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Be able to describe the anatomy of the gallbladder and hepatobiliary duct system 2 benemid 500 mg amex. Its anterior surface is fused to the liver between the right and quadrate lobes discount benemid 500 mg, and its fundus 500mg benemid sale, lateral, and posterior surfaces are covered with visceral peritoneum. It is anatomically divided into fundus, body, and neck, which is continuous with the cystic duct. The mucosa of the neck and cystic duct are spiral fold, which acts as a valve to keep the lumen of the duct and neck open to receive bile. The gallbladder and cystic duct are supplied by the cystic artery, typically a branch of the right hepatic artery (see Figure 19-1). The biliary duct system begins as bile canaliculi between hepatocytes within the liver. The canaliculi empty into microscopic interlobular bile ducts, which unite to form increasingly large ducts, eventually forming segmental and lobar ducts drain- ing anatomical subdivisions of the liver of the same name. Ultimately, right and left hepatic ducts emerge from the liver’s porta hepatis and unite to form the common hepatic duct within the hepatoduodenal ligament (a portion of the lesser omen- tum). The cystic duct joins the common hepatic duct from the right to form the common bile duct, which passes inferior within the hepatoduodenal ligament and then passes posterior to the first part of the duodenum. It turns slightly to the right on or within the posterior surface of the pancreas. As it approaches the posterome- dial wall of the duodenum, it is typically joined by the main pancreatic duct to form the hepatopancreatic ampulla, which opens on the major duodenal papilla. At the porta hepatis, the right and left hepatic ducts are the most anterior struc- tures. The common hepatic duct (on the left), the cystic duct (on the right), and the inferior border of the liver (superior) form the cystohepatic triangle of Calot, which contains the right hepatic artery and its cystic artery branch. Within the hepatoduodenal ligament, the anterior boundary of the epiploic fora- men (of Winslow), the common bile duct lies to the right, the common hepatic artery lies to the left, and the portal vein lies posterior and between the duct and the artery. The gallbladder is normally located at the junction between the right semi- lunar line and the right subcostal margin. The first part of the duodenum will lie inferior to a finger within the epi- ploic foramen. The diagnosis is likely gallstone ileus, in which a large gallstone is impacted in the ileocecal valve. Air in the biliary tree is caused by a fistula between the bowel and the biliary tree, allowing air from the bowel to enter the biliary system. The electrolytes show a low bicarbonate level at 15 mEq/L, and the serum lactate level is high, which are indicative of tissue receiving insufficient oxygenation leading to tissue injury. A surgeon who is concerned about intestinal ischemia has been called to evaluate the patient. Although she is writhing in pain, her bowel sounds are normal, and there is minimal tenderness. Blood is present in the stool, and electrolytes show low levels of bicarbonate at 15 mEq/L and high levels of lactate; these findings are attributed to a lack of oxygen to intestinal tissue, leading to anaerobic metabolism. She has a history of widespread atheroscle- rotic vascular disease affecting the coronary arteries and peripheral vasculature. The presence of blood in the stool suggests bowel injury, and the low level of serum bicarbonate is consistent with a metabolic acidemia. Arterial occlusion may occur from rupture of the atherosclerotic plaque or embolization from another clot. Be able to describe the general plan for the arterial blood supply to the abdomi- nal viscera 2. These three arteries supply organs embryologically derived from the foregut, midgut, and hindgut, respectively. Theduodenumproximal to the entrance of the common bile duct receives its blood supply from the superior pancreaticoduodenal artery, a branch of the gastroduode- nal artery from the celiac artery. As it emerges from behind the pancreas, it passes anterior to the uncinate process of the pancreas and the third part of the duodenum and enters the root of the mesentery. As it enters the mes- enteric root, it gives off its inferior pancreaticoduodenal and middle colic arteries, the latter to the transverse colon within its mesentery, the transverse mesocolon. Aorta Duodenum Inferior Superior mesenteric pancreaticoduodenal artery artery Middle colic artery Right colic artery Ileocolic artery Anterior and posterior cecal arteries Appendicular artery figure 20-1. The arcades closest to the mesenteric attach- ment to the jejunum and ileum give off increasingly shorter straight arteries (vasa recta) that enter the small intestines. A radiolo- gist has been called to cannulate and embolize the artery supplying the ulcer. The middle colic artery courses through the transverse mesocolon to supply the transverse colon. The superior pancreaticoduodenal artery is a terminal branch that arises from the celiac artery. The appendix is a small diverticulum that arises from the cecum and is typically free in the peritoneal cavity. Not infrequently, however, it is retrocecal in location and causes right-side or flank tenderness and very few peritoneal signs. Men and women are equally affected by appendicitis, but the diagnosis is usually more straightforward in men. Ultimately, the suspicion is a clinical one, and diagnostic laparoscopy is undertaken to visualize the appendix. The appendix is an elongated diverticulum that arises from the cecum inferior to the ileocecal junction (Figure 21-1). The three longitudinal smooth muscle bands characteristic of the cecum and colon, the teniae coli, can be traced inferiorly to the posteromedial origin of the appendix from the cecum. The appendix lies in the margin of a small triangular mesentery, the mesoappen- dix, within which the appendicular artery (a branch of the ileocolic artery) is also found. The posterior surface of the cecum is often covered with visceral peritoneum, creating a retrocecal recess. In close to 66 percent of individuals, the appendix is retrocecal in position and is found in this recess. In almost 33 percent of indi- viduals, the appendix is free and extends inferiorly toward or over the pelvic brim.
Alternatively generic benemid 500 mg on-line, as mentioned before buy cheap benemid 500mg line, to narrow the intratip columella buy 500 mg benemid with mastercard, and to diminish a hanging the caudal edge of an alar strut graft to the level of the dome infratip. The previously mentioned techniques itself will also help to improve the contour of the dome. Sutures are applied in a graduated fashion to achieve the ideal out- may also be used to achieve a similar eﬀect. Great precision is attainable through meticulous suture graft can also be used—this is a graft very similar to the alar adjustment. This shorter graft is also used to create a more natural curve to the dome and strengthen it, especially in cases of knuckling. Regardless of technique, the goal should be to achieve an ideal angle of the intermediate domal transition area. The exact position, angle, and definition of the unilateral domal arch angle can be meticulously set using single-dome unit binding sutures. Using the single-dome unit binding suture can ensure that both domal angles have similar anatomic shape (▶ Fig. A double-dome unit binding suture can then be placed to medialize the domes, narrow the lobule, and bring the domes together to a symmetric height Fig. These techniques will also lengthen the M- overall tip shape and correct divergent tip abnormalities. As with tip suturing, tip grafts will increase projection as well and, depending on the placement, can increase or decrease tip rotation. These grafts can take various forms, depending on the size and shape required to achieve an ideal lobule aesthetic. These grafts can be fashioned in such a way as to provide improved symmetry of the nasal tip. It is important to contour the edges of the grafts meticulously the graft is placed. Not only will this graft add fullness, but it and/or cover them with soft tissue when necessary to avoid will camouflage irregularities of the lower lateral cartilage. This is especially true in Often, tip asymmetry may be seen in the form of asymmetric thin-skinned patients. The alar margin graft can be placed in the soft grafts in place with 5–0or6–0 permanent sutures to prevent tissue at the nostril margin, caudal to the lower lateral cartilage graft displacement. It is eﬀective to The infratip graft, placed just below the domal angle, will improve mild to moderate alar retraction and concavity of the provide better definition to the infratip lobule, add fullness to soft tissue nostril margin. The size and shapes of these grafts this area, add projection to the nose, and derotate the tip are determined by the structural deficiency or asymmetry. They must be sculpted and placed in whatever fashion spanning the entire lobule or unilaterally placed on the domal required to achieve optimal improvement, both structurally arch, both of which will increase projection and definition and aesthetically. In the case of the twisted asymmetric tip, it is more common to place a thin unilateral graft, once all of the 42. The The ultimate shape and aesthetics of the nasal tip involve the buttress graft is placed behind the infratip lobule graft to create soft tissue structures as well. The soft tissues of the nasal tip, more counterrotation and better lobule definition. The interdo- ala, and nostrils are an integral part of the overall complexity of mal spacer graft is placed between the intermediate crura, rhinoplasty surgery and should be evaluated as part of every thereby widening the dome in cases where the tip defining rhinoplasty consult and plan. The alar batten graft is placed over the sion principles in conjunction with operative experience will lower lateral crura, which will add fullness to the side where result in more favorable long-term appearance and heightened 330 The Crooked Nasal Tip Fig. The first step in planning an alar base reduction is deciding whether to perform an external base reduction, internal base patient satisfaction. If the columellar-alar base distance (and soft tissues should be to achieve an aesthetic balance and a nat- therefore the width of the lower third of the nose) is within ural appearance, maintain natural borders, and prevent revisio- normal range, then a decision needs to be made whether the nal surgery. In addition, these aims must be achieved in combi- nostril diameter needs to be decreased to reduce nostril width nation with acceptable scarring. Once the internal structure (cartilage) has been optimized, Alar base reduction is best performed in the nasal sill. If only an external reduction is planned to reduce the shape (internal alar base), columella-alar base width (external columellar-alar width, the appropriate estimation of resection alar base), alar flare, and alar hooding. The intrinsic thickness of is planned, marked along the upper and lower portion of the the skin—soft tissue envelope (flap) should also be considered, nasal sill, and the excision is performed (▶ Fig. The but the ability of the surgeon to sculpt this parameter is severely excision is wide at the bottom of the sill and tapered in an limited for fear of compromising blood supply to the envelope. In most cases of alar base reduction, we feel it necessary Columella-Alar Base Width—External Alar to create a true advancement-rotation flap of the entire alar Base Reduction base to prevent notching, allow for a more natural curve, and reduce tension along the suture line, thereby optimizing scar As described by Sheen, there are two surfaces to the ala that outcome (▶ Fig. Exceptions include patients with an impact to a varying degree the width and contour of the alar 10 obtuse alar-cheek junction, patients with a predisposition to base. It is essential to understand that there is a cutaneous poor scarring, and patients with limited isolated internal base surface of the ala and a vestibular surface. With the rotation-advancement flap closure are considered independently, maintaining or narrowing the eﬀected with a single suture, alar flaring assessment can then width of alar base and maintaining or narrowing the nostril size be performed. Internal Alar Base Reduction Reduction of the circumference of the nostril to attain a more aesthetic shape or size and to improve symmetry between the nostrils is performed along the vestibular surface of the nasal sill. The surgical steps to carry out the internal alar base reduc- tion are the same as for external alar base reduction with one critical diﬀerence—the sill excision in this case is wide at the top of the sill and tapered in a “V” pattern to address only the internal reduction. If both internal and external alar base reductions are deemed necessary, the appropriate amount of resection is marked both at the top of the sill and at the bottom and these marks are Fig. Following the excision, the wound is dosed with a remainder of the surgical steps are then identical to those above. Reduction Once the alar base reduction has been performed and the alar Closing the Nose base flap has been advanced medially and held securely with one suture, a determination can be made as to whether an alar Closing the incisions after completing an open approach rhino- flare reduction is necessary. Ideally, the alae should be relatively straight as they keep a couple of things in mind. Alar flaring is seen when the the inferior edge of the opening incision to allow proper ever- lateral aspect of the ala extends significantly beyond the alar- sion and optimal scar healing to avoid an asymmetric scar facial groove. Second, critically evaluate the closure of the mar- lateral side, they can be made straighter by shortening the dis- ginal incisions to make sure that the alar rim is not distorted tance from the tip to the alar base. If alar flare reduc- with the opposite rim may result in continued asymmetry of tion is indicated, the amount of resection is planned, marked, the tip. Splints on either side Alar hooding is best analyzed from the direct lateral view and is of the septum, extending up to the membranous septum, help seen when the most caudal curve of the ala hangs excessively to stabilize the caudal septum and columellar strut along with low, either from excessive bulk of the ala or from an excessively the tip complex.
Inspiratory muscle function Muscle weakness may be caused by increased lung volumes together with shortening and ﬂattening of the diaphragm buy benemid 500 mg fast delivery. Supplemental oxygen may attenuate this response with a subsequent decrease in minute ventilation safe benemid 500mg. Ventilation-perfusion misdistribution • Areas of local alveolar hypoxia result in hypoxic pulmonary vasoconstriction in breathing room air even in healthy patients best 500 mg benemid. Spotting individuals who may be at risk of severe hypercapnia This is a subset of individuals who have advanced disease. The development of hypercapnia in patients at risk may not be accompanied by changes in the respiratory pattern or conscious level. The Standards of Care Committee of the British Thoracic Society have published a comprehensive set of guidelines4 on the emergency use of oxygen in adults based on the best evidence available (see box). This second group is encountered in three main situations: • Post operative: a mixture of hypoventilation from fatigue, opiates, · · diaphragmatic splinting, and pleural effusions, with V/Q mismatch from infection, oedema, or atelectasis. British Thoracic Society guidelines for the use of emergency oxygen • Before blood gas results are available use a 28% Venturi mask at 4L/min and aim for a saturation of 88–92% for patients with risk factors for hypercapnia but no prior history of respiratory acidosis. Maintain saturation at 88–92% and recheck blood gases at 30–60min, looking for hypercapnia or acidosis. Oxygen delivery devices In the patient with respiratory failure the FiO2 administered by the car- egiver is often not that which reaches the distal airways or alveoli. Factors such as respiratory rate and pattern, expiratory pause, mask ﬁt and posi- tion, and the presence or absence of a reservoir bag all have an inﬂuence on the ﬁnal concentration of oxygen delivered to a patient’s lungs. This additional gas will be air round the mask or may be oxygen from a reservoir bag, if present. In order to deliver a ﬁxed or high concentration of oxygen, the delivery ﬂow rate is as important as the set FiO2. Most oxygen ﬂow meters are calibrated up to 15L/min, but in an emergency situation they can deliver up to 100L/min if the spindle valve is fully opened. This entrainment ratio varies according to the mask and determines both the ﬁnal oxygen concentration and gas delivery rates. The variability in performance should be borne in mind when interpreting blood gas results. High ﬂow oxygen delivery Devices with an oxygen reservoir Often called trauma masks or non-rebreathing masks, these devices increase the ﬁnal delivered oxygen concentration by incorporating a res- ervoir bag ﬁlled with oxygen. True non-rebreathing masks are ﬁtted with both an inhalation valve and an exhalation valve so that all exhaled gas is vented to the atmosphere and inhaled gas comes only from a reservoir connected to the mask. Most ‘non’-rebreathing masks are really partial rebreathing masks where intake of some exhaled and outside air is inevitable. In a correctly ﬁtting mask, the oxygen reservoir should be seen to collapse with inspiration. Combination of devices Devices can be combined to increase the ﬁnal gas delivery rate. This may increase the ﬁnal inspired O2 concentration by reducing the entrainment of room air. Examples include: • Nasal cannulae and face mask • ‘Double jet’—oxygen from two ﬂow meters can be combined via a Y-connector. This should only be performed by someone who has full understanding of the principles of the circuits. Failure to do so results in a rapid drying of secretions, which become tenacious and difﬁcult to expectorate. There are commercially available devices that combine high ﬂow oxygen with humidiﬁcation (e. FiO2 delivered from different oxygen delivery devices It is not possible to accurately predict the precise FiO2 that will be deliv- ered by a particular oxygen delivery device. A Whisperﬂow® valve uses a surprising 140L/min and will exhaust a size E cylinder in less than 5min. In this situation the normally small proportion of oxygen dissolved in blood becomes more important and increasing supplemental oxygen is reasonable. Entrainment of air, because of the unpredictable peak inspiratory ﬂow rate seen in critical illness, can be highly variable. At the ward level it is almost impossible to say with any degree of accuracy what the actual FiO2 is. Summary There are many ﬁrmly held, opposing views amongst the medical profession regarding oxygen administration. In the absence of oximetry, continue to use a mask with a reservoir bag until deﬁnitive treatment is available. Volume can be estimated by integrating the ﬂow delivered by the ventilator, making adjustments for the intentional and unintentional leaks. In comparison, patients with neuromuscular problems, obesity-hypoventila- tion, or scoliosis may be more comfortable with a longer rise time (0. This usually indicates that there is a lot of leakage around the mask, with a ventilator that does not have the ﬂow capacity to compensate. Failure to activate the ﬂow trigger may be due to lack of patient effort, ineffective triggering, or exces- sive leaks. This is used as a backup to prevent failure of cycling because of excess leaks and is useful in neuromuscular conditions (see below). Expiratory time should be sufﬁcient to allow complete emptying and avoid breath stacking and dynamic hyperinﬂation (Fig. Watch the patient’s respiratory pattern or look at the ventilator ﬂow/time trace to ensure that the ventilator settings allow the patient to spend adequate time in each phase of the respiratory cycle. Expiratory trigger point at 50% of peak inspiratory flow Peak inspiratory flow Expiratory trigger point with high leak flow Time Fig. During nocturnal ventilation, this may lead to better quality sleep and falling bicarbonate levels (with improved daytime respiratory drive). This is perfectly reasonable when intervening earlier in the natural history of respiratory failure, in an attempt to help prevent further deterioration to a stage where invasive ventilation will be needed. The ventilators are designed to generate sufﬁcient ﬂow to compen- sate for these leaks. Adjusting the mask straps may be sufﬁcient, but often it will be necessary to try a different style of mask (see below).
Medication for neuroprotection: Magnesium sulfate may be given for pregnancies of < 32 weeks when there is imminent delivery benemid 500 mg cheap. Understand that the basic approach to preterm labor is tocolysis purchase 500mg benemid overnight delivery, identification of an etiology buy benemid 500 mg low cost, steroids, and magnesium sulfate (if appropriate). Co n s i d e r a t i o n s This 19-year-old nulliparous woman is at 29 weeks’ gestation and complains of intermit tent abdominal pain. The monit or indicat es ut erine cont ract ions every 3 to 5 minutes, and her cervix is dilated at 3 cm and effaced at 90%. Because of the significant prema- turity, many practitioners may elect to treat for preterm labor. A single examina- tion revealing 2-cm dilation and 80% effacement in a nulliparous woman would be sufficient t o diagnose pret erm labor. Anot her object ive test for preterm delivery risk is transvaginal cervical length ultrasound measurements. A shortened cervix, espe- cially wit h lower ut er ine segment ch anges (fun n eling or beaking of the amn iot ic cavit y int o the cer vix), is wor r isom e. Tocolysis sh ou ld be in it iat ed, u n less t h er e is a cont raindication (such as intra-amniotic infection or severe preeclampsia). A careful search should also be undertaken to identify an underlying cause of preterm labor, such as urinary tract infection, cervical infection, bacterial vaginosis, generalized infection, trauma or abruption, hydramnios, or multiple gestations. Last,recent studies have shown that if the pregnancy is < 31 6/ 7 weeks, starting magnesium could help the neurodevelopment of the preterm baby, reducing cases of cerebral palsy in preterm infants. In a nulliparous woman, uter- ine cont ract ions and a single cervical examinat ion revealing 2-cm dilat ion and 80% effacement or great er are sufficient t o make t he diagnosis. T h e most commonly used agent s are indomet hacin, nifedipine, terbutaline, and ritodrine. Recent evidence has indicated that magnesium sul- fat e may be ineffect ive as a t ocolyt ic agent but h as been sh own t o decrease the risk of cerebral palsy in surviving infants if birth is anticipated before 32 weeks’ gest at ion. It s best ut ilit y is a negat ive result, wh ich is associat ed wit h a 99% ch an ce of n ot d eliver in g wit h in 1 week. Cer vical len gt h of < 25 m m r esu lt s in an in cr eased r isk of pr et er m delivery. Also an impinging of the amniotic cavity into the cervix, so-called funnel- ing, increases t he risk of pret erm delivery. H owever, a sh ort cervix or a posit ive fet al fibr on ect in alon e sh ou ld n ot be u sed exclu sively t o d iagn ose pr et er m labor in an acut e situat ion, as t he posit ive predict ive value is poor. T his is the subset of preterm births that are most rapidly increasing and comprises most preterm deliveries. The incidence in the United States is approximately 11% of pregnancies, and it is the cause of significant perinatal morbidity and mortality. There are many risk factors associated with preterm deliv- ery, but t he most significant one is a h ist ory of a prior spont aneous pret erm birt h (see Table 17– 1). The main symptoms of preterm labor are uterine contractions and abdominal tightening. The diagnosis is established by confirming cervical change over time by the same examiner, if possible, or finding t he cervix to be 2-cm dilated and 80% effaced in a nulliparous woman. Tocolysis is considered if t he gest at ional age is less than 34 to 35 weeks, and steroids are administered if the gest at ional age is < 34 weeks. Recent randomized controlled trials have suggested that magnesium sulfate is not effective as a tocolytic agent but may be useful for fetal neuroprotection. The spec- ulated mechanism of action of magnesium is competitive inhibition of calcium to decrease its availability for actin– myosin interaction, thus decreasing myometrial act ivit y (see Table 17– 3). Nifedipine reduces intracellular calcium by inhibiting voltage-activated calcium ch an n els. Sid e effect s in clu d e p u lmon ar y ed ema, r espir at or y d epr ession, n eon at al depression, and, if given for a long term, osteoporosis. Pulmonary edema is often the most serious side effect, and is seen more often with the β-agonist agents. A complication of indomethacin is closure of the ductus arteriosus, leading to severe neonat al pulmonary hypertension; oligohydramnios may also be seen. Antenatal steroids should be given between 23 and 34 weeks’gestation wh en t h er e is no evidence of overt syst emic infect ion. H owever, if 7 t o 14 days or more h ave elapsed and the pat ient re-ent ers pre- term labor and is still < 34 weeks, one additional “rescue” course of corticosteroids may be considered. Weekly injections of 17 α -hydroxyprogesteronecaproate from 16 to 36 weeks’ gest at ion h ave been sh own t o h elp r edu ce the in cid en ce of p r et er m bir t h in wom en at high risk. An o t h er ar ea o f r esea r ch is the u s e o f an t en at al co r - ticosteroids in pregnancies beyond 34 weeks. At the time of this writing, there is some evidence about it s efficacy up to 36 weeks gest at ion. In screening for various types of infection, which of the following is most likely to be associated with preterm delivery? She is noted to have regular uterine contractions, and her cervix is dilated at 2 cm and 80% effaced. The physician reviews the record and notes that the patient should not have tocolytic therapy. O n admission, the fetal heart rate is 140 bpm with accelerations and no decelerations. Over the course of the next 24 hours, the patient was examined and noted to have cervical dilation from 1 to 2 cm and effacement from 30% to 90%. A repeat fetal heart rate pattern reveals a baseline of 140 bpm with moderate repetitive variable decelerations. Sh e also received bet amet hasone int ramuscularly t o enhance fet al lung maturit y. The following day, the patient develops dyspnea, tachypnea, and an oxygen saturat ion level of 80%. I V h ep ar in t h er ap y fo r p r o b ab le d eep ven o u s t h r o m b o sis C. G on ococ- cal cer vicit is is st r on gly associat ed wit h pr et er m d eliver y, wh er eas ch lamydial infect ion is not as st rongly associat ed. Urinary t ract infect ions, part icularly pyelonephritis, are associated with preterm delivery. Bacterial vaginosis may be linked with preterm delivery, although treatment of this condition does not seem to affect the risk.