By H. Hernando. University of Nebraska, Lincoln.
Supervised exercise programs have been shown to improve pain-free walking distance up to 180% from resting values 260 mg extra super avana. When compared to individuals treated with optimal medical therapy alone 260mg extra super avana, those treated with either stenting or supervised exercise experienced increase in peak walking time as well as claudication onset time extra super avana 260mg. It is also suggested that this be discussed as a treatment option for claudication prior to possible revascularization (class I) extra super avana 260 mg. Cilostazol also beneficially increases high-density lipoprotein , decreases triglycerides , and inhibits vascular cell adhesion molecule-1 expression , thereby decreasing vascular smooth cell proliferation . Randomized controlled trials of patients with moderate to severe claudication have demonstrated 40% to 60% increases in maximal walking distances after 12 to 24 weeks of therapy with cilostazol 100 mg twice daily . Cilostazol is contraindicated in patients with congestive heart failure , owing to an increased risk of sudden death associated with related phosphodiesterase inhibitors. Common side effects associated with cilostazol include diarrhea, palpitations, and headaches. This was predominantly due to limited procedural success and worse patency rates with endovascular as compared to surgical intervention. However, with improved operator experience, various technical advances, and institution of modern pharmacologic treatment regimens, better outcomes were seen in patients treated via an endovascular approach. This, in concert with relatively high morbidity associated with surgery, led to increased adoption of an “endovascular-first” strategy. Options for percutaneous revascularization include angioplasty with or without stenting. There are fortunately several tools available to address such disease, including atherectomy devices, various specialized balloons (including cutting, Chocolate, drug- coated, and lithotripsy), and various stents (nitinol, wire-interwoven nitinol, drug-eluting, and covered). This concern and a lack of consensus for the optimal treatment strategy have led to several clinical trials designed to address various approaches. As of now, there is not a clear consensus as to the optimal treatment strategy in patients with femoropopliteal disease, and as such clinicians must individualize treatment by carefully weighing patient, lesion, and device-specific characteristics. Several devices including atherectomy devices, standard peripheral balloons, a variety of specialized balloons, and coronary drug-eluting stents may be used depending on the specific clinical scenario. In a recent meta-analysis which compared angioplasty to femoral tibial bypass surgery, there was no difference in rates of limb salvage between treatment groups, further supporting the feasibility of endovascular approaches in this disease subset. Surgery is used to bypass long segments of diffuse disease (particularly involving the femoropopliteal segment) or when endovascular therapy fails. This is reflected in the class I recommendation for use of autogenous vein bypass to the popliteal artery over prosthetic grafts. Ultimately, the decision to pursue endovascular versus surgical intervention is a complex one which must weigh several patient and procedural factors. Aneurysms of the peripheral arteries, as in the aorta, are most commonly due to atherosclerotic disruption of the arterial media. The incidence of bilateral involvement in lower extremity aneurysm is high (45% to 68%). The greatest concern with lower extremity aneurysms is thrombosis and thromboembolism. Lower extremity aneurysms infrequently rupture (7% to 12%), but up to 60% will have an ischemic complication. As an aneurysm increases in size, it can compress adjacent venous and lymphatic structures causing lower extremity edema. Associated clinical symptoms include arm and hand claudication, digital ulceration, and neurologic symptoms caused by vertebral–subclavian steal. The diagnostic modalities are similar to those in lower extremity arterial disease. Risk factor modification for atherosclerotic lesions and revascularization (for symptomatic patients) are the mainstays of therapy. Finally, a high index of suspicion for concurrent cardiovascular and cerebrovascular disease should be maintained. Renal imaging can reveal an atrophic kidney or a size discrepancy between the two kidneys. Incidence increases with age and in community- based samples has a prevalence of approximately 7% in individuals >65 years old. It is the most common cause of secondary hypertension, may account for 1% to 5% of all cases of hypertension, and may be the cause of end-stage renal failure in up to 20% of new dialysis patients. Blood urea nitrogen and serum creatinine are readily available and are often used in practice as screening tools. Some data suggest that patients with an elevated resistive index may not improve after revascularization. The test may be limited by difficulty in obtaining measurements because of excess bowel gas or obesity. Its limitations include expense, limited availability, lack of resolution in the setting of high-grade stenosis (often appearing as an occlusion or loss of signal), a tendency to overestimate lesion severity, and difficulty with post-stent imaging because of artifact. In addition, in patients with advanced renal insufficiency or renal failure, gadolinium-containing contrast agents have been linked to nephrogenic systemic fibrosis in 2% to 3% of patients. It allows for excellent visualization of the main renal and accessory renal arteries and their branches. Disadvantages include the requirement for intra-arterial access and nephrotoxic radiocontrast. Atherosclerotic nephropathy is complex and not simply related to stenosis of the renal artery. Examination of renal histology in patients with atherosclerotic nephropathy reveals other potential mechanisms for loss of function, including small-vessel occlusion from atheroemboli, intrarenal arterial stenoses, and preexisting hypertensive nephrosclerosis. Importantly, as with other peripheral vascular disease processes, a high index of suspicion for concurrent cardiovascular and cerebrovascular disease should be maintained. Aggressive atherosclerotic disease risk factor modification should be part of a comprehensive treatment plan. The primary outcome of progression of renal dysfunction and key secondary outcomes including major cardiovascular and renal events were similar between groups. Despite this result, it is worthwhile to note that patients with a clear indication for revascularization as well as those with a high likelihood of needing revascularization within 6 months were excluded from the trial— both important factors which limit the generalizability of the results to the patients the procedure is actually intended to benefit. Additionally, of the 403 patients randomized to revascularization, 40% had lesions <70% in severity, which brings into question whether the correct selection criteria were used. The primary outcome of decrease in creatinine clearance >20% did not differ between groups at 2-year follow-up. It is noteworthy that of the 64 patients randomized to stenting, 30% did not undergo revascularization, predominately because of the fact that the lesion was not deemed to be severe at the time of angiography. Overall, only a small proportion of patients in both arms reached the primary endpoint, which resulted in the study being underpowered and thereby limiting its applicability to clinical practice. Since the study has been published, concern has been raised about whether the study population reflected a less high-risk population and therefore not one that would be expected to garner the greatest benefit of revascularization as compared to medical therapy. Therefore, the crux of the issue in defining a subset of patients who may benefit from revascularization largely rests upon accurately defining high-risk characteristics that would predict improved outcome with stenting versus medical therapy. In patients undergoing renal stenting, baseline azotemia is the strongest predictor of long-term mortality (70% 5-year mortality with serum creatinine >2. Annually, there are nearly 800,000 strokes in the United States and 15 million strokes worldwide. Stroke is the third leading cause of deathin western societies and the leading cause of long-term disability in the United States. Of these, 60% are embolic in nature whereas small vessel disease and large vessel atherothrombotic lesions account for 25% and 15%, respectively. Smoking and age are the two most important risk factors for developing carotid atherosclerosis. The others, in order of importance, are hypertension, diabetes, gender (men more than women if younger than 75 years; women more than men if older than 75 years), and hyperlipidemia. The reasons that carotid stenoses become symptomatic are not completely understood, but there is a linear increase in the risk of stroke as the stenosis increases to >70%. Rupture of this vasculature or rupture of the plaque can result in plaque hemorrhage or ulceration, with subsequent in situ thrombus formation. This mechanism accounts for most cerebrovascular events caused by carotid disease. Larger plaques can result in high-grade carotid stenosis or obstruction, with subsequent ischemic stroke because of a reduction in cerebral flow, in the setting of inadequate or absent collateral circulation. Hemispheric symptoms include unilateral weakness, numbness, difficulty with speech, and visual field defects, whereas vertebrobasilar symptoms can include cerebellar disturbances such as ataxia or brain stem symptoms including syncope, dysphagia, dysarthria, or diplopia. Amaurosis fugax is transient, unilateral vision loss ipsilateral to a carotid lesion. An assessment for the presence of a cervical bruit is an important part of the physical examination but should not be relied on as the sole marker for the presence of carotid disease. In the Framingham study, the presence of a carotid bruit in asymptomatic patients doubled the risk of stroke, but most of these strokes occurred in vascular beds different from those of the carotid bruit. The presence of a bruit may be a general marker for patients at higher risk for cerebrovascular and cardiovascular events. In addition to auscultation for carotid bruits, a complete evaluation in a patient with symptoms includes a focused neurologic examination to correlate symptoms with neurologic territory, a fundoscopic examination to detect retinal embolization, and a cardiac examination to rule out potential cardioembolic sources for symptoms. Symptomatic patients with 70% or more stenosis have an 8% risk of stroke at 30 days and a 13% annual incidence of stroke. The risk of stroke in asymptomatic patients increases as the degree of carotid stenosis increases. Asymptomatic patients with 60% or more stenosis have a stroke risk of approximately 2% per year. Asymptomatic patients with 80% or more stenosis have a risk of approximately 5% per year. It has a sensitivity and specificity of >80% among patients with 70% to 99% stenoses and sensitivity and specificity of >95% among patients with complete carotid occlusion. Because of its high sensitivity and specificity in severe carotid disease as well as its noninvasive nature, duplex ultrasound should be the first study performed to assess for carotid disease. Duplex ultrasound criteria for carotid stenosis vary by institution, and each vascular laboratory must assess the accuracy of its criteria for stenosis in a quality assurance program. Compared with angiography, duplex ultrasound is noninvasive, is less expensive, and can be done at the bedside. Limitations include the inability to image intracranial disease, limited ability to assess collateral flow, occasional inaccuracy in distinguishing high-grade stenoses (“string sign”) from complete obstructions, and the need for an experienced sonographer. Advantages include high sensitivity (particularly for carotid artery occlusion), reproducibility, and the ability to visualize the entire carotid artery including the extracranial and intracranial portions. Disadvantages include cost and the need for contrast injection, which may be unsuitable for patients with chronic kidney disease or volume overload. Advantages include high sensitivity, reproducibility, and the ability to visualize the entire carotid artery, including the extracranial and intracranial portions. The use of a paramagnetic agent as a vascular contrast confers higher quality images less prone to artifact. Disadvantages include high cost and the inability to study critically ill patients, claustrophobic patients, or patients with ferromagnetic implants such as pacemakers. When there is concern regarding the accuracy of one study, it is justifiable to perform both. Contrast angiography with digital subtraction angiography is the gold standard for assessment of carotid atherosclerosis. It allows the simultaneous assessment of the aortic arch, subclavian arteries, vertebral arteries, and intracranial circulation. This is important because the presence of collateral circulation in medically treated patients with high-grade stenosis reduces the risk of ipsilateral stroke. Aggressive cardiovascular risk factor modification is recommended to reduce the risk of stroke and prevent the progression of existing disease, regardless of whether or not revascularization is indicated. This includes careful attention to smoking cessation and optimal control of various cardiovascular comorbidities including hypertension, hyperlipidemia, and diabetes mellitus according to established guidelines. Aspirin is the most extensively studied antiplatelet drug for the prevention of stroke and should be initiated in all patients with evidence of carotid atherosclerosis. Clopidogrel 75 mg daily may be used in primary prevention settings when there is a contraindication to aspirin therapy. Following a stroke, it is reasonable to use clopidogrel as an alternative to aspirin in select clinical situations depending on the risk factor profile of the patient. Low-dose aspirin (25 mg twice daily) plus dipyridamole (200 mg twice daily) has been found to be more beneficial than aspirin alone or dipyridamole alone for the secondary prevention of stroke in the European Stroke Prevention Study 2. The Prevention Regimen for Effectively avoiding Second Strokes trial, which enrolled over 20,000 patients with noncardioembolic ischemic stroke, showed that clopidogrel monotherapy and aspirin plus extended-release dipyridamole have similar risks and benefits for secondary stroke prevention. However, despite the nearly identical event rates, the trial failed to meet the prespecified noninferiority criteria for treatment with aspirin and extended-release dipyridamole. Several studies have consistently shown carotid plaque regression in patients treated with statins, and clinical trials have shown a reduction in stroke among patients treated with statins. In the Scandinavian Simvastatin Survival Study, nonembolic strokes were significantly reduced in the statin arm. The beneficial effects of statins in reducing strokes are highest among patients at the highest risk for stroke. Hypertension is the single most modifiable risk factor in the prevention of stroke, and epidemiologic data suggest that approximately 60% of all strokes are attributable to hypertension. Current guidelines recommend antiplatelet agents rather than anticoagulants in patients with extracranial carotid or vertebral atherosclerosis whether or not they have ischemic symptoms, unless there is an alternate indication for anticoagulation (i. It is important to keep in mind that high-risk patients were not enrolled in these trials. Because the risk of surgery among such patients probably would be higher than reported in these trials, extrapolation of these data to high-risk patients must be done with caution. Other complications include bleeding and wound hematoma, cranial nerve injury, wound infection, bradycardia, hyper- or hypotension, and, rarely, seizures and intracerebral hemorrhage.
Bitemarks in forensic dentistry: a review of legal 260 mg extra super avana, the key to the ability to search the database of antemor- scientific issues 260mg extra super avana. Symposium on forensic dentistry: offered within this chapter were selected to give the legal obligations and methods of identification for the prac- novice a practical and representative introduction to titioner extra super avana 260 mg. Mass fatality incidents: are California den- Journal of the California Dental Association extra super avana 260mg. This manual can be obtained from the American Society of Forensic Odontology at http://www . A precise drawing on graph paper of a model of a mandibular right canine by a first-year dental hygiene student . Remember that almost all teeth taper toward the narrower lingual sur- Draw these two boxes in the lower left and right face , but the overall outline from the lingual is the same corner of the page (Fig . Professional drawing (by medical artist) of a model of a maxillary canine based on dimensions given in Table 1-7 . Mark the faciolingual width of the ber of the squares of the mesiodistal crown measure- cervix . Hold the tooth facial side down the four-square border at each side and below these and in such a position that you are looking exactly in views. Be sure that the tooth crown The cingulum is normally centered on, or slightly distal is not tilted up or down. The incisal edge of on any tooth other than those lines that have been pro- the tooth will normally have a slight lingual twist of the duced by attrition? Labeling the grooves, the fossae, lingual to the center (in the same position it is shown and the ridges on the occlusal surfaces of the posterior on your drawings of the mesial and distal aspects). It is not specified view as might be expected during a conver- expected that a student will remember the exact sation with an instructor or a patient. On maxillary central incisors, the root is quickly sketch a specific tooth and view from memory. Based on this In order to sketch a facial view of a recognizable fact, three parallel horizontal lines can be drawn to tooth from memory, the drawer must have knowledge denote the distance of the crown length from incisal of the following characteristics related to the tooth edge to the cervical line relative to the root length being drawn: (a) approximate crown-to-root ratio (i. For this maxillary central incisor, the crown the crown heights of contour (crests of curvature), (d) length is on the bottom. If one consid- to memorize that the average crown width for this ers each of these tooth characteristics in the appropri- tooth is 8. Five steps involved in sketching the facial view of a tooth (in this case, a right maxillary central incisor). Chapter 13 | Guidelines for Drawing, Sketching, and Carving Teeth 367 knowledge, two parallel vertical lines can be placed crown box. If a sketch of the crown were all that you perpendicular to the horizontal lines to establish are reproducing, you would be finished. We know that the apex of the the formation of two boxes: a crown box that will root is near the center of the tooth root axis (a ver- surround the crown and a root box that will enclose tical line in the center of the root at the cervix). At this time, label the mesial (M) and distal We also know that roots are broadest in the cervical (D) surfaces of the crown box that is dependent on third (but not very much narrower than the width whether you are viewing a right or left incisor. For of the crown), may be nearly parallel in the cervi- this right incisor, the mesial surface is on the right cal third, and taper toward the rounded apex. Based side of the box, and the distal is on the left side, as if on this knowledge, you can finish the sketch. Since these the rounded apex just touches the apical line of the two points are the widest parts of the tooth crown root box. When the teeth are in ideal alignment, “boxes” and crests of curvature, and refer to the Appendix they are the location of the proximal contacts. On all pages for tooth traits when sketching the actual tooth incisors, the proximal heights of contour (contacts) outlines. Also, on this surface is not until this step is complete that you actually of anterior teeth, there is normally evidence of a nar- begin sketching the tooth crown shape (outline). On maxil- example, on a maxillary central incisor, we know lary molars, the lingual root is now in the foreground. The facial crest of curvature is similar for all line from the facial view is broad and curves toward teeth: in the cervical third. Based on this knowledge, begin sketching ture is in the cervical third on the cingulum for anterior the crown outline by placing subtle convexities that teeth but in the middle third for most posterior teeth. See the student sketch of a mandibular the mesial and distal crown walls, and these walls second molar from the mesial view in Figure 13-5B. The Posterior teeth from the occlusal view are viewed proximal convexities also curve incisally to blend looking directly down along the axis of the root. The the incisal line of the crown box in the mesial half and crown outline box is developed for this view by using tapers shorter (farther from the box outline) toward the mesiodistal and faciolingual crown proportions. Finally, the cervical line appears as a con- On mandibular premolars, the crown proportions are tinuation of the mesial and distal walls and curves slightly longer buccolingually than mesiodistally, but toward the apex, just touching the cervical line of the close to square. Four sketches of teeth by first- quarter dental and dental hygiene students: although not perfectly drawn, each sketch is recog- nizable as the tooth being drawn. It may be helpful to remember these basic guidelines Mandibular molars from the occlusal view are wider regarding pits and grooves. Most premolars have a mesiodistally than buccolingually, whereas maxillary mesial and distal pit connected by a groove running molars are slightly wider buccolingually than mesiodis- mesiodistally between buccal and lingual cusps. The crests of curvature on molars and premolars molars (and three-cusped mandibular second premo- on the mesial and distal surfaces are located in the cen- lars) have three pits (mesial, central, and distal) that ter or slightly to the buccal of the buccolingual midline. Molars also have one located mesial to the middle, except on the buccal of the or two buccal grooves that separate the two or three mandibular first molar where it is close to the middle. On mandibular molars, the After the outline “box” is sketched and crests of curva- lingual groove comes off near the central pit, but on ture have been noted, sketch the crown outlines using maxillary molars, a lingual (distolingual) groove comes descriptions from the Appendix pages. An additional challenge on these views involves Developmental triangular or fossa grooves or supple- reproducing the location of the cusp tips, grooves, and mental grooves may angle off from the mesial and dis- pits (as must be accomplished by dental personnel tal pits of most posterior teeth, directed toward the every time a restoration is placed on an occlusal sur- “corners” of the tooth. See the student sketches of the face, finished and polished, or constructed or carved in occlusal views of two recognizable molars in Figure wax in the laboratory). While eventually you may be able to carve a tooth from a block of wax without preliminary measurement, the beginner can only do well by approaching the carving systematically in the same way you approached the drawings: first, by drawing a box on the wax block; second, by sketching an outline of the tooth in the box; and third, by carving around the sketch or out- line, one view or aspect at a time (sequence is shown in Fig. When approaching the task of carving a tooth, con- sider Michelangelo who conceived of his task of pro- ducing a marble statue by “liberating the figure from the marble that imprisons it. To minimize this, as you cut away wax, repeatedly examine your carving from all sides; turn it around and around and compare it with your speci- men from each view. Where too much wax has been removed, you have one of three choices: add molten wax to the deficient region, make the entire carving proportionally smaller, or start with a new block of wax. The sequential method described in this chapter for carving a tooth from a block of wax. Allowance is made for the greater length of some lingual cusps, which are longer than the measured buccal cusp. Figure 13-7 as you follow the following guidelines: Maxillary central incisor wax carvings by first-year dental hygiene students as seen from the mesial (M), Step 1: Shave the sides of the block flat and make all lingual (L), incisal (I), facial (F), and mesial-facial (M, F) aspects: The crown and half of the root were carved to specific angles right angles. These excellent carvings were each draw a line at this level, encircling the block (on all done in less than 3 hours as a required skill test. At this time, do not carve around here is to provide for the extra length of the lingual the outline of the tooth, but rather carve up to the cups on molars that are longer than the mesiobuccal straight vertical lines that form the box in which cusp that established crown length. Be Step 3: From the 2-mm line, measure the crown length sure they are perfectly flat and smooth. Step 12: Now carve away the shaded regions seen in Step 4: From this cervical line, measure one half of the Figure 13-7C around and down to the facial and lin- length of the root and draw a third line around the gual outlines of the tooth. Keep the carving surface smooth; Step 5: On the base of the block, carve, on appropriate if it becomes chopped up, it will be impossible to sides, F (facial), L (lingual), M (mesial), and D (dis- smooth it without losing both the shape and the size tal). F and L so that you will carve a right or a left tooth, Step 13: With a sharp pencil, very lightly draw center whichever you intend. Be sure they are exactly lengthwise on the block in the center of the mesial opposite. Using this the curved surface as wide as the greatest mesiodistal measurement, draw a line this distance on either crown measurement plus 0. These two outer lines length distance from the incisal edge on the facial should be parallel to the center line and extend and lingual sides (since the original line was carved from the top of the block to the base. Then draw the facial outline of the crown lines form a box whose dimension faciolingually and half of the root on the curved facial side of the is equal to the crown dimension plus 0. Step 16: On the lingual surface of the block, draw an Do not make trouble for yourself by allowing more outline the same shape as the one on the facial sur- than this extra 0. Be on the lingual surface too, so the crown will not be careful to place the incisal edge and the labial and too long. Your carving Step 17: Carve away all the wax outside the drawing will probably be no better than this drawing. Be sure that on both sides, the drawings roots may extend beyond the box lines, and these are oriented so that the facial surface of the tooth roots should be carved accordingly. Maxillary canine wax carvings viewed from the distal (D), lingual (L), incisal (I), and facial (F) aspects. First-year dental hygiene students carved these during a skill test (2 hours, 50 minutes time limit). Maxillary right canine carving done by senior made by dental hygiene students at The Ohio State dental student Keith Schmidt: observe the nearly perfect University, are shown in Figure 13-8. Five aspects contours from all aspects and that the root is not becoming of another very fine carving by a dental student are narrower as it joins the crown (a very common carving error in attempting to refine the cervical line). Outlines within which you may draw three views of a maxillary canine: the boxes are proportional to the natural tooth average measurements in Table 3-2. The widest portions of the crown (mesial and distal contacts) should touch the sides of the wider lower box. Only the widest part of the root should touch the sides of the narrower box above with the root apex touching the top of this box. On the incisal view, be sure to position the incisal ridge just labial to the faciolingual middle of this box. Drawing these three views will be helpful to you when you outline similar contours on a block of wax for carving a maxillary canine. Be an honest critic of your work, con- to sketch teeth into the blank boxes of Figure 13-12 is stantly looking for regions where the carving could shown in Figure 13-13. You do not discard your first ones, but keep them for future should have a tooth model or extracted tooth specimen comparisons. Proportionally outlined boxes for drawing the lower right first and second premolars and first molar in their usual relationship to one another: select three nice tooth specimens or tooth models and go to work. Outlined proportional boxes for drawing several views of the maxillary first and second premolars in their usual relationship to each other: Use Lingual the same guidelines given in the legend for Figure 13-10. A dental hygiene student’s drawing of these two teeth within the outlined boxes is seen in Figure 13-13. These drawings within the outlined boxes are examples to help you with your drawings in the blank boxes in Figure 13-12. For example, in the lingual view, the maxillary first premolar’s lingual cusp is too long. Berlin: Buch-und Zeitschriften-Verlag “Die Quintessenz,” Average measurements from 4572 extracted teeth are 1976. You may find the General References helpful in perfecting your carving techniques. Also, as you study this section, you should Foramen rotundum: a specific round foramen; recall relate the location of each bony structure on the skull the Capitol’s rotundum or dome is round when viewed to its location on your own head, that is, where it is from above located under the skin of the face or under the mucosa Meatus [me A tus]: a natural passage or opening in of the mouth. Many terms have similar defini- muscle is within the cheek; the buccal surface of a tions, so they are defined here in groups to facilitate tooth is the side toward the cheek learning. Since anatomy terms are often similar to com- Cervix: of the neck or neck-like; compare a cervical mon familiar words, the new terms are compared to vertebrae in the neck familiar words whenever possible. Planes of the Frontal plane head and directions used to iden- tify relative location of structures Inferior direction or surfaces of the head. The frontal bone is a single, large bone (not to be confused with molar) midline bone that forms the “forehead” and eyebrow Meatus [mee A tus]: a pathway or opening region. Human skull, left side: The following large bones of the neurocranium: the single frontal bone (blue) forms the anterior superior portion, the parietal bones (yellow) form the lateral and superior surfaces, and the occipital bone (light green) forms the posterior inferior portion and the greater wing of the sphenoid bone (light red). Note the outline of the shallow temporal fossa, which includes portions of temporal, parietal, sphenoid, and frontal bones. They the posterior view resembles an upside-down “V” and can all have holes (foramen) for the passage of nerves to the be compared to the shape of the Greek letter lambda (λ). Human skull: inferior surface with half of the mandible removed on the right side of the drawing. Note the location of the hypoglossal canals (in the lateral walls of the foramen magnum) and the jugular foramen just adjacent to the occipital bone. Also, notice the portion of the midline ethmoid bone (green) that is visible in the anterior braincase. The complex shape of the each eye orbit (the orbital lamina of the ethmoid bone sphenoid bone can only be appreciated by looking is visible in Fig. It also has at it from several different views (seen from above in scrolled processes extending into the nasal cavity simi- Fig. Finally, a vertical midline plate of noid bone is important to dental professionals because the ethmoid bone extends downward into the nasal it has processes that serve as part of the attachment cavity (along with the separate single vomer bone) to for three of the four pairs of major chewing muscles. Part of human skull, lateral view, with the lateral wall of the left maxilla removed, exposing the large maxillary sinus: Note the lateral surface of the lateral pterygoid plate of the sphenoid bone (shaded light red) just behind the maxilla. The pterygoid hamulus of the medial pterygoid plate is also visible and is just posterior (and slightly medial) to the third molars. Also, note the part of the midline ethmoid bone (green) that balloons out between the right and left eye orbits to form part of their medial walls, and the part of the palatine bone (light green) that extends superiorly from the palate to form part of the maxillary sinus (and part of the pterygopalatine space). Notice the relative location of the medial and lateral pterygoid plates and fossae just posterior to the bones of the hard palate. Human Superior orbital fissure skull, frontal aspect: The left Frontal process maxilla is shaded red (on the Orbital Lamina of maxilla right side of the drawing), and of ethmoid bone Infraorbital fissure the right zygomatic bone is Zygomatic bone shaded purple (on the left side (right) Infraorbital foramen of the drawing). Also, the Sphenoid bone (infraorbital nerve) facial surface of the arch- Zygomatic bone Nasal septum shaped alveolar process of the (vomer and Zygomatic process left maxilla (process that ethmoid bone of maxilla Body of maxilla (left) surrounds the tooth roots) Nasal cavity and the alveolar process of (seen through Inferior nasal concha the entire mandible are piriform aperture) Canine fossa shaded blue.
An exception is one type of maxillary lateral incisor (called a peg lat- Accessory (or lateral) canals also occur extra super avana 260 mg, located eral with an incisal edge that somewhat resembles one most commonly in the apical third of the root (Fig extra super avana 260mg. Refer to Table 8-1 8-3A and B) and 260mg extra super avana, in maxillary and mandibular molars 260 mg extra super avana, for a summary of the number of pulp horns related to are common in the furcation area . A scanning electron photomicrograph of an instrumented (cleaned) root canal of a maxillary central incisor . After cleaning the root canal , the tooth was split and mounted for viewing with the scanning electron microscope . This view shows the apex of the tooth at the top of the picture and includes the apical third of the root . Near the bottom of the picture (right wall of canal) , an accessory canal can be seen at the arrow. A scanning electron photomi- crograph at a higher power of the accessory canal is observed in A. The adherent “stringy” extensions around the blood vessels are supporting collagen fiber bundles. Dennis Foreman, Department of Oral Biology, College of Dentistry, Ohio State University. Operating the lathe at a fairly best studied by the interesting operation of grind- high speed is less apt to flip the specimen from your ing off one side of an extracted tooth. If you can teeth should always be sterilized as described in the devise an arrangement by which a small stream of introduction of this text and kept moist. Wearing water is run onto the surface of the wheel as the a mask and gloves, you can use a dental lathe tooth is ground, you will eliminate flying tooth dust equipped with a fine-grained abrasive wheel about and the bad odor of hot tooth tissue. Pulp Chamber and Pulp Horns frequently dipping the surface being ground in water of Anterior Teeth or by dripping water onto the wheel with a medicine dropper. Look often at the tooth surface you are When an incisor is cut mesiodistally and viewed from cutting and adjust your applied pressure to attain the facial (or lingual) (similar to the view on dental the plane in which you wish the tooth to be cut. A radiographs), the pulp chambers are broad and may high-speed dental handpiece and bur will greatly appear as three pulp horns. However, the incisal border of the pulp wall (roof of the chamber) As you examine different sides of each kind of tooth, of a young tooth may show the configuration of three notice how the external contours of the pulp cham- mamelons, that is, has developed with three pulp horns: ber are similar to the external morphology of the located mesially, centrally, and distally. On incisors and canines, you can remove that there is an unusual peg lateral incisor that only has either the facial or lingual side from some teeth to one pulp horn. When an anterior tooth is cut labio- On premolars and molars, the removal of either the lingually and viewed from the proximal, the pulp cham- mesial or distal side will expose the outline of the bers taper to a point toward the incisal edge (Fig. Finally, on Recall that all anterior teeth are most likely to have one molars, the removal of the occlusal surface will reveal root. The number of root canals in each type of anterior the openings (orifices) to the root canals on the floor tooth is also most frequently one. Maxillary central inci- of the pulp chamber (as seen later in the diagram in sors, lateral incisors, and canines almost always have Fig. Sectioned teeth showing pulp cavity shapes relative to the external tooth surface. Mesiodistal section of a maxil- lary central incisor showing only two of its three pulp horns. Faciolingual section of a maxillary first premolar with two roots and two obvious pulp horns, one under each cusp. The high pulp horns (only two are visible in this tooth section) and the broad root canal indicate that this is a young tooth. The pulp chamber of this older tooth is partially filled with secondary dentin, and the root canal is narrower than in the tooth shown in A. Thus, two roots (though still uncommon), one facial and one the buccal horns are longer than the lingual horns. Therefore, the premolars that are the two- cusp type most often have two pulp horns (Fig. Pulp Chambers and Pulp Horns in Premolars molars that have a functionless lingual cusp may have When premolars are cut mesiodistally and viewed from only one pulp horn (Fig. Root Canal(s) and Orifices of Premolars the pulp chamber is curved beneath the cusp similarly to the curvature of the occlusal surface. When cut bucco- Maxillary first premolars most often have two roots lingually and viewed from the proximal, the pulp cham- (one buccal and one lingual) and two canals (one in ber often has the general outline of the tooth surface, each root as seen in Fig. Even maxillary first pre- sometimes including a constriction near or apical to the molars with a single root almost always have two canals. As commonly occurs, much of the pulp chamber is located in the cervical Root canal third of the root. There is wear (attrition) on the incisal edge, and secondary dentin has begun to fill in the incisal part of the pulp cham- Pulp chamber ber. Curvature of the root prevented cutting the pulp cavity in one plane so that the apical portion of the root canal was lost. Even extensive attrition on the incisal edge would not likely expose the pulp since secondary dentin would form in the incisal part of the pulp chamber and the A B pulp would be additionally protected. The buccal canal orifice in the maxillary first premolar (viewed through the pre- pared access opening and the roof of the pulp chamber removed in Fig. Maxillary second premolars most often have one root and one canal, but two canals are frequently present. E When there is one canal, its orifice on the pulp chamber floor is located in the exact center of the tooth (Fig. If the orifice is located toward the buc- cal or the lingual, it probably means that there are two canals in the root. There is no attrition evident on the incisal edge, and the pulp cavity is still large. The pulp chamber of maxillary first and second molars is broader buccolingually than mesiodistally (like the The average incidence of two canals, one in the buccal crown shape) and is often constricted near the floor of root and one in the lingual root, is 90%C although there the chamber (seen in Fig. D The dentist must first and second molars, the chamber is broader mesi- know the location of each canal opening on the pulp odistally than buccolingually (like the crown shape). Radiograph of a mandibular left second premolar showing the shape of the root canal as though sectioned mesiodistally. Radiograph of a maxillary first premolar reveals the two root canals (filled with a filling material that makes the canals appear whiter). Maxillary first premolar sectioned faciolingually, mesial side removed (young tooth). The curvature of the tips of the roots prevented cutting the root canals in one plane. The two pulp horns are sharp; there is little, if any, secondary dentin; and the floor of the pulp chamber is rounded. Young maxillary molar with mesial side removed; lingual side (with cusp of Carabelli) is on the right. The tooth is sectioned through the center of the lingual root canal but not through the center of the mesiobuccal canal. The floor of the pulp chamber Access preparations into pulp chambers is relatively flat as it often is on young teeth. Ideally shaped openings provide molar with mesial side removed; lingual side is on the right. Pulp tooth is sectioned through the mesiobuccal and lingual root canal orifices on the floor of each pulp chamber correspond canals. The mesiobuccal and mesiolingual pulp horns extend a little into the left half of the arch shows maxillary teeth; the right half shows anatomic crown. As in all cusped teeth, molars have one pulp horn per functional cusp, and they are located in the roof of the pulp chamber well beneath each cusp. Therefore, if we consider the cusps of Carabelli to be functionless, all four-cusp types of molars have four pulp horns, three- cusp maxillary molars have three pulp horns, and the mandibular first molar with five cusps is the only type of molar to have five pulp horns. The pulp chamber is normally deep to, or some distance from, the occlusal surface, actually located within the cervical part of the root trunk (Fig. The floor of the pulp chamber is consider- The pulp horn in the buccal cusp is large; in the lingual cusp, it ably apical to the cervical line; it is located in the root is very small, almost nonexistent. The pulp floor has multiple openings (orifices), of a pulp horn beneath the nonfunctional lingual cusp on mandibular first premolars. The floor is level or flat in young side removed, with root and root canal divided near the apex teeth. On maxillary first molars, there are therefore four orifices on the floor of the pulp chamber: one for each canal (Fig. Maxillary second molars, like maxillary first molars, most frequently have three roots and four canals. The location of the orifices in the maxillary second molar is similar to the maxillary first molar, except that they are closer together (Fig. Both mandibular first and second molars most fre- quently have two roots (mesial and distal) and three canals. Most of the pulp distal root is on the distal side of the root, not at the root tip. Location of the Notice the three pulp horns (at arrows) under the three buccal K orifices of mandibular molars is shown in Figure 8-9. Old tooth (exhibiting Maxillary third molars usually have three root canals, considerable occlusal wear) with lingual side removed. However, that the roof of the pulp chamber is about at the level of the they do vary considerably in root form. The floor of completing their development later in life than first and the pulp chamber is convex (a condition founded in older teeth) second molars. Therefore, on radiographs (x-ray films), because of the deposition of secondary dentin. Root Canal(s) and Orifices of Molars root canals related to the number of roots normally Maxillary first molars most frequently have three roots found within different tooth types. In the palatal root, a single canal is Primary teeth generally have thinner amounts of den- larger and more easily accessible from the floor of the tin and enamel, so their pulp cavities are proportionally pulp chamber than for the other two roots,G but this larger than on permanent teeth, and their pulp horns root and its canal often curve toward the buccal in the are closer to the incisal or occlusal surfaces. A pulp cap is a term describing a procedure where horns extending beneath the cusps or mamelons in the the dentist places calcium hydroxide on very thin den- roof of the chamber and is usually constricted some- tin that covers the pulp (an indirect pulp cap), or over what at the cervix. As teeth get older, the pulp chamber a small bit of exposed healthy pulp (a direct pulp cap) becomes smaller and is more apically located because in order to stimulate the formation of a new layer of of deposits of secondary (additional) dentin produced dentin to help the tooth heal. The floor of the pulp chamber in molars is nearly flat in young teeth, but later The dentist’s knowledge of normal pulp shape, size, and becomes more convex. L In some cases, the pulp cham- depth beneath the enamel is important to him or her ber may become entirely filled. When the makes finding and accessing the pulp chamber more dentist determines that the tooth can be restored without difficult in an older patient than in the younger patient the need to remove the pulp, he or she must prepare the where the teeth still have larger chambers. Whenever possible, the goal is to leave canal decreases in size with age, getting small in older some sound (undecayed) dentin on the floor of the cav- teeth because of the gradual addition of dentin on the ity preparation to provide support for the restoration internal walls. On the other hand, teeth (other than (such as a filling using composite resin or amalgam) third molars) that exhibit unusually large pulp cham- and to avoid exposing any part of the pulp cavity with bers on dental radiographs are immediately suspected a cutting bur or hand instrument. This is accomplished of having necrotic pulps, that is, pulps that no longer through knowledge of the shape of the pulp chamber have vital nerve or blood supply. Without vital pulp tis- and canals and a careful evaluation of the patient’s sue, dentin formation ceases, and the pulp chamber size radiographs to determine the location of the pulp remains constant (once the pulp died) rather than con- relative to the decay and external surface of the tooth. An example of deep decay that has reached the pulp Necrotic pulps can be a possible source of infection. Radiograph of a lower left first molar with a very large distal decay (seen as an area of lost enamel and darkened dentin) that has reached (exposed) the pulp. There is also mesial decay on this tooth that does not appear to have reached the pulp. Sometimes, however, signs (what is seen), symptoms (what the patient feels), and diagnostic tests may indicate 2. Irreversible pulpitis (inflammation of the pulp that When these signs, symptoms, and diagnostic test results cannot be healed) is a condition of the pulp tissue indicate a pulp is not likely to respond well by placing where the pulp will not heal and root canal treatment is just a filling (dental restoration of amalgam or compos- indicated. Teeth with irreversible pulpitis are unusually ite), the pulp tissue must be removed and a root canal sensitive to cold or hot, and sometimes either stimulus filling placed (endodontic therapy must be performed). The implications of dental anatomy on restorative den- The patient may also experience spontaneous pain in tistry are discussed in more detail in Chapter 10. The proximity of caries to the pulp can often be evaluated best using dental radio- 1. As the caries approaches the pulp, Endodontics is a specialty branch of dentistry con- a normal defense reaction will occur involving inflam- cerned with the morphology, physiology, and pathol- mation and eventually the formation of additional den- ogy of human dental pulp and periapical tissues. However, when the caries study and practice encompass the related basic and reaches or exposes the pulp, bacteria can overwhelm clinical sciences, including biology of the normal pulp; the defenses, and the tooth usually becomes painful. Access to and removal of affected pulp tissue pathologic conditions that occur around the root. The pulp tissue can- An endodontist is a dentist who specializes in endo- not be successfully treated with medications alone once dontics (root canal therapy). When the disease process in the Chapter 8 | Application of Root and Pulp Morphology Related to Endodontic Therapy 241 crown has overwhelmed the pulp, the pulp tissue in the pain. Once the bacteria and prod- infection will usually provide relief within two to three ucts of pulpal breakdown contained within the root days. A chronic inflammatory response in the bone tooth crown to a gray or brownish color, which indi- can lead to the formation of a granuloma (i. Since a granuloma is less dense than bone, canal, the discoloration can be greatly reduced by using a radiograph will usually reveal radiolucency (a peria- an intracoronal bleaching technique where the bleach pical radiolucency is the dark area at end of the root; is placed within the pulp chamber for a period of time. In some cases, the granuloma undergoes See the change of tooth color in Figure 8-16.
Because real-time imaging of the needle tip accessing the pericardial fluid is not always possible extra super avana 260mg, it is of vital importance to maintain the trajectory of the needle during the pericardiocentesis identical to the trajectory of the echocardiographic probe when imaging extra super avana 260 mg. Once the best window is selected 260 mg extra super avana, the probe’s location is marked with a permanent marker and scrubbed with sterile chlorhexidine–alcohol or povidone–iodine solution 260mg extra super avana. The entire torso is draped with sterile towels or a full-body sterile field if available . The patient should not move between the echocardiographic examination and the procedure . We use a sterile sleeve over the echo probe so that the operator has it to hand when performing the pericardiocentesis . Using a sterile pen , a mark can be made on the pericardiocentesis needle at the approximate distance between the skin and effusion that was noted on the echocardiogram . The needle used should be 5 to 8 cm in length , with a short bevel to lessen the risk of lacerating structures at the needle’s tip. Then deeper anesthetic is given over the superior aspect of the rib (if a chest wall approach is used). Occasionally, in a relatively superficial pericardial effusion, the pericardial space will be entered with the anesthetic needle and pericardial fluid may be aspirated. Care should be taken when using an apical or intercostal approach to avoid damaging the neurovascular bundle at the lower rim of the rib at the superior aspect of the rib space. Using a three-way stopcock, an 18G Cook needle is attached to a syringe that contains a few more milliliters of local anesthetic. The needle is advanced through the anesthetized tract while maintaining negative pressure in the syringe, over the rib, along the same trajectory as the echocardiographic probe, until the fluid is aspirated. Upon aspiration of the fluid, the catheter is advanced over the needle, and the needle is withdrawn. If no fluid is retrieved at the depth calculated from the echo images, it is recommended to withdraw the needle and reassess the trajectory with the ultrasound probe as it may need to be redirected. Once fluid is obtained during aspiration, it does not necessarily confirm access to the pericardial space, because pleural and peritoneal collections may be traversed during pericardiocentesis. When confirmation that the needle is in the pericardial sac is needed, agitated saline contrast may be injected through the stopcock while imaging the heart from a remote location. The appearance of bubbles in the pericardial space confirms an appropriate location. Bubbles appearing within a cardiac chamber suggest that the heart has been perforated and that the needle or catheter should be withdrawn. If agitated saline cannot be visualized, one should reconsider the needle position. If the effusion is large, the contrast may not be visible from all echocardiographic windows; occasionally, it may be necessary to reinject saline and image from an alternative location. Of note, it is recommended to inject agitated saline when the needle is in the pericardial fluid and before using the dilator and inserting the catheter. With this approach, it is possible to avoid dilating the myocardium with a larger bore device in case of perforation of the ventricular wall. A scalpel blade is then used to nick the skin over the needle, the needle is withdrawn, and a 6F dilator is used to broaden the tract into the pericardium. Finally, the dilator is removed and a 6F to 8F pigtail angiocatheter with side holes is threaded over the wire well into the pericardial space, ensuring at all times that the end of the wire is controlled. The wire is removed, and catheter placement can again be confirmed with agitated saline injection if needed. With a three-way stopcock, fluid for laboratory analysis should be collected with a large syringe upon initial drainage; the catheter is then attached to a 30-cm length of plastic tubing, which in turn may be connected to a vacuum bottle or drainage bag. If the catheter is being left to drain for some time, it should be sutured in place. Occasionally, very bloody fluid may be aspirated during pericardiocentesis, and confirmation of the needle placement may be difficult. Therefore, differentiating between blood (chamber perforation) and bloody effusion can be challenging. A few milliliters of the aspirate can be placed on a gauze pad; classical teaching suggests that if the fluid coagulates, it is blood from chamber perforation. Conversely, fluid that spreads out on the gauze forming a pinkish halo suggests an intrapericardial origin. In reality, effusions caused by cardiac rupture, dissection, or ongoing bleeding into the pericardial space may clot upon aspiration; this fluid should be sent for hematocrit (to confirm that it is blood), and cardiothoracic surgery consultation should take place emergently. This approach may be used if echocardiography is unavailable or it may be used in conjunction with echocardiography. However, most experts agree that electrocardiographic guidance adds little to the safety of a carefully performed echocardiographically guided procedure. The xiphoid process is identified, and a point just inferior and to one side of the process is marked. The region is prepared and draped sterilely, and local anesthetic is given around the mark with a 25G needle. The needle should be directed posteriorly at approximately 90° to the patient until the tip is below the costal margin. Then the hub of the needle should be depressed toward the patient’s skin and advanced toward the left shoulder at an angle of 15° to 30° to the patient. Local anesthetic is injected as needed, and gentle suction should be applied to the syringe when advancing. In the average adult, the distance from skin to pericardium is approximately 6 to 8 cm (1). Fluoroscopy was previously the most common method used as to guide pericardiocentesis, but this approach has largely been supplanted by echocardiography. For this approach, either a polytef-sheathed needle with an attached saline-filled syringe or a Tuohy-17, blunt-tip introducer needle can be used. The needle is directed to the left shoulder and toward the anterior diaphragmatic border of the right ventricle, at about 30° angle to the skin. The purpose is to avoid the coronary, pericardial, and internal mammary arteries with this direction and angulation. Upon penetration into the pericardial space, needle position may be confirmed with injection of radiopaque contrast media. The left lateral with a slight left anterior angiographic view, or an anteroposterior view, provides the best visualization of the puncturing needle in relation to the diaphragm and the pericardium. As the needle is advanced, the operator should perform moderate suction, and once fluid is obtained, it is advised to inject very small amounts of contrast until the pericardial silhouette is demarcated on the fluoroscope, a phenomenon known as the “halo sign. The soft J-tip wire may be confirmed to be in the pericardium by identifying how it crosses from the right to the left chambers, because a wire in the right ventricle would not cross to the left side unless a ventricular septal defect is present. A subxiphoid approach is used as described above, aiming the needle toward the left shoulder. However, because of the significantly higher rates of complications and because of the increased availability of bedside ultrasound, blind taps should be avoided unless absolutely necessary. If the cause of the pericardial effusion is not clear, the fluid should be sent for analysis. Therefore, all fluid from idiopathic effusions should be sent for bacterial, mycobacterial, and viral cultures; cytologic examination; acid-fast bacillus smear; cell count; protein; glucose; and lactate dehydrogenase. Blood samples should be sent for chemistry, complete blood count, blood cultures (if bacterial infection is likely), thyroid-stimulating hormone, erythrocyte sedimentation rate/C- reactive protein, antinuclear antibody, and rheumatoid factor (if connective tissue disease is suspected). Consideration should also be given to conducting a tuberculin purified protein derivative skin test. Blind pericardiocentesis has been associated with morbidity rates as high as 20% and mortality rates as high as 6%. Therefore, complications are relatively rare in experienced centers, although one must be mindful of the following: A. If the parasternal approach is used, remaining close to the sternum decreases the risk of pneumothorax. This is usually asymptomatic and self-sealing, particularly if the left ventricle is entered. Right ventricular perforations have a somewhat higher likelihood of bleeding when perforated, but right atrial lacerations carry the highest risk. If laceration is suspected, the needle or catheter should be withdrawn and the patient should be observed overnight in an intensive care setting. The left internal thoracic/mammary artery runs down the chest wall about 1 to 2 cm lateral to the sternum, with the vein running slightly more medial. Left chest wall and subxiphoid approaches must take this anatomy into consideration. The posterior descending artery may be lacerated on subxiphoid approaches if the needle is aimed too medially. On a chest wall approach, the intercostal arteries and nerves are avoided by passing the catheter just superior to the rib. Sterile technique during the procedure and meticulous catheter care afterward if a drain is left in place minimize this risk. As the Mayo series suggests, the risk of catheter-related infection is very low, even among cancer patients. This is exceptionally rare when procedures are performed by experienced operators with echocardiographic guidance. A postprocedure chest film should be obtained in all patients to exclude pneumothorax. Patients without significant comorbidities who have uncomplicated diagnostic taps do not require inpatient care following the procedure. Care of an indwelling pericardial catheter is similar to that for any central line. After the catheter is sutured in place, the site is treated with an antibacterial ointment and then dressed sterilely. Continuous drainage can also be used, but the risk of catheter obstruction is higher. If the fluid becomes purulent or the patient becomes septic, the catheter must be removed. The catheter is typically left in place for 1 to 2 days, but extended drainage has been associated with lower rates of effusion recurrence. Before pulling the drain, an echocardiogram should be obtained to ensure resolution of the effusion. Sometimes, when the drainage volume is minimal, it may be useful to clamp the catheter for few hours and observe the patient for clinical signs of tamponade. Alternatively, an echocardiogram can also be performed in order to assess for reaccumulation once the drain is clamped. Consecutive 1127 therapeutic echocardiographically guided pericardiocenteses: clinical profile, practice patterns, and outcomes spanning 21 years. Safety, efficacy, and complications of pericardiocentesis by real-time echo-monitored procedure. Pericardial effusion after cardiac surgery: risk factors, patient profiles, and contemporary management. Systematic review of percutaneous interventions for malignant pericardial effusion. Choosing Among Antibiotics Within a Class: Beta-lactams and Beta-lactamase Inhibitors, Macrolides, Aminoglycosides, and Fluoroquinolones 1 Gram-negative organisms as one goes from the frst-generation cephalosporins (cepha- lexin and cefadroxil), to the second generation (cefaclor, cefprozil, and cefuroxime) that demonstrates activity against Haemophilus infuenzae (including beta-lactamase– producing strains), to the third-generation agents (cefdinir, cefxime, cefpodoxime, and cefibuten) that have enhanced coverage of many enteric Gram-negative bacilli (Escherichia coli, Klebsiella spp). The palatability of generic versions of these products may not have the same better-tasting characteristics as the original products. A second-generation cephalosporin (cefuroxime) and the cephamycins (cefoxitin and cefotetan) provide increased activity against many Gram-negative organisms, particularly Haemophilus and E coli. Cefoxitin has, in addition, activity against approximately 80% of strains of Bacteroides fragilis and can be considered for use in place of the more active agents, like metronidazole or carbapenems, when that organism is implicated in nonseri- ous disease. Tird-generation cephalosporins (cefotaxime, cefriaxone, and cefazidime) all have enhanced potency against many enteric Gram-negative bacilli. As with all cephalosporins, at readily achievable serum concentrations, they are less active against enterococci and Listeria; only cefazidime has signifcant activity against Pseudomonas. Cefotaxime and cefriaxone have been used very successfully to treat meningitis caused by pneumococ- cus (mostly penicillin-susceptible strains), H infuenzae type b, meningococcus, and susceptible strains of E coli meningitis. Tese drugs have the greatest usefulness for treat- ing Gram-negative bacillary infections due to their safety, compared with other classes of antibiotics (including aminoglycosides). Because cefriaxone is excreted, to a large extent, via the liver, it can be used with little dosage adjustment in patients with renal failure. With a serum half-life of 4 to 7 hours, it can be given once a day for all infections, includ- ing meningitis, that are caused by susceptible organisms. Cefepime, a fourth-generation cephalosporin approved for use in children in 1999, exhibits (1) enhanced antipseudomonal activity over cefazidime; (2) the Gram-positive activity of second-generation cephalosporins; (3) better activity against Gram-negative enteric bacilli; and (4) stability against the inducible ampC beta-lactamases of Entero- bacter and Serratia (and some strains of Proteus and Citrobacter) that can hydrolyze third-generation cephalosporins. It can be used as single-drug antibiotic therapy against 2019 Nelson’s Pediatric Antimicrobial Therapy — 3 these pathogens, rather than paired with an aminoglycoside, as is commonly done with 1 third-generation cephalosporins to decrease the emergence of ampC-resistant clones. The pharmacokinetics of cef- taroline have been evaluated in all pediatric age groups, including neonates and children with cystic fbrosis; clinical studies for pediatric community-acquired pneumonia and complicated skin infection have now been published. Neither renal function nor drug levels need to be followed with cefaroline therapy. Penicillinase-Resistant Penicillins (dicloxacillin [capsules only]; nafcillin and oxacillin [parenteral only]). Nafcillin difers pharmacologically from the others in being excreted primarily by the liver rather than by the kidneys, which may explain the relative lack of nephrotoxicity compared with methicillin, which is no longer available in the United States. The combinations extend the spectrum of activity of the primary antibiotic to include many beta-lactamase–positive bacteria, including some strains of enteric Gram-negative bacilli (E coli, Klebsiella, and Entero- bacter), S aureus, and B fragilis.
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