By L. Narkam. College of William and Mary.
Indications include flank pain buy himcolin 30 gm with mastercard, kidney stones buy himcolin 30gm cheap, hematuria discount himcolin 30 gm without a prescription, UTI purchase himcolin 30 gm on line, trauma order himcolin 30gm on line, and malignancy. Nephrotomograms often included that include cuts of the kidney to further define the three-dimensional location or nature of renal lesions or stones Lymphangiography. Iodinated oil injected to opacify lymphatics of the leg, inguinal, pelvic, and retroperitoneal areas. Used to test the integrity of the lymphatic system or evalu- ate for metastatic tumors (testicular, etc) or lymphoma 15 Imaging Studies 329 Myelogram: Evaluating the subarachnoid space for tumors, herniated disks, or other cause of nerve root injury. Using LP technique, contrast injected in the subarachnoid space OCG: Visualizing gallbladder in the evaluation of cholelithiasis or cholecystitis. Used infrequently PTHC: Visualizing biliary tree in a patient unable to concentrate the contrast media (bilirubin >3 mg/100 mL). Percutaneous Nephrostogram: In the management of renal obstruction, percuta- neous placement through the renal parenchyma and into the collecting system to relieve and or evaluate the level and cause of obstruction RPG: Contrast material injected into the ureters through a cystoscope. Indications in- clude allergy to IV contrast, a kidney or ureter that cannot be visualized on an IVP, filling defects in the collecting system, renal mass, and ureteral obstruction RUG: Demonstrates traumatic disruption of the urethra and urethral strictures SBFT: Usually done after a UGI series. Used in the work-up of diarrhea, abdominal cramps, malabsorption, and UGI bleeding T-Tube Cholangiogram: Resolution of swelling in some patients who have a T-tube placed in the common bile duct for drainage after gallbladder and common bile duct surgery. To evaluate the degree of swelling, look for residual stones, and evaluate patency of bile duct drainage UGI Series: Includes the esophagogram plus the stomach and duodenum. Useful for vi- sualizing ulcers, masses, hiatal hernias, and in the evaluation of heme-positive stools and upper abdominal pain VCUG: Bladder filled with contrast through a catheter, then catheter is removed, and the 15 patient allowed to void. Used for diagnosis of vesicoureteral reflux and urethral valves and in the evaluation of UTI Venography, Peripheral: Contrast slowly injected into small foot or ankle vein to evaluate patency of deep veins of leg and calf. Noninvasive exams for DVT, such as Doppler ultrasound and impedance plethys- mography, often used together before invasive venography and are highly sensitive (>90%) for proximal thrombi. A radionuclide scan with technetium-99-labeled RBCs sometimes used but is less sensitive and specific than the previously mentioned tests. Fetal dating (biparietal diameters); diagnosis of multiple gestations; de- termination of intrauterine growth retardation, hydrocephalus, and hydronephrosis; localization of the placenta • Gynecology. Transrectal: Most useful in the diagnosis of prostate pathology and directing prostate biopsies Echocardiograms • M-mode. Valve mobility, chamber size, pericardial effusions, septal size • Two-dimensional. Valvular vegetations, septal defects, wall motion, chamber size, pericardial effusion, valve motion, wall thickness • Doppler. Cross-valvular pressure gradients, blood flow patterns, and valve orifice areas in the work-up of cardiac valvular disease Other Ultrasound Uses Testicular (identify and characterize masses, eg, hydrocele versus tumor), intraoperative, de- termine bladder emptying CT SCANS Computerized tomography (also called CAT for computerized axial tomography) can be performed with or without intravenous contrast. A dilute oral contrast agent administered prior to abdominal or pelvic scans helps delineate the bowel. IV contrast is used to provide vascular and tissue enhancement for some CT scans; a current creatinine level should be available to determine suitability of IV contrast administration. Virtually any body part can be scanned depending on the indications, but it is most helpful in evaluating the brain, lung, mediastinum, retroperitoneum (pancreas, kidney, nodes, aorta), and liver, and to a lesser ex- 15 tent in the pelvis, colon, or bone. CT scans allow for the use of density measurements (also known as Hounsfield units) to differentiate cysts, lipomas, hemochromatosis, vascular (“enhancing”) and avascular (“nonenhancing”) lesions. In Hounsfield units, bone is +1000, water is 0, fat is −1000, and other tissues fall within this scale, depending on the machine settings. Head: Evaluation of tumors, subdural and epidural hematomas, atrioventricular (A-V) malformations, hydrocephalus, and sinus and temporal bone pathology. Initial test of choice for trauma; may be superior to MRI in detecting hemorrhage within first 24–48 h Abdomen: Images virtually all intraabdominal and retroperitoneal organs or disease processes. Good accuracy with abscesses, but ultrasound may show smaller collections ad- jacent to the liver, spleen, or bladder. IV contrast usually given, so check creatinine level; when using a water-soluble contrast (Tomocat, others) to visualize the gut, the patient must receive an oral contrast beforehand. Retroperitoneum: Useful for evaluating pancreatitis and its complications; pancreatic masses; nodal metastasis from colon, prostate, renal, or testicular tumors; adrenal masses (>3 cm suggestive of carcinoma); psoas masses; aortic aneurysms 15 Imaging Studies 331 Pelvis: Staging and diagnosis of bladder, prostate, rectal, and gynecological carcinoma Mediastinum: Masses, ectopic parathyroids Neck: Work-up of neck masses, abscesses, and other diseases of the throat and trachea Chest: Able to find 40% more nodules than whole lung tomograms, which demonstrate 20% more nodules than plain chest x-ray. Although calcification is suggestive of benign dis- ease (eg, granuloma), no definite density value can reliably separate malignant from benign lesions. Useful in differentiating hilar adenopathy from vascular structures seen on plain chest x-ray Spine: MRI generally preferred over CT. However, rare conditions, contraindication to MRI, or artifact from metal may make the CT the preferred test. SPIRAL (HELICAL) CT SCAN Spiral CT can be used for any type of imaging (not commonly used for brain).
Figure 15-1 shows trients and oxygen to all the tissues and carry waste ma- the vessels in these two circuits; the anatomic relation of terials away from the tissues for disposal himcolin 30gm free shipping. The pulmonary vessels that ◗ The systemic capillaries himcolin 30gm without prescription, through which materials are carry blood to and from the lungs include the following: exchanged ◗ The systemic veins order himcolin 30 gm with amex, which carry blood back toward the ◗ The pulmonary artery and its branches purchase 30 gm himcolin with amex, which carry heart purchase 30gm himcolin with visa. The venous blood flows into the right atrium of blood from the right ventricle to the lungs the heart through the superior vena cava and inferior ◗ The capillaries in the lungs, through which gases are vena cava. BLOOD VESSELS AND BLOOD CIRCULATION ✦ 309 Vessel Structure The vessels become narrower (constrict) when the mus- cle contracts and widen (dilate) when the muscle relaxes. The arteries have thick walls because they must be In this manner, the arterioles regulate the amount of strong enough to receive blood pumped under pressure blood that enters the various tissues at a given time. The three tunics Change in the diameter of the arterioles is also a major (coats) of the arteries resemble the three tissue layers of factor in blood pressure control. The capillary walls are transparent and are cells makes up the endothelium (en-do-THE-le-um), made of smooth, squamous epithelial cells that are a con- forming a smooth surface over which the blood flows tinuation of the lining of the arteries. Elastic tissue between the layers of the arterial wall al- The smallest veins, the venules, are formed by the lows these vessels to stretch when receiving blood and union of capillaries, and their walls are only slightly then return to their original size. A vein wall is much 15 Artery Vein Elastic tissue Inner tunic (endothelium) Middle tunic (smooth muscle) Outer tunic (connective tissue) Blood flow Valve Arteriole Venule Capillary Figure 15-2 Sections of small blood vessels. In the digestive tract, fenestrated capillaries permit found in muscle, connective tissue, the lungs, and the central rapid absorption of water and nutrients into the bloodstream. In addition to fenestrations, they have large spaces be- ies are the least permeable, water and small molecules can dif- tween endothelial cells that allow the exchange of water, large fuse easily through their walls. Albumin, clotting factors, and other proteins formed in tightly together, making the capillaries impermeable to many the liver enter the bloodstream through sinusoids. As uous artery, but it may be divided into sections: a result, the blood within the veins is carried under much ◗ The ascending aorta is near the heart and inside the lower pressure. Only slight pressure on a vein by a ◗ The aortic arch curves from the right to the left and tumor or other mass may interfere with return blood also extends posteriorly. BLOOD VESSELS AND BLOOD CIRCULATION ✦ 311 The arch of the aorta, located im- Right common Left common mediately beyond the ascending aorta, carotid artery carotid artery divides into three large branches. Right subclavian Left subclavian ◗ The brachiocephalic (brak-e-o-seh- artery artery FAL-ik) artery is a short vessel that Brachiocephalic supplies the arm and the head on the artery right side. After extending upward Aortic arch Ascending aorta somewhat less than 5 cm (2 inches), it divides into the right subclavian Coronary (sub-KLA-ve-an) artery, which ex- arteries Thoracic aorta tends under the right clavicle (collar bone) and supplies the right upper Celiac trunk to: Intercostal extremity (arm), and the right com- Left gastric artery arteries mon carotid (kah-ROT-id) artery, Splenic artery which supplies the right side of the Hepatic artery neck, head and brain. Branches of the Thoracic Aorta 15 The thoracic aorta supplies branches to the chest wall, esophagus (e-SOF-ah- gus), and bronchi (the subdivisions of the trachea), and their treelike subdivi- Common sions in the lungs. There are usually 9 iliac to 10 pairs of intercostal (in-ter-KOS- External iliac artery tal) arteries that extend between the artery ribs, sending branches to the muscles Testicular Internal iliac artery and other structures of the chest wall. Arch The first, or ascending, part of the aorta has two ◗ The superior mesenteric (mes-en-TER-ik) artery, the branches near the heart, called the left and right coronary largest of these branches, carries blood to most of the arteries, which supply the heart muscle. Subdivisions The paired lateral branches of the abdominal aorta in- The abdominal aorta finally divides into two common clude the following right and left vessels: iliac (IL-e-ak) arteries. This vessel gives rise to ◗ Four pairs of lumbar (LUM-bar) arteries extend into branches in the thigh and then becomes the popliteal the musculature of the abdominal wall. The subdivisions include the posterior and anterior tibial Checkpoint 15-5 What are the subdivisions of the aorta, the arteries and the dorsalis pedis (dor-SA-lis PE-dis), which largest artery? BLOOD VESSELS AND BLOOD CIRCULATION ✦ 313 Arteries That Branch to the Arm carotid arteries and from the basilar (BAS-il-ar) artery, which is formed by the union of the two vertebral ar- and Head teries. This arterial circle lies just under the center of Each common carotid artery travels along the trachea en- the brain and sends branches to the cerebrum and other closed in a sheath with the internal jugular vein and the parts of the brain. Just anterior to the angle of the mandible ◗ The superficial palmar arch is formed by the union of (lower jaw) it branches into the external and internal the radial and ulnar arteries in the hand. In this type of shunt, a small vessel known as a the transverse processes of the first six cervical vertebrae metarteriole or thoroughfare channel, connects the arterial and supplies blood to the posterior portion of the brain. It first be- rapid flow and a greater blood volume to these areas, thus comes the axillary (AK-sil-ar-e) artery in the axilla protecting these exposed parts from freezing in cold (armpit). The brachial artery subdivides Cerebrum (frontal lobe) into two branches near the elbow: the radial artery, which continues down Cerebrum 15 the thumb side of the forearm and (temporal lobe) Arteries of the circle of Willis: wrist, and the ulnar artery, which ex- Anterior communicating tends along the medial or little finger Anterior cerebral side into the hand. Middle cerebral Just as the larger branches of a tree divide into limbs of varying sizes, so Internal carotid the arterial tree has a multitude of sub- Posterior communicating divisions. Examples of these include the femoral Artery and the external and internal iliac ves- Precapillary sels of the lower part of the body, and sphincter the brachial, axillary, and subclavian vessels of the upper extremities. The two jugular Capillary (JUG-u-lar) veins on each side of the neck drain the areas supplied by the carotid arteries (jugular is from a Latin word meaning “neck”). The larger of the two veins, the internal jugular, re- Thoroughfare channel ceives blood from the large veins (cra- (metarteriole) nial venous sinuses) that drain the head and also from regions of the face and neck.
A marker for mitosis could indicate when the SAH insult has led to the initial changes responsible for vessel necrosis and thickening discount 30 gm himcolin with visa. One hypothesis is that smooth muscle cell turnover begins rapidly after the SAH insult generic himcolin 30gm otc, and reaches a peak after 5 to 7 days discount himcolin 30gm with mastercard. The vessel thickening would then correspond to a combination of vessel necrosis of smooth muscle cells in the media and mitosis and hypertrophy of an underlying population of cells cheap himcolin 30 gm with visa, which would lead to smooth muscle renewal and proliferation cheap himcolin 30 gm fast delivery. The smooth muscle cell proliferation would presumably then proceed over days to a few weeks, leading to a repopulation of the media and resumption of normal vessel reactivity and caliber. Thus, the time course of DCV is presumably delayed due to the slow onset of smooth muscle necrosis over several days. This, together with the combination of mitotic activity and hypertrophy of remaining cells, markedly increases the width of the media, leading to shrinkage of the vessel lumen. The 5-day period may be an unfortunate superimposition of these two processes of necrosis with associated cell swelling and the secondary hypertrophy and mitotic activity of smooth muscle cell turnover. This time period is compounded by the slow lysis of blood products by CSF and a correspondingly slow resumption of adequate vessel nutrition, pre- sumably as CSF adventitial pores are reopened or reconstituted. Cerebral vessels may show luminal narrowing for reasons other than media thickening and direct changes in smooth muscle cells. For example, there may be an infiltrative component suggestive of inflammation within the vessel wall in response to the SAH that may be separately treatable. The possible role of inflam- mation in vasospasm should be the focus of a search to determine the exact cellular content (other than smooth muscle precursor cells and mature or dying smooth muscle cells) within the thickened media. If inflammatory cells are specifically identified as significant components of thickened vessel walls, new therapeutic options for vasospasm may be developed in the future. The most probable explanation for the correlation of thickness of SAH on CT scans with the risk of DCV is that blood deposition adjacent to the vessel induces vascular wall necrosis by interfering with vessel nutrition and releasing spasmogens such as oxyhemoglobin. Theoretically, enhancing blood lysis in the CSF early after SAH © 2005 by CRC Press LLC could lead to decreased risk of and faster recovery from DCV (but promote rebleeding if early aneurysm clipping is not performed). This approach is advocated by those attempting to treat vasospasm with infusion of urokinase or tissue plasmi- nogen activator (tPA) into the subarachnoid space after SAH. Several trials have demonstrated the potential benefits of intracisternal urokinase or tPA infusion after SAH in the reduction of DCV. Although the benefits of tPA could potentially reach statistical significance in a larger trial, the results of this trial have dampened enthusiasm for fibrinolytic agents in SAH patients. Cerebral blood vessels are composed primarily of smooth muscle cells (long, taper- ing, single nuclei cells with thick-to-thin filaments aligned with the long axis) within the media. Smooth muscle contraction is involuntarily triggered by the autonomic system or by hormones, and is designed for slow, long-lasting contraction. Smooth muscle cells are specifically designed to maintain tension for prolonged periods (passive maintenance) while hydrolyzing five- to tenfold less ATP than skeletal muscle cells performing the same task. The actin in smooth muscle cells has a different amino acid sequence than that of cardiac or skeletal muscle cells, but there appears to be no known functional significance. Smooth muscle myosin resembles skeletal myosin; functionally, the level of ATPase activity is tenfold lower, which allows more direct calcium regulation of contraction. Also, smooth muscle myosin can interact with actin filaments and cause contraction only when its light chains are phosphorylated. Specific enzymes accomplish this calcium-dependent phosphorylation and dephosphoryla- tion of the myosin light chain. Arteries have thick walls of connective tissue and vascular smooth muscle cells (VSMCs) lined by monolayers of endothelial cells. The endothelial cells are sepa- rated from the smooth muscle cells by a basal lamina and then the elastic fibers of the internal elastic lamina. Hypertrophy occurs by adding cytoplasmic elements, but is reversible because the cells enlarge without changes in DNA. Unlike skeletal and cardiac muscle, smooth muscle can divide and may recruit undifferen- tiated cells (pericytes) to become smooth muscle cells. When stimulated by any of these growth factors at appropriate concentrations, VSMCs can begin execution of the mitosis program within hours. For vascular smooth muscle cells, PDGF-BB precipitates the greatest degree of growth, with PDGF-AA stimulating small but significant growth, and PDGF-AB causing an intermediate amount of growth. TNF receptor activation is known to induce SMC apoptosis more in rapidly proliferating neointimal cells than in more slowly replicating medial cells.
The following are key concepts in determining nitrogen balance: • Nitrogen balance = Nitrogen input – Nitrogen output order himcolin 30 gm line. Fecal nitrogen measure- 12 ments can be obtained but are difficult for nursing staff to perform buy generic himcolin 30 gm. Sample Determination of Nitrogen Balance A patient is receiving 2 L TPN/24 h with 27 order himcolin 30 gm online. TPN SOLUTIONS Different strength CAA solutions are available (Table 12–1) to which the pharmacy can add varying concentrations of dextrose cheap himcolin 30gm with amex, electrolytes discount himcolin 30 gm line, vitamins, and trace elements. Most hospi- tals supply a “house,” or standard, formula for patients with normal renal and hepatic func- tion. Changes in the standard formulas can be made when necessary while a TPN solution is being infused based on measured laboratory parameters. Administration of TPN is never an emergency and in most cases can be provided within 24 h of prescribing. If a formula change is necessary based on a change in patient status, discontinue the TPN and replace it with D10W at the same rate until a new bag of TPN can be provided. These are diluted by the pharmacy to varying concentrations to provide for the necessary protein dose (2. Fat emulsions should be given with solution 1 to provide essential fatty acids (10%, 500 mL 3×/wk) or as an additional calorie source. Solu- tion 2 is designed to be given at a maximum rate of 125 mL/h, but this only provides 1275 Cal from dextrose and must be supplemented with a fat emulsion (10% 500 mL = 550 Cal, 20% 500 mL = 1000 Cal). Many hospitals have adopted a “three-in-one” solution for the standard house formula. This involves the administration of protein, carbohydrate, and fat from the same TPN bag over a 24-h period; in other words, the fat is not administered peripherally through a sepa- rate site. Caution should be used when altering the standard formula in this situation be- cause the fat emulsion may be less stable to additives and makes incompatibilities less visible. For example, the solution will be milky in color, and a calcium–phosphate problem, normally easily seen, would not be apparent. Additions to these formulations should be done in conjunction with a pharmacist to ensure that precautions are taken for appropriate addi- tive concentrations. Remember, the solutions described in Table 12–1 contain full concentrations of elec- trolytes and are for patients with normal renal function. For patients with renal impairment, the concentrations of potassium, magnesium, phosphorus, and protein should be reduced (see page 235). PERIPHERAL PARENTERAL NUTRITION If a deep line is contraindicated or impossible, a peripheral TPN solution (<7% dextrose with 2. A posi- 12 Total Parenteral Nutrition 231 tive nitrogen balance will not be achieved in most patients receiving parenteral nutrition by this route. A product conforming to recommen- dations of the American Medical Association Nutrition Advisory Group is usually used, such as multivitamin infusion-12 (MVI-12). In addition to MVI-12, 5–10 mg of vitamin K (phytonadione) must be given IM weekly. Trace element deficiencies are rare in hospitalized patients receiving short-term TPN supplements. Supplementation should be routine, however, to ensure trace element avail- ability for cell restoration. In patients receiving long-term support or home TPN, additional trace element supplementation may be necessary. Note, however, that owing to the inconvenience of its administration, many clinicians avoid in- jectable iron–dextran. A complete medical and hematologic work-up is often indicated be- fore instituting parenteral iron replacement. Anaphylaxis is rare, but a period of 1h should elapse before the therapeutic dose of iron is administered. Use the following equation to determine the dose of iron: Total replacement dose (mL) = 0. The calculated dose should be added to TPN at 2 mL/L until the entire dose has been given. TABLE 12–2 Typical Vitamins Provided in 1 L of TPN by Adding 2 Vials of Standard MVI–12 Ascorbic acid 100 mg Pyridoxine (B6) 4 mg Vitamin A 3300 IU Dexpanthenol 15 mg Vitamin D 200 IU Vitamin E (α tocopherol) 10 IU Biotin 60 µg Thiamine (B1) 3 mg Folic acid 400 µg Riboflavin (B2) 3. Insulin, when required, can be given subcutaneously as regular insulin using a sliding scale, as shown in Table 12–4. This allows a constant infusion of insulin along with the infusion of dex- trose, which avoids the peaks and valleys in blood glucose that occur when the sliding scale is used.
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