By C. Hatlod. Virginia State University. 2019.

The acquisi­ dresses some of the limiting factors of traditional transsphe­ tion of endoscopic skills inherently involves the ability to noidal surgery: the long cheap 0.18 mg alesse with amex, narrow operative corridor 0.18 mg alesse otc, which translate a 2D image into a mental three-dimensional (3D) limits the feld of view 0.18mg alesse, and the inability to adequately assess representation of a given area order genuine alesse online. This occurs partially through extension of the pathology behind and around critical neuro­ monocular signals, including variations in color, size, and vascular structures. Despite these advances, conversion of overlap between the various displayed objects. Trained sur­ many neurosurgeons to this technology has been limited, geons also learn to infer spatial relations from haptic cues due partly to the nature of monocular vision of endoscopes. Despite these compensatory fac­ Monocular endoscopes create a two-dimensional (2D) im­ tors, 2D visualization does not match the depth perception age that impairs the surgeon’s perception of depth, spatial aforded by binocular cues, including vergence, stereopsis, relations, and the size of the anatomical structures. This leads to steeper learning curves for trainees, ice and experienced surgeons using 3D as compared with 2D such as residents and neurosurgeons, attempting neuroen­ endoscopes. Depth perception is mance time and error rates in surgical tasks for both resident thought to be critical to precise motor movement. This has and attending surgeons7,14 This appears to be more sensitive been demonstrated in one study that showed the primary as tasks increase in complexity. This works by surgery using a group of practicing skull base surgeons and placing a microscopic array of lenses in front of a single residents performing surgical tasks designed to simulate the video chip on the end of the scope. Hence, as demonstrated in other technology is based on a dual pupil imaging objective and studies, the 3D stereoendoscope makes a more signifcant an image sensor coated by an array of microlenses (a ple­ diference for novice users. The image is created by using a dual pupil laparoscopic surgeons reported improved subjective depth objective that splits light into two paths and a single lens perception but failed to identify any diference in task per­ that then multiplexes these two paths and focuses them formance using 2D versus 3D visualization. These data are processed through a would be in decreasing the learning curve for new users. This provides a natural stereoscopy, which some of the limitations described previously, could become is the two-eyed ability to judge depth, volume, or distance the wave of the future for all endoscopic procedures if de­ accurately. Although the optical resolution of well­designed lenses is generally greater than the resolution of digital image I Three-Dimensional Technology There are several current technologies available that create stereoscopic 3D images. The most widely available is based on dual­channel technology, which incorporates informa­ tion from two distinct perspectives to render a single 3D view, similar to human vision. Another version of this is dual chip-on- the­tip, similarly using a dual­channel video generated by two video chips on a single camera. The main disadvantage that exists with dual­camera technology is related to user side efects, such as fatigue, headache, dizziness, and eye strain, resulting from viewing two images that difer slightly in picture angle, brightness, color, optical distortion, and sharpness. The system also calculates volumetric information that limit the optical resolution. Endoscopes must have a small can be used to create hybrid images with other data sets in­ lens with a high depth of feld and a wide feld of view. The ini­ the endoscope and camera unit and separate light carrier tial endoscopes created with this technology were designed connect directly to the tower and monitor. The resolution for use in laparoscopic surgery and have been approved by of this camera is 800 × 400 pixels with a refresh rate of 50 the Food and Drug Administration for such use. The depth of feld is 15 to 70 mm with the endoscopes were available only as 0­degree endoscopes a feld of view of 70 degrees. Furthermore, the endoscope is of similar profle to display the images in 3D space. Furthermore, although little advantage appears when transitioning from a 2D endoscope to 3D, when con­ Perhaps the most exciting potential of 3D vision is the abil­ verting back to 2D the surgeons have noticed a signifcant ity to see anatomy that is present but not yet visible (i. Future studies will help to better structures deep to the plane of dissection or lying behind Fig. The pituitary gland was dissected from the sur- rounding dura, and the inferior hypophyseal arteries were cut. This would be accomplished by mapping out these critical structures are at potential risk without being in the structures preoperatively on an image­guided system and feld of vision. Specifcally, knowing where the internal ca­ then merging this on the monitor, so that the exact loca­ rotid artery, cavernous sinus, and optic nerve are at all times tion of a structure, such as the internal carotid artery, can could add an extra level of safety to these procedures. This type of image overlay rently available technology such as image­guided navigation provided through fusion of endoscopic and neuronavigation systems and micro-Dopplers can assist in these endeavors. The 3D en- doscopic image (A) and the designated object renderings in the neu- ronavigation software (B) (carotid arteries, circle of Willis, and tumor in this case) are combined to form the real-time endoscopic image C overlay (C). Neurosurgery 2004;55:933–940, discussion Three-dimensional endoscopy may represent the next 940–941 4. The endoscopic versus the technologic frontier in endoscopic anterior skull base and traditional approach in pituitary surgery. The ability to judge depth can only assist 2006;83:240–248 in understanding the location of critical structures. J Neurooncol 2001; more, it will ultimately allow the surgeon to gain better rec­ 54:187–195 ognition of the depth of the tumor to obtain a more complete 6. Finally, in addition to improvement in task comple­ transsphenoidal, transplanum transtuberculum approach for resec­ tion, it will likely decrease the barrier of entry into endoscopy tion of suprasellar lesions. Comparison of two- dimensional and three-dimensional suturing: is there a diference in a robotic surgery setting? Endoscopic pituitary surgery: a second-generation 3D endoscope on the laparoscopic precision of systematic review and meta-analysis. Causes and prevention of laparo­ tions associated with the endoscopic endonasal transsphenoidal ap­ scopic bile duct injuries: analysis of 252 cases from a human factors proach for pituitary adenomas. Curr Biol 1994;4:604–610 dimensional vs three­dimensional camera systems in laparoscopic 12. Infuence of two­dimensional versus three­dimensional imaging on performance three-dimensional vision on surgical telemanipulator performance. Comparison of three-dimensional and two-dimensional laparo­ improves surgical performance for both novice and experienced oper­ scopic video systems. A new 3-D laparoscope in neuroendoscopy: initial descriptions of application to clinical prac­ gastrointestinal surgery. Comparison of learn­ sional endoscopic sinus surgery: feasibility and technical aspects. Microendoscopic lumbar sional endoscopic exposure of midline cranial base targets using discectomy: technical note. Neurosurgery 2002;51(5, Suppl):S129– expanded endonasal and transcranial approaches. J Vasc Surg 2004;39:1305–1311 2009;64(5, Suppl 2):288–293, discussion 294–295 Endoscope-Assisted Transsphenoidal 20 Surgery Joshua R. Kelly The direct endonasal transsphenoidal approach for re- I Surgical Technique moval of pituitary adenomas was described over two decades ago. The panoramic vision provided by the endoscope allows one to visualize and access parasellar areas not pos- fcations as described below and in our recent publica- tions. Efective endoscopic assistance in endonasal pituitary adenoma removal can are given and continued for 24 hours. In patients with nor- translate into a more complete tumor removal in a wid- mal preoperative adrenal function or those with Cushing’s disease, no preoperative glucocorticoids are administered. This chapter describes the technique of endoscopic-assisted Those with adrenal insufciency or borderline adrenal func- endonasal pituitary surgery and methods of complication tion are given 100 mg of intravenous hydrocortisone. Transsphenoidal surgery emerged into the microsurgi- Patient Positioning and Room Setup cal era in the early 1970s with the advent of the operating microscope3,4 and the technique of selective adenomec- The endotracheal tube emerges from the left corner of the tomy as described by Hardy. An arterial line and Foley catheter are safety and efcacy of transsphenoidal surgery. The patient is placed supine with the head resting and Veerapen2 in 1987 and Cooke and Jones1 in 1994 freely in the horseshoe head-holder and angled approximately subsequently described the direct endonasal approach, 30 degrees toward the left shoulder as originally described by Laws,37 which allows the surgeon to stand comfortably on which minimizes patient discomfort associated with the sublabial approach. The patient’s head is typically inclined minimal posterior nasal mucosal dissection and no turbi- in a neutral plane (0 degrees) relative to the foor for most nate removal, is now commonly used with the operating pituitary adenomas. The nos- in the technique have resulted largely from better instru- trils and the perinasal and right lower abdominal areas are mentation, surgical navigation, and, most importantly, prepped and draped in standard fashion. Regardless of the tech- nique used, the surgical goal for patients with pituitary Surgical navigation for trajectory guidance is recommended adenomas should be a selective adenomectomy with pres- for all endonasal transsphenoidal surgeries, unless one is ervation or improvement of pituitary gland function. For most patients goal is best achieved by performing a wide and tall sphe- with a pituitary adenoma, C-arm fuoroscopy is simple and noidotomy and complete sellar bony opening to maximize efective for giving excellent trajectory guidance in the sag- sellar exposure and instrument maneuverability. It is particularly helpful in 202 20 Endoscope-Assisted Transsphenoidal Surgery 203 patients with prior surgery or large invasive tumors with markedly distorted anatomical landmarks. If fuoroscopy is used, the base of the operating microscope is placed just outside the arc of the C-arm above the patient’s head, with the microscope to the patient’s right side. Endoscopic Equipment and Setup The endoscope video monitor and tower are placed above the patient’s head on the patient’s left side to allow for com- fortable viewing by the surgeon and the assistant who will be standing on the patient’s right side. Standard 4-mm rigid endoscopes (18 cm long) with 0-, 30-, and 45-degree angled lenses should be available.

M3G is the major metabolite and about54 60% of morphine is converted into M3G alesse 0.18 mg with amex, while just 5% to 10% is converted to M6G 0.18 mg alesse visa. Due to its low lipophilicity buy 0.18 mg alesse otc, passage of54 M6G across the blood–brain barrier is slow and consequently limited order alesse 0.18mg on-line. In the gut both glucuronides54 are deglucuronidated and the resultant morphine molecule is partly absorbed by the enterocytes. Enterocytes are able to metabolize morphine and transport the resultant M3G and M6G and remnant morphine to the bloodstream (the enterohepatic cycle). Since the morphine-glucuronides are excreted via the kidney, patients with renal failure are at risk for M6G-related side effects. In patients with compromised renal function morphine treatment causes M6G to accumulate in high concentrations that may cause loss of consciousness and severe respiratory depression. Fentanyl, alfentanil, and sufentanil are metabolized by the liver, catalyzed by the cytochrome P450 enzyme system. This causes a rapid clearance of the drug (context sensitive half-life of 2 minutes) making it the most rapidly acting opioid currently available. Clearance of remifentanil is 3 to 5 L/min, which exceeds liver blood flow affirming its extrahepatic clearance. Remifentanil is usually administered as a continuous infusion since its plasma level decreases by 50% in as little as 40 seconds. Methadone has a 60%60 to 95% oral bioavailability, high potency, and a long duration of action. Furthermore, there is considerable variation among recipients in the response to the drug. While methadone has properties which make it attractive for use intravenously as a perioperative analgesic, in a controlled and well-monitored environment, these same properties may prove hazardous when methadone is administered orally for treatment of patients with chronic pain. Large numbers of patient deaths have been attributed to the long, and often unpredictable, duration of action of methadone when administered orally. The most important metabolic pathway of naloxone is glucuronidation into the inactive naloxone-3-glucuronide. Its duration of effect is short, ranging from 15 to 45 minutes, which requires it to be redosed or administered as a continuous infusion when antagonism is required for 1318 long-acting opioids or for patients experiencing an opioid overdose. These models allow dosing regimens to62 be constructed on the basis of patient characteristics such as total or lean body weight, gender, age, and other characteristics, making them particularly helpful when treating individual patients. In compartmental models, the concentration–time profiles are described by drug transfer between interconnected hypothetical compartments, mimicking drug absorption, distribution, elimination, and metabolism. The delay between the peak drug concentration in the plasma and the peak concentration at the effect site is described by the plasma–effect site equilibration constant ke0 (or its half-life t½k = ln 2/e0 ke0),63,64 which is commonly referred to as hysteresis. For the analgesic and respiratory depressive effects of opioids, the hysteresis is determined by the drug’s passage across the blood–brain barrier (the more lipophilic an opioid, the faster the transfer into the brain compartment), receptor kinetics, and neuronal dynamics. This is related to differences in physiology, underlying disease, age, weight, ethnicity, and other factors. The C50 and t½ke0 derived from these studies are useful to compare the potency and onset/offset of opioids. For alfentanil and fentanyl C50 values range from 75 and 1 ng/mL for sedation to 150 and 2 ng/mL for analgesia, respectively. In Table 20-2 values of t½k for the end points of pain relief and respiratory depression are givene0 for various analgesics currently in use. This variability is not restricted to69 morphine, but is observed for all opioids used for treatment of acute, perioperative, and chronic pain, including strong opioids such as fentanyl and remifentanil. Recently it was shown that the ability to score pain in a consistent and reliable fashion depends on various factors, including the presence of chronic pain and prior opioid administration (Fig. In chronic pain patients these changes may be due to neuroplastic changes in the frontal and parietal cortices. Scores are divided into good, mediocre, and poor, reflecting the amount of deviation from an expected pain score. Translation of random painful stimuli into numerical responses in fibromyalgia and perioperative patients. This admonition to carefully titrate the administration of opioids is perhaps even more crucial when administering long-acting opioids orally for the treatment of chronic pain. During surgery opioids are titrated in doses sufficient to dampen and prevent exaggerated hemodynamic responses to painful surgical stimuli. In the postoperative period (and in chronic pain patients) opioids are usually titrated to the patient’s verbal response to pain. This distinction requires not only a difference in administration, but also a difference in vigilance with respect to opioid side effects. During anesthesia one should be aware of hypotension and 1322 bradycardia, a common side effect of strong opioids. In contrast, in the postoperative period the most important side effects to avoid are respiratory depression and severe sedation, while other non–life-threatening side effects impacting patient satisfaction and health costs are nausea/vomiting and loss of bowel motility. Morphine In two studies on the postoperative effects of morphine following major surgery, the average intravenous dose of morphine to reach 50% pain relief was 20 mg. This dose resulted in a plasma concentration of 34 ng/mL and a t½k of about 2 hours, although the initial onset of analgesia occurrede0 between 15 and 30 minutes. Surprisingly, these parameters are not influenced by the patient’s age, weight, and gender. Given the long time to peak analgesia, a practical strategy for dosing morphine in adults is to give an initial morphine bolus dose (0. Figure 20-7 Simulated effect of multiple bolus doses of fentanyl (100 to 150 μg) during anesthesia, and morphine during and following anesthesia, on the analgesic and 1323 hemodynamic state of the patient. The blue and red lines are the simulated fentanyl and morphine plasma concentration (Cp). During anesthesia, the combination of fentanyl and propofol (orange line) provides greater analgesia than opioids alone (green line). When propofol infusion is terminated the analgesic profile reverts to a lower level (from orange via orange-green to green line). The dotted lines are the arbitrary divisions between adequate anesthesia and inadequate anesthesia, and adequate analgesia and inadequate analgesia. First, the postoperative analgesic regimen should be multimodal with morphine (or any other opioid), and combined with opioid-sparing drugs such as acetaminophen and nonsteroidal anti-inflammatory drugs such as diclofenac. Second, some patients require large doses of morphine, yet their pain appears unresponsive to morphine. Both drugs are analgesics in their own right and enhance morphine’s analgesic effect. Like all opioids the analgesic response to intravenous fentanyl is highly variable. However, fentanyl’s t½k for analgesic effect is longer with valuese0 ranging between 10 and 20 minutes ; fentanyl’s potency (66 C ) for analgesia 50 ranges from 1 to 2 ng/mL. Fentanyl is used during anesthesia to dampen66 cardiovascular responses to noxious stimulation from laryngoscopy, intubation, skin incision, and surgical stress. On average, the requirements for inhalational anesthetics and propofol are reduced by about 50% when 1324 administering 1. Be aware that a continuous infusion leads to the accumulation of the drug in the body as its 50% context-sensitive half-time increases rapidly with the duration of infusion (Fig. Taking into account the drug’s t½k fentanyl shoulde0 be administered 5 to 10 minutes prior to an anticipated painful/stressful event such as laryngoscopy or skin incision (Fig. In the 1980s, high-dose fentanyl was often used in combination with nitrous oxide to provide both analgesia and suppression of consciousness. Although this combination provided excellent hemodynamic stability, it could not assure amnesia. For example, the fentanyl patch is used in a large number of cancer and noncancer chronic pain patients. The transcutaneous delivery of fentanyl ranges from 12 to 100 μg/hr, although absorption depends on a variety of factors such as skin thickness, subcutaneous fat layer, and subcutaneous perfusion. Peak analgesic effect is reached only after 10 to 12 hours and the effect of one patch lasts 3 to 4 days. Other methods of administration include intranasal fentanyl, sublingual fentanyl, fentanyl lozenges (a solid preparation in the form of a lollipop), mucosal patch—all four methods are used for treatment of breakthrough pain—and iontophoretic transdermal fentanyl applications. The home use of fentanyl in chronic pain patients comes with the danger of misuse and abuse by the patients or by family members or friends.

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However buy alesse 0.18 mg mastercard, by the 1980s it was clear that comparisons at the genomic level would provide the most fundamen- tal measure of epidemiological relatedness generic 0.18mg alesse mastercard. Goering While a wide range of etiological agents are of clinical concern purchase 0.18 mg alesse otc, this review focuses on molecular approaches to the epidemiological analysis of bacterial pathogens buy 0.18 mg alesse visa. In any area of scientific investigation, state of the art methodology may be viewed from two different perspectives. There are cutting-edge techniques requiring spe- cialized equipment and expertise that perform remarkably well but are of limited availability to many investigators. Alternatively, there are functional state of the art approaches, meaning that one is using the best method available within the prevail- ing (financial, geographic, technical expertise, etc. In this context, it is important to recognize that while one may not have access to the most recently published sophisticated methods, from an epidemiological standpoint, it is better to do something rather than nothing. Thus, this review begins with examples of estab- lished molecular typing techniques which, depending on the (financial, geographic, scientific) environment, may still be viewed as state of the art while also consider- ing more recently described cutting-edge approaches. Nevertheless, the totality of these sequences makes the cell a specific strain of Pseudomonas aeruginosa , Staphylococcus aureus, Escherichia coli, etc. Thus, the bacterial genome represents the most fundamental molecule of identity in the cell and the common goal of molecular typing approaches is to pro- vide a measure of isolate genomic relatedness [10 ]. While all bacterial cells can theoretically be analyzed by such a process, the 13 Molecular Typing Techniques: State of the Art 241 Fig. Consequently, at the present time this method continues to be recommended only for use with Clostridium dif fi cile [12]. For diagnostic purposes, tests to detect the presence or absence of clinically relevant sequences (e. For epidemiological analysis, probes specific for sequences found at multiple chromosomal locations can be hybridized against chro- mosomal restriction enzyme fragments which have been electrophoretically sepa- rated. However, electrophoretic analysis of the megabase-size restriction fragments generated is complicated by their size-independent migration during conventional agarose-gel electrophoresis [16, 17]. This is especially true for molecular typing where for the majority of bacterial pathogens it remains the acknowledged “gold standard” for assessing isolate interrelationships. A wide range of bacterial pathogens can be analyzed using a small number of different restriction enzymes (commonly SmaI and XbaI for gram-posi- tive and -negative isolates, respectively). After staining with a fluorescent dye, fluorescent microscopy coupled with appropriate software converts the optical image to a digital format producing restriction maps of the individual molecules. The overlapping maps are then assembled to produce an ordered restric- tion map of the entire chromosome. While a large group of restriction fragments are initially created, only specific subsets are utilized for isolate compari- son. The adapter design includes extra nucleotides beyond the restriction-site sequence allowing only a subset of fragments to be amplified. Using labeled primers the specificity of the process may be further controlled, ultimately leading to an electrophoretic pattern of amplified products that becomes the basis for assessing isolate interrelationships. However, issues regarding data analysis and inter-laboratory sharing, and the specialized equipment required for electrophoresis have limited the use of this method in the clinical setting. The resulting amplicons represent inter-repeat distances that do not exceed the capability of the Taq polymerase (Fig. Goering than by conventional agarose gel electrophoresis, and software for data analysis. However, it is important to note that the amplicons generated typically include a variety of similar sizes which are a challenge to separate by agarose gel electropho- resis. Nevertheless, the patterns obtained are amenable to databasing and inter- laboratory comparison especially with regard to highly toxigenic strains such as C. Staphylococcal Cassette Chromosome mec Typing Staphylococci resistant to the antibiotic methicillin, especially S. These occur by slipped strand mispairing during chro- mosomal replication resulting in the insertion or deletion of repeat units [43–45]. However, it is important to emphasize that strain typing based on electrophoretic banding patterns is primarily a comparison of chromosomal fragment sizes rather than specific genomic content. Goering regarding issues of typing pattern nomenclature, databasing, and interlaboratory sharing. Nevertheless, as noted earlier, in the context of locally available economic and scientific resources these methods continue to remain of value as options for the epidemiological evaluation of problem bacterial pathogens. Sequence-based approaches have a number of addi- tional advantages over electrophoresis-based typing methods including: 1. Older molecular methods for epidemiological analysis involve numerous experi- mental variables including types of equipment, reagents, experimental protocols, etc. Electronic storage and sharing of data from electrophoresis-based typing meth- ods is accomplished using bitmapped (e. However, the larger the number of isolates the more unwieldy the process can become. In addition, some form of nomenclature must be used to identify and interrelate isolate banding patterns. With large data sets, the use of appropriate computer software is essential to accomplish this process. However, the frame- work for data sharing, storage, and retrieval is necessarily based on visual images and the limits that format imposes. Conversely, nucleotide sequences represent simple, highly portable, quaternary data that can much more easily be shared, stored, and retrieved. As will be discussed more fully later, the most crucial aspect of any typing method is its ability to detect significant (epidemiologically-relevant) differ- ences between isolates. While the goal of molecular typing is a comparison of chromosomal similarity, electrophoretic banding patterns only indirectly address this issue. Despite computer programs which can assist the process, there is always an element of end user judgment that can affect the final evaluation. In contrast, nucleotide sequence data allows direct and unambiguous genomic comparison. Single-Locus Sequence Typing Since the genome of bacterial pathogens is mega-base in size, it is remarkable to think that a single locus of ca. In Europe this has led to the formally organized use of spa typ- ing in the epidemiological monitoring of specific S. Strepcococcus pyogenes M Protein (emm ) Typing The cell surface M protein is an important virulence factor in S. Genomic analysis has revealed that the M protein locus (emm) is variable and can encode at least 100 different M protein types which were initially detected and cata- loged serologically. As a result, sequence-based emm typing is currently the most widely used approach to group A streptococcal epidemiology [53–56 ]. Goering of emm types contributing to specific disease in different global regions (e. Seven genes are typically employed, the sequences of which are assigned numeric allelic designations (Fig. However, this is not the case with array-based methods where thousands of specific oligonucleotide probes 254 R. The power of this approach has been applied to the characterization of a wide variety of clinically relevant organisms [3, 70–72 ]. However, while microar- rays have the potential for high-throughput genomic analysis their use is not cost- effective for routine clinical use. In addition, a high level of technical expertise is required especially for data analysis which can be complicated by “background” noise due to partial hybridization, etc. However, the utility of this suspension-based approach for strain typing remains to be thoroughly evaluated. Whole Genome Sequence Typing As noted earlier, the goal of molecular strain typing is epidemiological assessment based on the most fundamental molecule of identity in the cell—the bacterial chro- mosome. While this was impossible with older dideoxy/ chain termination sequencing technology [74], newer (i. All of these are currently in a state of flux as commercial technology improves and positions itself in the scientific market- place.

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Nitroglycerin dilates both normal and poststenotic epicardial coronary arteries 0.18mg alesse fast delivery, enhances blood flow through coronary collateral vessels generic alesse 0.18 mg free shipping, and preferentially improves subendocardial perfusion buy alesse 0.18mg otc. These effects are particularly important in patients with acutely decompensated heart failure resulting from myocardial ischemia purchase alesse 0.18 mg. Thus, nitroglycerin is a very effective first-line drug for the treatment of myocardial ischemia. Nevertheless, caution should be exercised when using nitroglycerin in patients with ischemia who are also hypovolemic because the drug may precipitate life-threatening hypotension by further compromising 851 coronary perfusion pressure and reducing coronary blood flow despite epicardial vasodilation. Not surprisingly, sodium nitroprusside is a first-line drug for the treatment of hypertensive emergencies. Unlike nitroglycerin, sodium nitroprusside is relatively contraindicated in patients with acute myocardial ischemia because the drug causes abnormal redistribution of coronary blood flow away from ischemic myocardium (“coronary steal”). This effect occurs because sodium nitroprusside produces greater coronary vasodilation in vessels that perfuse normal myocardium compared with those that supply the ischemic territory, the latter of which are already maximally vasodilated. This reflex tachycardia dramatically increases heart rate and myocardial oxygen consumption, thereby exacerbating acute myocardial ischemia. Sodium nitroprusside is often combined with a β -adrenoceptor antagonist such as1 esmolol to decrease arterial pressure, depress myocardial contractility, and reduce ascending aortic wall stress in patients with acute aortic dissection until direct surgical control of the injury can be achieved. Clinical use of sodium nitroprusside is limited by its toxic metabolites, which predictably accumulate when administration is prolonged or relatively high doses are used. Metabolism of sodium nitroprusside produces cyanide, which binds with cytochrome C to inhibit aerobic metabolism and cause lactic acidosis. Cyanide derived from sodium nitroprusside metabolism also binds with hemoglobin to form methemoglobin and with sulfur to form thiocyanate. The latter metabolite may accumulate in patients with renal insufficiency and produce neurologic complications including delirium and seizures. Hydralazine Hydralazine is a direct vasodilator that reduces intracellular Ca2+ concentration in vascular smooth muscle. The primary reduction in afterload stimulates baroreceptor reflex-mediated tachycardia and increases cardiac output. The magnitude of tachycardia observed with administration of hydralazine is often greater than expected based solely on baroreceptor reflexes alone and may reflect a direct effect of the drug on cardiovascular regulation in the central nervous system. This pronounced tachycardia might produce acute myocardial ischemia in patients with critical coronary stenoses based on increases in myocardial oxygen demand. Hydralazine-induced tachycardia responds appropriately to β -adrenoceptor antagonists, but1 caution should be exercised because further declines in arterial pressure may also occur. Hydralazine is commonly used for management of sustained postoperative hypertension in the absence of tachycardia. Calcium Channel Blockers Ca2+ channels are asymmetric biochemical pores consisting of at least four subunits (α , α /δ, and β with or without gamma) that traverse many1 2 biologic membranes. Myocardial and vascular smooth muscle cell membranes contain two types of voltage-dependent Ca2+ channels that are defined on the basis of the duration of opening: T (transient) and L (long). The L-type Ca2+ channel is the predominant target of Ca2+ channel blockers in current clinical use. Ca2+ channel blockers may be divided into four chemical groups including 1,4-dihydropyridines (e. In general, Ca2+ channel blockers produce varying degrees of vasodilation; direct negative chronotropic, dromotropic, and inotropic effects; and baroreceptor reflex-mediated increases in heart rate, depending on each drug’s selectivity for myocardial and vascular smooth muscle L-type Ca2+ channels. All Ca2+ channel blockers produce greater relaxation of arterial, compared with venous, vascular smooth muscle. Ca2+ channel blockers cause coronary arterial vasodilation and inhibit coronary artery 853 vasospasm. These actions may enhance coronary blood flow assuming that coronary perfusion pressure is not substantially reduced as a result of arterial vasodilation. As a result, these Ca2+ channel blockers may not exert anti-ischemic effects in patients with hemodynamically significant coronary artery stenoses. Like other Ca2+ channel blockers, nifedipine is a relatively selective arterial vasodilator that does not substantially affect venous vasomotor tone. 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.

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There are pale rounded structures order 0.18 mg alesse free shipping, the glomeruli purchase alesse 0.18 mg otc, with no residual cellular or nuclear features and no associated inflammation generic alesse 0.18mg without prescription. The infarcted nephron elements are packed closely 0.18mg alesse, with little intersti- tial space. The loss of tubular volume results in the depressed lesions noted on gross examination 4. Because the central portions of the renal pyramids have the most marginal blood supply, small infarcts usually affect this region. More severe ischemic injury may result in infarction of most, or all, of the pyramid. When papillary necrosis is severe and bilateral, it is a devas- tating disease that usually leads to death Causes of renal papillary necrosis include: • Diabetes mellitus • Urinary tract obstruction • Acute pyelonephritis Fig. This image shows the interface between a • Analgesic abuse remote infarct and viable cortex. Between the infarcted glomeruli and • Sickle cell disease the normal cortex is a thin zone of glomeruli showing ischemic obsoles- • Hypoxia cence. Note the yellow linear lesions in the central portion of the inner medulla; this is the zone with the most mar- ginal blood supply. This is an example of diffuse not infarcted renal papillary necrosis that developed in a diabetic patient. In addition to necrosis of the entire compound pyramid on the right, there also is sloughing of two pyramids on either side of it. Sloughed renal pyramids occasionally are detected in the urine of affected patients Fig. This patient had nephrotic kidney with diffuse papillary necrosis in most pyramids lim- lower urinary tract obstruction and developed acute pyelonephritis as ited to the inner medulla or papillae. Because the papillae contain the terminal confluence of the medullary collecting ducts, all nephrons in the affected lobes can no longer function and will undergo atrophy 4. Although it is referred to as renal cortical necrosis, renal medullary necrosis also exists. It usually is bilateral but may be unilateral in patients with unilateral injury to the main renal artery. Only the gross is illustrated here, because the histology is identical to that of acute renal infarction. Causes of renal cortical necrosis include: • Obstetric complications – Abruptio placentae – Septic abortion – Intrauterine fetal demise • Infections Fig. The nephrectomy kidney contained several renal pyramids • Burns with centrally located remote medullary infarcts. This was an unsus- • Gastrointestinal hemorrhage pected fi nding • Transfusion reactions • Toxins • Hemolytic uremic syndrome • Trauma • Iatrogenic causes Fig. The parenchyma is soft and pale, the cortex more so than the medulla, although both were necrotic. This renal pyramid in an autopsy kidney from a patient with severe diabetic nephropathy shows a remote infarct of the central medulla and papillary tip that has under- gone dystrophic calci fi cation and osseous metaplasia 170 4 Renal Vascular Diseases 4. Renal artery thrombosis may be unilateral or bilateral, and may be associ- ated with concomitant aortic thrombosis. Causes of renal artery thrombosis include: • Umbilical artery catheters in neonates • Blunt abdominal trauma Fig. In this example of renal cortical • Intra-aortic balloons necrosis, although the outer cortex is pale with a hyperemic rim along • Renal transplantation the inner cortex and the outer medulla, the entire kidney was histologi- • Electrical injury cally necrotic Fig. If blood flow is reestablished fol- lowing renal cortical necrosis, hemorrhage into the parenchyma may Fig. This is a pediatric case in which there was sepsis with hypoten- in a young adult female with fibromuscular dysplasia of the renal artery. Re-establishment of the blood flow prior to death resulted in An arterial graft was placed, which thrombosed soon after surgery. The the severely hemorrhagic appearance of the kidneys at autopsy kidney was deemed not salvageable. Patients with renal vein throm- bosis may present with flank pain and hematuria, as well as nephrotic syndrome and renal failure if bilateral. Renal histo- logic findings are few, but interstitial edema marginating neutrophils within dilated capillaries and bland thrombi may be present. Renal venous thrombosis involves the intrarenal veins, such as arcuate and interlobular veins, not the main renal vein. Pediatric patients are most often affected, and like renal cortical necrosis, it usually is a complication of a serious sys- temic disease. There also is thrombosis of several tributaries, includ- ing several lobar veins and possibly even more proximal veins Fig. This was a traumatic complication of a motor vehicle accident 172 4 Renal Vascular Diseases Fig. The venous location of the thrombi may be difficult to appreci- able as such because its endothelial cell lining is visible. Notice also ate because cortical veins lack a smooth muscle media and resemble that it is located adjacent to an artery supporting the venous location of large-caliber capillaries. Both are associated with acute renal fail- • Arterial aneurysm erosion ure, high-output heart failure, and risk of sudden death from • In fl ammation rupture. In this example of an arterio- venous malformation presenting in a young adult, two major vessels are apparent: one is arterial and one is venous; each has aneurysmal dilata- Fig. Although the vein has a thickened wall and is becoming arterial- ized, the differing organization of its medial smooth muscle helps dis- tinguish it from an artery Fig. This arteriovenous fistula from a renal transplant consists of several tortuous large arteries and thick-walled veins. This may be a renal biopsy–associated complication because the patient had undergone prior biopsy 174 4 Renal Vascular Diseases 4. The classification schema most commonly used is the Chapel Hill Classification (Table 4. Typically when vasculitis illustrated here: microscopic polyangiitis (most common affects the kidney, glomerular involvement predominates, member of this group), polyarteritis nodosa (very uncom- with development of a crescentic glomerulonephritis (dis- mon, affecting arteries of arcuate caliber or larger), granulo- cussed in detail in Chap. The proper classification of a matosis with angiitis (previously known as Wegener’s patient with vasculitis often is challenging because there is granulomatosis), and a very rare entity, isolated giant cell clinical and histologic overlap between the most common arteritis. This case of microscopic poly- angiitis shows three interlobular arteries with transmural fibrinoid necrosis. On gross examination, the kidney affected by necrotizing vasculitis may have a “flea-bitten” appearance as a result of numerous foci of hemorrhagic necrosis, similar to what may be seen in malignant hypertension. This autopsy case shows small hemorrhagic foci in the cortex representing necrotic arteries with adja- cent hemorrhage (see Fig. This artery shows circumferential transmural fibrinoid necrosis of an interlobular artery. Diffuse crescentic glomerulonephritis was also present, the more com- mon renal manifestation of this disease 4. Shown is an arcuate artery showing necrotizing arteritis with complete destruction of the arterial wall, that Fig. In this example of arteritis in a patient with granulomatosis with methenamine silver–stained specimen. A few remnants of the adventi- polyangiitis, the artery is inflamed with both neutrophils and multinu- tial elastic fibers are visible at the edge of the fibrinoid material. Although severely damaged, fibrinoid necrosis is not is early organization or healing in the lower left, a typical feature of present. This was associated with diffuse crescentic glomerulonephri- polyarteritis nodosa tis, the more common manifestation of this disease in the kidney Fig. In this patient with organ-iso- nodosa with necrotizing lesions restricted to arcuate arteries. This arcu- lated granulomatous arteritis, there was no evidence of extrarenal dis- ate artery also shows both acute and chronic lesions. However, this artery cannot normalize forms a cuff around the central artery but curiously there is no apparent its structure arterial damage, such as fibrinoid necrosis or thrombosis, by the granu- lomatous reaction. Cholesterol crystal embolization: Hypertension-Associated Renal Disease a review of 221 cases in the English literature.

In addition to the promotion of pyocyanin production order alesse on line, Pseudosel agar also enables the detection of fluorescent products by some Pseudomonas species other than P generic 0.18mg alesse visa. A blue-green pigmentation surrounding the growth on the agar slant indicates positive reaction purchase alesse 0.18mg on line. Negative Pseudosel slants should be examined under short-wavelength (254 nm) ultraviolet light to check for fluorescent products produced by some Pseudomonas species purchase alesse in india. Urea Agar Slant Microorganisms that possess the enzyme urease are capable of hydrolyzing urea, which releases ammonia. This reaction raises the pH of the medium and is detected by phenol red, which turns pink-red above pH 8. The color change first appears in the slant since the oxidative decarboxylation of amino acids in the air-exposed portion of the medium enhances the alkaline reaction. Stuart’s urea broth and Christensen’s urea agar are the two most common media used in the detection of urease activity. Streak the surface of the urea agar slant with a heavy inoculum of a pure culture. Production of intense pink-red color on the slant, which may penetrate into the butt, is considered positive reaction. The utilization of peptones or other proteins in the medium by some urease-negative organisms may raise the pH due to protein hydrolysis and release of amino acid residues, resulting in false positive reactions [ 1, 15 ]. Aslanzadeh Citrate Agar Slant Some organisms have the ability to utilize citrate, an intermediate metabolite in the Krebs cycle, as the sole external source of carbon. These organisms also utilize inorganic ammonium salts in the medium as the sole source of nitrogen. The resulting production of ammonia creates an alkaline environment that turns the bromthymol blue indicator to an intense blue. Using an inoculating loop, select a well-isolated colony and streak the surface of the Simmons’s citrate slant (do not stab the agar). Growth with an intense blue color on the agar slant indicates positive reaction and no growth and no color change (green) indicate negative reaction. Luxuriant growth on the slant without an accompanying color change may indicate a positive test. Therefore, the medium should not be stabbed, and the cap must be kept loose during incubation. Carryover of protein and carbohydrate substrates from previous media may provide additional sources of carbon and therefore, cause false-positive reactions [15 ]. Cetrimide Agar Cetrimide agar is a selective differential medium used for the identification of P. The principle of the test is to determine the ability of an organism to grow in the presence of cetrimide. The magnesium chloride and potassium sulfate of the medium stimulate the production of pyocyanin and pyoverdin (fluorescein). Using an inoculating loop, select a well-isolated colony and streak the surface of the cetrimide slant (do not stab the agar). Growth on the agar slant indicates positive reaction and no growth indicates negative reaction [4, 15]. Gelatin The gelatin test is used to identify bacteria that produce the proteolytic enzyme, gelatinase. Organisms that produce gelatinase are capable of hydrolyzing gelatin and cause it to lose its gelling characteristics. Inoculate several well-isolated colonies deep into the gelatin and repeat to inoculate heavily. Alternatively, strips of exposed but undeveloped X-ray film are placed in the bacterial suspension of equivalent to at least 2. The strip is examined after 24 and 48 h for loss of gelatin coating that leaves the X-ray clear [6 ]. Acetate slants contain a mixture of salts and sodium acetate in a medium without organic nitrogen. Organisms that can utilize acetate as a sole carbon source break down sodium acetate causing the pH of the medium to shift toward the alkaline range, turning the bromthymol blue indicator blue. Organisms that cannot utilize acetate as a sole carbon source do not grow on the medium. Streak the surface of the acetate differential agar slant (do not stab the agar) with a colony and cap the tube loosely. Growth with an intense blue color on the agar slant indicates positive test and no growth or no color change (green) indicates negative test. Luxuriant growth on the slant without an accompanying color change may indicate a positive test. Therefore, the medium should not be stabbed, and the cap must be kept loose during incubation. Carryover of protein and carbohydrate substrates from previous media may provide additional sources of carbon and therefore, cause false-positive reactions [15 ]. Lead Acetate for Hydrogen Sul fi de Detection Some organisms are capable of enzymatically liberating sulfur from sulfur-containing amino acids or inorganic sulfur compounds. The released hydrogen sulfide reacts with lead acetate to yield lead sulfide, an insoluble black precipitate. Lead acetate is the most sensitive H2S indicator reagent and is useful with organisms that produce trace amounts of H2S, especially organisms that are not in the family Enterobacteriaceae. The pH indicator, bromcresol purple, is changed to a yellow color at or below pH 5. Ferric ammonium citrate and sodium thiosulfate are indicators of hydrogen sulfide formation. Lysine serves as the substrate for detect- ing the enzymes lysine decarboxylase and lysine deaminase. Alkaline (purple) reaction in butt indicates Lysine decarboxylation; red slant indicates Lysine deamination and black precipitate indicates H S 2 production. H2S may not be detected in this medium by organisms, which are negative for lysine decarboxylase activity since acid production in the butt may suppress H S2 formation. For this reason, H S-producing 2 Proteus species do not blacken this medium [ 15]. Phenol red serves as an indicator to detect pH change, and ferrous sulfate detects the formation of H S. If the organism ferments lactose and/or sucrose, the slant will remain acidic (yellow). If the organism is unable to ferment lactose or sucrose, the slant will revert to alkaline (red) when the glucose is used up and alkaline amines are produced in the oxidative decarboxylation of peptides (derived from protein in the medium) near the surface of the agar. If acid slant–acid butt (yellow–yellow): glucose and sucrose and/or lactose fermented. The presence of black precipitate (butt) indicates hydrogen sulfide production and presence of splits or cracks or air bubbles indicates gas production. Early readings may result in false acid–acid results, while delayed readings may result in false alkaline–alkaline results. The utilization of sucrose may suppress the enzyme mechanism that results in the production of H2S. Trace amounts of H2S may not be detectable with the ferrous sulfate indicator in the agar [1, 15]. Following the incubation, add 4–5 drops of 10 % ferric chloride solution to the slant. The development of green color on the surface of the slant indicates positive reaction. Decarboxylase (Moeller’s Method) Decarboxylases are a group of substrate-specific enzymes that are capable of decar- boxylate (or hydrolyze) amino acids to form alkaline-reacting amines. Lysine, ornithine, and arginine are the three amino acids used routinely in the identification of Enterobacteriaceae, Aeromonas, Plesiomanas, and Vibrio species. The decarboxylation of lysine and ornithine yields cadaverine and putrescine, respectively. A control tube containing the base without an added amino acid to verify that the organism utilizes glucose must accompany all decarboxylase tests. Since decarboxylation is an anaerobic reaction, the tubes must be overlaid with mineral oil prior to incubation. If the organism is viable, both the control and the test tube with amino acid should turn yellow because of fermentation of the small amount of glucose in the medium.

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Intraoperative transesophageal echocardiography provides excellent assessment of left and right ventricular functions as well as guidance of fluid resuscitation buy alesse 0.18 mg low price. There is no place for either furosemide or mannitol therapy in the early discount 0.18mg alesse, resuscitative phase of trauma 3544 management buy cheap alesse on-line, except in the case of head injury with elevated intracranial pressure or when massive rhabdomyolysis is suspected effective alesse 0.18 mg. Vascular surgery requiring aortic clamping has deleterious effects on renal function regardless of the level of clamp placement. Atheromatous renal artery emboli and prolonged aortic clamp time may contribute to ische-mic renal injury in these patients. The endovascular approach (endostent) to major aortic surgery has gained popularity. Although hemodynamic changes during endovascular procedures on the aorta may be less dramatic than those accompanying open repair, the prevalence of renal complications appears to be similar. During endovascular procedures, patients may be exposed to substantial amounts of radiocontrast dye, which can exacerbate postoperative renal dysfunction, especially in those with pre-existing renal insufficiency. The long-term incidence of renal insufficiency/failure (followed up to 24 months postoperatively) is similar after endovascular and open repair of aortic aneurysm. It is thus important that before endovascular procedures, patients are adequately hydrated, and the total dose of radiocontrast dye is limited. Although increased urine flow rate is a consistent finding with low-dose infusion of dopamine, there is no evidence in collective analysis of numerous randomized studies that this is associated with preservation of renal function during aortic surgery. Fenoldopam, a selective dopamine-1 receptor agonist, showed some promise as a renal protective agent but has not been tested in large multicenter prevention trials in the perioperative setting. When the serum conjugated bilirubin exceeds 8 mg/dL, endotoxins from the gastrointestinal tract are absorbed into the portal circulation, causing intense renal vasoconstriction. Intravenous mannitol and/or oral administration of bile salts in the preoperative period may limit renal dysfunction in patients with cholestatic jaundice. For each section, general disease principles and treatment rationales are briefly discussed, perioperative management and potential complications reviewed, and then important aspects related to specific procedures within the section highlighted (e. Notably, a deliberate approach has been taken to minimize repetition by referring the reader to other chapter sections whenever appropriate. Nephrectomy Nephrectomy procedures involve partial, radical, or simple resection of the kidney. Each year in the United States, there are approximately 46,000 3546 nephrectomies for benign or malignant disease, and an additional 5,500 donor surgeries for renal transplant. Although radical nephrectomy is the standard for resectable kidney cancer, simple nephrectomy is typical for benign disease. Kidney transplant donor nephrectomy involves simple nephrectomy with measures to avoid organ trauma and optimize graft function. The so-called nephron-sparing or partial nephrectomy is indicated for limited benign disease but increasingly is being considered for wider indications, including selected cancerous lesions. The approach and incision for nephrectomy are based on surgical priorities and surgeon preference. Retroperitoneal approaches require a flank incision and lateral decubitus positioning with flank extension (Fig. This approach has obvious advantages for treatment of infection but also simplifies procedures in those with prior abdominal surgery or obesity. Difficulties with the retroperitoneal approach include access to the vena cava, risk of unintentional pneumothorax, and the adverse effects of lateral decubitus position and flank extension on respiratory vital capacity, which can be reduced up to 20% (see Chapter 29). Anterior approaches to nephrectomy involve supine positioning and breach of the peritoneal cavity through midline, subcostal, or thoracoabdominal incisions that provide direct access to both the kidney and major vascular structures. Although transperitoneal approaches add the risk of visceral injury and peritonitis, they improve access to the renal pedicle (e. The thoracoabdominal approach enters both the peritoneal and pleural spaces and rarely may require single-lung ventilation. In recent years, laparoscopic retro- and transperitoneal approaches to nephrectomy have surpassed their open equivalents in popularity, particularly for simple and donor procedures, but these techniques are even being used for nephron-sparing partial nephrectomy. Other recent innovations include robotic-assisted, single-port laparoscopic, and even transvaginal minimally invasive nephrectomies. Preoperative Considerations Recruits for donor nephrectomy surgery are typically healthy individuals; however, perioperative risk for other nephrectomy procedures often relates to the indication for surgery. Hence, protocols for assessment and management of perioperative cardiac risk are particularly relevant to nephrectomy surgery. Elective procedures involve irreversible kidney damage due to chronic pyelonephritis (e. Figure 50-7 Common positioning options for urologic surgery include right lateral decubitus with waist extension (A), lithotomy (B), supine with steep (30 to 45 degrees) Trendelenburg (C), and exaggerated lithotomy (D). Ten to forty percent of patients presenting with renal cancer have associated paraneoplastic syndromes. Renal tumors may also be associated with a hypercoagulable state; sudden intraoperative clot formation has been reported. Urologic surgery patients often present with additional disease workup that can provide a wealth of information beyond routine studies and assessment of their urinary tract. Standard recommended preoperative management of chronic drug therapies is all that is necessary for most nephrectomy procedures, although dose adjustment may be considered if significant changes in renal function are anticipated. Intraoperative Considerations Preparation for even the most straightforward nephrectomy surgery demands sufficient monitoring and vascular access to respond to complications, most notably significant hemorrhage, an uncommon but ever-present risk in such procedures. Although central venous line placement is not essential for most nephrectomy surgeries, patient and procedural factors such as comorbidities (e. If placement of a central venous catheter is deemed necessary, selection of the side ipsilateral to the nephrectomy surgery for subclavian or internal jugular central venous puncture should be considered to minimize the risk of bilateral pneumothorax. Assessment of infection, bony metastases, and bleeding risk may influence the decision to include neuraxial procedures in the anesthesia plan. If a lumbar or thoracic epidural catheter is placed, this is usually done prior to anesthesia induction to allow for a meaningful test dose sequence and to facilitate preincision administration of epidural opiates. Varied opinions regarding intraoperative local anesthetic dosing of the epidural catheter involve concerns over hemodynamic stability and the likelihood of significant blood loss during the procedure. Bladder catheter placement is essential for all nephrectomy procedures; urinary output monitoring provides information on intravascular volume status in the absence of central venous pressure monitoring, avoids the possibility of urinary retention, and also provides valuable information postoperatively regarding renal function, bleeding sources, and the possibility of clot-related urinary tract obstruction. Standard preanesthesia induction considerations include postoperative planning (e. Plans for postoperative analgesia strategy may dictate disposition particularly to involve a care team capable of recognizing and treating potential complications of the various analgesia strategies. Intraoperative and postoperative pain management can be accomplished by intravenous or other opioid therapies such as patient- controlled analgesia or neuraxial analgesia. Continuous epidural analgesia attenuates the neuroendocrine response but may also improve postoperative ventilatory mechanics and resolve ileus sooner, and has been associated with improved survival in intermediate- to high-risk noncardiac surgery. Complications associated with hemorrhage during nephrectomy are uncommon but mandate preparatory steps beyond monitoring and generous intravenous access. Confirmation that blood products are present or readily available should occur immediately prior to surgery. Routine fluid and patient warming technology, availability of colloid volume expanders, and even a rapid transfusion device for selected cases should also be considered. Because unexplained changes in pulmonary mechanics or hypotension during a nephrectomy procedure may reflect diaphragmatic injury and pneumothorax, such changes should be discussed with the surgeon to facilitate prompt intervention. This may require direct repair of a rent in the diaphragm as well as needle decompression of a pneumothorax and chest tube insertion. Particularly in the setting of limited renal reserve, in addition to consideration of transfusion triggers and strict avoidance of unjustifiable blood product administration, a note of caution is warranted regarding the potential for resuscitation “overshoot” in response to acute hemorrhage. Strict attention to appropriate monitors during fluid resuscitation and appropriate use of arterial blood gas assessment, assisted by good communication with the surgeon, will help avoid the risk of pulmonary edema from fluid overload. Postoperative Considerations Up to 20% of patients undergoing nephrectomy develop postoperative complications, and operative mortality rates following radical nephrectomy are as high as 2%. Added to standard concerns, such as hemorrhage and unrecognized visceral injury, are atelectasis, ileus, superficial and deep wound infections, temporary or permanent renal failure, and incisional hernia. The most common radical nephrectomy complications are adjacent organ (4% bowel, spleen, liver, diaphragm, or pancreas) and vascular injury (2%). Overall complication rates are similar whether an open or laparoscopic 3551 approach is used. Analgesia can be achieved with epidural or spinal analgesia strategies, systemic opioids, and nonopioid adjuncts. Recent findings of improved recovery using epidural analgesia for major abdominal surgeries149 have not been assessed specifically for nephrectomy surgery. Specific Procedures Simple and Donor Nephrectomies Simple nephrectomy is sufficient intervention for irreversible nonmalignant disease such as untreatable infection, unsalvageable kidney trauma, or a nonfunctioning kidney due to calculi or hypertensive disease.

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