Groups cheap 30 mg vytorin otc, departments order vytorin 20mg visa, and facilities are obligated to have sufficient backup equipment to cover any reasonable incidence of failure. The equipment removed from service must be clearly marked with a prominent label (so it is not returned into service by a well-meaning technician or practitioner) containing the date, time, person discovering, and the details of the problem. The responsible personnel must be notified so they can remove the equipment, make an entry in the log, and initiate the repair. As indicated in the protocol for response to an adverse event, a piece of50 equipment involved or suspected in an injury-causing anesthesia accident must be immediately sequestered and not touched by anybody—particularly not by any equipment service personnel. If a severe accident occurred, it may be necessary for the equipment in question to be inspected at a later time by a group consisting of qualified representatives of the manufacturer, the service personnel, the plaintiff’s attorney, the insurance companies involved, and the practitioner’s defense attorney. The equipment should thus be impounded following a catastrophic adverse event and treated similarly to any object in a forensic “chain of evidence,” with careful documentation of parties in contact with and responsible for securing the equipment in question following such an event. Also, major equipment problems may, in some circumstances, reflect a pattern of failure due to a design or manufacturing fault. This system accepts voluntary reports from users and requires reports from manufacturers when there is knowledge of a medical device being involved in a serious incident. Whether or not filing 156 such a report will have a positive impact in subsequent litigation is impossible to know, but it is a worthwhile practice management point that needs to be considered in the unlikely but important instance of a relevant event involving equipment failure. Malpractice Insurance All practitioners need liability insurance coverage specific for the specialty and role in which they are practicing. It is absolutely critical that applicants for medical liability insurance be completely honest in informing the insurer what duties and procedures they perform. Failure to do so, either from carelessness or from a foolishly misguided desire to reduce the resulting premium, may well result in retrospective denial of insurance coverage in the event of an untoward outcome from an activity the insurer did not know the insured engaged in. Proof of adequate insurance coverage is usually required to secure or renew privileges to practice at a health-care facility. The facility may specify certain minimum policy limits in an attempt to limit its own liability exposure. It is difficult to suggest specific dollar amounts for policy limits because the details of practice vary so much among situations and locations. The malpractice crisis of the 1980s eased significantly in the early 1990s for anesthesia professionals, largely because of the decrease in number and severity of malpractice claims resulting from anesthesia catastrophes as anesthesia care in the United States became safer. Therefore, anesthesia professionals must be absolutely certain what they are buying when they apply for malpractice insurance. There are specific parts of the United States known for a pattern of exorbitant settlements and jury verdicts, and liability insurance coverage limits of $2 to $5 million or even greater may be considered prudent in some circumstances. Note also that malpractice insurance premiums for anesthesiologists practicing chronic pain management are moderately higher due to the potential liabilities associated with pain procedures. An additional feature in regard to choosing malpractice56 157 insurance policy limits is the potential to employ “umbrella” liability coverage above the limits of the base policy, as will be noted. Background The fundamental mechanism of medical malpractice insurance changed significantly some years ago because of the need for insurance companies to have better ways to predict their “losses” (amounts paid in settlements and judgments). Traditionally, medical liability insurance was sold on an “occurrence” basis, meaning that if the insurance policy was in force at the time of the occurrence of an incident resulting in a claim, whenever within the statute of limitations that claim might be filed, the practitioner would be covered. Occurrence insurance was somewhat more expensive than the alternative “claims-made” policies, but was seen as worth it by some (many) practitioners. These policies created some open-ended exposure for the insurer that sometimes led to unexpected large losses, even some large enough to threaten the existence of the insurance company. As a result, medical malpractice insurers over the years have converted almost exclusively to “claims-made” insurance, which covers only claims that are filed while the insurance is in force. Premium rates for the first year a physician is in practice are relatively low because there is less likelihood of a claim coming in (a majority of malpractice suits are filed 1 to 3 years after the event in question). The premiums usually increase yearly for the first 5 years and then the policy is considered “mature. If the physician simply discontinues the policy and a claim is filed the next year, there will be no insurance coverage. Therefore, the physician must secure “tail coverage,” sometimes for a minimum number of years (e. It may be possible in some circumstances to purchase tail coverage from a different insurer than was involved with the primary policy, but by far the most common thing done is to simply extend the existing insurance coverage for the period of the tail. This very often yields a bill for the entire tail coverage premium, which can be quite sizable, potentially staggering a physician who simply wants to move to another state where his or her existing insurance company is not licensed to or refuses to do business. Individual situations will vary widely, but it is reasonable for anesthesiologists organized into a fiscal entity to consider this issue at the time of the inception of the group and record their policy decisions regarding providing tail coverage as a benefit in writing, rather than facing the potentially difficult question of how to treat one individual later. Whatever strategy is adopted, it is critical that the individual practitioner is absolutely certain through personal verification that he or she is thoroughly covered at the time of any transition. The potential stakes are much too great to leave such important issues solely to an office clerk. Further, a practitioner arriving in a new location is often filling a need or void and is urged to begin clinical work as soon as possible by others who have been shouldering an increased load. It is essential that the new arrival verify with confirmation in writing (often called a “binder”) that malpractice liability insurance coverage is in force before there is any patient contact. Another component to the liability insurance situation is consideration of the advisability of purchasing yet another type of insurance called umbrella coverage, which is activated at the time of the need to pay a claim that exceeds the limits of coverage on the standard malpractice liability insurance policy. Because such an enormous claim is extremely unlikely, many practitioners are tempted to forgo the comparatively modest cost of such insurance coverage in the name of economy. As before, it is easy to see that this is potentially a very false economy—if there is a huge claim. Practitioners should consult with their financial managers and advisors, but it is likely that it would be considered wise management to purchase “umbrella” liability insurance coverage. Medical malpractice insurers are becoming increasingly active in trying to prevent incidents that will lead to insurance claims. Clearly, it is sound practice management strategy for practitioners to participate maximally in such programs. Likewise, some insurers make coverage conditional on the consistent implementation of certain strategies such as minimal monitoring, even stipulating that the practitioner will not be covered if it is found that the guidelines were being consciously ignored at the time of an untoward event. Again, it is obviously wise from a practice management standpoint to cooperate fully with such stipulations. It is probable that the involved personnel will have no relevant past experience regarding what to do. Although an obvious resource is another anesthetist who has had some exposure or experience, one of these may not be available either. Unfortunately, however, the principal personnel involved in a significant untoward event may react with such surprise or shock as to temporarily lose sight of logic. At the moment of recognition that a major anesthetic complication has occurred or is occurring, help must be called. A sufficient number of people to deal with the situation must be assembled on site as quickly as possible. For example, in the unlikely but still possible event that an esophageal intubation goes unrecognized long enough to cause a cardiac arrest, the immediate need is for enough skilled personnel to conduct the resuscitative efforts, including making the correct diagnosis and replacing the tube into the trachea. Whether the anesthesiologist apparently responsible for the complication should direct the immediate remedial efforts will depend on the person and the situation. In such a circumstance, it would seem wise for a senior or supervising anesthesiologist quickly to evaluate the scenario and make a decision. This person becomes the “incident supervisor” and has responsibility for helping prevent continuation or recurrence of the incident, for investigating the incident, and for ensuring documentation while the original and helping anesthesiologists focus on caring for the patient. As noted, involved equipment must be sequestered and not touched until such time as it is certain that it was not involved in the incident. With the hope of preventing or mitigating catastrophic anesthesia accidents, the utilization of emergency manuals, usually including checklists, as “cognitive aids” within the application of “crisis resource management”61 when an adverse threatening situation develops during an anesthetic has gained significant attention. Although the incident supervisor could seek guidance by reading a manual in real time during a crisis, having a “reader” who may or may not be another anesthesia professional whose sole activity during the crisis is to read out loud the relevant diagnostic and therapeutic suggestions in the protocol that applies to the crisis situation could be helpful. Overall, evidence from studies in simulated anesthesia crisis situations indicates on balance that the use of “emergency manual” type cognitive aids can improve patient outcome from an intraoperative anesthesia crisis. If not already involved, the chief of anesthesiology must be notified as well as the facility administrator, risk manager, and the anesthesiologist’s insurance company. The latter are critical to allow consideration of immediate efforts to limit later financial loss. Full disclosure of facts as they are best known—with no confessions, opinions, speculation, or placing of blame—is still believed by many to be the best presentation. Any attempt to conceal or shade the truth will later only confound an already difficult situation.
The lingual cortex make the hole far enough away from the osteotomy edge so that of the genial segment should not be advanced beyond the facial the wire does not pull through the bone cheap vytorin 30mg without prescription. There The appropriate-size plate (based on the preoperative virtual should be minimal space between the advanced segment and treatment objective) is chosen purchase 20 mg vytorin visa. If there is a small osteotomy gap, it can be ment may be appropriate based on the esthetic assessment on grafted with autogenous and/or allogeneic bone. All four wings of the plate are bent to the appropriate Various prebent genioplasty plate designs are available for contour of the underlying bone. They come in 2-mm size increments and are secured frst to the body of the mandible. The H-shaped design allows easy visu- is brought through the middle of the two arms of the plate. The alization and alignment of the genial segment midline mark genial segment is then advanced and stabilized with the wire. It because the two prebent arms are off-centered from the plate is also important to palpate and manually stabilize the wings of midline. Screws are fnally placed through advance and stabilize it while the fxation screws are placed. Typically, A hole is placed obliquely through the edge of the facial cortex screws 10 to 12 mm long are used (Figure 29-2, F to H). Continued F G Figure 29-2, cont’d F, Straight genial advancement with minimal space in the osteotomy gap. G, Te positioning wire helps advance the genial segment and stabilize it while fxation screws are placed. A Tegaderm occlusive dressing is then placed to minimize pended using three interrupted 3-0 Vicryl sutures. The mucosa is then closed in continuous fashion with 4-0 who underwent a Le Fort I posterior impaction and mandibular chromic gut. A surface pressure dressing is placed to further autorotation to close an anterior open bite and a concomitant support the soft tissue envelope, minimize edema, and prevent advancement genioplasty (Figure 29-2, I to L). Then, strips of 4-inch brown paper I J Figure 29-2, cont’d I, Te mentalis muscle is resuspended with Vicryl sutures to help prevent soft tissue ptosis. L, Postoperative Panorex and lateral cephalogram after an advancement sliding osteotomy. Tis includes correction of an asym- inferior osteotomy frst so that the ostectomy is not per- metry in a patient with hemimandibular hyperplasia. It is important to For augmentation, the osteotomy is performed as previ- stay at least 5 to 6 mm below the canine roots and mental ously described, and the genial segment is mobilized. If a foramina when planning the position of the superior oste- concomitant advance is performed, a prebent genioplasty otomy. Otherwise, two straight plates placed of plates placed of midline are used to fxate the genial segment midline are used with two holes superior and two holes infe- (Figure 29-3, B). Te posterior wings of the genial For vertical chin asymmetry that occurs with hemifacial segment are maintained in contact with the body of the hyperplasia, mark the midline of the chin (genial segment) mandible for stability as the anterior portion is down-grafted and separately mark the facial midline of the mandible above the desired amount and fxated in place. Te inferior osteotomy is performed frst, allogeneic bone graft should be placed into the osteotomy parallel to the inferior border of the chin. Particulate grafts are easier to tomy of the asymmetric bone segment is performed. Te shaded area is the area of ostectomy that occurs when the superior osteotomy is made. An inferior and then a superior osteotomy are performed, and the asymmetric bone segment is repositioned to the opposite side. Approximately 10 minutes should cone extended preformed implants are a common material be allowed after infltration for vasoconstriction to occur. Tey create a subtle increase in lateral fullness to Te incision is made through skin and subcutaneous augment the pre-jowl sulcus in addition to increasing chin tissue. A short skin fap is raised to the inferior border super- projection (Figure 29-4, A and B). Electrocautery is used to incise in small, medium, and large sizes that primarily vary in the through periosteum just anterior to the platysma muscle amount of anterior augmentation. Tis in conjunction with other cosmetic procedures, such as rhyt- minimizes intraoperative bleeding and potential postopera- idectomy and neck liposuction (see Figure 29-1). A #9 periosteal elevator is then Te chin midline is marked to aid correct implant posi- used to dissect in a subperiosteal plane along the inferior tioning. Te dissection proceeds superiorly onto to the posterior extent of the implant and dissection. Care is taken to extraoral submental approach is ideal if a concomitant neck identify the mental nerve and avoid overmanipulation. Tis sively along the facial aspect of the inferior border, but not prevents deepening of the crease with scar contracture. A sizer eral inferior alveolar nerve blocks are performed using 2% set corresponding to the actual preformed implant sizes (i. Te submental inci- small, medium and large) can be used to help determine the sion and entire area of subperiosteal dissection in the chin best size. If a virtual treatment objective was performed, this are infltrated with the local anesthetic. C, Markings for submental crease incision, inferior border of mandible, and facial midline. D, Super- osteal dissection is carried out along the facial aspect of the inferior border. Eventually a capsule After insertion of the appropriate-size implant, the marked develops around the implant to help further stabilize it in midline of the implant is aligned with the patient’s previously place. Te wound is irrigated with sterile saline and then marked soft tissue chin midline. Te sively along the facial aspect of the inferior border with no subcutaneous layer is closed with 4-0 Monocryl. Steri-Strips has been verifed, the implant should be fxated to prevent can be placed across the incision site. Stable fxation may minimize long-term dressing is applied, as previously described (see Figure 29-2, mobility and bone resorption. A more extensive submental and neck pressure dressing screws are placed of midline to secure the implant in place. When Avoidance and Management of the foreshortened genial segment is advanced, it leaves a Intraoperative Complications greater defect along the inferior border that disrupts a smooth inferior jaw line (Figures 29-5 and 29-6). It can also deepen Genioplasty involving an osteotomy is technically more chal- the pre-jowl sulcus with remodeling and aging. To avoid this lenging than an implant and thus has the potential for more problem, the osteotomy should extend posteriorly to the frst complications. If the chin segment is positioned superiorly for bony contact, it creates an unesthetic contour defect along the inferior border and reduction of chin height. A B C Figure 29-6 A, Tis osteotomy is foreshortened; it does not extend back into the frst molar region. Note the resorption of the posterior wings of the genial segment over time, which contributes to notching of the inferior border of the mandible. Preoperative photographs (F and G) and 1-year postoperative photographs (H and I) showing an inferior border contour defect due to the fore- shortened osteotomy. C, An injectable, self-setting calcium phosphate cement can be used to fll craniofacial bony defects that are not intrinsic to the stability of the bony struc- C ture. It is important to review segment advancement or to graft particulate hydroxyapatite radiographs carefully before surgery to assess the position of along the inferior border defect at the time of surgery (Figure the nerve. Tis can occur if the nerve runs low in sected, a neurorrhaphy procedure using 7-0 Nurolon or relation to the inferior border of the mandible and the situ- Prolene suture can be attempted. However, it can be difcult ation is not appreciated preoperatively and adjusted for to free enough of the proximal and distal segments for passive during surgery. Tis can occur with undue trauma to the foor of the mouth muscles during osteotomies. Also, the surgeon must avoid overinserting the reciprocating saw through the lingual cortex. If a hematoma is noted, it should be evacuated and the source of bleeding should be controlled. Injection of a local anesthetic with vasoconstrictor or placement of a hemo- static agent (e.
A left-sided endobronchial tube is preferred buy generic vytorin 30mg, because a right-sided tube may be difficult to position relative to the right upper lobe bronchus discount vytorin 20mg. Fluid restriction and lung ventilation strategies designed to protect the lung allograft are indicated, because these patients are at increased risk for acute lung injury and pulmonary edema. Strategies to improve oxygenation and ventilation are discussed in detail in Chapter 38. This can be accomplished via either anterior thoracotomy with partial sternotomy or lateral thoracotomy with decreased angulation of the hips to allow access to the femoral vessels. Determination of operative side is based on preoperative ventilation–perfusion studies and prior thoracic surgeries. Circulation is restored to the donor lung, suture lines are checked for hemostasis, and then ventilation is begun. Systemic hypotension can occur during reperfusion but is usually not as significant as that with liver graft reperfusion. The anesthesiologist is often asked to assess the bronchial anastomosis using fiberoptic bronchoscopy and to perform bronchopulmonary toilet on the transplanted lung if necessary (removal of blood, secretions). Along with ex vivo perfusion, Perfadex, a low–molecular-weight dextran solution, improves early graft function and is used widely for preservation during procurement. Pulmonary vein anastomotic obstruction can be diagnosed with careful Doppler examination of the pulmonary venous inflow (see Chapter 27). At the completion of the procedure, the patient should be evaluated for exchange of the double-lumen endotracheal tube to a large (8-mm internal diameter or larger) single-lumen tube. The large diameter facilitates postoperative bronchopulmonary toilet and diagnostic bronchoscopy, as needed. Double-lung Transplantation Bilateral lung transplant is performed in the supine position, using a “clamshell” incision. The arms can be suspended on a padded bar above the patient or tucked at the sides. If the arms are suspended, care must be taken to avoid stretching the brachial plexi. Bilateral sequential transplantation requires lung isolation, preferably via a double-lumen endotracheal tube. Bilateral sequential transplantation is now the preferred procedure because a tracheal anastomosis is unnecessary, and there is less surgical bleeding. Serial implantation implies longer ischemic time for the second lung, but this has not been shown to adversely affect outcome. One hundred and twenty-four pediatric lung transplants were reported worldwide in 2013, compared to only 73 in 1999. There now appear to be age-related survival differences, with infants doing better than adolescents, but overall, survival is improving. Grade 3 is defined as PaO2/FiO2 less than 200 with radiographic infiltrates consistent with pulmonary edema. Grade 0 is essentially a normal lung, in which the PaO2/FiO2 ratio is greater than 300 and there are no pulmonary infiltrates. However, data are limited on transfusion during lung 3695 transplantation, in contradistinction to the data available on transfusion requirements during liver transplantation. Further study is needed to determine whether transfusion negatively affects lung transplant outcomes. Because a tracheal anastomosis is performed, a single-lumen endotracheal tube is sufficient. Pulmonary reperfusion injury can also occur, requiring management of acute lung injury as described for lung transplantation. Heart Transplantation Since Christian Barnard performed the first successful heart transplant in South Africa in 1967,197 the procedure has become accepted practice for treatment of heart failure recalcitrant to medical therapy. Over 50,000 individuals have received heart transplants in the United States since 1988. Overall 1-year survival has improved from 74% in the early 1980s to 86% currently. As our population ages and the use of cardiac transplantation and mechanical assist devices expands, increasing numbers of patients will present for transplantation, management of previous transplantation, or mechanical assist devices. One-year survival has 3697 been reported to be approximately 63%, with 5-year survival as low as 20%. Variations include flow pattern (pulsatile or nonpulsatile), requirement for anticoagulation (none, aspirin, warfarin), filling pattern, power source (battery or alternating current), potential for electromagnetic interference, and impact of dysrhythmias and defibrillation on the device. Acetone-containing products and Betadine should be avoided near these devices because they can damage the cannula or drive lines. An individual familiar with the device should be present to assist with management and troubleshooting if the clinician does not have sufficient experience. These facilitate perioperative management of volume status, assessment of forward flow, and administration of vasoactive medications. An inflow cannula is in the left ventricle, and an outflow cannula is in the aorta. The prosthetic left ventricle (pump) propels blood from the left ventricle to the aorta, offloading some or all of the demand on the left ventricle. The cannulas and pump are within the patient, and the controller, drive line, and battery pack are external. The indications are short-term hemodynamic support for patients in cardiogenic shock or temporary support of a patient undergoing high-risk percutaneous intervention. The left-sided cannula is advanced from the femoral vein into the left atrium by puncturing the interatrial septum (Fig. The HeartMate devices (Thoratec) 3699 are currently approved as therapy for patients with intractable heart failure who are not candidates for transplantation (destination therapy). Cannulas are placed percutaneously into the femoral vein and femoral artery, and the drive mechanism and power supply are external. The femoral venous line is placed across the atrial septum so as to drain the left atrium. Less common diagnoses include valvular heart disease, retransplant, and congenital heart disease. For transplants performed in 2009 to 2013, 40% of recipients were receiving intravenous inotropic support and 49% were receiving mechanical circulatory support. Consensus guidelines for selection of patients for heart transplantation were published in 2006 and updated in 2016. Surgical correction of coronary artery disease or valvular heart disease should be considered prior to listing, and patients with severe mitral regurgitation and low ejection fraction should be considered for mitral valve repair instead of transplantation. Pulmonary arteriolar resistance (the ratio of transpulmonary gradient to cardiac output, expressed as Wood units) greater than 2. Patients with elevated transpulmonary gradient or pulmonary arteriolar resistance require a trial with nitroprusside, prostacyclin, dobutamine, or milrinone in an attempt to decrease pulmonary resistance. Contraindications to cardiac transplantation include some significant 3701 noncardiac diseases. Some patients with multiorgan disease can be considered for combined heart–kidney or heart– liver transplantation. The presence of significant atherosclerosis is a contraindication because of the increased perioperative risk of atheroembolic complications. Preanesthetic Considerations Donor heart function worsens with donor cold ischemia times above 6 hours. For this reason, timing of transplantation depends on when the donor surgery can be done, frequently during night hours. Close communication between the donor and recipient teams facilitates optimal use of donor organs while minimizing ischemia times. Ideally, the recipient heart is excised as soon as the donor heart arrives at the recipient hospital. Induction of anesthesia and surgical incision of the recipient begin when the donor team has evaluated the donor and made the final determination that the organ is acceptable. Timing decisions are based on distance and time necessary to transport the donor organ, as well as time it will take to prepare the recipient. History of prior sternotomy or difficult airway can increase recipient preparation time.
These systems rely on a titanium skull base: the evolving role of transsphenoidal surgery buy vytorin 20mg low cost. Crista galli to the theless generic vytorin 20 mg without prescription, the ultrasonic aspirators with handpieces and tips sella turcica. Neurosurg Focus 2005;19:E3 for use in endonasal surgery were too bulky to be used 12. Posterior clinoids recently, specifcally designed endonasal transsphenoidal to the foramen magnum. Neurosurg Focus 2005;19:E4 tips were introduced for the ultrasonic aspirator (Sonopet; 13. Expanded Miwatec, Tokyo, Japan), which is very low profle and can endonasal approach: fully endoscopic, completely transnasal ap easily be inserted together with the endoscope, as with any proach to the middle third of the clivus, petrous bone, middle cranial other surgical instrument, and can be quite useful in tumor fossa, and infratemporal fossa. A series of 51 con New dedicated instruments have greatly contributed to the secutive cases. Neurosurgery 2008;62:556–563, discussion 556–563 evolution of endoscopic endonasal transsphenoidal surgery 16. Outcomes following and have permitted its progressive extension from the sella endoscopic, expanded endonasal resection of suprasellar craniopha ryngiomas: a case series. Fully endoscopic expanded tions are continuously evolving, as are the techniques to endonasal approach treating skull base lesions in pediatric patients. Neurosurgery 2004;55:933–940, discussion of the anterior cranial fossa and ventral skull base. Current state and future de donasal transsphenoidal surgery: procedure, endoscopic equipment velopment of intracranial neuroendoscopic surgery. Endoscopic transnasal approach to the cavernous sinus Springer; 2003:9–19 versus transcranial route: anatomic study. Application of neuroen Suppl):379–389, discussion 379–389 doscopy to intraventricular lesions. Extended endoscopic en 2):575–597, discussion 597–598 donasal transsphenoidal approach to the suprasellar area: anatomic 24. Endoscopic endonasal 1998;12:389–392 surgery of the midline skull base: anatomical study and clinical con 25. Neurosurg Focus 2005;19:E2 versus endoscope for paranasal sinus surgery: infuence on visual 8. The extended direct endonasal 2008;31:309–317 transsphenoidal approach for nonadenomatous suprasellar tumors. Anatomical study of the ptery J Neurosurg 2005;102:832–841 gopalatine fossa using an endoscopic endonasal approach: spatial 27. Minim Inva 2007;106:157–163 sive Neurosurg 2004;47:145–150 3 Endoscopic Equipment 33 28. In noidal transclival removal of prepontine epidermoid tumors: techni struments for endoscopic endonasal transsphenoidal surgery. Neurosurgery 2005;56(2, Suppl):E443, discussion E443 rosurgery 1999;45:392–395, discussion 395–396 29. Neurosurgery 1998; tions associated with the endoscopic endonasal transsphenoidal ap 42:81–85, discussion 86 proach for pituitary adenomas. Endoscopic transsphenoidal artery injuries in transsphenoidal surgery with the Doppler probe approach: adaptability of the procedure to diferent sellar lesions. Neurosurgery 2007;60(4, Suppl 2):322–328, Neurosurgery 2002;51:699–705, discussion 705–707 discussion 328–329 35. Neurosurgery 1996;38:95–97, discussion 97–98 ing; 2007:45–56 Preoperative Endocrine Evaluation 4 John C. Freda The preoperative evaluation of a patient with a pituitary tu- ment in visual feld loss with dopamine agonist therapy. The mor or sellar mass should involve the combined eforts of a majority of sellar masses, however, are diagnosed in neuro- neurosurgeon and an endocrinologist. Evaluations for defciencies in the a Pituitary or Sellar Mass remaining anterior pituitary hormone axes can be pursued af- ter surgery. I Hormone-Secreting Pituitary Tumors Prolactinomas with a hormonally active tumor, with the exception of those The most common pituitary tumors are prolactinomas ac- with a gonadotropin-secreting tumor, present with clear signs counting for approximately 40% of all adenomas. However, some patients may often presents with symptoms of gonadal dysfunction, such as present with more subtle fndings that are not immediately at- decreased libido, impotence, or infertility, or with neurologic tributable to the hormone excess. Therefore, additional endo- or visual symptoms because the tumors tend to be macroad- crine laboratory studies should be performed preoperatively to enomas by the time medical care is sought. At our institution, our preopera- bring them to medical attention earlier when their tumors are tive testing typically includes measurements of serum levels of microadenomas. If circulating levels of none pregnancy or during the postpartum period if a woman is of the aforementioned hormones are elevated, the tumor may nursing. Thus, preoperative knowledge of the tu- antidepressants, metoclopramide, methyldopa, reserpine, mor type is benefcial, as it may impact the preoperative, peri- and verapamil, or from the use of illicit drugs such as co- operative, and postoperative management of the patient. With regard sions or pituitary adenomas other than prolactinomas that to anterior pituitary function, it is most important preopera- involve the hypothalamus or hypothalamic-pituitary stalk. This phenomenon, the “hook efect,” management of prolactinomas suggest that prolactin levels is well documented and is secondary to antibody saturation by greater than 150 µg/L are very suggestive of a prolactinoma the high prolactin concentration in a immunoradiometric as- and levels greater than 250 µg/L are suggestive of a prolactin- say, which leads to artifcially low prolactin values. Defnitive proof should be assessed in all subjects in whom a prolactinoma is of a prolactinoma comes from the demonstration of a clini- being considered. Approximately 20% of patients with acro- cal response to a dopamine agonist because biopsy is not megaly have elevations in prolactin,7 making it necessary to routinely pursued. A trial of a dopamine agonist in unclear rule out this condition in patients with an elevated prolactin cases may be informative because a prolactinoma should level. The 48-hour test, still Indications for surgery include failure of medical therapy to performed at some centers,9 requires the administration of normalize prolactin levels when hyperprolactinemia is clin- 0. The latter test is more cumbersome but also more cal therapy, or the presence of apoplexy with neurologic specifc. Patients with hypercortisolism in general seen in patients with obesity, chronic illness, major depres- (including Cushing’s disease) may present with a variety of sion, or other psychiatric illnesses. A random el- syndrome, and a level <150 ng/dL is not suggestive of the evated serum cortisol is not sufcient to confrm a diagnosis condition, with intermediate levels prompting further test- because the stress from venipuncture alone may increase ing. Each of the options discussed above and the intermittent nature of hypercortisolemia in other remains viable screening tests as long as the limitations of patients. Once acromegaly is identifed, both surgical and medi- However, in patients with microadenomas, because of the cal therapeutic options for primary therapy are available. A lengthy discussion of preoperative evalua- responses to octreotide therapy in 26 patients who received tion of Cushing’s disease is beyond the scope of this chap- it as primary therapy, and 81 patients who received it fol- ter, but decisions regarding further diagnostic testing and lowing unsuccessful surgery or radiotherapy. For most patients we favor surgical debulking, even delay from disease onset to clinical recognition, earlier stage if not curative, because additional therapeutic modalities disease, prior to development of obvious clinical manifesta- are typically more feasible or efective following surgery. Other manifesta- (pegvisomant) therapy can be administered more safely tions include headache, arthralgias, jaw prognathism and once the threat of compression of surrounding structures is bite changes, arthritis, sleep apnea, diabetes mellitus, and reduced. Most authors accept a criterion of a peak cor- tisol after 250 µg of cortrosyn of greater than 18 to 20 µg/dL Gonadotropin-Secreting Tumors to be indicative of normal adrenal function. Some of these tumors do secrete ily exclude recent onset of secondary adrenal insufciency gonadotropins, but rarely do they produce clinical mani- because the adrenal glands in these patients may still re- festations. If a pathology analysis reveals tumor cells of stimulation test 1 to 3 months later, highlighting the limita- gonadotroph origin and preoperative levels are elevated, tions of this test in early secondary adrenal insufciency. Assessment of pituitary function is a critical part of the Therefore, at many centers, including ours, the assessment preoperative evaluation of a patient with a pituitary or sel- of pituitary-adrenal function preoperatively is typically be- lar mass given the risks of partial or complete hypopituita- gun with measurement of a morning cortisol level. These risks appear to be increased in patients with studies, mostly in the post-transsphenoidal surgery setting, macroadenomas or pituitary apoplexy at the time of pre- have attempted to determine what cortisol levels signify sentation. In addition to anterior pituitary dysfunction, some response, and those less than 110. In general, the preopera- 450 nmol/L (16 µg/dL) considered sufcient and a level less tive evaluation of anterior pituitary function requires the than 100 nmol/L (3. We prescribe glucocorticoid Patients with a pituitary or sellar mass should be assessed replacement therapy preoperatively always in patients with for signs and symptoms suggestive of secondary adrenal in- morning cortisol levels ≤5 µg/dL and usually in those patients sufciency, such as weakness and fatigue, hypotension, ab- with levels less than 270. The optimal test aim for the lowest dose, 10 mg in the morning and 5 mg in to establish the integrity of adrenal function preoperatively is the evening, so long as the patient feels well. For patients 40 Endoscopic Pituitary Surgery with morning cortisol levels greater than 270.
Like other Ca2+ channel blockers 30 mg vytorin free shipping, nifedipine is a relatively selective arterial vasodilator that does not substantially affect venous vasomotor tone discount 30 mg vytorin. This effect decreases arterial pressure, but in so doing, activates the sympathetic nervous system and elicits baroreceptor reflex-mediated increases in heart rate. Nifedipine produces direct myocardial depression in vitro, but this negative inotropic effect is not evident when the drug is used clinically because arterial vasodilation occurs at plasma concentrations that are substantially less than those required for reductions in myocardial contractility. Another more specific indication for this Ca2+ channel blocker is variant angina, a disease process in which reductions in coronary blood flow occur as a result of regional coronary vasoconstriction independent of coronary artery stenoses. Vasospasm may also occur in patients with unstable angina resulting from atherosclerosis, and nifedipine may also be beneficial in this setting. Nicardipine produces cardiovascular effects that are similar to nifedipine, but has a longer half-life than the latter drug. Nicardipine is a profound vasodilator because of its pronounced inhibition of Ca2+ influx in vascular smooth muscle. Like other dihydropyridine Ca2+ channel antagonists, nicardipine preferentially dilates arteriolar vessels; this effect decreases arterial pressure. As a result, stroke volume and cardiac output are relatively preserved or may increase. Nicardipine-induced decreases in arterial pressure trigger increases in heart rate through activation of baroreceptor reflexes, but the tachycardia observed during administration of nicardipine is less pronounced than typically occurs with sodium nitroprusside at comparable levels of arterial pressure. Nicardipine is also a highly potent coronary vasodilator and is often used to dilate arterial conduits during coronary artery bypass graft surgery. Because of its relatively long half-life, nicardipine is primarily used for treatment of sustained perioperative hypertension and not for acute, often transient hypertensive episodes that are commonly observed during surgery. Clevidipine Clevidipine is an ultra–short-acting dihydropyridine Ca2+ channel antagonist with a plasma half-life of approximately 2 minutes after intravenous administration. As a result of these differences in cellular electrophysiology, clevidipine is highly selective for arterial vascular smooth muscle and is nearly devoid of negative chronotropic or inotropic effects. Modest increases in heart rate may also occur during administration of clevidipine as a result of baroreceptor reflex activation. Unlike other short-acting antihypertensive drugs, clevidipine is not associated with the development of tachyphylaxis, and abrupt discontinuation of the drug does not appear to cause rebound hypertension. Because tissue and plasma esterases are responsible for 856 clevidipine metabolism, little to no accumulation of the drug occurs even in the setting of hepatic or kidney dysfunction. Clevidipine compares favorably with nitroglycerin, sodium nitroprusside, and nicardipine for the treatment of acute hypertension in cardiac surgery patients. As a result, nimodipine exerts more cerebral arterial vasodilation than other dihydropyridines. Food and Drug Administration for treatment of cerebral vasospasm after aneurysmal subarachnoid hemorrhage. Instead, nimodipine appears to reduce cerebral arteriolar resistance and enhance blood flow through pia mater collateral vessels. In addition, nimodipine may attenuate Ca2+-mediated neurotoxicity and thereby exert clinically beneficial neuroprotective effects. Intravenous administration of diltiazem produces arterial vasodilation and decreases arterial pressure. Oral administration of diltiazem reduces heart rate, 857 arterial pressure, and myocardial oxygen consumption. Both routes of administration cause coronary vasodilation and moderate negative inotropic effects. These combined properties make diltiazem a useful alternative medication for the treatment of patients with hypertension and symptomatic coronary artery disease155 in clinical situations in which β-adrenoceptor antagonists may be relatively contraindicated (e. Similarly, diltiazem may also prevent subsequent myocardial infarction in patients who have already suffered an infarction but cannot receive a β-adrenoceptor antagonist. As a result, baroreceptor reflex-mediated increases in heart rate that may be expected because of reductions in arterial vasomotor tone and systemic vascular resistance do not occur. Like diltiazem, verapamil is a coronary vasodilator and decreases myocardial oxygen consumption as a result of its hemodynamic effects. Thus, verapamil may be effective for the treatment of angina pectoris and myocardial infarction in patients who may be unable to tolerate β -adrenoceptor antagonists. For example, verapamil has been shown to significantly reduce the risk of supraventricular tachyarrhythmias in patients undergoing cardiac and noncardiac surgery because of these actions on the proximal cardiac conduction system. Verapamil is also contraindicated in patients with sick sinus syndrome or atrioventricular node dysfunction. Renal cortical juxtaglomerular cells secrete renin in response to decreases in Na reabsorption by the macula densa, reduced+ perfusion pressure to preglomerular arterioles, and β -adrenoceptor1 stimulation resulting from sympathetic nervous system activation. The net result of these+ + collective effects is elevated arterial pressure and increased intravascular volume. Sympathetic nervous system tone does not change despite the decrease in arterial pressure, and baroreceptor-mediated reflexes remain intact. The hemodynamic effects serve to reduce chronically elevated sympathetic nervous system tone because tissue perfusion improves, whereas the renal actions result in beneficial reductions in intravascular volume. Occupational exposure limits for 30 organophosphate pesticides based on inhibition of red blood cell acetylcholinesterase. Central mechanisms underlying short- and long-term regulation of the cardiovascular system. The effects of antimuscarinic treatments on overactive bladder: a systematic review and meta-analysis. Paradoxical pharmacodynamic effect of atropine on parasympathetic control: a study of spectral analysis of heart rate fluctuations. Complex dose-response curves of atropine in man explained by different functions of M1- and M2-cholinoreceptors. Abnormal intracellular calcium handling, a major cause of systolic and diastolic dysfunction in ventricular myocardium from patients with heart failure. Influence of beta1- versus beta2- adrenoceptor blockade on left ventricular function in humans. Differences between the mechanisms of adrenaline and noradrenaline secretion from isolated, bovine, adrenal chromaffin cells. Epinephrine and left ventricular function in humans: effects of beta-1 vs nonselective beta blockade. Dobutamine increases heart rate more than epinephrine in patients recovering from aortocoronary bypass surgery. Perioperative use of dobutamine in cardiac surgery and adverse cardiac outcome: propensity-adjusted analyses. Peripheral vascular effects of noradrenaline, isopropylnoradrenaline, and dopamine. Coronary perfusion pressure and the return of spontaneous circulation in human cardiopulmonary resuscitation. Part 7: Adultadvanced cardiovascular life support: 2015 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Methylene blue: the drug of choice for catecholamine-refractory vasoplegia after cardiopulmonary bypass? Meta-analysis: low-dose dopamine 864 increases urine output but does not prevent renal dysfunction or death. Influence of positive inotropic therapy on pulsatile hydraulic load and ventricular-vascular coupling in congestive heart failure. Dynamics of functional mitral regurgitation during dobutamine therapy in patients with severe congestive heart failure: A Doppler echocardiograhic study. Changes in regional myocardial function after coronary artery bypass are predicted by intraoperative low-dose dobutamine echocardiography. Management strategies for patients with pulmonary hypertension in the intensive care unit. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008. Drugs for the perioperative control of hypertension: current issues and future directions. A protocol for prevention of radiographic contrast nephropathy during percutaneous coronary intervention: effect of select dopamine receptor agonist fenoldopam. Fenoldopam mesylate blocks reductions in renal plasma flow after radiocontrast dye infusion: a pilot trial in the prevention of contrast nephropathy. Beneficial impact of fenoldopam in critically ill patients with or at risk for acute renal failure: a meta-analysis of randomized clinical trials.