (VATS) in pediatric patients may involve intravenous opioid analgesics and continuous local anesthetic infusions via an epidural infusion catheter. The use of epidural catheters may avoid systemic side effects of intravenous opioids in this vulnerable population.DesignOur primary aim was to compare total morphine equivalents (MEQ) required, and pain scores between local anesthetic epidural infusion catheters combined with intravenous opioids, versus intravenous opioids alone in pediatric patients following VATS procedure.MethodsFollowing Institutional Review Board approval, we performed a retrospective chart review of children (ages 1 month to 18 years) who underwent VATS procedure for noncardiac thoracic surgery. Based on the postoperative analgesic technique used, the study population was divided into two groups that is, epidural group and nonepidural group. Both groups received intravenous systemic opioids. The primary outcome variables were total MEQ required and pain scores in the perioperative period.FindingsNinety-two patients were included in the study. Of these, 22 patients belonged to the epidural group versus 70 patients to the nonepidural group. There was no statistical difference in MEQ requirements or pain scores between the groups intraoperatively (P = .304), in the postanesthesia care unit (P = .166), or at postoperative time intervals of 24 hours (P = .805) and 48 hours (P = .844). The presence of infection or empyema was a significant factor for the avoidance of epidural placement by providers (P = .003).ConclusionsThere was no significant difference in the perioperative MEQ or postoperative pain scores between the epidural catheter group and the nonepidural group. More research is necessary to determine if this could be due to epidural catheter malposition and/or inadequate dermatomal coverage of surgical chest tubes.     

Nerve blocks

Local and regional analgesia, achieved by injecting a local anesthetic into tissues, or in proximity to certain parts of the peripheral nervous system, or into the epidural/subarachnoid space, to relieve pain has been used widely for many years. While nerve blocks no longer have the preeminent role as the pain management in cancer patients, they will remain useful tools in managing pain and increasing 'quality of life' of the cancer patients, only if they properly applied. The purpose of this chapter is to present an updated version of the regional analgesia in cancer pain management.     

Gefahren und Komplikationen bei rückenmarknahen Katheterverfahren

Pain therapy with epidural or intrathecal catheters is an invasive method. These techniques have specific indications in both acute and chronic pain therapy. However, complications can occur. Thus, the potential complications and the therapy necessary must be known.Drugs: Complications resulting from acute local anesthetic intoxication's are rare. High plasma levels during chronic therapy may lead to confusion. Respiratory depression can occur in opioid naive patients up to 12 (-24) h after injection. Adequate monitoring is a prerequisite for this therapy. After application of clonidine, hypotension is frequent in hypertonic and hypovolemic patients. Epidural or intrathecalcatheter placement can result in therapeutic failure, trauma by punction and inability to place the catheter. During chronic therapy, technical problems can occur, e.g., dislocation, occlusion. To exclude intrathecal and intravascular placement, application of a test dosage of a local anesthetic with adrenaline is recommended.Neurological complications can result in nerve root deficit or "simple" post-spinal headache, but cauda equina syndromes, paralyses, intracranial bleeding, sinus thrombosis and central neurological deficits have been reported. Skininfection at the insertion site of the catheter has been observed with an incidence of 1.9 to 7.7%. A spinal infection with neurological deficit is rare. Spinal infections are often associated with other diseases. Spinalhematomas are rare. Coagulation disorders and anticoagulants can lead to bleeding. Intravenous heparin should be avoided, because this is frequently associated with spinal bleeding. Therapy with cumarines is a contraindication for insertion of spinal catheters.Monitoring: During treatment with spinal catheters, adequate monitoring increases safety for the patients. Efficacy of the injections, puncture site and the neurological status should be documented daily. Neurological deficits must be diagnosed without losing time and adequate therapy must be initiated.     

Initial clinical experience with the SKY epidural catheter

The new SKY epidural catheter was evaluated, based upon information collected about implant and use of 53 catheters by 51 patients. Catheters were used to treat chronic pain of a malignant (n = 25) and nonmalignant (n = 28) origin. Of 3450 treatment days, 89% occurred at home. Mean catheter use for malignant and nonmalignant conditions were 58.6 and 76.3 days/patient, respectively. Visual analogue pain scores in the first wk after implant indicated 79% of patients achieved good to excellent pain relief. Clinical impressions indicated this group achieved substantial long-term pain relief. No serious complications were observed. Two types of leakage required removing 5 catheters, prompting changes that eliminated subsequent leakages of both types. Accidental patient retraction and subcutaneous infection each required a catheter removal. No subarachnoid or epidural infections occurred. The SKY catheter proved to be safe and reliable. Therapy was cost-effective, since patients achieved substantial pain relief while treated at home.     

Failure of epidural opioid to control cancer pain in a patient previously treated with massive doses of intravenous opioid

A patient with disseminated cancer pain failed to obtain pain relief despite the intravenous infusion of hydromorphone at a rate equivalent to over 7 g of morphine/day. Temporary pain relief occurred with an epidural injection of the local anesthetic lidocaine. Subsequently, the patient failed to obtain pain relief with a dose of epidural hydromorphone equivalent to approximately 3 g of morphine epidurally/day. At this time a syndrome of agitation, sweating, tachycardia and severe muscle cramps developed in the lower half of the body. After eliminating the possibility of spinal cord compression by diagnostic CT scanning, the patient was treated by reducing the dose of hydromorphone and adding local anesthetic, which provided pain relief but did not eliminate the severe muscle spasms and other symptoms. The addition of oral clonidine followed by clonidine dermal patch rapidly and completely eliminated the other symptoms, suggesting that the response was due to too rapid withdrawal of opioid. Maintenance of pain relief required the simultaneous administration of epidural bupivacaine and hydromorphone. A low-dose infusion of epidural bupivacaine was continued for more than 3 weeks and during this entire period the patient showed no evidence of motor or sympathetic block.