Asacol
Mr. Leo Pinczewski MBBS FRACS
- North Sydney Orthopaedic and Sports Medicine Centre
- Sydney, NSW
- Australia
The uterine cavity (in particular treatment xdr tb guidelines purchase discount asacol online, the cervical canal) and the lumen of the vagina together constitute the birth canal symptoms 2 days after ovulation order asacol 400mg overnight delivery, through which the fetus passes at the end of gestation medicine grace potter discount asacol master card. Perimetrium-the serosa or outer serous layer-consists of peritoneum supported by a thin layer of connective tissue medicine 44291 buy asacol with amex. Myometrium-the middle layer of smooth muscle-becomes greatly distended (more extensive but much thinner) during pregnancy medicine 035 cheap asacol online mastercard. The main branches of the blood vessels and nerves of the uterus are located in this layer medicine 223 buy asacol with a mastercard. During childbirth, contraction of the myometrium is hormonally stimulated at intervals of decreasing length to dilate the cervical os and expel the fetus and placenta. Endometrium-the inner mucous layer-is firmly adhered to the underlying myometrium. The endometrium is actively involved in the menstrual cycle, differing in structure with each stage of the cycle. If conception occurs, the blastocyst becomes implanted in this layer; if conception does not occur, the inner surface of this layer is shed during menstruation. The amount of muscular tissue in the cervix is markedly less than in the body of the uterus. The cervix is mostly fibrous and is composed mainly of collagen with a small amount of smooth muscle and elastin. The two layers of the broad ligament are continuous with each other at a free edge that surrounds the uterine tube. Laterally, the peritoneum of the broad ligament is prolonged superiorly over the vessels as the suspensory ligament of the ovary. Between the layers of the broad ligament on each side of the uterus, the ligament of the ovary lies posterosuperiorly and the round ligament of the uterus lies antero-inferiorly. The uterine tube lies in the anterosuperior free border of the broad ligament, within a small mesentery called the mesosalpinx. Similarly, the ovary lies within a small mesentery called the mesovarium on the posterior aspect of the broad ligament. The largest part of the broad ligament, 1422 inferior to the mesosalpinx and mesovarium, which serves as a mesentery for the uterus itself, is the mesometrium. The principal supports of the uterus holding it in this position are both passive and active or dynamic. Its tone during sitting and standing and active contraction during periods of increased intra-abdominal pressure (sneezing, coughing, etc. When intra-abdominal pressure is increased, the uterus is pressed against the bladder. Uterosacral ligaments pass superiorly and slightly posteriorly from the sides of the cervix to the middle of the sacrum; they are palpable during a rectal examination. Together, these passive and active supports keep the uterus centered in the pelvic cavity and resist the tendency for the uterus to fall or be pushed through the vagina (see the Clinical Box "Disposition of Uterus"). Anteriorly, the uterine body is separated from the urinary bladder by the vesico-uterine pouch, where the peritoneum is reflected from the uterus onto the posterior margin of the superior surface of the bladder. Posteriorly, the uterine body and supravaginal part of the cervix are separated from the sigmoid colon by a layer of peritoneum and the peritoneal cavity and from the rectum by the recto-uterine pouch. The peritoneum is intact, lining the pelvic cavity and covering the superior aspect of the bladder, fundus and body of uterus, and much of the rectum. In this supine cadaver, the uterine tube and mesosalpinx on each side are hanging down, obscuring the ovaries from view. The round ligament of the uterus follows the same subperitoneal course as the ductus deferens of the male. Anteriorly (antero-inferiorly in its normal anteverted position): the supravesical fossa and vesico-uterine pouch of the peritoneal cavity and the superior surface of the bladder. The supravaginal part of the cervix is related to the bladder and is separated from it by only fibrous connective tissue. Posteriorly: the recto-uterine pouch containing loops of small intestine and the anterior surface of rectum. Only the visceral pelvic fascia uniting the rectum and uterus here resists increased intra-abdominal pressure. Laterally: the peritoneal broad ligament flanking the uterine body and the fascial cardinal ligaments on each side of the cervix and vaginal. The uterine veins enter the broad ligaments with the arteries and form a uterine venous plexus on each side of the cervix. The vaginal orifice, external urethral orifice, and ducts of the greater and lesser vestibular glands open into the vestibule of the vagina, the cleft between the labia minora. The vaginal orifice is usually collapsed toward the midline so that its lateral walls are in contact on each side of an anteroposterior slit. The vagina lies anterior to the rectum, passing between the medial margins of the levator ani (puborectalis) muscles. The posterior vaginal fornix is the deepest part and is closely related to the recto-uterine pouch. Muscles that compress the vagina and act as sphincters include the pubovaginalis, external urethral sphincter (especially its urethrovaginal sphincter part), and bulbospongiosus. These veins are continuous with the uterine venous plexus as the uterovaginal venous plexus and drain into the internal iliac veins through the uterine vein. Presynaptic sympathetic fibers 1428 traverse the sympathetic trunk and pass through the lumbar splanchnic nerves to synapse in prevertebral ganglia with postsynaptic fibers; the latter fibers travel through the superior and inferior hypogastric plexuses to reach the pelvic viscera. Visceral afferent fibers conducting pain from subperitoneal structures, such as the cervix and vagina. Most of the vagina (superior three quarters to four fifths) is visceral in terms of its innervation. Nerves to this part of the vagina and to the uterus are derived from the uterovaginal nerve plexus, which travels with the uterine artery at the junction of the base of the (peritoneal) broad ligament and the superior part of the (fascial) transverse cervical ligament. The uterovaginal nerve plexus is one of the pelvic plexuses that extend to the pelvic viscera from the inferior hypogastric plexus. Sympathetic, parasympathetic, and visceral afferent fibers pass through this plexus. The visceral afferent innervation of the superior (intraperitoneal; fundus and body) and inferior (subperitoneal; cervical) parts of the uterus and vagina differs in terms of course and destination. The two different routes followed by visceral pain fibers is clinically significant in that it offers mothers a variety of types of anesthesia for childbirth (see the Clinical Box "Anesthesia for Childbirth"). All visceral afferent fibers from the uterus and vagina not concerned with pain (those conveying unconscious sensations) also follow the latter route. Conversely, inflammation of a tube (salpingitis) may result from infections that spread from the peritoneal cavity. A major cause of infertility in women is blockage of the uterine tubes, often the result of salpingitis. Accumulation of radiopaque fluid or the appearance of gas bubbles in the pararectal fossae (pouch) region of the peritoneal cavity indicates that the tubes are patent. Arrowheads, uterine tubes; c, catheter in the cervical canal; vs, vaginal speculum. Oocytes released from the ovaries that enter the tubes of these patients degenerate and are soon absorbed. Surgical tubal sterilizations are performed using either an abdominal or laparoscopic approach. Open abdominal tubal sterilization is 1431 usually performed through a short suprapubic incision made at the pubic hairline and involves removal of a segment or all of the uterine tube. In this procedure, tubal continuity is interrupted by applying cautery, rings, or clips. A hysterosalpingography is performed after 3 months to ensure that the uterine tubes are completely occluded. Ectopic Tubal Pregnancy Tubal pregnancy is the most common type of ectopic gestation (embryonic implantation and initiation of gestational development outside of the body of the uterus); it occurs in approximately 1 of every 250 pregnancies in North America (Moore et al. If not diagnosed early, ectopic tubal pregnancies may result in rupture of the uterine tube and severe hemorrhage into the abdominopelvic cavity during the first 8 weeks of gestation. In some women, collections of pus may develop in a uterine tube (pyosalpinx) and the tube may be partly occluded by adhesions. In these cases, the morula (early embryo) may not be able to pass along the tube to the uterus, although sperms have obviously done so. When the blastocyst forms, it may implant in the mucosa of the uterine tube, producing an ectopic tubal pregnancy. Ectopic pregnancies also occur idiopathically (without demonstrable or understood reason) in women, and there is increased risk in cases of faulty tubal sterilization. This relationship explains why a ruptured tubal pregnancy and the resulting peritonitis may be misdiagnosed as acute appendicitis. In both cases, the parietal peritoneum is inflamed in the same general area, and the pain is referred to the right lower quadrant of the abdomen. The epoophoron forms from remnants of the mesonephric tubules of the mesonephros, the transitory embryonic kidney (Moore et al. There may also be a persistent duct of the epoophoron (duct of Gartner), a remnant of the mesonephric duct that forms the ductus deferens and ejaculatory duct in the male. It lies between layers of the broad ligament along each side of the uterus and/or vagina. A vesicular appendage is 1434 sometimes attached to the infundibulum of the uterine tube. It is the remains of the cranial end of the mesonephric duct that forms the ductus epididymis. Although these vestigial structures are mostly of embryological and morphological interest, they occasionally accumulate fluid and form cysts. Once marked, retroversion and/or retroversion was thought to be a potential predisposing factor in uterine prolapse or to present a potential complication in pregnancy; however, this has proven to be unjustified. The size and other characteristics of the uterus can be determined in this way. When softening of the uterine isthmus occurs (Hegar sign), the cervix feels as though it were separated from the body of the 1436 uterus. Because of the small size of the pelvic cavity during infancy, the uterus is mainly an abdominal organ. The cervix remains relatively large (approximately 50% of total uterus) throughout childhood. During this phase of life, the uterus undergoes monthly changes in size, weight, and density in relation to the menstrual cycle. All these stages represent normal anatomy for the particular age and reproductive status of the woman. Cervical Cancer Screening Until 1940, cervical cancer was the leading cause of death in North American women (Krebs, 2000). The decline in the incidence and number of women dying from cervical cancer is related to the accessibility of the cervix to direct visualization and to cell and tissue study by means of cervical cytology (invented in 1946 by Dr. Cervical cytology allows detection and treatment of premalignant cervical conditions (Hoffman et al. Because no peritoneum intervenes between the anterior cervix and the base of the bladder, cervical cancer may spread by contiguity to the bladder. It may also spread by lymphogenous (lymph-borne) metastasis to external or internal iliac or sacral nodes. Hematogenous (bloodborne) metastasis may occur via iliac veins or via the internal vertebral venous plexus. The incidence of hysterectomy for noncancerous reasons has markedly declined in favor of exploring other options. The procedure stops abnormal bleeding but also stops menstrual periods and ends the ability to conceive. The incidence of 1440 hysterectomy for noncancerous reasons has markedly declined in favor of exploring other options. Depending on the location, extent, and nature of the pathology, a subtotal (supracervical or cervical), total, or radical hysterectomy may be performed, the latter involving removal of the ovaries in addition to the uterus. When cervical or total hysterectomies are performed, the vaginal fornices are incised, encircling the cervix, to separate the uterus from the vagina. Ligation of the uterine artery is performed distal to the vaginal artery and vaginal branches to enable maximal blood flow to the superior end of the vagina to facilitate healing. Distension of Vagina 1441 the vagina can be markedly distended, particularly in the region of the posterior part of the fornix. For example, distension of this part allows palpation of the sacral promontory during a pelvic examination (see the Clinical Box "Pelvic Diameters (Conjugates)").
Opposite the ischial spine medications mothers milk thomas hale buy asacol 800 mg low price, they curve anteromedially medications used for depression order asacol without prescription, superior to the levator ani treatment glaucoma cheap 400mg asacol mastercard, and enter the urinary bladder symptoms 10 weeks pregnant discount asacol 400mg with visa. The ureters pass obliquely through the muscular wall of the urinary bladder in an inferomedial direction symptoms lymphoma cheap asacol, entering the outer surface of the bladder approximately 5 cm apart treatment xdr tb buy line asacol, but their internal openings into the lumen of the empty bladder are separated by only half that distance. This oblique passage through the bladder wall forms a one-way "flap valve," the internal pressure of the filling bladder causing the intramural passage to collapse. In addition, contractions of the bladder musculature act as a sphincter preventing the reflux of urine into the ureters when the bladder contracts, increasing internal pressure during micturition. The ureter lies posterolateral to the ductus deferens 1366 and enters the posterosuperior angle of the bladder, just superior to the seminal gland. In females, the ureter passes medial to the origin of the uterine artery and continues to the level of the ischial spine, where it is crossed superiorly by the uterine artery (see the Clinical Box "Iatrogenic Injury of Ureters"). It then passes close to the lateral part of the fornix of the vagina and enters the posterosuperior angle of the bladder. The ureteric branches anastomose along the length of the ureter forming a continuous blood supply, although not necessarily effective collateral pathways. The most constant arteries supplying the terminal parts of the ureter in females are branches of the uterine arteries. The blood supply of the ureters is a matter of great concern to surgeons operating in the region (see the Clinical Box "Iatrogenic Compromise of Ureteric Blood Supply"). Branches supplying the abdominal half of the ureter approach medially, while those supplying the pelvic half approach laterally. If necessary, traction of the ureters is applied gently and only toward the blood supply to avoid disruption of the small branches. The venous drainage from the pelvic parts of the ureters generally parallels 1368 the arterial supply, draining to veins with corresponding names. Ureteric pain is usually referred to the ipsilateral lower quadrant of the abdomen, especially to the groin (inguinal region). The bladder is a temporary reservoir for urine and varies in size, shape, position, and relationships according to its content and the state of neighboring viscera. Compare its relation to the anterior abdominal wall, pubic symphysis, and level of the supravesical fossa to that of the nondistended (empty) bladder in part B. In this female pelvis, the uterus was sectioned in its own median plane and is depicted as though it coincided with the median plane of the body, which is seldom the case. With the bladder empty, the normal 1372 disposition of the uterus shown here-bent on itself (anteflexed) at the junction of the body and cervix of the uterus and tipped anteriorly (anteverted)-causes its weight to be borne mainly by the bladder. The bladder usually enters the greater pelvis by 6 years of age; however, it is not located entirely within the lesser pelvis until after puberty. Adult bladder and prostate demonstrating their pelvic location (inset) and the surfaces of the bladder. Coronal section of urinary bladder and prostate in the plane of the prostatic urethra. At the end of micturition (urination), the bladder of a normal adult contains virtually no urine. The apex of the bladder points toward the superior edge of the pubic symphysis when the bladder is empty. The fundus of the bladder is opposite the apex, formed by the somewhat convex posterior wall. The body of the bladder is the major portion of the bladder between the apex and the fundus. Toward the neck of the male bladder, the muscle fibers form the involuntary internal urethral sphincter. This sphincter contracts during ejaculation to prevent retrograde ejaculation (ejaculatory reflux) of semen into the bladder. In males, the muscle fibers in the neck of the bladder are continuous with the fibromuscular tissue of the prostate, whereas in females, these fibers are continuous with muscle fibers in the wall of the urethra. The ureteric orifices are encircled by loops of detrusor musculature that tighten when the bladder contracts to assist in preventing reflux of urine into the ureter. The main arteries supplying the bladder are branches of the internal iliac arteries (see Table 6. In males, the inferior vesical arteries supply the fundus and neck of the bladder. The obturator and inferior gluteal arteries also supply small branches to the bladder. The veins draining blood from the bladder correspond to the arteries and are tributaries of the internal iliac veins. It also receives blood from the deep dorsal vein of the penis, which drains into the prostatic venous plexus. The vesical venous plexus is the venous network that is most directly associated with the bladder itself. It mainly drains through the inferior vesical veins into the internal iliac veins; however, it may drain through the sacral veins into the internal vertebral venous plexuses. The parasympathetic fibers are motor to the detrusor muscle and inhibitory to the internal urethral sphincter of the male bladder. Consequently, when visceral afferent fibers are stimulated by stretching, the bladder contracts reflexively, the internal urethral sphincter relaxes (in males), and urine flows into the urethra. With toilet training, we learn to suppress this reflex when we do not wish to void. The sympathetic innervation that stimulates ejaculation simultaneously causes contraction of the 1376 internal urethral sphincter, to prevent reflux of semen into the bladder. Sensory fibers from most of the bladder are visceral; reflex afferents follow the course of the parasympathetic fibers, as do those transmitting pain sensations. The superior surface of the bladder is covered with peritoneum and therefore is superior to the pelvic pain line (see Table 6. The distal intermediate part and spongy urethra will be described further with the perineum. A portion of the posterior wall of the bladder has been removed to reveal the intramural part of ureter and the ductus deferens posterior to the bladder. The interureteric fold runs between the entrances of the ureters into the bladder lumen, demarcating the superior limit of the trigone of the bladder. The prominence of the posterior wall of the internal urethral orifice (at the tip of the leader line indicating this orifice), when exaggerated, becomes the uvula of the bladder. This enlarged detail of the boxed area in (A) demonstrates the bulbo-urethral glands embedded in the substance of the external urethral sphincter. The intramural (preprostatic) part of the urethra varies in diameter and length, depending on whether the bladder is filling. During filling, the neck of the bladder is tonically contracted so the internal urethral orifice is small and high. During emptying, the neck of the bladder is relaxed so the orifice is wide and low. The seminal colliculus is a rounded eminence in the middle of the urethral crest with a slitlike orifice that opens into a small cul-de-sac, the prostatic utricle. The utricle is the vestigial remnant of the embryonic uterovaginal canal, the surrounding walls of which, in the female, constitute the primordium of the uterus and a part of the vagina (Moore et al. The ejaculatory ducts open into the prostatic urethra via minute, slit-like openings located adjacent to and occasionally just within the orifice of the prostatic utricle. The prostatic plexus is one of the pelvic plexuses (an inferior extension of the vesical plexus) arising as organ-specific extensions of the inferior hypogastric plexus. The musculature surrounding the internal urethral orifice of the female bladder is not organized into an internal sphincter. The female external urethral orifice is located in the vestibule of the vagina, the cleft between the labia minora of the external genitalia, directly anterior to the vaginal orifice (ostium). The urethra passes with the vagina through the pelvic diaphragm, external urethral sphincter, and perineal membrane. One group of glands on each side, the para-urethral glands, are homologs to the prostate. These glands have a common para-urethral duct, which opens (one on each side) near the external urethral orifice. The external urethral sphincter is located in the perineum and is discussed in that section. The nerves to the urethra arise from the vesical (nerve) plexus and the pudendal nerve. Visceral afferents from most of the urethra run in the pelvic splanchnic nerves, but the termination receives somatic afferents from the pudendal nerve. The sigmoid colon is intraperitoneal, suspended by the sigmoid mesocolon, but the rectum becomes retroperitoneal and then subperitoneal as it descends. The peritoneum has been removed superior to sacral promontory and right iliac fossa, revealing the superior hypogastric plexus lying in the bifurcation of the abdominal aorta and the internal iliac artery, ureter, and ductus deferens crossing the pelvic brim to enter the lesser pelvis. The rectum follows the curve of the sacrum and coccyx, forming the sacral flexure of the rectum. The rectum ends antero-inferior to the tip of the coccyx, immediately before a sharp postero-inferior angle (the anorectal flexure of the anal canal) that occurs as the gut perforates the pelvic diaphragm (levator 1382 ani). With the flexures of the rectosigmoid junction superiorly and the anorectal junction inferiorly, the rectum has an S shape when viewed laterally. The flexures are formed in relation to three internal infoldings (transverse rectal folds): two on the left side and one on the right side. The folds overlie thickened parts of the circular muscle layer of the rectal wall. The ampulla receives and holds an accumulating fecal mass until it is expelled during defecation. The ability of the ampulla to relax to accommodate the initial and subsequent arrivals of fecal material is another essential element of maintaining fecal continence. Despite their name, the inferior rectal arteries, which are branches of the internal pudendal arteries, mainly supply the anal canal. The three sharp lateral flexures of the rectum reflect the way in which the lumen navigates the transverse rectal folds (shown in part B) on the internal surface. This coronal section 1383 of the rectum and anal canal demonstrates the arterial supply and venous drainage. The internal and external rectal venous plexuses are most directly related to the anal canal. Peritoneum covers the anterior and lateral surfaces of the superior third of the rectum, only the anterior surface of the middle third, and no surface of the inferior third because it is subperitoneal (see Table 6. In males, the peritoneum reflects from the rectum to the posterior wall of the bladder, where it forms the floor of the rectovesical pouch. In females, the peritoneum reflects from the rectum to the posterior part of the fornix of the vagina, where it forms the floor of the recto-uterine pouch. The rectum lies posteriorly against the inferior three sacral vertebrae and the coccyx, anococcygeal ligament, median sacral vessels, and inferior ends of the sympathetic trunks and sacral plexuses. The rectovesical septum lies between the fundus of the bladder and the ampulla of the rectum and is closely associated with the seminal glands and prostate. Inferior to this pouch, the weak rectovaginal septum separates the superior half of the posterior wall of the vagina from the rectum. The right and left middle rectal arteries, which often arise from the anterior divisions of the internal iliac arteries in the pelvis, supply the middle and inferior parts of the rectum. The inferior rectal arteries, arising from the internal pudendal arteries in the perineum, supply the anorectal junction and anal canal. Anastomoses between the superior and inferior rectal arteries may provide potential collateral circulation, but anastomoses with the middle rectal arteries are sparse. Anastomoses occur between the portal and systemic veins in the wall of the anal canal. The submucosal rectal venous plexus surrounds the rectum, communicating with the vesical venous plexus in males and the uterovaginal venous plexus in females. Although these plexuses bear the term rectal, they are primarily "anal" in terms of location, function, and clinical significance (see "Venous and Lymphatic Drainage of Anal Canal"). The sympathetic supply is from the lumbar spinal cord, conveyed via lumbar splanchnic nerves and the hypogastric/pelvic plexuses and through the peri-arterial plexus of the inferior mesenteric and superior rectal arteries. The 1386 lumbar and pelvic splanchnic nerves and hypogastric plexuses have been retracted laterally for clarity.
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In the Norwood repair medications post mi asacol 400mg free shipping, a new aorta is created from the hypoplastic aorta and the main pulmonary artery medicine vile buy cheap asacol 800 mg line. A hybrid approach has also been advocated for the palliation of hypoplastic left heart syndrome medications diabetes asacol 400 mg on-line. These patients may present to the operating room early in the postoperative period for mediastinal exploration or retransplantation medicine norco buy asacol 800mg amex, or they may appear later for incision and drainage of infections 1950s medications asacol 800mg discount, orthopedic surgery symptoms nausea dizziness cheapest asacol, or unrelated procedures. Although sympathetic fibers are similarly interrupted, the response to circulating catecholamines is normal or even enhanced because of denervation sensitivity (increased receptor density). Cardiac output tends to be low-normal and increases relatively slowly in response to exercise because the response is dependent on an increase in circulating catecholamines. Because the Starling relationship between end-diastolic volume and cardiac output is normal, the transplanted heart is also often said to be preload dependent. Preoperative evaluation should focus on evaluating the functional status of the transplanted organ and detecting complications of immunosuppression. Rejection may be heralded by arrhythmias (in the first 6 months) or decreased exercise tolerance from a progressive deterioration of myocardial performance. Periodic echocardiographic evaluations are commonly used to monitor for rejection, but the most reliable technique is endomyocardial biopsy. Accelerated atherosclerosis in the graft is a very common and serious problem that limits the life of the transplant. Moreover, myocardial ischemia and infarction are almost always silent because of the denervation. Because of this, patients must undergo periodic evaluations, including angiography, for assessment of coronary atherosclerosis. Important side effects include nephrotoxicity, bone marrow suppression, hepatotoxicity, opportunistic infections, and osteoporosis. Anesthetic Management Almost all anesthetic techniques, including regional anesthesia, have been used successfully for transplanted patients. The preload-dependent function of the graft makes maintenance of a normal or high cardiac preload desirable. Moreover, the absence of reflex increases in heart rate can make patients particularly sensitive to rapid vasodilation. Isoproterenol or epinephrine infusions should be readily available to increase the heart rate if necessary. Direct arterial pressure monitoring should be used for major operations; strict asepsis should be observed during placement. In a recently transplanted patient, the right ventricle of the transplanted heart may not be able to overcome the resistance of the pulmonary vasculature. Right ventricular failure can occur perioperatively, requiring the use of inhaled nitric oxide, inotropes, and, at times, right ventricular assist devices. Maintenance of right heart function is essential to adequately supply the left side of the heart with sufficient blood for the device to eject. A history of syncope in elderly patients should always raise the possibility of arrhythmias and underlying organic heart disease. Although arrhythmias can occur in the absence of organic heart disease, the two are commonly related. Cardiac syncope usually results from an abrupt arrhythmia that suddenly compromises cardiac output and impairs cerebral perfusion. Lightheadedness and presyncope, may reflect lesser degrees of cerebral impairment. Reversible abnormalities may be due to abnormal vagal tone, electrolyte abnormalities, drug toxicity, hypothermia, or myocardial ischemia. Irreversible abnormalities, which initially may be only intermittent before they become permanent, reflect either isolated conduction system abnormalities or underlying heart disease (most commonly hypertensive, coronary artery, or valvular heart disease). She gives a history of two episodes of lightheadedness several days prior to her fall today. The significance of a conduction system abnormality depends on its location, its likelihood for progression to complete heart block, and the likelihood that a more distal pacemaker site will be able to maintain a stable and adequate escape rhythm (>40 beats/min). The term hemiblock is often used if only one of the two fascicles of the left bundle-branch is blocked (left anterior or left posterior hemiblock). Patients may experience intermittent dizziness, syncope, confusion, fatigue, or shortness of breath. During isorhythmic dissociation, the atria and ventricles beat independently at nearly the same rate. A bifascicular block exists when two of the three major His bundle-branches (right, left anterior, or left posterior) are partially or completely blocked. Intracardiac electrocardiographic recordings would be necessary to confirm the site of the conduction delay. One of two approaches can be recommended, depending on the urgency of the surgery. If the surgery is truly emergent, a temporary transvenous pacing catheter or a transcutaneous pacemaker is indicated prior to induction of general or regional anesthesia. The first three indications generally require ventricular pacing, whereas the fourth requires atrial pacing electrodes and a programmable rapid atrial pulse generator. Pacing can be established by transvenous, transcutaneous, epicardial, or transesophageal electrodes. The most reliable method is generally via a transvenous pacing electrode in the form of a pacing wire or a balloon-tipped pacing catheter. A pacing wire should always be positioned fluoroscopically, but a flow-directed pacing catheter can also be placed in the right ventricle under pressure monitoring. Transcutaneous ventricular pacing is also possible via large stimulating adhesive pads placed on the chest and should be used whenever transvenous pacing is not readily available. Pacing the left atrium via an esophageal electrode is a simple, relatively noninvasive technique, but it is useful only for symptomatic sinus bradycardias and for terminating some supraventricular tachyarrhythmias. Once positioned, the pacing electrodes are attached to an electrical pulse generator that periodically delivers an impulse at a set rate and magnitude. The lowest current through the electrode that can depolarize the myocardium is called the threshold current (usually <2 mA for transvenous electrodes). Ventricular pacing often reduces cardiac output because the atrial contribution to ventricular filling is lost. The spike rate should be identical to the programmed (permanent pacemaker-usually 72/min) or set (temporary) pacemaker rate; a slower rate may indicate a low battery. If the patient has a temporary pacemaker, the escape rhythm can be established by temporarily slowing the pacing rate. In this instance, ventricular capture cannot be evaluated unless the pacemaker rate increases or the spontaneous heart rate decreases. Chamber Paced O = none A = atrium V = ventricle D = dual (atrium and ventricle) Chamber Sensed O = none A = atrium V = ventricle D = dual (atrium and ventricle) Response to Sensing O = none T = triggered l = inhibited D = dual (triggered and inhibited) Programmability O = none P = simple M = multiprogrammable C = communicating R = rate modulation Antitachyarrhythmia Function O = none P = pacing S = shock D = dual (pacing and shock) What intraoperative conditions may cause the pacemaker to malfunction Electrical interference from surgical electrocautery units can be interpreted as myocardial electrical activity and can suppress the pacemaker generator. Problems with electrocautery may be minimized by limiting its use to short bursts, limiting its power output, placing its grounding plate as far from the pacemaker generator as possible, and using bipolar cautery. Moreover, continuous monitoring of an arterial pulse wave (pressure, plethysmogram, or oximetry signal) is mandatory to ensure continuous perfusion during electrocautery. If a temporary pacemaker fails intraoperatively, the inspired oxygen concentration should be increased to 100%. Most units have a battery-level indicator and a light that flashes with every impulse. The generator should be set into the asynchronous mode, and the ventricular output should be set on maximum. Failure of a temporary transvenous electrode to capture the ventricle is usually due to displacement of the electrode away from the ventricular endocardium; careful slow advancement of the catheter or wire while pacing often results in capture. Pharmacological management (atropine, isoproterenol, or epinephrine) may be useful until the problem is resolved. If an adequate arterial blood pressure cannot be maintained with adrenergic agonists, cardiopulmonary resuscitation should be instituted until another pacing electrode is placed or a new generator box is obtained. If a permanent pacemaker malfunctions (as with electrocautery), it should generally be converted to an asynchronous mode. Some units will automatically reprogram themselves to the asynchronous mode if malfunction is detected. Other pacemaker units must be reprogrammed by placing either an external magnet, or, preferably, a programming device over the generator. The effect of an external magnet on some pacemakers-particularly during electrocautery-may be unpredictable and should generally be determined prior to surgery. All anesthetic agents have been safely used in patients who already have pacemakers. Local anesthesia with moderate to deep intravenous sedation is usually used for placement of permanent pacemakers. Patient selection for cardiac resynchronization therapy: From the Council of Clinical Cardiology Subcommittee on Electrocardiography and Arrhythmias and the Quality of Care and Outcomes Research Interdisciplinary Working Group in Collaboration with the Heart Rhythm Society. Blood should be immediately available for transfusion if the patient has had previous cardiac surgery (a "redo"); when there has been a previous sternotomy, the right ventricle or coronary grafts may be adherent to the sternum and may be accidentally entered during the repeat sternotomy. Severely compromised patients should be given anesthetic agents in incremental, small doses. Intrathoracic bleeding at a site not adequately drained may cause cardiac tamponade, requiring immediate reopening of the chest. Inadequate surgical control of bleeding sites, incomplete reversal of heparin, thrombocytopenia, platelet dysfunction, hypothermia-induced coagulation defects, undiagnosed preoperative hemostatic defects, or newly acquired factor deficiency or hypofibrinogenemia may be responsible. The period of greatest hemodynamic instability follows the release of the aortic cross-clamp; the abrupt decrease in afterload together with bleeding and the release of vasodilating acid metabolites from the ischemic lower body can precipitate severe systemic hypotension. Surgery on the aorta, the carotid arteries, and the pericardium presents special problems, which are also discussed herein. This technique provides distinctly nonphysiological conditions, because mean arterial pressure is usually less than normal and blood flow is usually nonpulsatile. To minimize organ damage during this stressful period, varying degrees of systemic hypothermia may be employed. Most machines also have separate accessory pumps that can be used for blood salvage (cardiotomy suction), venting (draining) the left ventricle, and administration of cardioplegia solutions. A number of other filters, alarms, and inline pressure, oxygen-saturation, and temperature monitors are also typically used. At the onset of bypass in adults, when using a crystalloid priming solution, hemodilution typically decreases the hematocrit to about 22% to 27%. Blood is included in priming solutions for smaller children and severely anemic adults to prevent excessive hemodilution. A membrane oxygenator permits the perfusion to have independent control of Pao2 and Paco2 by varying the inspired oxygen concentration and the gas flow rate. Heat Exchanger Blood from the oxygenator enters the heat exchanger and can either be cooled or warmed, depending on the temperature of the water flowing through the exchanger; heat transfer occurs by conduction. Because gas solubility decreases as blood temperature rises, a filter or trap is built into the unit to catch any bubbles that may form during rewarming. Thus, the driving force for flow into the pump is directly related to the difference in height between the patient and the reservoir and inversely proportional to the resistance of the cannulas and tubing. Entrainment of air in the venous line can produce an air lock that may prevent blood flow. With some circuits (eg, use of an unusually small venous cannula) assisted venous drainage may be required; a regulated vacuum together with a hard shell venous reservoir or centrifugal pump (see below) is used in 2 such instances. If a "roller" pump is used and the reservoir is allowed to empty, air can enter the main pump and be propelled into the patient where it may cause organ damage or fatality. Centrifugal pumps will not pump air but have the disadvantage of not impelling a well-defined volume with each revolution of the head (unlike roller pumps). Roller Pumps Roller pumps produce flow by compressing largebore tubing in the main pumping chamber as the roller heads turn. The rollers pump blood regardless of the resistance encountered, and produce a nearly continuous nonpulsatile flow. In some pumps, an emergency backup battery provides power in case of an electrical power failure. All roller pumps have a hand crank to allow manual pumping, but those who have hand cranked a roller pump head will confirm that this is not a good long-term solution to an electric power failure. Centrifugal Pumps Centrifugal pumps consist of a series of cones in a plastic housing. As the cones spin, the centrifugal forces created propel the blood from the centrally located inlet to the periphery.
This fact was evident because the pain of a recurrent peptic ulcer sometimes persisted after complete vagotomy treatment x time interaction buy asacol 800 mg fast delivery, whereas patients who had a bilateral sympathectomy could have a perforated peptic ulcer without experiencing pain medications when pregnant buy asacol now. Organic pain arising from an organ such as the stomach varies from dull to severe; however 2d6 medications purchase 800 mg asacol visa, the pain is poorly localized medications with acetaminophen order genuine asacol online. It radiates to the dermatome level treatment integrity checklist purchase 400mg asacol free shipping, which receives visceral afferent fibers from the organ concerned treatment efficacy buy asacol 400 mg with visa. The brain interprets the pain as though the irritation occurred in the skin of the epigastric region, which is also supplied by the same sensory ganglia and spinal cord segments. Pain arising from the parietal peritoneum is of the somatic type and is usually severe. The anatomical basis for this localization of pain is that the parietal peritoneum is supplied by somatic sensory fibers through thoracic nerves, whereas a viscus such as the appendix is supplied by visceral afferent fibers in the lesser splanchnic nerve. When digital pressure is applied to the anterolateral abdominal wall over the site of inflammation, the parietal peritoneum is stretched. When the fingers are suddenly removed, extreme localized pain is usually felt, known as rebound tenderness. Most (65%) duodenal ulcers occur in the posterior wall of the superior part of the duodenum within 3 cm of the pylorus. Occasionally, an ulcer (especially one located anteriorly) perforates the duodenal wall, permitting the contents to enter the peritoneal cavity and causing peritonitis. Because the superior part of the duodenum closely relates to the liver, gallbladder, and pancreas, any of these structures may become adherent to the inflamed duodenum. They may also become ulcerated as the lesion continues to erode the tissue that surrounds it. Developmental Mesoduodenum Changes in During the early fetal period, the entire duodenum has a mesentery; however, most of it fuses with the posterior abdominal wall because of pressure from the overlying transverse colon. Because the attachment of the mesoduodenum to the wall is secondary (occurred through formation of a fusion fascia; discussed under "Embryology of Peritoneal Cavity"), the duodenum and the closely associated pancreas can be separated (surgically mobilized) from the underlying retroperitoneal viscera during surgical operations involving the duodenum without endangering the blood supply to the kidney or the ureter. The paraduodenal fold and fossa are large and lie to the left of the ascending part of the duodenum. During repair of a paraduodenal hernia, care must be taken not to injure the branches of the inferior mesenteric artery and vein or the ascending branches of the left colic artery, which are closely related to the paraduodenal fold and fossa. Brief Review of Embryological Rotation of Midgut An understanding of the rotation of the midgut clarifies the adult arrangement 1130 of the intestines. Pain arising from foregut derivatives-esophagus, stomach, pancreas, duodenum, liver, and biliary ducts-localizes in the epigastric region. Pain arising from midgut derivatives-the small intestine distal to bile duct, cecum, appendix, ascending colon, and most of the transverse colon-localizes in the peri-umbilical region. Pain arising from hindgut derivatives-the distal part of the transverse colon, descending colon, sigmoid colon, and rectum-localizes in the hypogastric region (see Table 5. It is attached to the umbilical vesicle (yolk sac) by the omphaloenteric duct (yolk stalk). As the relative size of the liver and kidneys decreases, the midgut returns to the abdominal cavity as increased space becomes available. Malrotation of the midgut (intestine) results in several congenital anomalies such as volvulus (twisting) of the intestine (Moore et al. Navigating Small Intestine When portions of the small intestine have been delivered through a surgical 1132 wound, the proximal (orad-toward the mouth) and distal (aborad-away from the mouth) ends of a loop of intestine are not apparent. Place your hands on each side of the intestine and its mesentery and then follow the mesentery with your fingers to its root (its attachment to the posterior abdominal wall), untwisting the loop of intestine as necessary. Once the mesentery and intestine are straightened to match the direction of the root, the cranial end must be the orad end, and the caudal end the aborad end. If the ischemia is severe, necrosis (tissue death) of the involved segment results and ileus (obstruction of the intestine) of the paralytic type occurs. Ileus is accompanied by a severe colicky pain, along with abdominal distension, vomiting, and often fever and dehydration. It is always at the site of attachment of the omphalo-enteric duct on the antimesenteric border (border opposite the mesenteric attachment) of the ileum. Although its mucosa is mostly ileal in type, it may also include areas of acid-producing gastric tissue, pancreatic tissue, or jejunal or colonic mucosa. An ileal diverticulum may become inflamed and produce pain mimicking that produced by appendicitis. When it lies beneath the peritoneal covering of the cecum, it may become fused to the cecum or the posterior abdominal wall. An inflamed appendix in this position is more difficult to remove, especially laparoscopically. The anatomical position of the appendix determines the symptoms and the site of muscular spasm and tenderness when the appendix is inflamed. Appendicitis Acute inflammation of the appendix, appendicitis, is a common cause of an acute abdomen (severe abdominal pain arising suddenly). Usually, digital pressure over the McBurney point registers maximum abdominal tenderness. Appendicitis in young people is usually caused by hyperplasia of lymphatic follicles in the appendix that occludes the lumen. In older people, the obstruction usually results from a fecalith (coprolith), a concretion that forms around a center of fecal matter. When secretions from the appendix cannot escape, the appendix swells, stretching the visceral peritoneum. Later, severe pain in the right lower quadrant results from irritation of the parietal peritoneum lining the posterior abdominal wall (usually formed by the psoas and iliacus muscles in the region of the appendix). Rupture of the appendix results in infection of the peritoneum (peritonitis), increased abdominal pain, nausea and/or vomiting, and abdominal rigidity (stiffness of abdominal muscles). Flexion of the right thigh ameliorates the pain because it causes relaxation of the right psoas muscle, a flexor of the thigh. Appendectomy Surgical removal of the appendix (appendectomy) may be performed through a transverse or gridiron (muscle-splitting) incision centered at the McBurney point in the right lower quadrant (see the Clinical Box "Abdominal Surgical Incisions," p. Traditionally, a gridiron incision is made perpendicular to the spino-umbilical line, but a transverse incision is also commonly used. While typically the inflamed appendix is deep to the McBurney point, the site of maximal pain and tenderness indicates the actual location. Laparoscopic appendectomy has become a standard procedure selectively utilized for removing the appendix. The peritoneal cavity is first inflated with carbon dioxide gas, distending the abdominal wall, to provide viewing and working space. The laparoscope is passed through a small incision in the anterolateral abdominal wall. One or two other small incisions ("portals") are required for surgical (instrument) access to the appendix and related vessels. When surgeons have trouble finding the base of the appendix, or the appendix itself (usually due to inflammatory changes), they look for the convergence of the three teniae on the surface of the cecum, after having first found the region of the ileocecal valve. When the cecum is high (subhepatic cecum), the appendix is in the right hypochondriac region (see Table 5. The appendix is also displaced cephalad by the enlarging uterus during pregnancy; hence, diagnosis and removal of appendix later in pregnancy must take this into 1137 account. Mobile Ascending Colon When the inferior part of the ascending colon has a mesentery, the cecum and proximal part of the colon are abnormally mobile. This condition, present in approximately 11% of individuals, may cause cecal bascule (folding of the mobile cecum) or, less commonly, cecal volvulus (L. In this anchoring procedure, a tenia coli of the cecum and proximal ascending colon is sutured to the abdominal wall. Colitis, Colectomy, Ileostomy, and Colostomy Chronic inflammation of the colon (ulcerative colitis, Crohn disease) is characterized by severe inflammation and ulceration of the colon and rectum. In some cases, a colectomy is performed, during which the terminal ileum and colon, as well as the rectum and anal canal, are removed. The terminating ileum is delivered through and sutured to the periphery of an opening in the anterolateral abdominal wall, allowing the egress of its contents. Sometimes surgeons create a temporary ostomy to allow the bowel to heal after resection and anastomosis. The ostomy prevents fecal contents from going through the anastomosis; thus, if the anastomosis has a small imperfection causing a leak, the result is not catastrophic peritonitis. The interior of the sigmoid colon is observed with a sigmoidoscope, a shorter endoscope, in a procedure called sigmoidoscopy. Small instruments can be passed through both instruments and used to facilitate minor operative procedures, such as biopsies or removal of polyps. Most tumors of the large intestine occur in the sigmoid colon and rectum (often near the rectosigmoid junction) or ascending colon. Colorectal cancers have different characteristics based on their location within the colon or rectum. For example, tumors in the ascending colon are more common among women and older patients whereas rectosigmoidal tumors are more common among men and younger patients. Diverticulosis Diverticulosis is a disorder in which multiple false diverticula (external evaginations or outpocketings of the mucosa of the colon) develop along the intestine. Colonic diverticula are not true diverticula because they are formed from protrusions of mucous membrane only, evaginated through weak points (separations) developed between muscle fibers rather than involving the whole wall of the colon. They 1140 occur most commonly on the mesenteric side of the two nonmesenteric teniae coli, where nutrient arteries perforate the muscle coat to reach the submucosa. Diverticula are subject to infection and rupture, leading to diverticulitis, which can distort and erode the nutrient arteries, leading to hemorrhage. Diets high in fiber have proven beneficial in reducing the occurrence of diverticulosis. Obstipation (inability of the stool or flatus to pass) and ischemia (absence of blood flow) of the looped part of the sigmoid colon result. Volvulus is an acute emergency, and unless it resolves spontaneously, necrosis (tissue death) of the involved segment may occur if untreated. Stomach: the stomach is the dilated portion of the alimentary tract between the esophagus and the duodenum, specialized to accumulate ingested food and prepare it chemically and mechanically for digestion. However, the position of the stomach can vary markedly in persons of different body types. Proximal to this point, it is supplied by branches of the celiac trunk; distal to this point, it is supplied by branches of the superior mesenteric artery. The jejunum and ileum make up the convolutions of the small intestine occupying most of the infracolic division of the greater sac of the peritoneal cavity. The orad (proximal relative to the mouth) two fifths is jejunum and the aborad (distal) three fifths is ileum, although there is no clear line of transition. The diameter of the small intestine becomes increasingly smaller as the semifluid chyme progresses through it. Large intestine: the large intestine consists of the cecum; appendix; ascending, transverse, descending, and sigmoid colon; rectum; and anal canal. Most commonly, 1143 the appendix is retrocecal in position, but 32% of the time, it descends into the lesser pelvis. The teniae, haustra, and omental appendices cease at the junction, located anterior to the third sacral segment. The part of large intestine orad (proximal) to the left colic flexure (cecum, appendix, and ascending and transverse colons) is served by branches of the superior mesenteric vessels. Aborad (distal) to the flexure, most of the remainder of the large intestine (descending and sigmoid colons and superior rectum) is served by the inferior mesenteric vessels. Surface anatomy of spleen relative to the rib cage, anterior abdominal organs, and thoracic viscera and costophrenic pleural recess. Surface anatomy of the spleen and pancreas relative to the diaphragm and posterior abdominal viscera. Concavities on the visceral surface are impressions formed by the structures in contact with the spleen. In spite of its size and the many useful and important functions it provides, it is not a vital organ (not necessary to sustain life). Consequently, it is capable of marked expansion and some relatively rapid contraction. The spleen varies considerably in size, weight, and shape; however, it is usually approximately 12 cm long and 7 cm wide. The close relationship of the spleen to the ribs that normally protect it can be a detrimental one in the presence of rib fractures (see the Clinical Box "Rupture of Spleen," p. Normally, the spleen does not extend inferior to the left costal margin; thus, it is seldom palpable through the anterolateral abdominal wall unless it is enlarged. When it is hardened and enlarged to approximately three times its normal size, it moves inferior to the left costal margin, and its superior (notched) border lies inferomedially (see the Clinical Box "Splenectomy and Splenomegaly," p. The notched border is helpful when palpating an enlarged spleen because, when the person takes a deep breath, the notches can often be palpated. The spleen normally contains a large quantity of blood that is expelled periodically into the circulation by the action of the smooth muscle in its capsule and trabeculae. Internally, the trabeculae (small fibrous bands), arising from the deep aspect of the capsule, carry blood vessels to and from the parenchyma or splenic pulp, the substance of the spleen. The spleen contacts the posterior wall of the stomach and is connected to its greater curvature by the gastrosplenic ligament and to the left kidney by the splenorenal ligament. The splenic hilum is often in contact with the tail of the pancreas and constitutes the left boundary of the omental bursa.