By Q. Rathgar. Alliant International University. 2019.
Invasive Procedures—Laparoscopic guided biopsy improves the yield by allowing biopsies to be taken in areas where abnormalities in the external capsule are seen; however buy cheap propecia 1mg online hair loss in men xy, this surgical procedure is rarely used buy propecia 5 mg with visa hair loss 9 year old. Bone marrow biopsy is also recommended as a routine invasive test if all noninvasive studies are negative and has a yield of nearly 25% discount propecia 5 mg fast delivery hair loss black book. Hematologic malignancies are most commonly identified, particularly malignant lymphoma and less commonly acute leukemia. Infectious diseases can also be identified, and the bone marrow should be cultured (see the earlier subsection titled “Cultures”), because disseminated tuberculosis, histoplasmosis, coccidiomycosis, and other fungal and mycobacterial infections often seed the bone marrow. Use of other invasive procedures will depend on the diagnostic findings, history, and physical findings to that point. It should be kept in mind that, because skip lesions are common in temporal arteritis, a long sample of the temporal artery should be obtained and multiple arterial sections examined. In addition to a complete series of cultures, all biopsy specimens should undergo Brown–Brenn, Ziehl–Neelsen, methenamine silver, periodic acid Schiff, and Dieterle silver staining in addition to routine hematoxylin and eosin. Frozen sections should be obtained for immunofluorescence staining, and the remaining tissue block should be saved for additional future studies. It should be emphasized that, when symptoms, signs, or a specific diagnostic abnormality is found, all other scheduled diagnostic tests should be delayed and Sutton’s law applied. Clinicians need to apply Baye’s theorem and predict the pretest and posttest probability of the particular disease. When ordering a test, the clinician needs to ask, “If this test is positive or negative how will it change how I manage my patient? When in doubt about performing additional tests, the wisest course of action is to wait. Over time, the patient’s fever may spontaneously resolve or new manifestations may develop, helping to identify the cause. Fever is commonly associated with chills, sweating, fatigue, and loss of appetite. Otherwise, these antipyretics will exacerbate rather than reduce the symptoms of fever. In cases of occult bacterial infection, empiric antibiotics may mask the manifestations of the infection and delay appropriate treatment. In the absence of a specific diagnosis, clinicians have difficulty justifying a prolonged course of antibiotics, and therefore antibiotics are often discontinued after 1-2 weeks, allowing the infection to relapse. These agents are very effective in treating temporal arteritis and polymyalgia rheumatica, they may be helpful in Still’s disease, and they are used to treat specific complications in lupus erythematosus. However, because these agents markedly reduce inflammation and impair host defense, administration of glucocorticoids can markedly exacerbate bacterial, mycobacterial, fungal, and parasitic infections. Therefore, before considering an empiric trial of glucocorticoids such as prednisone, dexamethasone, or methylprednisone, infection must be convincingly ruled out. However, if these diseases are carefully excluded, lack of a diagnosis after an extensive workup is associated with a 5-year mortality of only 3%. The prognosis is somewhat worse in elderly patients because of their increased risk of malignancy. If fever persists for an additional 4-6 months, a complete series of diagnostic studies may then be repeated. Disseminated histoplasmosis may be difficult to detect and, in our experience, is most readily diagnosed by bone marrow culture. A prospective multicenter study on fever of unknown origin: the yield of a structured diagnostic protocol. Yield of bone marrow examination in diagnosing the source of fever of unknown origin. From prolonged febrile illness to fever of unknown origin: the challenge continues. What are the symptoms, signs, and diagnostic tests that help to differentiate viral from bacterial pneumonia? How useful is sputum Gram stain, and what are the parameters that are used to assess the adequacy of a sputum sample? How should the clinician interpret the sputum culture, and should sputum cultures be obtained in the absence of sputum Gram stain? What are some of the difficulties encountered in trying to determine the cause of acute pneumonia? How often should chest X-ray be repeated, and how long do the radiologic changes associated with acute pneumonia persist? Which antibiotic regimens are recommended for empiric therapy of community-acquired pneumonia and why? Estimates suggest that pneumonia is responsible for more than 10 million physician visits, 500,000 hospitalizations, and 45,000 deaths annually. Overall, 258 people per 100,000 population require hospitalization for pneumonia, and that number rises to 962 per 100,000 among or nearly 1/100 for those over the age of 65 years. It is estimated that, annually, 1 in 50 people over 65 years of age and 1 in 20 over 85 years will develop a pneumonia. Causes Improved diagnostic techniques have shown that the number of pathogens that cause acute pneumonia is ever expanding (Table 4. Mycoplasma and Chlamydophila pneumoniae also account for a significant percentage of acute pneumonias. Legionella species vary in importance, depending on the season and geographic area. Anaerobes such as anaerobic streptococci and bacteroides can cause acute pneumonia following aspiration of mouth contents. Common viral pathogens include influenza, parainfluenza, and respiratory syncytial virus. Pathogenesis and Pathology Under normal conditions, the tracheobronchial tree is sterile. The respiratory tract has a series of protective mechanisms that prevent pathogens from gaining entry [ure 4. The epiglottis covers the trachea and prevents secretions or food from entering the trachea. Mucin contains a number of antibacterial compounds including immunoglobulin A antibodies, defensins, lysozymes, and lactoferrin. Mucin also is sticky, and it traps bacteria or other foreign particles that manage to pass the epiglottis. Cilia lining the inner walls of the trachea and bronchi beat rapidly, acting as a conveyer belt to move mucin out of the tracheobronchial tree to the larynx. When significant volumes of fluid or large particles gain access to the trachea, the cough reflex is activated, and the unwanted contents are quickly forced out of the tracheobronchial tree.
Cardiac output begins to rise during the first trimester and peaks around the 20th week of gestation at 30% to 45% above resting purchase line propecia hair loss 4 months after surgery, nonpregnant levels purchase propecia master card hair loss on one side of head. Thus purchase propecia 1mg with amex hair loss 5 month post partum, measured cardiac output during gestation that is in the normal range for a nonpregnant patient would represent significant hemodynamic compromise for the pregnant patient and, potentially, decreased oxygen delivery for the fetus. In the supine position, cardiac output can be reduced by 25% to 30% because of compression of the inferior vena cava by the gravid uterus and a resultant decrease in venous return. Estimates of expected cardiac output during gestation should be revised upward for intercurrent stresses, such as fever, infection, and pain. Heart rate increases progressively throughout gestation, reaching a 20% increase over nonpregnant levels of approximately 15 beats per minute. Left ventricular compliance must increase in pregnancy because the increased stroke volume appears to be related more to left ventricular enlargement than to increased emptying. The cardiac silhouette on chest radiography may appear enlarged as a result of mild normal left ventricular enlargement and lateral and upward displacement by the gravid uterus. Further increases of cardiac output occur during labor; cardiac output increases up to 45% over third-trimester values, and, during uterine contraction, cardiac output transiently increases another 10% to 15% because of increased venous return from the contracting uterus. In the first few minutes postpartum, cardiac output may increase as much as 80% over prelabor levels, then decrease to 40% to 50% over prelabor values by 1 hour postpartum, and finally return to nearly prepregnant levels by 1 to 2 weeks postpartum. On the other hand, afterload may increase sharply during labor contractions because of inhibition of blood flow to the contracting uterine muscle. Because uterine blood flow at term accounts for a significant proportion of the cardiac output, marked increases in afterload can occur during contractions and immediately postpartum. These changes in afterload may be important in patients who are sensitive to afterload, such as patients with underlying cardiac disease. Systemic vascular resistance is generally reduced during pregnancy because of vasodilatation and the low resistance of the uteroplacental vascular circuit. Pressures in the right ventricle, pulmonary artery, and pulmonary capillaries are no different from nonpregnant values. During pregnancy, there is expansion of the extracellular fluid volume, with the plasma fluid volume increasing more than the interstitial volume. However, the plasma volume increases more than the erythrocyte volume, resulting in the physiologic anemia of pregnancy. Colloid osmotic pressure measurements during gestation reveal a mean decrease of 5 mm Hg, which reaches a plateau at 26 weeks. A further decline in colloid osmotic pressure of roughly 4 mm Hg occurs immediately postpartum, probably as a result of a combination of factors, such as recumbency, crystalloid administration, and blood loss. Neither the absolute value of colloid osmotic pressure nor the colloid osmotic pressure–pulmonary capillary wedge pressure gradient is an accurate predictor of pulmonary edema because of the multiplicity of contributing variables. However, these trends of colloid osmotic pressure should be considered when interpreting pulmonary capillary wedge pressures, especially for patients who have received large amounts of crystalloid. The major determinants of oxygen delivery to the placenta are the oxygen content of uterine artery blood, which is determined by maternal PaO ; hemoglobin concentration2 and saturation; and uterine artery blood flow, which depends on maternal cardiac output. Thus, a decreased PaO can be offset somewhat2 by increased blood hemoglobin concentration or by increased cardiac output. The combination of maternal hypoxemia and decreased cardiac output likely has a profoundly deleterious effect on fetal oxygenation. Alkalosis causes vasoconstriction of the uterine artery, resulting in decreased fetal oxygen delivery. This effect is magnified by a leftward shift in the maternal oxyhemoglobin saturation curve, which increases oxygen affinity and, consequently, decreases oxygen transfer to the umbilical vein. Although mild maternal acidosis does not enhance uterine blood flow because the uterine vasculature is already maximally dilated, it shifts the maternal oxyhemoglobin saturation curve to the right, leading to decreased oxygen affinity and increased fetal oxygen delivery. Maternal hypotension and increased sympathetic stimulation (exogenous or endogenous) both cause uterine arterial vasoconstriction. The importance of maternal cardiac output is supported by the observation that women with left ventricular outflow obstruction have an increased incidence of fetal death and surviving infants have an increased incidence of congenital heart disease. Data from a sheep model, however, suggests that a decrease in uterine blood flow up to 50% for brief periods does not appreciably decrease fetal and placental oxygen uptake. Chronically decreased maternal cardiac output may have other effects, perhaps on placental development, that explain the results in women with left ventricular outflow obstruction. The interaction of maternal and fetal circulations in the placenta most likely follows a concurrent exchange mechanism. This is less efficient than a countercurrent exchange mechanism and partly explains why the PaO in the fetal umbilical vein, which carries oxygenated blood to fetus,2 is in the range of 32 mm Hg, far lower than uterine vein PaO, and why2 increased maternal inspired oxygen increases uterine artery oxygen tension but does not cause major increases in umbilical vein PaO. The fetal oxyhemoglobin saturation curve is relatively unaffected by changes in pH; although acidosis may decrease maternal oxygen affinity, fetal oxygen affinity remain unchanged. There seem to be no placental autoregulatory mechanisms that increase blood flow in response to decreased maternal PaO. This appears to be another compensation mechanism for the apparent inefficiency (concurrent exchange mechanism) of the placenta. One disadvantage in terms of oxygen delivery to fetal tissues is that oxygenated umbilical vein blood is mixed in the fetal inferior vena cava with deoxygenated systemic venous blood before delivery to the systemic circulation. This is2 compensated for in part by a high fetal cardiac output relative to oxygen consumption, thus enhancing oxygen delivery to fetal tissues. The fetal circulation appears to have the ability to autoregulate in the face of hypoxemia to protect the brain, adrenal glands, and heart. How well do the compensatory mechanisms that provide adequate oxygen supply to the fetus under normal conditions manage during maternal hypoxia? Calculation of oxygen stores in the term infant with 60% hemoglobin saturation yields a total oxygen content of 40 mL. Given an oxygen consumption of 6 mL/kg/min, or approximately 18 mL per minute at term, this reserve lasts barely 2 minutes when the maternal oxygen supply is completely interrupted. The shape of the fetal oxyhemoglobin dissociation curve places umbilical vein PaO values2 below 30 mm Hg on the steep part of the curve, so small changes in maternal PaO may cause significant changes in fetal oxygen content. A2 maternal PaO greater than 70 mm Hg should be maintained to prevent2 adverse consequences to the fetus. Concern regarding the adequacy of fetal oxygen supply is further reduced if a normal maternal PaO of 902 mm Hg or greater is achieved without too great a risk of maternal barotrauma or oxygen toxicity . The increased frequency of thromboembolic disease in pregnancy may be attributable to a hypercoagulable state along with venous stasis. The activity of plasminogen activator inhibitor types 1 and 2, which are inhibitors of fibrinolysis, also increases . Venous stasis may occur because of a hormonally induced dilation of capacitance veins and uterine pressure on the inferior vena cava . The usefulness of the serum D-dimer levels in diagnosing thromboembolic disease in pregnancy is limited because D- dimer levels are increased during normal pregnancy, with levels increasing as gestation progresses and peaking at delivery and in the early postpartum period . Fetal exposure to radiation during imaging studies can be minimized by abdominal shielding and using brachial access.
Therefore buy 1 mg propecia otc hormonal hair loss cure, triptans should not be administered to patients with risk factors for coronary artery disease without performing a cardiac evaluation prior to administration purchase propecia from india hair loss cure year. Other adverse events with the use of triptans include pain and pressure sensations in the chest discount propecia online mastercard hair loss in men quiff, neck, throat, and jaw. Ergotamine is currently available sublingually and is mostly effective when used in the early stages of the migraine. It is also available as an oral tablet or suppository containing both ergotamine and caffeine. Ergotamine is used with strict daily and weekly dosage limits due to its ability to cause dependence and rebound headaches. Dihydroergotamine is administered intravenously or intranasally and has an efficacy similar to that of sumatriptan. Ergotamine and dihydroergotamine are contraindicated in patients with angina and peripheral vascular disease because they are significant vasoconstrictors. Nonspecific therapies Other therapies for acute migraine attacks include analgesics, antiemetics, nonsteroidal anti-inflammatory drugs, and corticosteroids. Prophylaxis for migraine headache Therapy to prevent migraine is indicated if the attacks occur two or more times a month and if the headaches are severe or complicated by serious neurologic signs. Triptans, along with inhalation of 100% oxygen, are used as first-line abortive strategies for cluster headache. Obesity is due in2 part to an energy imbalance; however, it is now well understood that genetics, metabolism, behavior, environment, culture, and socioeconomic status play a role in obesity, as well. Serotonin agonists have been used in the treatment of obesity for the appetite suppression that they produce. Drugs for obesity are considered effective if they demonstrate at least a 5% greater reduction in body weight as compared to placebo (no treatment). The majority of drugs approved to treat obesity have short-term indications for usage. Serotonin agonists the first serotonin agonists used for weight loss, fenfluramine and dexflenfluramine, were withdrawn from the market following an increase in potentially fatal adverse effects, including valvulopathy. In contrast to many other weight loss drugs, it is used for chronic weight management. If a patient does not lose at least 5% of his or her body weight after 12 weeks of use, the drug should be discontinued. Pharmacokinetics Lorcaserin is extensively metabolized in the liver to two inactive metabolites that are then eliminated in the urine. Lorcaserin has not been studied for use in severe hepatic impairment and is not recommended in severe renal impairment. Adverse effects the most common adverse effects observed with lorcaserin are nausea, headache, dry mouth, dizziness, constipation, and lethargy. The development of life- threatening serotonin syndrome or neuroleptic malignant syndrome has been reported with the use of serotonin agonists. Therefore, patients should be monitored for the emergence of these conditions while on lorcaserin. For that reason, individuals with a history of heart failure should use this agent with caution. Other agents for obesity In addition to lorcaserin, several agents with varying mechanisms of action are available for weight loss and the management of obesity. They exert pharmacologic action by increasing the release of norepinephrine and dopamine from the nerve terminals and by inhibiting reuptake of these neurotransmitters, thereby increasing levels of neurotransmitters in the brain. The increase in norepinephrine signals a “fight-or-flight” response by the body, which, in turn, decreases appetite. Tolerance to the weight loss effect of these agents develops within weeks, and weight loss typically plateaus. An increase in the dosage generally does not result in further weight loss, and discontinuation of the drug is usually recommended once the plateau is reached. The anorexiants are classified as controlled substances due to the potential for dependence or abuse. Therefore, these drugs should be avoided in patients with a history of uncontrolled hypertension, cardiovascular disease, arrhythmias, heart failure, or stroke. Orlistat is a pentanoic acid ester that inhibits gastric and pancreatic lipases, thus decreasing the breakdown of dietary fat into smaller molecules that can be absorbed. The loss of calories from decreased absorption of fat is the main cause of weight loss. The clinical utility of orlistat is limited by gastrointestinal adverse effects, including oily spotting, flatulence with discharge, fecal urgency, and increased defecation. These effects may be minimized through a low-fat diet and the use of concomitant cholestyramine. Orlistat is contraindicated in pregnancy and in patients with chronic malabsorption syndrome or cholestasis. The drug also interferes with the absorption of fat-soluble vitamins and β-carotene. Patients should be advised to take a multivitamin supplement that contains vitamins A, D, E, and K and β-carotene. Orlistat can also interfere with the absorption of other medications, such as amiodarone, cyclosporine, and levothyroxine, and clinical response to these medications should be monitored if orlistat is initiated. Combination therapy the combination of phentermine and topiramate has been approved for long-term use in the treatment of obesity. Initial studies of the anticonvulsant topiramate observed weight loss in patients taking the medication. Because of the sedating effects of topiramate, the stimulant phentermine was added to counteract sedation and promote additional weight loss. If a patient does not achieve a 5% weight loss after 12 weeks on the highest dose of this medication, then it should be discontinued. It is also important to note that this medication should not be stopped abruptly as seizures may be precipitated. Topiramate has been associated with birth defects including cleft palate, and, thus, the combination of phentermine/topiramate is contraindicated in pregnancy. Bupropion and naltrexone is 1425 another combination therapy approved for chronic weight management. Important characteristics of the medications for obesity are summarized in ure 37. The use of first-generation H antihistamines is contraindicated in the treatment of pilots and1 others who must remain alert. Because of its lower potential to induce drowsiness, fexofenadine may be recommended for individuals working in jobs in which wakefulness is critical. Because of the established long-term safety of first-generation H antihistamines, they are the first choice for1 allergic rhinitis. The motor coordination involved in driving an automobile is not affected by the use of first-generation H1 antihistamines.
The headache is retro-orbital and bifrontal buy propecia 5 mg mastercard hair loss lack of vitamins, comes on suddenly cheap propecia 1mg otc hair loss edges, and is unremitting purchase genuine propecia online himalaya anti hair loss. Skin rash is observed in 60% of patients and begins on the trunk, spreading outward over 24-48 hours. Lesions are initially macular, but quickly progress to a maculopapular form and then to petechiae. Central nervous system involvement can lead to drowsiness and confusion, and in severe cases, grand mal seizures and focal neurologic deficits can result. Louse-borne typhus, caused by Rickettsia prowazekii, and is the most serious form. This reactivated form of typhus is called Brill–Zinsser disease, and it is similar in clinical presentation to primary disease, except that the disease is milder. The prognosis for Brill–Zinsser disease and flea-borne typhus is much better than for primary louse-borne typhus, mortality being less than 5% for both diseases. These insects crawl on vegetation and then attach themselves to small mammals and humans as they pass through the brush. This disease is most often contracted by agricultural workers and military personnel in endemic areas. Scrub typhus is found in Japan, eastern Asia, Australia, and in the western and southwestern Pacific islands. The incubation period is similar to that of the other rickettsial diseases (6-21 days); however, the onset is usually gradual rather than sudden. Diffuse lymphadenopathy, splenomegaly, conjunctivitis, and pharyngitis are common physical findings. Within 1 week of the onset of symptoms, a high percentage of patients develop a maculopapular skin rash. A black eschar may be noted at the site of the chigger bite in approximately half of patients. Diagnosis and Treatment the diagnosis of these febrile illnesses is presumptive and based on clinical and epidemiologic findings. Acute and convalescent antibody titers to the specific forms of Rickettsia can be performed, and the specific diagnosis made retrospectively. Immunofluorescence staining of the primary eschar (where available) can yield a more rapid diagnosis. The once-popular Weil– Felix Proteus agglutination test is no longer recommended because of its poor sensitivity and lack of specificity. The treatment for all forms of typhus is identical to that for the spotted fever group: doxycycline or chloramphenicol (see Table 13. However, a subgroup of patients without headache, but having jaundice and bradycardia, demonstrate a delay in the resolution of fever, and require more prolonged treatment. In some regions in which antibiotic resistance has developed, oral rifampin (600-900 mg daily) may be more efficacious. Early treatment aborts the antibody response, and as a consequence, relapse may occur after treatment is completed. Antibody titers are available; immunofluorescence staining of primary lesion is helpful. Treat with doxycycline or chloramphenicol: a) Patients may relapse, requiring retreatment. Epidemiology Both species of Ehrlichia are transmitted to humans by ticks, and the seasonal nature of these diseases is identical to those of other tick-borne illnesses. Most cases of human monocytotropic ehrlichiosis are associated with bites from the lone star tick (Amblyomma americanum). This disease is very common in the southeast, and attack rates have been estimated to be 5 per 100,000 population; however, in certain endemic areas, incidences as high as 660 per 100,000 have been reported. In addition to hikers and outdoor workers, golfers are at risk of contracting this disease. Cases have been reported in California, Minnesota, Wisconsin, Massachusetts, Connecticut, New York, and Florida. Nosocomial person-to-person spread of anaplasma was reported in a Chinese hospital following exposure to blood and/or respiratory secretions from a patient with fatal disease. Pathogenesis Once the organism is inoculated into the skin by the tick, it enters the lymphatic system and bloodstream. In addition, this organism blocks the signal transduction pathways that enhance production of interferon-γ and simultaneously upregulates cytokine genes important for generation of the inflammatory response. Finally, it induces clustering of transferrin receptors in the phagolysosome membrane, allowing it to compete effectively for iron, a vital nutrient for bacterial growth. As the bacteria divide by binary fusion, they cluster together, forming intracellular inclusions called morulae. He was given trimethoprim–sulfamethoxazole by his primary physician for presumed sinusitis, but he failed to improve. An epidemiologic history indicated that the patient was an avid hunter and had been hunting with his father on several occasions during the last 2 months. His father had died in the hospital from “influenza pneumonia” that had developed at the same time as his current illness. A few hyperpigmented macular lesions over the anterior shins were observed, but there was no evidence of tick bites. One week after hospital discharge, his serum IgG and IgM titers came back positive for E. Ehrlichia varies in its severity, and fatality rates of approximately 5% have been reported in both diseases. Both forms of Ehrlichia present with the gradual onset of fever, chills, headache, myalgias, anorexia, and malaise. The monocytotropic form can result in respiratory insufficiency, renal insufficiency, and meningoencephalitis. Hypotension can develop with either infection and mimic other forms of gram-negative sepsis. Thrombocytopenia is a prominent finding in both diseases, and this finding combined with the epidemiology strongly suggested the diagnosis of ehrlichiosis in case 13. Platelet counts can drop below 20,000/mm in severe disease and can be associated with gastrointestinal bleeding. In the granulocytotropic form, neutropenia predominates and is commonly associated with a left shift and relative lymphocytosis. Diagnosis and Treatment If the diagnosis of Ehrlichia is being considered, a Wright stain of the peripheral blood and a buffy coat smear should be carefully examined for the presence of morulae. The percentage of granulocytes containing morulae varies from 1% to 44%, with higher levels of intracellular invasion being seen in elderly patients.
Alternatively order generic propecia hair loss in men 90s fashion, the ductus is divided between clamps and oversewn with fine cheap propecia 1 mg amex hair loss cure november 2015, nonabsorbable sutures discount 5 mg propecia otc hair loss diabetes. This latter technique is especially applicable to premature infants and is the most commonly practiced. Injury to the Recurrent Laryngeal Nerve during Ligation of the Ductus Arteriosus the surgeon must always pay special attention to the recurrent laryngeal nerve. A Ductus Arteriosus Tear the ductus arteriosus is liable to be injured and torn any time during dissection, ligation, or division, resulting in massive hemorrhage. Digital pressure over the ductus usually controls the bleeding and provides adequate exposure in a dry field. The aorta can then be temporarily clamped above and below the ductus while the torn ductus is oversewn with nonabsorbable sutures. Under these circumstances, while continuing digital control of the bleeding, the surgeon must gain access to the pericardium by incising it longitudinally, anterior to the left phrenic nerve. Control of bleeding from the ductal end is then achieved by temporarily occluding the left pulmonary artery from within the pericardium. Clamping for Division of Ductus Whenever the surgeon elects to divide the ductus arteriosus, it is essential that the clamps are applied on the aorta and the pulmonary artery, and not on the ductus itself, which is friable and liable to be disrupted. Inadvertent Ligation of the Aortic Arch the ductus arteriosus and aortic arch must both be identified. Occasionally, the ductus is very much larger than the arch, which may be underdeveloped and hypoplastic. Inadvertent ligation of the arch instead of the ductus is a catastrophe that can be prevented by sequentially occluding the ductus and arch while monitoring the blood pressure in the left arm. Inadvertent Ligation of the Left Pulmonary Artery A clip placed too far toward the mediastinum runs the risk of impinging upon the left pulmonary artery; in the most exaggerated form of this error, the left pulmonary artery itself can be ligated. Occluding the Ductus Arteriosus In certain circumstances, the ductus arteriosus can be occluded temporarily with an atraumatic tissue forceps before its ligation or division. The occurrence of hypotension, bradycardia, or changes in oxygen saturation suggests that the patient has a ductal-dependent congenital anomaly and needs further diagnostic studies. Closure of the Ductus Arteriosus in Premature Infants the ductus arteriosus is visualized through a short, left lateral thoracotomy in the fourth intercostal interspace. The clip applier is positioned over the ductus arteriosus, directing the tips of the clip slightly inferiorly and away from the wall of the descending aorta and orienting the clip parallel with the aorta. Erosion or Cutting by the Clip If the ends of the clip are adjacent to the descending aorta or distal aortic arch, the clip may cut into these structures, resulting in immediate or delayed bleeding. Scissoring of Metal Clip Some clip appliers may cause the two sides of the metal clip to miss each other and cut through the ductus rather than occlude it. The surgeon should test the clip applier with a clip away from the operative field to verify proper closure of the clip before using the applier on the ductus itself. Tearing of Ductus with Tip of Instrument the scissors or clamp used to create an adequate opening above and below the ductus for clip placement should have a rounded, smooth tip. The surgeon must inspect the instrument to verify that there is not a burr at or near the tip that could tear the delicate ductal tissue. Completing the Operation Rib blocks have been most effective in reducing postoperative thoracotomy pain. A long-acting local anesthetic agent is injected near the neurovascular bundle at least two interspaces above and two below the level of the incision. The chest tube is brought through the skin and muscle opening and introduced through the fifth or sixth intercostal space. The muscle layers, subcutaneous tissues, and skin are closed around the chest tube, which is connected to an underwater seal suction system. When the skin closure reaches the chest tube, several vigorous sustained ventilations are administered by the anesthesiologist. A chest x-ray obtained in the operating room confirms reexpansion of the left lung and absence of pneumothorax. Bleeding Caused by Intercostal Injections In patients with coagulopathies or who are anticoagulated, rib blocks should be avoided to prevent extrapleural hematomas or intrapleural bleeding. The ideal placement of the clip allows distance from the recurrent nerve and also a “ductal bump” of tissue on the descending aorta (thus not causing a coarctation). Placement of Pericostal Sutures the suture should hug the top of the rib to avoid injury to the intercostal artery or vein. Injury to the Lung If injury to the lung is noted, the chest tube should be left in place on suction for 12 to 24 hours. Thoracoscopic Closure of the Ductus Arteriosus Some surgeons use thoracoscopic techniques for closure of the ductus arteriosus. The risk of recurrent laryngeal nerve injury is slightly higher with this approach; however, some surgeons feel that avoiding a thoracotomy incision may prevent future chest wall deformities. Transcatheter Closure of the Ductus Arteriosus Transcatheter closure of a small patent ductus arteriosus with a coil or occluder device can be accomplished satisfactorily and avoids surgery in selected patients. Calcification of the Ductus Arteriosus the ductus may be calcified and/or aneurysmal, and simple ligation or division may not be feasible. Under these circumstances, it may be easier and safer to close the ductal opening through the left pulmonary artery under direct vision with the patient on cardiopulmonary bypass (see later). Friable Tissues If the tissues are friable, the patch can be sewn into place with interrupted pledgeted sutures. Technique in Infants and Children Before the initiation of cardiopulmonary bypass, the ascending aorta is retracted slightly to the right and the main pulmonary artery is retracted gently downward. The ductus is then dissected free of the left pulmonary artery and the aortic arch using scissors or a fine-tipped clamp. The ductus is encircled with a 2-0 braided suture and ligated or occluded with a metal clip at the onset of cardiopulmonary bypass. Flooding of the Pulmonary Circulation With the initiation of cardiopulmonary bypass, flooding of the pulmonary circulation and low systemic blood pressure are likely to occur unless the ductus is occluded. All children undergoing cardiopulmonary bypass are evaluated for the presence of a patent ductus either by echocardiogram, direct inspection, or both. Tearing of Ductal Tissue the ductal tissue is friable, and care must be taken to prevent the suture or clip from cutting through the ductus. Stenosis of the Left Pulmonary Artery the tie or clip should be placed far enough away from the origin of the left pulmonary artery to prevent narrowing of this vessel. This can result from external compression by the ligature or clip or from extrusion of ductal tissue into the lumen of the left pulmonary artery. Technique in Adults Closure of a patent ductus arteriosus in an adult can be safely accomplished through a median sternotomy on cardiopulmonary bypass. The opening of the ductus is identified, and an appropriately sized Foley catheter is passed into the aorta. Cardiopulmonary bypass flow can be increased while a patch of autologous pericardium treated with glutaraldehyde, Gore-Tex or hemashield is sewn away from the edges of the ductal orifice using 5-0 monofilament suture. Just before placing the last one or two stitches, the pump flow is turned very low while the Foley balloon is deflated, the catheter is removed, and the final stitches placed. Flooding of the Pulmonary Circulation During cooling, the ductal flow must be occluded to prevent runoff of the aortic cannula flow into the pulmonary arterial bed. Air Embolism through the Ductus Arteriosus When the pulmonary artery is opened, some flow must be maintained through the aortic cannula to prevent air embolism.