By U. Finley. Westmont College.

AFFERENT PAIN FIBERS Action potentials are generated in nerve fibers that respond exclusively to potentially tissue-damaging Most fibers that transmit acute nociceptive pain are stimuli—mechanical cheap cipro 750 mg otc infection videos, thermal purchase cipro 500 mg on line non penicillin antibiotics for sinus infection, or chemical. Not all Aδ and C fibers transmit pain information; While some are specific to one modality (eg, cold or many code for innocuous temperature, itch, and a particular chemical like histamine) the majority are touch. Many of injury or peptides released from collaterals of acti- these are thought to play a prominent role in arthritis vated nociceptive nerve terminals (eg, calcitonin pain and other diseases associated with tissue damage gene-related peptide [CGRP] and substance P) induce or inflammation. The viscera contain a particularly increased vascular permeability and escape of plasma large proportion of silent nociceptors. This causes edema at the Parallel experiments comparing electrophysiological injury site and the flare around it. Primary afferent data in single C nociceptive fibers with human 7 Copyright © 2005 by The McGraw-Hill Companies, Inc. This suggests that nociceptive pri- mechanoreceptors or thermoreceptors or they may mary afferent fiber activity mediates pain and that exhibit convergence; that is, they receive input from inhibition of this activity diminishes pain. If these convergent cells vated by capsaicin and contain a variety of neuropep- fire significantly more action potentials in response to tides, while others are capsaicin insensitive. All have noxious stimuli, they are called wide dynamic range monosynaptic terminations in laminae I and II of the (WDR) cells. C fibers have polysy- Convergence of input from the outer body surface naptic connections with neurons in lamina V as well (skin) and from viscera onto individual spinal neurons as with neurons in deeper dorsal horn. When activity is initiated in viscera, pain tive afferents from viscera have monosynaptic input is referred to the portion of the body surface that to lamina X around the central canal as well as “shares” those neurons. Some of the peptides are released along with the glutamate only when the afferent fibers fire action potentials at high frequencies (equivalent to severe SPINAL CORD SENSORY CELLS injury). These are called non-NMDA-type glutamate tion up to the brainstem and midbrain. Some peptides, like substance P, prolong project to various thalamic nuclei that serve as way the initial depolarization; this change in transmem- stations for the discriminative and affective compo- brane voltage enables another subtype of glutamate nents of pain. These ascending pathway nuclei are receptor, the N-methyl-D-aspartate (NMDA) receptor, predominantly crossed and ascend in the anterolateral to become activated. NMDA receptors are also linked quadrant of the spinal cord contralateral to the cell to ion channels; however, these channels allow influx body and the innervated body part. Increased intracellular calcium leads to a magni- tion in tandem with nociceptive transmission; these fication of the incoming response, such that each pathways tend to be bilateral. In addition to ascending incoming signal results in successively more output pathways, intrinsic pathways in the spinal cord con- (“windup”). Many are multimodal and tissue injury, the allodynia or secondary hyperalgesia respond to both intense mechanical and thermal usually extends into uninjured tissue. Others respond exclusively to noxious heat or sensitivity is only to mechanical stimuli; thermal cold. There are also cells here that respond to only thresholds are usually unchanged distant from the chemical stimulation, including histamine release in injury site. A small population of One such cascade includes Ca2+ activation of nociception-specific cells are located in the deep dor- the enzyme phospholipase A2 (PLA2); this frees sal horn. This “classical” pathway projects to cyclooxygenase and results in the production of somatosensory (S1) cortex and is postulated to be prostaglandins. Prostaglandins (PGs) diffuse out of integral in sensory discrimination of pain, that is, the spinal neurons and back to the central terminal of where is it, is it sharp, is it hot, and so on. There, they act on specific PG receptors to posterior thalamus (VMpo); this nucleus, in turn, increase the amount of neurotransmitter released per projects to posterior insula cortex. Other recently been proposed to be a unique cortical pain enzymes, including nitric oxide synthase, are acti- center as well as to be involved in homeostatic control vated by Ca2+ in a similar manner, also resulting in a of the internal environment, including tissue integrity. This alternative hypothesis proposes that dorsal pos- Prostaglandins also act via specific PG receptors on terior insula rather than S1 cortex is the primary focus astrocytes to activate them and cause them to release of the sensory-discriminative aspect of pain. This area projects to the anterior cingulate that use of local anesthetics around the incision cortex. This medial pathway is likely to represent the (injury site) would block the high-frequency C-fiber motivational affective component of pain. Studies with maintained peripheral blockade of afferent input are under way.

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An AP reduction) according to Smith-Petersen via an anterior ap- and axial x-ray must also be recorded postoperatively purchase cipro 750 mg line antibiotic resistance markers in genetically modified plants. This Femoral head necrosis is a serious complication of slipped measure also corrects the loss of offset buy generic cipro 1000 mg line antibiotics for sinus infection how long to work. The femoral neck is capital femoral epiphysis and can occur, for example, narrowed slightly depending on the anatomical configura- if force is used to reduce a chronic case. The advantage of the wedge osteotomy is performed open reduction can also cause this complica- the much reduced risk of femoral head necrosis compared tion. When faced with evidence of a chronic process on that associated with open reduction. If a rotation deformi- the x-ray, the surgeon therefore has to decide whether a ty remains, this can, if necessary, be corrected secondarily reduction can be performed at all, or should only be fixed by an intertrochanteric osteotomy. Otherwise, the subcapital osteotomy represents a in only a third of cases. Of course, a chronically dislocated femoral infection rate in slipped capital femoral epiphysis is no head should not be returned to its original position with higher than for other interventions involving metal im- force, otherwise the risk of femoral head necrosis be- plants. Metal breakage only occurs if excessively thin nails comes much greater. If the history is not clear, we also always attempt a (gentle) reduction since, in the majority of diagnosed cases, Metal removal an acute slippage has already been complicated by a chroni- On completion of growth we generally remove nails and cally dislocated position. Normal screws are difficult to remove as they can particularly important with open reductions. In two cases we have found that the head was avascular even before Correction of the deformity (after completion of the reduction. However, we also have to report two cases of Subcapital wedge osteotomy iatrogenic femoral head necrosis in our own hospital. If the femoral head has slipped by more than 40°, a correc- The surgical technique described by Leunig et al. Although the wedge oste- implement this as close as possible to the deformity, i. Nevertheless, we currently prefer to flexion-valgus osteotomy for the correction of the defor- implement corrections close to the joint. After Southwick described the same opera- Contouring of the femoral neck tion in the English literature in 1967, the technique If ventral protrusion of the femoral neck and resulting is more commonly associated with the name »Southwick« impingement has occurred after only slight slippage, the in the English-speaking world than with the name »Im- impingement can be eliminated by appropriate contour- häuser« (⊡ Fig. This operation represents an alter- ing of the femoral neck (bump resection«). If a relevant native to the subcapital wedge osteotomy, and the risk of labrum lesion is already present (which can be visualized femoral head necrosis is slightly reduced. As a rule, it can by arthro-MRI), the contouring can be performed in also be performed during puberty, even in the florid stage connection with a surgical hip dislocation. Flexion of the femoral neck can If no labrum lesion is present, the contouring can also reduce the anterior impingement, but only to a limited be performed via a ventral approach without surgical hip extent. Consequently, the osteotomy aims to increase epiphysis not only flexion and valgization, but anteversion as well. Our therapeutic strategy for epiphyseal separation is Although no correction is performed at the site of the shown in ⊡ Table 3. Our therapeutic strategy for epiphyseal separation Acute and acute on chronic epiphyseal separation (unstable hip) Slip angle <40° Careful closed reduction of the slipped side and nailing with hook-pin or screw fixation of both the affected and unaffected sides Slip angle >40° Subcapital wedge osteotomy or open reduction with trochanteric flip osteotomy, screw fixation Chronic epiphyseal separation (stable hip) Slip angle <40° Nailing with hook-pin or screw fixation of both the affected and unaffected sides Slip angle >40° Subcapital wedge osteotomy Deformity after completion of growth Slip angle <40° Shaping of the femoral neck by bump resection with surgical hip dislocation, poss. The Imhaeuser-Southwick osteotomy is an intertrochanteric osteo- tomy involving concurrent valgization and flexion. Kochs A, Abeler E, Niethard F (2004) Die minimalinvasive Behandlung severe slipped capital femoral epiphysis with extracapsular base-of- der Epiphysiolysis capitis femoris. J Pediatr Orthop 13: 294–302 gen Vereinigung für Kinderorthopädie,Wiesbaden, 13. Koczewski P (2001) An epidemiological analysis of bilateral slipped black children. Aronson DD, Aronson RT (1996) Treatment of the unstable (acute) Pol 66: 357–64 slipped capital femoral epiphysis.

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The origins of the greater cipro 500 mg amex antimicrobial cleaning cartridge 6 pack, lesser cheap cipro 1000 mg otc antibiotic for sinus infection, and least will travel medially to reside at the costovertebral splanchnic nerves begin at the midthoracic spine and junction. Once the catheter is placed, the needle is end at the lower thoracic vertebra. Due to the proximity of the thoracic sym- The catheter is then aspirated, and a test dose of lido- pathetic chain, diffusion of local anesthetic may also caine is injected to evaluate possible intravascular provide unilateral sympathetic blockade, which may placement. TECHNIQUE DRUG PLACEMENT Bupivacaine has been the most evaluated drug, and has a history of safety and efficacy. Brachial plexus blockade Interpleural analgesia for the treatment of severe cancer pain Empyema in terminally ill patients. The use of interpleural Phrenic nerve paralysis (evident on chest radiograph) analgesia using bupivicaine for pain relief in advanced can- Bronchospasm cer. Post-thoracotomy *Pupillary constriction, ptosis of upper eyelid, slight elevation of lower spirometric lung function: The effect of analgesia. Interpleural analgesia with bupivicaine following thoraco- Interpleural spread (T3 to L1) of the bolus is similar tomy: Ineffective results of a controlled study and pharma- in the supine and lateral positions, usually within an cokinetics. Silomon M, Claus T, Huwer H, Biedler A, Larsen R, For Continuous Infusion: Bupivacaine 0. Interpleural analgesia does not influence posttho- rate of 5 to 10 mL/h (0. Interpleural bupivicaine for intraoperative analgesia: A dan- Addition of opioid to infusion or bolus does not add gerous technique? Diffusion of bupivicaine into the intercostal mus- significant benefit over intravenous delivery. Kowalski SE, Bradley BD, Greengrass RA, Freedman J, and local anesthetic effects. Is there a bilateral block of the tho- should be reabsorbed within 24–48 hours and is rarely racic sympathetic chain after unilateral intrapleural analge- clinically significant. The falling column: A new technique sion setup will limit the incidence of infection. Kaukinen S, Kaukinen L, Kataja J, Karkkainen S, Monitoring of blood levels for local anesthetic may Heikkinen A. Interpleural analgesia for postoperative pain relief in renal surgery patients. A randomized double-blind study of interpleural analgesia after cholecys- tectomy. Distribution of local REFERENCES anesthetics injected in the interpleural space, studied by computerized tomography. Side effects and com- ing analgesia during percutaneous biliary interventional pro- plications related to interpleural analgesia: An update. Eric Rey Amador, MD Persistent paresthesias are rare and, if they do occur, Sean Mackey, MD normally resolve within 6 weeks. GENERAL PRINCIPLES METHODS Peripheral nerve blocks and/or continuous perineural catheters can be used in the management of both Peripheral nerve blocks should be performed only by acute and chronic pain. They are especially effective practitioners who have a thorough understanding of in the perioperative period when a balanced, multi- the relevant functional neuroanatomy, surrounding modal therapeutic approach is used. Perioperative anatomic landmarks, and the resources and skills to techniques can be used as the sole anesthetic or in handle potential complications. Except in pediatric or unusual cases, nerve blockade should not BENEFITS AND RISKS be performed under general anesthesia. Specific nerve blocks also carry site-specific of sensory and motor blockade. Evidence suggests that bupivacaine is TABLE 21–1 Effects of Additives on Neural Blockade MEDICATION DOSE EFFECT COMMENT Epinephrine 1/200,000–1/400,000 Marker of intravascular injection Increased duration of action with lidocaine Increases block duration or mepivicaine Sodium bicarbonate 1cc in 10cc Decreases onset time Precipitates with bupivicaine, ropivicaine, and levobupivicaine Clonidine 0. Rarely, this block is associated anatomic location or paresthesia or with a nerve stim- with complications such as pneumothorax, seizures ulator. When a nerve stimulator is used, continued (due to intra-arterial injection), and epidural/intrathe- twitches at a current of <0. SUPRACLAVICULAR AND UPPER EXTREMITY INFRACLAVICULAR BLOCKS The brachial plexus is composed of the nerve roots Performed at the level of the cords of the brachial C5 to T1, which combine to form the superior, mid- plexus, these blocks are excellent for surgeries distal dle, and inferior trunks. Utilization of a nerve stim- form the lateral, medial, and posterior cords, which ulator is preferred.

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