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The epidural space is also of clinical interest since its cranial part contains vessels (e.g. the middle meningeal artery) susceptible to lesions after head traumas, causing a lethal (if not treated immediately) Epidural Hematoma . EPIDURAL ANESTHESIA Most commonly, Anesthesiologist s conducting an epidural place the catheter in the Lumbar , or lower back region of the Spine , although sometimes a catheter is placed in the thoracic (chest) or cervical (neck) spines. In adults, the spinal cord terminates at the first lumbar vertebra, below which lies a bundle of nerves known as the Cauda Equina ("horse's tail"). Hence lumbar epidurals carry virtually no risk of injuring the spinal cord. Patients getting modern epidurals generally receive a combination of local anesthetics and Opioid s. Common Local Anesthetic s include Lidocaine , Bupivicaine , Ropivicaine , and Chloroprocaine . Common opioids are Morphine , Fentanyl , Sufentanil , and Pethidine ( Meperidine in the U.S.). These are then injected in relatively small doses. In epidural anesthesia, to allow surgical procedures, larger dose are given in order to remove all feeling (sensory block) and to relax the muscles (motor block) in a large region of the body. Motor block is experienced as short-term weakness or immobility of the affected region, not to be confused with the disease process Paralysis . Technique Using a strict Aseptic Technique a small volume of local anaesthetic, such as 1% Lignocaine ( Lidocaine in the U.S.), is injected into the Skin and Interspinous Ligament . A 16, 17, or 18 gauge Tuohy Needle is then inserted into the interspinous ligament and a "loss of resistance" technique is used to identify the epidural space. Traditionally anaesthetists have used either air or Saline for identifying the epidural space, depending on personal preference. However, evidence is accumulating that saline may result in more rapid and satisfactory quality of analgesiaNorman D. ''Epidural analgesia using loss of resistance with air versus saline: does it make a difference? Should we reevaluate our practice?'' AANA J 2003;71:449-53. PMID 15098532. After placement of the tip of the Tuohy needle into the epidural space the catheter is threaded through the needle. The needle is then removed. Generally the catheter is then withdrawn slightly so that 4-6 cm remains in the epidural space. Side effects
Complications these include:
Contraindications
EPIDURAL ANALGESIA Epidural drug infusion can change the perception for pain and sensation. Epidural analgesia is similar to epidural anesthesia but uses lower concentrations of local anesthetic drugs to remove most, but not necessarily all, pain. Therefore, epidural analgesia causes less muscle weakness, or paralysis, than epidural anesthesia. It is possible to continue epidural analgesia for several weeks, although there is an increasing risk of infection if the catheter is left in place for more than four or five days. A common solution for epidural infusion in Childbirth or for post-operative analgesia is 0.2 percent Ropivicaine and 2 μg/mL of Fentanyl . This solution is infused at a rate between 4 and 14 mL/hour, following a loading dose to initiate the Nerve Block . EPIDURAL IN CHILDBIRTH Epidural analgesia is a safe and effective method of relieving pain in labor. It provides immediate pain relief, and unlike opioid injections, does not cross the placenta into the fetus. Epidural analgesia is associated with longer labor. Some claim that it is correlated with an increased chance of operational intervention. The clinical research data on this topic is conflicting. For example, a recent study in Australia (Roberts, Tracy, Peat, 2000) demonstrated that having an epidural reduced the woman's chances of having a vaginal birth, without further interventions (such as Episiotomy , Forceps , Ventouse or Caesarean Section ) from 71.4% to 37.8%. Conversely, a 2001 study by researchers at the National Institute Of Child Health And Human Development and a 2002 study by researchers at Cornell University and the University Of Ontario demonstrated that epidurals do not increase the likelihood of a caesarean section. In 2005, a meta-analysis of 21 studies also showed that epidurals do not increase the likelihood of caesarean section, but they do increase the chance of a forceps or ventouse delivery by a factor of about 1.4 (Anim-Somuah, Cochrane Review, 2005). What explains these differing outcomes? There is some data that demonstrates that the likelihood of increased intervention is directly related to the quality of the institution or practitioner providing the care: epidurals administered at top-rated institutions do not generally result in a clinically significant increase in caesarean rates, whereas the risk of caesarean delivery at the worst-ranked practitioners seems to increase with the use of epiduralThorp JA, Breedlove G. ''Epidural analgesia in labor: an evaluation of risks and benefits.'' Birth. 1996 Jun;23(2):63-83. PMID 8826170. An alternative explanation is that women having difficult labours are more likely to request epidurals, and are also less likely to have an unassisted vaginal birth. It is important that expectant mothers receive accurate information about the benefits and risks of the procedure, as well as about their other pain-relief options, in order that they may make an informed decision. Less common in labor is Spinal Anaesthesia in which a much smaller needle (26G or 27G) is advanced slightly further to penetrate the dura and allow a rapid achievement of analgesia or anaesthesia depending on the dose given. EPIDURAL STEROID INJECTION An epidural injection, or epidural steroid injection, is used to help reduce pain caused by a herniated disc, degenerative disc disease, or spinal stenosis. These spinal disorders often affect the cervical (neck) and lumbar (low back) levels of the spine. Pain may be accompanied by numbness or tingling that radiates into the arms or legs. An epidural steroid injection (ESI) may be part of a patient’s multidisciplinary treatment plan that includes physical therapy. The effects of an epidural steroid injection may be temporary or long-term. The injection works by reducing the inflammation and/or swelling of nerves in the spine’s epidural space. The epidural space surrounds the spinal cord and nerves that branch off from the cord. Epidural steroid injections are administered in a sterile setting such as an outpatient facility or hospital. The medicine used in the injection is a combination of a local anesthetic (such as Lidocaine ) and a steroid. The procedure involves numbing the skin by injection of a local anesthetic, allowing time for the anesthetic to work, and then inserting a needle into the epidural space. The procedure is performed using Fluoroscopy (a live x-ray) which enables the physician to view the placement of the needle. When the needle is properly positioned, the steroid is injected into the epidural space. After the procedure, the patient is returned to the recovery area and monitored for a period of time before being released home. Patients may be asked to keep a pain diary to help them discuss their pain progress during a follow-up appointment. Some patients who have some residual pain after the first injection may receive a second or third epidural steroid injection. Patients who do not receive any relief from the first injection usually do not receive a second injection. It is important that patients scheduled for an epidural steroid injection follow the pre-procedure instructions provided. Instructions include stopping certain medications such as blood thinning agents (e.g. Aspirin , Warfarin , Clopidogrel ) which can increase the risk of bleeding and hence epidural hematoma formation. An epidural steroid injection, like other medical procedures is not risk-free. There is a possibility of side effects and complications from the needle puncture and medications used. REFERENCES OTHER READING
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